COSEWIC Assessment and Status Report on the Steller Sea Lion Eumetopias jubatus in Canada - 2013

Steller Sea Lions

Special Concern
2013

Top of Page

Top of Page

Top of Page

Top of Page

Document Information

COSEWIC Logo and Wordmark

COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows:

COSEWIC. 2013. COSEWIC assessment and status report on the Steller Sea Lion Eumetopias jubatus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xi + 54 pp. (Species at Risk Public Registry website).

Previous report(s):
COSEWIC. 2003. COSEWIC assessment and status report on the Steller Sea Lion Eumetopias jubatus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 50 p.

BIGG, M.A. 1987. COSEWIC status report on the Steller Sea Lion Eumetopias jubatus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 63 pp.

Production note:

COSEWIC would like to acknowledge Andrew W. Trites for writing the status report on the Steller Sea Lion, Eumetopias jubatus, in Canada, prepared under contract with Environment Canada. This report was overseen and edited by Jane Watson and Hal Whitehead, Co-chairs of the COSEWIC Marine Mammals Specialist Subcommittee.

For additional copies contact:

COSEWIC Secretariat
c/o Canadian Wildlife Service
Environment Canada
Ottawa, ON
K1A 0H3

Tel.: 819-953-3215
Fax: 819-994-3684
COSEWIC E-mail
COSEWIC web site

Également disponible en français sous le titre Évaluation et Rapport de situation du COSEPAC sur le L'otarie de Steller (Eumetopias jubatus) au Canada.

Cover illustration/photo:
Steller Sea Lion - photo: A.W. Trites.

©Her Majesty the Queen in Right of Canada, 2014.

Catalogue No. CW69-14/687-2014E-PDF
ISBN 978-1-100-23568-4

Top of Page

COSEWIC logo

COSEWIC Assessment Summary

Assessment Summary - November 2013

Common name
Steller Sea Lion
Scientific name
Eumetopias jubatus
Status
Special Concern
Reason for designation
This species is restricted to only five breeding locations (consisting of 7 rookeries) in British Columbia that occupy less than 10 km2, with approximately 70% of births occurring at a single location (Scott Islands). The population is increasing, but is sensitive to human disturbance while on land and is vulnerable to catastrophic events such as major oil spills due to its highly concentrated breeding aggregations. The species is near to qualifying for Threatened, but has recovered from historical culling and deliberate persecution.
Occurrence
British Columbia, Pacific Ocean
Status history
Designated Not at Risk in April 1987. Status re-examined and designated Special Concern in November 2003 and November 2013.

Top of Page

COSEWIC Executive Summary

Steller Sea Lion
Eumetopias jubatus

Wildlife Species Description and Significance

The Steller or Northern Sea Lion (Eumetopias jubatus) is the largest member of the family Otariidae and is the only extant representative of its genus. Two subspecies are recognized based on patterns in morphology, demography and genetics: E. j. jubatus (Asia, Aleutian Islands, and Gulf of Alaska) and E. j. monteriensis (Southeast Alaska, British Columbia, Washington, Oregon and California). Only E. j. monteriensis occurs in Canada. The two subspecies are commonly referred to as the western and eastern populations of Steller Sea Lions.

The Steller Sea Lion is the largest species of sea lion and exhibits significant sexual dimorphism. Adult females average 2.1-2.4 m in length and weigh 200-300 kg; and adult males are 2.7-3.1 m and weigh 400-800 kg. Pups are born from late May to early July and weigh 16-23 kg at birth.

The Steller Sea Lion is the only otariid that breeds and resides year-round in Canadian waters. The world’s largest rookery (breeding aggregation) of Steller Sea Lions occurs in British Columbia at Triangle Island. Steller Sea Lions contribute to the tourism industry and may be important indicators of coastal ecosystem health given their wide distribution, long life­span, and position near the top of the food chain.

Distribution

Steller Sea Lions inhabit the cool-temperate and subarctic coastal waters of the North Pacific Ocean from southern California, north to the Bering Strait, and south along the Asian coast to Japan. They are typically found within about 15 km of shore during summer, but can range over 200 km from shore in winter. They are non-migratory, but may disperse considerable distances from rookeries.

Habitat

The terrestrial sites used by Steller Sea Lions include: 1) rookeries where animals congregate during May-August to give birth, mate, and nurse young pups; 2) year-round haulouts that are usually occupied continuously and where mating can occur; and 3) winter haulouts that are used less regularly and primarily during the winter months. In Canada, Steller Sea Lions occur at over 40 resting sites (haulouts), but only five breeding sites (rookeries)--two of which were established since 2008. These five highly concentrated breeding aggregations cover <10 km2 of land. Sea lions haul out on a regular basis throughout the year between feeding trips, and are highly gregarious while on land. While at sea, most Steller Sea Lions feed over the continental shelf and along the shelf break in water depths < 400 m.

Biology

Steller Sea Lions are polygynous breeders. Females become sexually mature at 3-6 years and give birth to a single pup, usually annually, which they typically nurse for just under a year--and occasionally for up to 2-4 years. Longevity is about 14 years for males and 22 years for females, and average age of breeding animals (males and females) is 10-11 years old. Preferred prey in British Columbia include Pacific Herring, Pacific Hake, Pacific Sand Lance, Salmon, Spiny Dogfish, Eulachon, Pacific Sardine, Rockfish, Flounder, Skate, Squid and Octopus.

Population Sizes and Trends

In 2010, 5,485 pups were counted in British Columbia. The total BC population (including pups) was ~32,000 individuals during the breeding season and increased to ~48,000 during winter with the arrival of animals dispersing from Southeast Alaska and Oregon. The number of sexually mature individuals during summer was ~11,400 (~40% of the population). Approximately 60% of the sea lions occur on rookeries during the summer (including pups) and the remaining 40% occur on haulouts.

Population increases have been observed since Steller Sea Lions were protected in 1970, but most of this increase occurred since 1990. Numbers of non-pups on rookeries and haulouts were stable from 1971-1983, but increased at a mean rate of 4.7% since the mid-1980s. In contrast, pups increased slowly at an annual rate of 1.7% per year from 1971-1994, and at 7.3% per year since the mid-1990s. This has resulted in a 4-5 fold increase in the size of the population in British Columbia since the 1970s--and the natural establishment of two new rookeries, and a more than doubling in numbers of year-round haulout sites. The population in 2010 appeared to be slightly larger than it was before harvesting and predator-control programs began in the early 1900s.

Threats and Limiting Factors

There are no known actual or imminent threats to the population at this time. Steller Sea Lions may be killed or injured by shooting, incidental take in fishing gear, entanglement in debris, acute oil spills, environmental contaminants, and displacement or degradation of their habitat. They are also affected by disease, fluctuating prey populations, and predation by Killer Whales. There are proposals to increase tanker traffic through the Sea Lions’ primary habitat, and acute oil spills have the potential to kill large numbers of Sea Lions near their five breeding areas (the Scott Islands, Cape St. James, Garcin Rocks, Banks Island and Virgin Rocks), as well as their haulouts.

Protection, Status, and Ranks

Since 1970, Steller Sea Lions have been protected by various regulations enacted under the Fisheries Act and enforced by the Department of Fisheries and Oceans. One of the five British Columbia breeding areas (Cape St. James) is protected under the National Parks Act, and another (Scott Islands) is part of a British Columbia Ecological Reserve. Originally assessed by COSEWIC in 1987 as Not at Risk, the species was re-examined and designated Special Concern in November 2003, and is protected under SARA as a Special Concern species. COSEWIC re-assessed this species in November 2013 as Special Concern. The Steller Sea Lion is blue-listed by the B.C. provincial government Conservation Data Centre.

Top of Page

Technical Summary

Eumetopias jubatus

Steller Sea Lion

Otarie de Steller

Range of occurrence in Canada:
Pacific Ocean (British Columbia)

Demographic Information

Generation time (calculated using a life table for the growing Steller Sea Lion population in SE Alaska and assuming breeding males are 9-13 y old and females are 4-20 y old)
10-11 y (females);
10-11 y (males)

Is there an observed continuing decline in number of mature individuals?
No

Estimated percent of continuing decline in total number of mature individuals within [5 years or 2 generations]
No decline occurring

Estimated percent increase in total number of mature individuals over the last 3 generations. (Inferred from changes in numbers of pups born between 1977-2010.)
>450% over past 33 years (1977-2010)

Projected percent increase in total number of mature individuals over the next 10 years [, or 3 generations].
unknown

Estimated percent increase in total number of mature individuals over 3 generations, over a time period including both the past and the future. (Inferred from changes in pups born―1977-2010.)
>450% over past 33 years (1977-2010)

Are the causes of the decline clearly reversible and understood and ceased?
No decline is occurring

Are there extreme fluctuations in number of mature individuals?
No

Extent and Occupancy Information

Estimated extent of occurrence
(Area of occurrence is based on sea lions occurring over most of the continental shelf and shelf break areas of British Columbia.)
~65,000 km2

Index of area of occupancy (IAO)
(The summed land area of the 5 breeding areas--7 rookeries.)
It should be noted that the breeding area of each of the 7 islands and rocks is smaller than the minimum grid size (2x2 km) used by COSEWIC to calculate the Areas of Occupancy. In addition, the sea lions are unable to use most of the surface of the islands and rocks that form their rookeries because of the steepness of the terrain. Thus, the actual area used by the sea lions for breeding (<10 km2) is much smaller than the calculated Area of Occupancy.
28 km2

Is the total population severely fragmented?
No

Number of locations
5 main breeding areas (some have >1 rookery)

Is there an observed continuing decline in extent of occurrence?
No

Is there an observed continuing decline in index of area of occupancy?
No

Is there an observed continuing decline in number of populations?
No

Is there an observed continuing decline in number of locations?
No

Is there an observed continuing decline in extent and quality of habitat?
No

Are there extreme fluctuations in number of populations?
No

Are there extreme fluctuations in number of locations?
No

Are there extreme fluctuations in extent of occurrence?
No

Are there extreme fluctuations in index of area of occupancy?
No

Number of Mature Individuals (in each population)
PopulationN Mature Individuals
40% of Canadian (breeding) population present in 2010. (Note that actual number would be lower if not all bulls hold territories.)~11,400 (range 10,800 – 11,800)

Quantitative Analysis

Probability of extinction in the wild is at least
unknown

Threats (actual or imminent, to populations or habitats)

There is potential for acute oil spills to kill large numbers of sea lions near rookeries and haulouts.

Rescue Effect (immigration from outside Canada)

Status of outside population(s)?
USA (SE Alaska, WA, OR, CA)
Increasing

Is immigration known or possible?
Yes

Would immigrants be adapted to survive in Canada?
Yes

Is there sufficient habitat for immigrants in Canada?
Probably

Is rescue from outside populations likely?
Probably

Data-Sensitive Species

Is this a data-sensitive species?
No

Status History

COSEWIC:
Designated Not at Risk in April 1987. Status re-examined and designated Special Concern in November 2003 and November 2013.

Status and Reasons for Designation

Status:
Special Concern
Alpha-numeric code:
Not applicable
Reason for Designation:
This species is restricted to only five breeding locations (consisting of 7 rookeries) in British Columbia that occupy less than 10 km2, with approximately 70% of births occurring at a single location (Scott Islands). The population is increasing, but is sensitive to human disturbance while on land and is vulnerable to catastrophic events such as major oil spills due to its highly concentrated breeding aggregations. The species is near to qualifying for Threatened, but has recovered from historical culling and deliberate persecution.

Applicability of Criteria

Criterion A (Decline in Total Number of Mature Individuals):
Not applicable. No decline.
Criterion B (Small Distribution Range and Decline or Fluctuation):
Not applicable. No decline or fluctuation.
Criterion C (Small and Declining Number of Mature Individuals):
Not applicable. No continuing decline.
Criterion D (Very Small or Restricted Population):
Not applicable. Comes close to meeting Threatened under D2 based on restricted IAO (breeding areas in Canada) <10 km2; 5 locations (breeding areas in Canada) with ~70% of pups born at one location; and the highly concentrated breeding aggregations are potentially affected by catastrophic events such as oil spills, although it is unlikely that all of these would be affected simultaneously.
Criterion E (Quantitative Analysis):
No applicable analysis.

Top of Page

Preface

The Steller Sea Lion was assessed by COSEWIC as a species of Special Concern in 2003. It met criteria for Threatened because there were only three breeding locations in British Columbia, but was designated as Special Concern because the population was increasing and there was a possible rescue effect.

The population has continued to increase since the last assessment. In addition, two new rookeries have been established bringing the number of breeding locations of Steller Sea Lions in British Columbia to five. Steller Sea Lion populations are also increasing in Southeast Alaska, Washington, Oregon and California.

Top of Page

COSEWIC logo

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Top of Page

Definitions (2013)

Wildlife Species

A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)
A wildlife species that no longer exists.
Extirpated (XT)
A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.
Endangered (E)
A wildlife species facing imminent extirpation or extinction.
Threatened (T)
A wildlife species likely to become endangered if limiting factors are not reversed.
Special Concern (SC)Footnote *
A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.
Not at Risk (NAR)Footnote **
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.
Data Deficient (DD)Footnote ***
A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction.

Footnotes

Footnote *

Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.

Return to footnote * referrer

Footnote **

Formerly described as “Not In Any Category”, or “No Designation Required.”

Return to footnote ** referrer

Footnote ***

Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994. Definition of the (DD) category revised in 2006.

Return to footnote *** referrer

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

Top of Page

Wildlife Species Description and Significance

Name and Classification

The Steller Sea Lion (Eumetopias jubatus Schreber 1776; Figure 1) is the largest member of the family Otariidae (order–Carnivora, suborder–Pinnipedia; Kenyon and Scheffer 1955; Jefferson et al. 1994; Rice 1998). It is the only extant representative of its genus, andwas named after the German naturalist George Wilhelm Steller who described the species in 1742 (Miller and Miller 1848). Other common names are Steller’s Sea Lion, Northern Sea Lion, Otarie de Steller (Fr), Lion de Mer de Steller (Fr), Sivuch (Ru), Todo (Jp), Lobo Marino de Steller (Sp), Qawax (pronounced ka-wa by Aleut natives), and Wiinaq (Alutiiq). Its scientific name means having a well-developed broad forehead (Eumetopias–Greek) and a mane (jubatus–Latin).

Figure 1. A mature male (bull) among a group of female Steller Sea Lions (photo: A.W. Trites).

Steller Sea Lions

Long Description for Figure 1

Photo of a mature male (bull) among a group of five or six female Steller Sea Lions, on a rocky haulout. The male is at least twice as massive as the females and has a mane of coarse hair on the neck and chest. Both male and female sea lions are pale yellow to light tan, darkening to chocolate brown on their undersides and near their flippers.

Top of Page

Two subspecies are recognized based on patterns in morphology, demography and genetics: E. j. jubatus (Schreber 1776 -- Asia, Aleutian Islands, and Gulf of Alaska) and E. j. monteriensis (Gray 1859 -- Southeast Alaska, British Columbia, Washington, Oregon and California (Phillips et al. 2009a; Phillips et al. 2011; Committee on Taxonomy 2012)). Only E. j. monteriensis occurs in Canada (Figure 2). The two subspecies are often referred to as the western (E. j. jubatus) and eastern (E. j. monteriensis) populations of Steller Sea Lions.

Figure 2. Worldwide range of Steller Sea Lions. Arrows denote breeding rookeries and the dashed line shows the separation between the two subspecies of Steller Sea Lions. (modified from Loughlin 1997 and Sease et al. 1999).

map

Long Description for Figure 2

Map indicating the global range of the Steller Sea Lion in the North Pacific Ocean, from the Channel Islands off southern California, north to the Bering Strait, and south along the Asian coast to Hokkaido, Japan. Range is shown by arrows pointing to breeding rookeries. A line at 144 degrees west (from about Cape Suckling, Alaska, southwards) denotes the separation between the two subspecies E. j. jubatus (Asia, Aleutian Islands, and Gulf of Alaska) and E. j. monteriensis (Southeast Alaska, British Columbia, Washington, Oregon and California. Only E. j. monteriensis occurs in Canada.

Top of Page

Morphological Description

Steller Sea Lions are sexually dimorphic (Fiscus 1961; Calkins and Pitcher 1982; Winship et al. 2001). Adult females average 2.1-2.4 m and 200-300 kg. Adult males (bulls) are larger, attaining a length of 2.7-3.1 m and weighing 400-800 kg, although they can weigh over 1,100 kg as they fatten prior to the breeding season. Mature males develop a prominent ‘mane’ of coarse hair on their large muscular neck and chest. The shape of their heads tends to be more robust with a flatter snout than that of females.

Pups weigh 16-23 kg at birth, with newborn males weighing about 2 kg more on average than females (Merrick et al. 1995; Brandon et al. 1996; Winship et al. 2001). They are born with a thick blackish-brown lanugo that is moulted at an age of 3-5 months (Scheffer 1964; Vania 1972; Daniel 2003).

Dry juveniles and adults are pale yellow to light tan, darkening to chocolate brown on their undersides and near their flippers (which are black and bare-skinned). When wet, Steller Sea Lions appear greyish white. Pelage of both sexes is composed of short coarse hairs (Scheffer 1964). Steller Sea Lions undergo an annual moult, shedding their entire pelage but not the epidermis. Juveniles (ages 1-2 y) are the first to moult (starting in June) followed by adult females (starting in August), bulls, and pups (starting in September) (Vania 1972; Calkins and Pitcher 1982; Daniel 2003). Duration of the moult is about 45 days (Daniel 2003).

Adult vocalizations in air consist of deep-throated bellows and roars. Territorial males wheeze as part of their threat displays (Orr and Poulter 1967; Gentry 1970), and produce a loud guttural sound both in the air and underwater (Schusterman et al. 1970). Newborns tend to bleat like sheep.

As with other members of the Otariidae, Steller Sea Lions can prop themselves on their fore flippers and rotate their hind flippers forward, rendering them agile on land.

Top of Page

Population Spatial Structure and Variability

There are no current geographical or ecological barriers to movement that might create genetic structure or strong demographic isolation of Steller Sea Lions within the Canadian part of their range or between populations outside Canada (Figures 2, 3 and 4). However, sea lions generally return to their natal rookeries to reproduce. This has resulted in animals from each rookery tending to be genetically distinct from animals in other rookeries although there is some movement between rookeries (Bickham et al. 1996; Baker et al. 2005; O’Corry-Crowe et al. 2006; Phillips et al. 2009b; Phillips et al. 2011).

Figure 3. Geographic location of Steller Sea Lion rookeries, year-round haulout sites and major winter haulout sites in British Columbia (and Forrester Island, Alaska). Updated from Bigg (1985).

map

Long Description for Figure 3

Map the geographic locations of Stellar Sea Lion rookeries, year-round haulout sites, and major winter haulout sites in British Columbia and Forrester Island, Alaska. Within Canada, Steller Sea Lions occur at five main breeding areas in British Columbia: 1) the Scott Islands off the northwestern tip of Vancouver Island, with rookeries situated on Triangle, Sartine and Maggot Islands; 2) Cape St. James off the southern tip of Haida Gwaii (Queen Charlotte Islands), with rookeries situated on the Kerouard Islands; 3) Garcin Rocks off the east coast of South Moresby Island in Haida Gwaii, 4) off Banks Island on the northern mainland coast, with rookeries situated on North Danger Rocks, and 5) Virgin Rocks (part of the Sea Otter Group located in Queen Charlotte Sound off the central mainland near Calvert Island).

Top of Page

Designatable Units

There is only one designatable unit that applies to Steller Sea Lions in Canada.

Top of Page

Special Significance

Once considered vermin, the Steller Sea Lion is one of the most intensively studied marine mammals in the North Pacific, and is viewed by many as a symbol of a healthy marine ecosystem. It is the largest species of otariid and the only one that breeds and resides year-round in Canadian waters. With the recent population declines in the Aleutian Islands and Gulf of Alaska, the British Columbia rookeries at the Scott Islands constitute the largest breeding aggregation in the world (as of 2010), and those at Cape St. James constitute the fifth largest (NMFS2008; Olesiuk 2011; NMFS2012).

Based on pups counted at rookeries in 2009 and 2010, British Columbia accounts for more than 35% of the E. j. monteriensis subspecies (eastern population)--and provides habitat for other sea lions breeding in Oregon and Alaska (Olesiuk 2011). As much as 70% of the subspecies may winter in British Columbia (based on winter surveys). The Steller Sea Lion is widely regarded as an important component of the coastal marine ecosystem, and contributes to a growing tourism industry. However, the role and therefore importance of seals and sea lions in marine ecosystems remains poorly understood (Beverton 1985; Bowen 1997; Merrick 1997; Trites 1997).

Steller Sea Lions have long been perceived as harmful to fisheries. Over 50,000 were killed in BC (1913-1970), and the breeding population at the Sea Otter Group was eradicated to protect the commercial salmon fishery (Figure 5). Recovery of sea lion populations since they were protected under the Fisheries Act in 1970 (Figures 6 and 7) has led to renewed concern about their impacts on fish stocks and to resumed lobbying for control programs. However, there is little evidence that Steller Sea Lion control programs had any beneficial effect on fisheries as salmon catches did not increase noticeably following the reduction of sea lion numbers on the Scott Islands (Spalding 1964).

The Steller Sea Lion may serve as an indicator of the general status of inshore marine ecosystems. It is widely distributed in coastal waters, has a long life­span, congregates on terrestrial sites where breeding populations can be readily assessed, and occupies a position near the top of the marine food chain.

Top of Page

Distribution

Global Range

Steller Sea Lions inhabit the cool-temperate and subarctic coastal waters of the North Pacific Ocean from the Channel Islands off southern California, north to the Bering Strait, and south along the Asian coast to Hokkaido, Japan (Figure 2, Kenyon and Rice 1961; Loughlin et al. 1984; Loughlin et al. 1992). They give birth on 55-60 rookeries and rest at >300 haulouts. Steller Sea Lions are non-migratory, but may disperse considerable distances from breeding sites (Rowley 1929; Fisher 1981; Calkins and Pitcher 1982; Loughlin 1997; Raum-Suryan et al. 2002).

Top of Page

Canadian Range

Within Canada (Figures 2 and 3), Steller Sea Lions occur at five main breeding areas in British Columbia: 1) the Scott Islands off the northwestern tip of Vancouver Island, with rookeries situated on Triangle, Sartine and Maggot Islands; 2) Cape St. James off the southern tip of Haida Gwaii (Queen Charlotte Islands), with rookeries situated on the Kerouard Islands; 3) Garcin Rocks off the east coast of South Moresby Island in Haida Gwaii, 4) off Banks Island on the northern mainland coast, with rookeries situated on North Danger Rocks, and 5) Virgin Rocks (part of the Sea Otter Group located in Queen Charlotte Sound off the central mainland near Calvert Island).

Of the five breeding areas, two did not exist when the species was last assessed in 2003. The first is a natural re-establishment of breeding animals on Virgin Rocks in 2006--a breeding aggregation that was extirpated following predator control programs during the 1920s and 1930s (Figures 5 and 6, Bigg 1985). The second new rookery was established at Garcin Rocks in 2008. Both sites were previously considered to be haulouts (resting sites where pups were not born) until small numbers of pups were observed (Appendix 1 and 2; Trites unpubl. Data; Olesiuk 2011). The sites were reclassified as rookeries (Olesiuk 2011) as numbers of bulls and pups increased, and numbers of immature animals using the sites declined. A small number of other haulouts in British Columbia may be reclassified as rookeries in the coming years (Pitcher et al. 2007).

In addition to the five breeding sites, there are about 30 haulout sites (Appendix 1) distributed mainly along the exposed outer coast that are used throughout the year, as well as additional winter sites used primarily during winter (Figures 3 and 4).

The at-sea distribution of Steller Sea Lions is not well known. In general, most Steller Sea Lions feed within about 15 km of shore during summer (Hui 2011), and can range over 200 km from shore in winter (Kenyon and Rice 1961; Merrick and Loughlin 1997). They feed primarily over the continental shelf and along the shelf break (Kajimura and Loughlin 1988; Gregr and Trites 2008; Hui 2011).

Top of Page

Extent of Occurrence and Area of Occupancy

Based on the size and distribution of breeding and haulout sites (Figures 3 and 4), the extent of occurrence for Steller Sea Lions in Canada is estimated to be ~65,000 km2, and the index of area of occupancy is 28 km2. The extent of occurrence is based on sea lions occurring over most of the continental shelf and shelf break areas of British Columbia, whereas the biological area of occupancy is based on the terrestrial space actually used by sea lions to breed (i.e., the surface area of the 5 breeding sites--rookeries). In British Columbia, these highly concentrated breeding aggregations use <10 km2 of land. . It should be noted that the breeding area of each of the 7 islands and rocks is smaller than the minimum grid size (2x2 km) used by COSEWIC to calculate the Index of Areas of Occupancy. In addition, the sea lions are unable to use most of the surface of the islands and rocks that form their rookeries because of the steepness of the terrain. Thus, the actual area used by the sea lions for breeding (<10 km2) is much smaller than the calculated Area of Occupancy (28 km2).”

Top of Page

Search Effort

The distribution and abundance of Steller Sea Lions have been assessed regularly in Canadian waters since 1971 (Figure 4 and Appendices 1 and 2). Systematic aerial surveys have been conducted during the summer and winter (Bigg 1985, 1988; Olesiuk 2011). Steller Sea Lions are also regularly surveyed in US waters (Pitcher et al. 2007; NMFS 2008; NMSF 2012).

Figure 4. Seasonal distribution of Steller Sea Lions in British Columbia during summer (2010) and winter (2009-2010). Colours indicate rookeries, year-round haulouts and winter haulouts, and circle sizes are proportional to the average site counts (from Olesiuk 2011).

map

Long Description for Figure 4

Two map panels illustrating the seasonal distribution of Steller Sea Lions in British Columbia during summer 2010 and winter 2009-2010. Distribution is represented by symbols that are differentiated according to whether they represent rookeries, year-round haulouts, or winter haulouts. Average site counts are indicated by symbol size.

Top of Page

Habitat

Habitat Requirements

The terrestrial sites used by Steller Sea Lions generally fall into three distinct categories: 1) rookeries where animals congregate during May-August to give birth, mate, and nurse pups; 2) year-round haulouts that are usually continuously occupied; and 3) winter haulout sites that are used less regularly and primarily during the non-breeding season (Figures 3 and 4, Bigg 1985). Rookeries generally have associated peripheral haulout sites occupied mainly by non-breeding males and juveniles. In most cases, animals continue to use rookeries as haulout sites throughout the year, albeit in much reduced numbers.

Steller Sea Lions are extremely tenacious regarding the sites they use to give birth and mate. Females tend to return to their rookeries of birth, and will return faithfully to a single rookery each year (Raum-Suryan et al. 2002; Parker et al. 2008). Three of the five breeding areas currently used in British Columbia appear to have been well established in the early 20th century when the first sea lion survey was conducted (Newcombe and Newcombe 1914), and these three have been used continuously despite the disturbances caused by predator control programs and commercial hunts (Pike and Maxwell 1958; Bigg 1985; Olesiuk 2011). One breeding area was extirpated in the 1930s and was re-established almost 80 years later (in 2006 at Virgin Rocks in the Sea Otter Group), and the fifth breeding site (established in 2008 at Garcin Rocks) represents an expansion of the breeding range within Canada (Figures 4 and 5).

Steller Sea Lions are habitat specialists. They use rookeries that are remote and free of terrestrial predators such as wolves and bears. Most rookeries are isolated, barren outcroppings located in regions that have relatively high currents, high salinity, low surface temperatures and shallow waters--which presumably reflects high ocean productivity and hence optimum feeding (Ban et al. 2003). Essential haulout features seem to be relatively flat terrain, accessibility, and protection from swell and waves (Edie 1977; Ban and Trites 2007). Sea lions use protected areas during storms and wet areas during extremely hot weather (Edie 1977). Access to high ground is also important for giving birth, although older animals capable of going to sea will use lower and more exposed areas. The rookeries in British Columbia occur on solid rocky substrates, except in recent years when increasing numbers of animals began breeding on the gravel beaches along the eastern (leeward) side of Triangle Island.

The 30 year-round haulout sites in British Columbia are generally situated in exposed areas along the outer coast on rocky islets and ledges. Approximately half of the haulouts were noted during the first surveys in 1913 (Newcombe and Newcombe 1914), whereas about one-quarter appear to have been colonized since aerial surveys were initiated in the early 1970s. As populations have grown, some sites formerly used mainly during winter (see below) have been occupied more continuously, and have been re-classified as year-round haulouts (Olesiuk 2011).

Use of winter haulouts appears to be more fluid than year-round sites. Most winter haulouts are situated in protected areas, such as the Strait of Georgia, Strait of Juan de Fuca and Queen Charlotte Strait. In addition to natural substrates, winter haulouts include log booms, floats, jetties and docks. Animals can also rest (raft) in the water during storms or heavy swells when haulouts are awash, or when they are near concentrations of prey without suitable nearby haulouts (Kenyon and Rice 1961). In the southern part of British Columbia, winter haulouts are often shared with adult- and subadult-male California Sea Lions (Zalophus californianus) (Hancock 1970; Brenton 1977; Bigg 1985).

Understanding of how Steller Sea Lions use their aquatic habitat is poor. Animals are generally observed within 15 km of land and in water depths less than 400 m (Hui 2011), but may venture several hundred kilometres offshore and occur off the continental shelf (Kenyon and Rice 1961; Merrick and Loughlin 1997). Steller Sea Lions also occasionally venture into freshwater (Jameson and Kenyon 1977; Roffe and Mate 1984; Beach et al. 1985). In British Columbia, Steller and California sea lions often congregate in the lower Fraser River during the spring Eulachon (Thaleichthys pacificus) run (Bigg 1985), and are occasionally seen rafting as far as 35 km upriver (Olesiuk unpubl. data). Steller Sea Lions also congregate in estuaries during autumn to feed on pre-spawning salmon (Bigg et al. 1990).

Top of Page

Habitat Trends

The first rookery abandoned following the culls of 1913-1915 may have been Watch Rock where a dozen pups were counted in 1913 (Bigg 1985). By 1938, control programs had extirpated the populations using the two other rookeries in the Sea Otter Group--Virgin and Pearl Rocks (Figures 5 and 6). Pupping resumed on one of the eradicated rookeries (Virgin Rocks) in 2006, and a second site was colonized two years later at Garcin Rocks off the east coast of South Moresby Island. New haulouts were also established in British Columbia as numbers increased through the 2000s (Olesiuk 2011).

Steller Sea Lions also breed in Alaska, California and Oregon, but not in Washington. In Southeast Alaska, rookeries were not known to occur during the early 1900s. However, sea lions began breeding at Forrester Island just north of the British Columbia-Alaska border (Figure 3) shortly after control programs were initiated in British Columbia. Additional rookeries were established in Southeast Alaska at the Hazy Islands in about 1985 and White Sisters Island in 1992, and more recently at Graves and Baili Rocks (Trites and Larkin 1996; Calkins et al. 1999; Pitcher et al. 2003; NMFS 2012).

Top of Page

Biology

The earliest accounts of Steller Sea Lions were provided by Scammon (1874), Allen (1880), Elliot (1882) and Rowley (1929). More recent and extensive overviews of the biology of Steller Sea Lions are contained in Loughlin (1998, 2009) and NMFS (2008, 2012).

Life Cycle and Reproduction

Only sexually mature Steller Sea Lions return to rookeries (along with a few dependent young with their mothers). Bulls are the first to arrive in early May to compete with other mature males and establish territories (Gisiner 1985). Pregnant females begin arriving on rookeries during the latter half of May and give birth to a single pup within a few days of their arrival (Gentry 1970). Mothers will stay on shore with their pups for about 7-10 days before leaving on regular feeding trips that average 1 day and are followed by 1 day on shore (Higgins 1984; Merrick 1987; Hood and Ono 1997; Milette and Trites 2003; Maniscalco et al. 2006). Copulations usually occur prior to the first feeding trip.

Pups are precocious--they have open eyes and can crawl at birth. They begin to enter tide pools and inter-tidal areas at about 2 weeks of age, and swim in the open ocean starting at about 4 weeks of age when mothers begin moving their pups from the rookeries to nearby sites (Sandegren 1970; Gentry 1974). By the end of August, few animals remain on the rookeries.

Year-round haulouts are used by immature animals, non-pregnant adults and females nursing pups from previous summers that do not return to the rookeries. Some bulls also use haulouts during summer and establish territories, and occasionally breed with mature females (Trites and Coombs 2010). Outside of the summer breeding season, Steller Sea Lions use year-round haulouts as well as winter haulouts that may be considerable distances from their rookeries. Females with dependent young may stay at a single haulout or may move their pups to any number of haulouts. Average length of feeding trips by lactating females in winter is about 2 days, followed by 1 day on shore (Trites and Porter 2002; Maniscalco et al. 2006). Haulouts are not restricted to any single age or sex class during the non-breeding season. However, sea lions without dependent young may spend extended time at sea between visits to shore.

Steller Sea Lions regularly use haulouts throughout the year to rest between feeding trips. They can easily climb steep rocks and are often found on haulouts many metres above sea level. Sea lions tend to be highly gregarious while on land and generally pack close together with little or no separation between individuals.

Steller Sea Lions have a polygynous mating system that appears to be synchronized throughout the entire range (Bigg 1985). Males may begin producing sperm by 3-7 years of age (Calkins and Pitcher 1982), but only those holding territories are known to mate. Most territorial males are 9-13 years old (Thorsteinson and Lensink 1962) and may hold a territory for several years in succession (range 1-7 years) (Gisiner 1985). The ratio of adult females to territorial bulls averages ~7:1 (see below) and may be as high as 10-15:1 (Pike and Maxwell 1958; Merrick 1987). Successful males will usually maintain their territory for an average of 40 days (20-68 days) without feeding (Gentry 1970). The advantages of larger body size in acquiring and defending territories, and in providing energy and possibly water reserves during tenure, probably accounts for the sexual dimorphism in body size in Steller Sea Lions (Fisher 1958; Repenning 1976).

Females ovulate first at about 3-6 years of age. Following fertilization, embryonic development is suspended for about 3 months until implantation occurs in September or October (delayed implantation), resulting in a gestation period of about 8-9 months (Vania and Klinkhart 1967; Calkins and Pitcher 1982). Most mature females appear to conceive each year (Trites and Coombs 2010), but the rate of reproductive failure and abortion appears to be high. Pitcher et al. (1998) reported that 97% of females sampled in the Gulf of Alaska were pregnant early in the gestation season, but that pregnancy rates declined to 67% and 55% at the end of the gestation season in the 1970s and 1980s respectively. Pregnancy rates have not been estimated for Steller Sea Lions in British Columbia.

The lactation period of Steller Sea Lions is extremely long for a pinniped species. A few pups have stayed with their mothers for 3-4 years, although most are believed to be weaned just prior to their first birthday (Calkins and Pitcher 1982; Trites et al. 2006; York et al. 2008). Male Steller Sea Lions have been found to suckle longer than females, with a greater proportion of males than females suckling at one year (Marcotte 2006). Extending the nursing period by more than one year may ensure the survival of offspring during times when the nutritional quality of prey available to sea lions is low (Trites et al. 2007c; Bernard et al. 2011). In some cases, females on rookeries may nurse both a newborn and a yearling, or two newborns (Maniscalco et al. 2007).

Mortality of pups during the first month of life generally appears to be high and influenced by factors such as storms (Pike and Maxwell 1958; Orr and Poulter 1967). The principal cause of death for pups is drowning because they are not able to get back out of the water (Orr and Poulter 1967; Edie 1977). Being bitten, tossed or trampled by older animals takes a toll on pups, as does being abandoned or separated from their mothers (Orr and Poulter 1967; Gentry 1970; Sandegren 1970; Sandegren 1976). Average annual survival probability for pups in Southeast Alaska was 0.60 for males and 0.64 for females (Hastings et al. 2011), and is likely similar for sea lions in British Columbia.

Juvenile mortality is difficult to estimate, but appears to be fairly high for both sexes. Hastings et al. (2011) estimate that about 37% of males and 46% of females survive to 3 years of age. Mortality rates are significantly lower for adults (~11% for males and ~9% per year for females). Higher mortality rates for males result in a progressively skewed sex ratio favouring females. The growing population of Steller Sea Lions in Southeast Alaska consists of about 37% males and 63% females of all ages (Hastings et al. 2011). The sex ratio is probably similar in British Columbia.

The oldest animals aged from the wild were about 18 years for males and 30 years for females (Calkins and Pitcher 1982). However, longevity (defined at the 99th percentile of known aged individuals) is about 14 years for males and 22 years for females (Trites and Pauly 1998).

Life tables for Steller Sea Lions (Calkins and Pitcher 1982; Trites and Larkin 1992; York 1994; Hastings et al. 2011) indicate that the average age of sexually mature males and females (generation time) is about 10-11 years for both males and females, and that the number of mature individuals (males and females) capable of reproduction is about 40% of the total population (all ages, including pups). These generation times and proportion mature were calculated using life tables (Hastings et al. 2011) and assumed that only bulls aged 9-13 years breed, and that females give birth between the ages of 4-20 years old. Based on these life table calculations, there is a ratio of ~7 breeding females for each breeding male. Number of mature individuals in 2010 was ~11,400 (range 10,800–11,800) based on a total population estimate of 28,600 (range 27,100–29,500 calculated as a function of numbers of pups born; Olesiuk 2011).

Top of Page

Physiology and Adaptability

Food requirements vary with the type and quality of prey (Perez 1994; Rosen and Trites 1999, 2000b,c 2004; Rosen 2009). Captive sea lions fed a mixed diet of various fishes consume an average 10-12 kg per day for full-grown females and 20 kg per day for full-grown males (Kastelein et al. 1990; Perez et al. 1990). However, bioenergetic models predict that daily food requirements for Steller Sea Lions in the wild (which are more active, reproduce and tend to consume a lower quality diet) are closer to 15-20 kg for mature females, and 30-35 kg for mature males (Winship et al. 2002). For females, the amount of food needed to meet daily energy requirements on a mixed diet equates to ~14% of sea lion body weight for a 1 year old and 7% for a mature individual. Sea lions that consume higher proportions of low fat fishes such as gadids (Cod family species) require significantly more prey than those that consume fattier fishes such as Pacific Herring (Clupea pallasii) (Trites and Donnelly 2003; Winship and Trites 2003; Rosen 2009).

Steller Sea Lions are capable of diving to depths of at least 310 m (Andrews 1999) and staying submerged for over 8 minutes (Merrick and Loughlin 1997; Swain and Calkins 1997). However, most dives tend to be shallow (range of 15-50 m) and short (1.5-2.5 min) (Merrick and Loughlin 1997; Swain and Calkins 1997; Loughlin et al. 1998; Swain 1999; Andrews et al. 2002; Rehberg et al. 2009; Gerlinsky et al. 2013). Diving capabilities are developed during the first year of life. Pups aged less than one month dive to a maximum depth of 10 m, but this increases to nearly 100 m by 5 months of age, and to over 200 m by 10 months of age (Merrick and Loughlin 1997; Rehberg and Burns 2008).

Steller Sea Lions are likely adaptable to periodic changes in the quality and quantity of prey available based on their ability to consume wide groups of prey, ranging from bottom fish to mid-water schooling species (Sinclair and Zeppelin 2002; Trites et al. 2007a; McKenzie and Wynne 2008). However, they may be less adaptable in terms of the rookeries and haulouts they use. Steller Sea Lions do not appear to frequent alternative haulout and rookery sites after nearby abundances and types of prey have changed (Trites et al. 2007c).

Top of Page

Dispersal and Migration

Steller Sea Lions generally return to breed on their natal rookery, although there may be some exchange between neighbouring rookeries (Calkins and Pitcher 1982, 1996; Raum-Suryan et al. 2002; Parker et al. 2008). At least one animal branded as a pup on Forrester Island in Southeast Alaska was subsequently seen 400 km away with a newborn pup on the Cape St. James rookery (Raum-Suryan and Pitcher 2000). In some cases, rookeries are augmented by breeding females from other rookeries, as evident from the rapid expansion of new rookeries in Southeast Alaska and British Columbia (Calkins et al. 1999; Pitcher et al. 2003; Olesiuk 2011).

Steller Sea Lions are considered non-migratory, but generally have well-defined seasonal movements. Telemetry and branding studies have shown that animals may travel hundreds of kilometres and use many haulout sites over the course of a few weeks or months (Merrick and Loughlin 1997; Loughlin et al. 1998, 2003; Raum-Suryan et al. 2002). Numbers of animals using year-round haulout sites are fairly constant throughout the year, but decline during the May-August breeding season as animals move to rookeries (Figure 4, Bigg 1985; Olesiuk 2011). Following the breeding season, male Steller and California Sea Lions have been observed travelling north along the Oregon coast (Mate 1975), coinciding with a sharp increase in the number of animals wintering off southern Vancouver Island (Bigg 1985). These movements of animals during the non-breeding season (September-May) are likely related to the distribution of forage fish.

Prior to weaning, dependent young (ages 0-3 yrs) appear to stay relatively close to haulouts while their mothers forage at sea (Trites and Porter 2002; Marcotte 2006). Once weaned, young males tend to disperse more widely than females and have been seen many hundreds of kilometres from their natal rookeries (Raum-Suryan et al. 2002).

Top of Page

Interspecific Interactions

Steller Sea Lion eat over 50 species of fish and invertebrates (Wilke and Kenyon 1952; Pike 1958; Spalding 1964; Pitcher 1981; Sinclair and Zeppelin 2002; Trites et al. 2007a; Trites and Calkins 2008; Tollit et al. 2009; Olesiuk et al. 2011). The diet appears to vary according to which prey are locally and seasonally most abundant or accessible. Preferred prey appear to be small or medium-sized schooling fishes, which in British Columbia include species such as Pacific Herring, Pacific Hake (Merluccius productus), Pacific Sand Lance (Ammodytes hexapterus), Salmon (Oncorhynchus spp.), Spiny Dogfish (Squalus suckleyi), Eulachon and Pacific Sardine (Sardinops sagax) (Pike 1958; Spalding 1964; Olesiuk and Bigg 1988; Tollit et al. 2009; Olesiuk et al. 2011; Trites and Olesiuk unpubl. data). Bottom fish, such as Rockfish (Sebastes spp.), Arrowtooth Flounder (Atheresthes stomias) and Skate (Rajidae), can also be important dietary items as well as Squid and Octopus (Cephalopods). Steller Sea Lions have also been observed to prey on gulls (O’Daniel and Schneeweis 1992) and other pinnipeds, including neonate Northern Fur Seals (Callorhinus ursinus) (Gentry and Johnson 1981) and Harbour Seals (Phoca vitulina) (Pitcher and Fay 1982; Mathews and Adkison 2010).

A shift in diets from fatty fishes (i.e., Pacific Herring) to low-fat fishes (i.e., Walleye Pollock, Theragra chalcogramma) has been implicated in the decline of Steller Sea Lions in the Gulf of Alaska and Aleutian Islands (Alverson 1992; Alaska Sea Grant 1993; DeMaster and Atkinson 2002; Trites and Donnelly 2003; Trites et al. 2007c; Bernard et al. 2011). Large-scale shifts in climatic and oceanic conditions can affect the dynamics of marine organisms (Benson and Trites 2002), as can selective-fishing or over-fishing (Pauly et al. 1998), both of which could affect the quantity or quality of Steller Sea Lion prey. Controlled-feeding studies have shown that sea lions, particularly young animals, consuming large amounts of low-fat prey such as Walleye Pollock may be unable to maintain body mass (Rosen and Trites 2000b, 2004). Thus, interactions between climate, fisheries, and prey may significantly influence the nutritional status and survival of Steller Sea Lions (Trites et al. 2007c).

Besides Humans, the main predators of Steller Sea Lions are Killer Whales (Orcinus orca) (Morton 1990; Ford et al. 1998; Ghai and Insley 2011), which may selectively prey on young sea lions and significantly affect population numbers (Barrett-Lennard et al. 1995; Guénette et al. 2007; Horning and Mellish 2012). White Sharks (Carcharodon carcharias) are known to prey on Steller Sea Lions in the southern part of their range (California) and occasionally occur in British Columbia waters--however, White Sharks and the Pacific Sleeper Sharks (Somniosus pacificus) that occur further north are not considered to be a significant source of Steller Sea Lion mortality (Stroud 1978; Ainley et al. 1981; Klimley et al. 1992; Klimley et al. 2001; Martin 2004; Sigler et al. 2006; NMFS 2012). Bears have been observed on rookeries in Russia and may prey on pups (T. Loughlin, National Marine Mammal Laboratory, Seattle, WA, pers. comm.).

Top of Page

Population Sizes and Trends

Sampling Effort and Methods

The abundance of Steller Sea Lions has been assessed in Canadian waters since 1971 by counting individuals seen in aerial photographs taken over rookeries and haulouts during summer and winter (Appendices 1 and 2; Bigg 1985, 1988; Olesiuk 2011). Typically, oblique 35 mm photographs are taken from a small fixed-wing aircraft as it circles a haulout or rookery. Aerial survey procedures for counting Steller Sea Lions were developed in the mid-1960s (Mathisen and Lopp 1963) and have been standardized since the early 1970s (Mate 1977; Withrow 1982; Bigg 1985; Olesiuk et al. 1993; Olesiuk 2011).

Counts consist of pups (during summer) and non-pups (>6 months old during summer and winter). A correction factor is applied to account for pups that are obscured (Olesiuk et al. 2008), but no correction factor is applied to non-pups to account for animals at sea during the surveys (Olesiuk 2011). They have been counted every 2 to 5 years since 1971.

The censuses provide an index of relative abundance because some animals are always foraging at sea and are missed. Surveys in British Columbia are conducted during the last week of June and first week of July, which represents the time by which most pups have been born, but most are still too young to have begun to disperse from rookeries (Olesiuk 2011). Steller Sea Lions are also occasionally counted during winter (Olesiuk 2011). In recent years, high-resolution vertical medium-format photography has been used, particularly to census pups (Snyder et al. 2001; Olesiuk et al. 2008). Life tables provide an estimate of the ratio of pups to older age-classes, and thereby a means to estimate the total population size (Calkins and Pitcher 1982; Loughlin et al. 1992; Trites and Larkin 1996; Sease et al. 1999; Olesiuk 2011).

Top of Page

Abundance

Between the late 1950s and 1970s, overall abundance of Steller Sea Lions in the North Pacific (range-wide: California to Japan) was believed to have been stable at about 250,000-300,000 individuals (Kenyon and Rice 1961; Loughlin et al. 1984). Abundance subsequently declined to about 116,000 by 1989, 97,500 by 1994-95, and 95,000 by 1999-2002 (Braham et al. 1980; Merrick et al. 1987; Loughlin et al. 1992; Trites and Larkin 1996; Sease et al. 1999; Burkanov 2000; Pitcher et al. 2003; Sease and Stinchcomb 2003; Olesiuk 2011). In 2009, the western population was stable at ~50,000 individuals in the US portion of its range, while the eastern population numbered ~63,000 and was increasing (southeast Alaska to California; Allen and Angliss 2012; NMFS 2012).

Based on numbers of pups born, the total British Columbia population was about 28,600 in 2010 (range 27,100 – 29,500; Olesiuk 2011), of which ~11,500 were mature animals (~40%). However, numbers of non-pups counted at rookeries and haulouts in British Columbia suggest there may be as many 32,000 Steller Sea Lions in summer (range 27,200 – 36,700) and as many as 48,000 in winter (95% CI 37,900 – 58,300) due to the movement of Steller Sea Lions from the large rookery that occurs on Forrester Island just north of the British Columbia-Alaska border and an influx of Steller Sea Lions from Washington and Oregon (Olesiuk 2011). Approximately 60% of the Steller Sea Lions in British Columbia occur on rookeries during the summer (including pups) and the remaining 40% occur on haulouts (Olesiuk 2011).

Top of Page

Fluctuations and Trends

Between 1910 and 1970, Steller Sea Lions declined in British Columbia as predator-control programs killed an estimated 49,100 sea lions, and commercial hunting took another 5,700 animals (Figures 5 and 6). The most intensive culling occurred at Virgin and Pearl rocks in the Sea Otter Group. Federal fishery officers attempted to protect the Rivers Inlet salmon fishery by shooting as many breeding animals as possible at these two rookeries (mid-June 1923-1939) before landing and clubbing pups, most of which were too young to escape into the water. A total of ~20,000 animals (including 7,000 pups) were killed. Pup production declined from ~1,200 pups when the control program was initiated to fewer than 10 by the time it had ended in 1938. Of these two targeted rookeries, pupping no longer occurs at Pearl Rocks, but has returned since 2006 at Virgin Rocks (Figure 7).

Once the sea lions breeding on the Sea Otter Group rookeries had been extirpated, control programs were directed toward the Scott Islands, where about 7,500 animals (including 2,800 pups) were killed during 1936-1939 (Figure 5). There was some effort to establish a commercial hunt for hides, but this proved uneconomic. Large-scale culls were suspended during World War II, although the Canadian air force and navy may have killed significant numbers of animals during bombing practices (Pike and Maxwell 1958; Bigg 1985). No information is available on the magnitude of these kills (Bigg 1985). Some people hunted pups on the Scott Islands during the early 1950s to remove and alter the snouts in order to claim Harbour Seal bounties (fraudulently) (Olesiuk unpub. data).

Figure 5. Total numbers of Steller Sea Lions reported to have been killed in British Columbia as part of control programs and commercial harvests during 1913-1970. Data have been grouped and totalled into 5-year periods, and are colour-coded by major breeding area. Data are from Bigg (1984).

Graph

Long Description for Figure 5

Bar chart illustrating trend in total numbers of Steller Sea Lions reported to have been killed in British Columbia as part of control programs and commercial harvests from 1913 to 1970. Each bar represents a five-year period. Coloured sections within bars indicate number of kills at major breeding areas (Scott Islands, Cape St. James, North Danger Rocks, and Sea Otter Group) and haulout sites. Over 50,000 Steller Sea Lions were killed in British Columbia from 1913 to 1970, and the breeding population at the Sea Otter Group was eradicated by the mid-1930s.

Top of Page

Predator control resumed during 1956-1966 and resulted in the deaths of ~11,600 animals at the Scott Islands, Cape St. James and North Danger Rocks (Figure 5). Of this total, ~5,000 animals were commercially harvested for mink food (Bigg 1984).

In addition to predator control and commercial hunting, 764 animals were reportedly killed from 1913-1969 for research (Bigg 1984). No additional attempts have been made to eradicate Steller Sea Lions since they were protected in 1970 under the Fisheries Act.

Bigg (1984, 1985) reconstructed historical trends in numbers of breeding animals on rookeries from compiled historical sightings and counts of Steller Sea Lions (1892-1984; Figure 6). He considered the likely reliability of observations, the timing of counts in the context of the life history of Steller Sea Lions, and the potential effect of repeated disturbances. Bigg (1985) concluded that control programs and commercial hunting had depleted breeding populations, and estimated that the British Columbia rookeries were inhabited by ~14,000 animals (all ages, including pups) when the first counts were made in 1913-16 (Figure 6). The extirpation of the population using the Sea Otter Group rookeries, concurrent with a slight increase in numbers breeding on the Scott Islands, resulted in a reduced overall population of about 12,000 by 1938. By 1956, numbers on rookeries had been further reduced to about 8,900-9,400 sea lions (including 2,850 pups) (Pike and Maxwell 1958; Bigg 1985). The population declined sharply from 1956-1966 following the resumption of predator control and commercial hunting. Numbers on rookeries in BC were reduced to ~4,550 by 1961--and 3,390 (including 940 pups) by the time the first aerial survey was conducted in 1971. Thus, Steller Sea Lions in British Columbia were depleted to about one-quarter of their historical size by predator control and commercial harvesting (Bigg 1985; Olesiuk 2011).

Figure 6. Historical numbers of Steller Sea Lions (pups and non-pups) on rookeries in British Columbia. Rookeries included the Scott Islands (Triangle I, Sartine I, and Maggot I), the Sea Otter Group (Pearl Rocks and Virgin Rocks), Cape St. James, North Danger Rocks, and Garcin Rocks. Data are from Olesiuk (2011) and Bigg (1985).

Graph

Long Description for Figure 6

Line chart illustrating trends in numbers of Steller Sea Lions (pups and non-pups) on rookeries in British Columbia from 1913 (approx.) to 2010. Rookeries include the Scott Islands (Triangle, Sartine, and Maggot), the Sea Otter Group (Pearl Rocks and Virgin Rocks), Cape St. James, North Danger Rocks, and Garcin Rocks. For detail, see text.

Top of Page

Population surveys indicate that non-pup abundance on rookeries and haulouts was stable from 1971-1983, but has increased at a mean rate of 4.7% since the mid-1980s (Figure 7, Olesiuk 2011). In contrast, pups increased slowly at an annual rate of 1.7% per year from 1971-1994, and at 7.3% per year since the mid-1990s (Figure 7, Appendices 1 and 2; Olesiuk 2011). This has resulted in a 4-5 fold increase the size of the Steller Sea Lion population in British Columbia since the 1970s, and a more than doubling in the number of year-round haulout sites they use (from 12 to 27; Olesiuk 2011). In 2010 the population appeared to be slightly larger than it was before harvesting and predator-control programs were instituted in the early 1900s―with no sign of population growth slowing (Figure 7).

Figure 7. Numbers of pups (rookeries) and non-pups (rookeries and haulout sites) counted during aerial surveys in British Columbia from 1971-2010. Fitted lines are piecewise log-linear regression models from Olesiuk (2011).

Graph

Long Description for Figure 7

Two chart panels illustrating trend in numbers of Steller Sea Lion pups (upper panel) and non-pups (lower panel) counted during aerial surveys in British Columbia from 1971 to 2010. The surveys indicate that non-pup abundance on rookeries and haulouts was stable at around 5,000 from 1971 to 1983, but has increased to around 18,000. In contrast, pups increased slowly from about 900 in 1971 to about 1,200 in 1994, then increased more rapidly to about 5,500 by 2010.

Top of Page

Changes in the relative numbers of pups born each year is a standard means of inferring changes in the relative numbers of breeding animals in the population. Thus― based on pup counts―the percent increase in total number of mature individuals over the last 3 generations (i.e., 30-33 years, 1977-2010) was >450%. This inferred rate of increase assumes constant birth rates and a relatively constant ratio of breeding females to bulls over time.

Rescue Effect

Observations over the past century suggest that new Steller Sea Lion rookeries can be established if sufficient numbers of pregnant females successfully give birth at haulouts. This has been observed at several sites in Southeast Alaska, one in the Gulf of Alaska (Calkins et al. 1999), and two more recently in British Columbia (Olesiuk 2011). Given the rigidness and traditional nature of breeding sites, along with the tendency of sea lions to flee en masse from Humans and immediate disturbances such as passing boats and low-flying aircraft (Lewis 1987; Porter 1997; Kucey 2005; Kucey and Trites 2006; Wilson et al. 2012), it seems unlikely that new rookeries could be established with human intervention. Steller Sea Lions have been successfully born and raised in captivity (e.g., Hardervijk Dolphinarium Holland, Mystic Aquarium), but it is unclear whether such individuals could survive on their own if released in the wild. Recolonization of British Columbia, if ever needed, would likely only occur through immigration from rookeries in Oregon or Southeast Alaska.

Dispersal from Steller Sea Lion populations that breed in Southeast Alaska and Oregon would likely repopulate Canadian waters should it disappear or experience a decline. Steller Sea Lions are increasing in Southeast Alaska (NMFS 2012) and many that are born in this region feed and rest in Canadian waters. Similarly, the relatively small rookeries in Oregon have increased since the 1970s (Brown and Reimer 1992; NMFS 2012), and many of the pups born there have also been seen resting at Canadian haulout sites. Thus a rescue effect would be likely.

Top of Page

Threats and Limiting Factors

There are two broad categories of factors that can limit Steller Sea Lions (Table 1). The first consists of anthropogenic threats such as shooting, incidental take in fishing gear, competition with fisheries, entanglement in debris, catastrophic accidents (oil spills), environmental contaminants, and displacement or degradation of their habitat. Of these threats, intentional and incidental killings are within sustainable levels (given the growth of the Steller Sea Lion population), and the other threats are likely to be localized and not population-wide (Table 1). The second category of limiting factors is natural changes in the ecosystem and includes naturally fluctuating prey populations, predation by Killer Whales, disease, and natural environmental factors (all of which will play an increasingly important role in dictating future population levels; Table 1).

Table 1. Threat assessment of Steller Sea Lions in Canada (based upon COSEWIC Threats Calculator).
ThreatImpactScopeSeverityTimingComments
Shooting / HuntingLowPervasiveSlightHighSmall numbers illegally killed and taken by Aboriginal hunting
Incidental take in fishing gearLowPervasiveSlightHighOccasionally drowned in gillnets and trawl nets
Entanglement in debrisLowPervasiveSlightHighAffects a minimum of 0.2% of sea lions.
Oil spills – catastrophic eventsLowRestrictedModerateMediumIs yet an unrealized threat in British Columbia, but could have devastating consequences to rookeries
Environmental contaminantsLowPervasiveSlightHighAccumulate in sea lion tissues, but no direct effects on sea lion births or survival yet reported
Displacement or degradation of habitatLowSmallSlightHighSteller Sea Lions are easily scared from haulouts by boats, aircraft and people; and may abandon some sites
Prey reductions –fishery causedLowRestrictedSlightLowCompetition with fisheries is difficult to establish, but is not thought to be currently occurring in British Columbia
Prey reductions –natural ecosystem changeLowRestrictedSlightLowThe most recent changes in the marine ecosystem appear to have favoured sea lion populations in British Columbia, unlike in the Aleutian Islands and Gulf of Alaska.
Predation by Killer WhalesLowPervasiveSlightHighKiller Whales appear to be the largest source of constant sea lion mortality, but sea lion populations appear to be large enough to sustain it
DiseaseLowPervasiveSlightHighThe gregarious nature of sea lions on land makes them susceptible to the transfer of disease and introduction of novel pathogens from terrestrial sources

Top of Page

For most of the 20th century, the main factor limiting Steller Sea Lions was killing by Humans. In recent years relatively small numbers have been taken by Aboriginals for subsistence (through a FSC–Food Social and Ceremonial Licence issued under the Fisheries Act) or killed at salmon farms and spawn-on-kelp operations (also done under licences issued by DFO; Jamieson and Olesiuk 2001; Olesiuk 2011), or killed illegally or incidentally in fisheries. However, the population trends of Steller Sea Lions since the mid-1980s imply that this mortality is within sustainable limits.

Although hunting occasionally occurs for food and whiskers (Aboriginal Traditional Knowledge Subcommittee of COSEWIC 2011), use of sea lions by First Nations’ people appears to have declined during the 1800s and sea lion meat has not been a mainstay of First Nation diets since the early 1900s (Duff 1977; Bigg 1985). In Alaska, household surveys indicate that ~200 Steller Sea Lions have been taken annually in recent years (2000-2007), mostly in the northern part of the range (NMFS 2012). Less than 5% of the numbers hunted (~8 sea lions per year) originates from Southeast Alaska (Wolfe 1997; Wolfe and Hutchinson-Scarbrough 1999; Loughlin and York 2000; NMFS 2012), an area which is probably indicative of Aboriginal hunting levels in British Columbia.

Predator control at fish farms and herring impoundments in British Columbia have been the largest known source of fishery-related mortality for Steller Sea Lions in the North Pacific (Jamieson and Olesiuk 2001; Olesiuk 2004; Allen and Angliss 2012). A total of 316 Steller Sea Lions and another 21 sea lions not identified to species were killed from 1990-2000. Numbers of Steller Sea Lions shot annually were low (averaging less than 10) until the mid-1990s, but increased and peaked at an estimated 91 in 1999 (Jamieson and Olesiuk 2001). A mean of 45.8 Steller Sea Lions were shot per year in British Columbia from 1999-2003 (Olesiuk 2004). Three Steller Sea Lions were reported drowned as a result of entrapment in finfish aquaculture installations between 1989 and 2012 although prior to 2011 there were no reporting requirements for such incidents (unpubl. data from DFO Marine Mammal Response Program, Pacific Region).

Since the listing of Steller Sea Lions as Special Concern in 2004, the 100 or so salmon farms currently operating in British Columbia waters are not permitted to kill Steller Sea Lions, but can apply for licences to shoot nuisance California Sea Lions and Harbour Seals (Fisheries and Oceans Canada 2011). Whether or not Steller Sea Lions are being misidentified and shot is unknown (Fisheries and Oceans Canada 2011). However, the sensitivity of markets in the United States to marine mammals being harmed to produce farmed salmon has likely reduced the numbers of pinnipeds killed at fish farms in recent years. In recent years, all nuisance seals that are killed are reported publicly on line by DFO. However, this public reporting initiative may have led to more inaccurate reporting (report wrong species intentionally or not reporting at all) for fear of public or legal repercussions.

Steller Sea Lions are also killed incidentally in various fisheries, particularly drift gillnet and seine net fisheries for salmon, but there is not enough observer coverage in British Columbia to adequately monitor bycatch levels (Fisheries and Oceans Canada 2011). Animals can get trapped in trawl nets or entangled in drift and gillnets, and ultimately drown.

Data from observers (groundfish fisheries) and log books (salmon fisheries) in British Columbia reported 92 Steller Sea Lions as bycatch from 1996-2012, of which 70 were dead and 22 were released alive. These 92 incidents were associated with bottom trawl (80%), seine (14%), gillnet (3%), and midwater trawl (3%) fisheries (DFO Marine Mammal Response Program). Impacts of groundfish fisheries may be inflated over other fisheries because of having 100% observer coverage, whereas salmon fisheries have incomplete coverage, and compliance with mandatory reporting in logbooks is unknown. On average, 4 Steller Sea Lions were reported to die each year due to bycatch in British Columbia fisheries (not including accidental drownings in aquaculture installations). Other fisheries that may interact with sea lions do not have observers or electronic monitoring.

In the Gulf of Alaska and Aleutian Islands, a minimum of 28.5 Steller Sea Lions die on average each year, but only 1 sea lion is believed to die annually in fishing gear in California, Oregon, Washington and Southeast Alaska based on observer and stranding data (Loughlin and York 2000; Allen and Angliss 2012). Steller Sea Lions occasionally take fish from commercial troll and recreational gear, and it is not uncommon to see animals hooked in the esophagus or stomach with salmon flashers dangling from their mouths. Illegal and undocumented killing occurs in British Columbia as many fishers consider sea lions to be a nuisance and to negatively impact fish stocks. There are records for 5 confirmed reports of shooting at Steller Sea Lions, and 5 reported that were probable shootings dating back to 2007 (DFO Marine Mammal Response Program). However, the actual extent of killing is poorly understood, and the effect on Steller Sea Lion populations is unknown (Fisheries and Oceans Canada 2011).

Entanglement in synthetic debris is a growing worldwide problem and has been implicated in the declines of other species of pinnipeds (Fowler and Merrell 1986; Fowler 1988). Debris such as net fragments and packing bands can get caught around necks, eventually leading to abrasion or cutting deeply into tissue as animals grow. In Steller Sea Lions, entanglement begins to occur at 2 to 4 years of age (entanglement of pups and yearlings has not been observed), with packing bands and net debris being the most common material (Calkins 1985; Mate 1985; Loughlin et al. 1986; Stewart and Yochem 1987; Fowler 1988; Raum-Suryan et al. 2009).

The most extensive survey of entangled sea lions in northern British Columbia and Southeast Alaska found 0.26% of sea lions at 69 rookeries and haulouts were entangled in debris or had ingested fishing gear (Raum-Suryan et al. 2009). Packing bands were the most common neck entangling material (54%), followed by rubber bands (30%), net (7%), rope (7%) and monofilament line (2%). However, much of the debris found at sea or washed ashore may be too large for an animal to transport, so the observed rate of entanglement at haulouts could represent a small fraction of numbers actually being entangled and drowned at sea. Some sea lions had ingested fishing gear including salmon fishery flashers (lures – 80%), longline gear (12%), hook and line (4%) spinners/spoons (2%), and bait hooks (2%). Additional data from the DFO Marine Mammal Response Program (1998-2012) indicate that 53% of reported entangled Steller Sea Lions had debris around their necks, and 47% had hooks and flashers dangling from their mouths. Of the neck entanglements, 14% were described as miscellaneous line/rope, 6% net, 1% anchor, 1% chain, 1% band, and 24% unidentified types of gear/debris (obscured or unidentifiable). Overall, entanglement in marine debris and ingestion of fishing gear can lead to a slow and excruciating death due to infection and inability to feed. Entanglement appears to affect many sea lions and is being monitored, but the impact on Steller Sea Lion populations is unknown.

Displacement from or degradation of essential habitat may also limit sea lion populations. Repeated disturbances by aircraft, boats, pedestrians, construction, and fishing activities can lead animals to temporarily leave haulouts and rookeries (Sandegren 1970; Calkins and Curatolo 1980; Johnson et al. 1989; Brown 1997; Kucey 2005) and eventually abandon­ them permanently (Pike and Maxwell 1958; Kenyon 1962). Acoustic disturbance related to oil and gas exploration, alternative energy development and other resource extraction also has the potential to disturb animals (Fisheries and Oceans Canada 2011). Steller Sea Lions can habituate to some level of disturbance, and some haulout sites are located in high traffic areas close to major urban centres such as Vancouver and Victoria (Bigg 1985; Olesiuk unpub . data).

Environmental contaminants such as heavy metals, polychlorinated biphenyls (PCBs) and other organochlorines such as DDT, dioxins and furans bioaccumulate through marine food chains and have been reported in Steller Sea Lions in British Columbia (Alava et al. 2012). As with other marine mammals, contaminant concentrations in Steller Sea Lions (predominantly organochlorines) increase with age and are highest among old males, whereas females reduce contaminant loads during lactation (Lee et al. 1996). The possible negative effects of contaminants on birth and survival rates are unknown, but are presumably dose-dependent.

Steller Sea Lions can be affected by catastrophic accidents such as chemical and oil spills (St. Aubin 1990), although population level effects have rarely been established. The main threat is likely through contact with heavy oil when the source of the spill is near rookeries and haulout sites, and to a lesser degree from absorption through skin, ingestion of oil directly or through feeding, exposure to vapours, and fouling of pelage by fresh oil (Smith and Geraci 1975; Engelhardt et al. 1977; Englehardt 1987; St. Aubin 1990). Sea lions are insulated by blubber, so oiled fur interferes less with thermoregulation than it would if the animals depended on fur for insulation (Kooyman et al. 1976). Heavy fouling in thick oil can impede swimming and result in drowning (Geraci and St. Aubin 1980), but light contamination and light-viscosity oil usually wears off within several days (Geraci and Smith 1976).

Calkins and Pitcher (1982) reported seeing Steller Sea Lions in the Gulf of Alaska with tar in their throats or around their lips, jaws and necks. Oil observed on the pelage of pinnipeds during the Exxon Valdez oil spill (EVOS) in Prince William Sound did not persist on the coats of Steller Sea Lions as long as it did on Harbour Seals (Calkins et al. 1994a). Nevertheless, Steller Sea Lions were observed in the vicinity of the oil spill and metabolites in the blood showed they had been exposed to hydrocarbons. Premature births were more common and pup production was somewhat lower in the year following the spill, but limited data prior to EVOS and the ongoing population decline in the area made it difficult to assess the statistical significance of the impact (Calkins et al. 1994b; Loughlin et al. 1996).

Several Steller Sea Lions with small patches of oiled fur were observed during the Nestucca spill that spread along the west coast of Vancouver Island in 1988 (Harding and Englar 1989). Reports of large numbers of completely fouled animals after this spill most likely concerned California Sea Lions, which have black pelage (Olesiuk unpub . data). Because Steller Sea Lions are widely dispersed along the entire British Columbia coast, the potential threat of oil and chemical spills is one of local depletion, particularly at rookeries during the breeding season, as opposed to a threat that would affect the entire population. However, considering that over 70% of pup production in British Columbia occurs on the Scott Islands, an oil spill in that area during the pupping season could have a significant impact. This threat is likely to increase due to the planned expansion of shipping from the port of Kitimat, due to the proposed Northern Gateway Project, as well as liquid natural gas pipelines and facility construction.

Environmental factors may limit Steller Sea Lion populations through changes in their prey base or by increasing their susceptibility to disease. Storms can cause pups to be washed from rookeries (Edie 1977), and El Nino events have led to abnormally high mortality in California (Allen et al. 1999). With the focus on climate change, researchers are beginning to appreciate that the environment fluctuates, and evidence is accumulating on decade-scale oscillations that affect the biota of the North Pacific (Benson and Trites 2002; Trites et al. 2007c; Maschner et al. 2013).

Environmental shifts and fishing can both affect the abundance and availability of prey (e.g., Alverson 1992; Benson and Trites 2002; Trites et al. 2007c), which in turn can affect both foraging behaviour and the population dynamics of pinnipeds (e.g., Trillmich and Ono 1991; Boyd et al. 1994), and ultimately carrying capacity (Trites et al. 1997). Steller Sea Lions consume many of the same prey resources sought by other predators, including Humans (McAlister and Perez 1976; Kajimura and Loughlin 1988; Fritz et al. 1995; Wada 1998; Trites et al. 1999b), but the effects of this competition are unknown (Bowen 1997; Trites 1997; Trites et al. 1999a).

One hypothesis suggests the decline of the western population of Steller Sea Lions was driven by a reduction in the quantity of available prey, which reduced body growth, birth rates and ultimately survival―while an alternative hypothesis suggests the decline was due to an increase in the abundance of low quality prey that reduced birth rates (Calkins and Goodwin 1988; Calkins et al. 1998; Pitcher et al. 1998; Trites and Donnelly 2003; NMFS 2008). However, debate continues over the relative influence of natural fluctuations in environmental conditions, regime shifts, and anthropogenic effects that may be the result of climate change, whaling and commercial fisheries (Pascual and Adkinson 1994; Fritz and Ferrero 1998; Trites et al. 1999b; Rosen and Trites 2000a; Shima et al. 2000; Benson and Trites 2002; Springer et al. 2003; Trites et al. 2007b; Trites et al. 2007c; Bernard et al. 2011; Horning and Mellish 2012; Maschner et al. 2013).

Natural predators may also limit populations, particularly when populations are at low numbers. In general, Steller Sea Lions and other high trophic level predators are thought to be regulated by bottom-up processes that limit the availability of prey (Trillmich and Ono 1991; Boyd et al. 1994; Trites et al. 1997; Trites et al. 2007c). However, it has been hypothesized that some populations may be limited by top-down processes, such as predation by Killer Whales (Estes et al. 1998; Springer et al. 2003; Horning and Mellish 2012). Although detailed data on Killer Whale predation rates are lacking, models show that predation by Killer Whales could be holding depressed populations of Steller Sea Lions below carrying capacity (Guénette et al. 2006; Guénette et al. 2007).

Finally, disease may also limit pinniped populations, especially at high densities (Harwood and Hall 1990; Lavigne and Schmitz 1990). Steller Sea Lions are host to a number of pathogens including Leptospira interrogans, caliciviruses, Chlamydia psittaci, Brucella sp., morbilliviruses, influenza A, Toxoplasma gondii, phocid herpesviruses, canine parvovirus and canine adenoviruses 1 and 2 (Burek et al. 2003; Burek et al. 2005). Steller Sea Lions in British Columbia have not been screened for disease, although the few recovered carcasses that showed cause for disease concern have been tested (S. Raverty, pers. comm.).

Number of Locations

Steller Sea Lions are most vulnerable to threats while concentrated at haulouts and the 5 rookeries (Table 1). Rookeries are groups of breeding sites within a radius of 20 km that would all likely be affected by the same catastrophic event, such as an oil spill. The distribution of haulouts throughout BC waters (Figure 4) lessens the threats posed by catastrophic events such as oil spills. Even the risk posed to the high concentration of sea lions at the three historical breeding sites (Figure 4) is somewhat mitigated by the creation of two new breeding sites (since 2006) and having ~40% of the population remaining at haulouts during the breeding season (Olesiuk 2011).

Top of Page

Protection, Status, and Ranks

Legal Protection and Status

The Steller Sea Lion was designated Not at Risk in April 1987, and reassessed as Special Concern in November 2003 based on an update status report. The 2003 assessment indicated that the species met criteria for Threatened because only three breeding locations occurred in British Columbia at that time--but it was designated as Special Concern because the population was increasing and a rescue effect was possible. Now listed as Special Concern under SARA, a management plan for Steller Sea Lions is in place (Fisheries and Oceans Canada 2011). COSEWIC re-assessed this species in November 2013 as Special Concern.

Management of marine mammals in Canadian waters is a federal responsibility. Since 1970, sea lions have been protected by various regulations enacted under the Fisheries Act and enforced by Fisheries and Oceans Canada (DFO). In the Pacific Region, which encompasses the entire Canadian range of Steller Sea Lions, protection was originally provided under Section 21 of the British Columbia Fishery (General) Regulations, which stipulated that: “No person shall fish for, catch and retain, kill, disturb or molest an elephant seal, a harbour seal, a sea lion or a sea otter or have in possession any such seal, sea lion or sea otter or any portion thereof except under licence issued by the Minister. Prior to being amended in 1984, however, the regulations also contained a provision giving blanket exclusion to commercially licensed fishers, who were allowed to disturb or kill seals and sea lions to protect their gear and catch. The provision was not widely known, and although no statistics on such kills are available, discussions with fishers suggest they were probably rare.

In 1993, the regional regulations were superseded by the national Marine Mammal Regula­tions under the Fisheries Act, which in Section 7 stipulated “No person shall disturb a marine mammal except when fishing for marine mammals under the authority of these Regulations”. Section 5 further states that: “Subject to section 6 (exclusion for natives), no person shall fish for marine mammals except under the authority of a licence issued under these Regulations or under the Aboriginal Communal Fishing Licences Regula­tions”. Section 6(1) allows that “An Indian or Inuk other than a beneficiary may, without a licence, fish for food, social or ceremonial purposes for (a) seals…”. Since 1993, the entire Pacific Region has been closed to commercial hunting of all marine mammals, including Steller Sea Lions.

In addition to protection from killing, Section 11 of the regulations stipulates that: “No person, other than the holder of a licence to fish for marine mammals for experimental, scientific, educational or public display purposes issued under the Fishery (General) Regulations, shall (a) move a live marine mammal from the immediate vicinity in which it is found; or (b) tag or mark, or attempt to tag or mark, a live marine mammal in any manner.” During the 1990s, three permits were issued to the North Pacific Universities Marine Mammal Research Consortium through the University of British Columbia to live-capture a total of 15 pups for captive studies. Six additional pups were captured in 2003.

Since being protected in 1970, small numbers of Steller Sea Lions have been killed in British Columbia under special permits. In 1990, DFO began issuing permits to salmon farm sites on the west coast (mainly salmon farms, but also a few herring spawn-on-kelp operations and fish traps) that allowed them to shoot seals and sea lions that were interfering with their activities. DFO has since amended the Marine Mammal Regulations to create a new class of licence for killing nuisance ‘seals’, which as defined in the regulations includes Steller Sea Lions. A nuisance ‘seal’ is defined as one that: “a) represents a danger to fishing equipment despite deterrence efforts, or b) based on a scientific recommendation, represents a danger to the conservation of anadromous or catadromous fish stocks because it inflicts great damage to them along estuaries and in rivers and lakes during the migration of those species”. However, the killing of Steller Sea Lions under a Nuisance Seal Permit has been prohibited by DFO since they were listed under SARA as a Species of Special Concern.

In the United States, the Steller Sea Lion is protected under the US Marine Mammal Protection Act and is listed as endangered in the western portion of its range under the US Endangered Species Act (NMFS 2008). In 2013, the US government delisted the eastern population (shared with Canada) because it has increased and new breeding sites have been established. Steller Sea Lions are not listed under CITES (the Convention on International Trade in Endangered Species).

Top of Page

Non-Legal Status and Ranks

Eumetopias jubatus monteriensis has increased steadily since 1979, and in 2011 it was 170% larger than in 1981. Therefore, E. j. monteriensis qualifies for Least Concern according to the IUCN Red List (Gelatt and Lowry 2012).

NatureServe Canada ranked the global status of Steller Sea Lions in 2011 as G3 – Vulnerable, noting that “The handful of Canadian breeding colonies, once considered small and peripheral to the heart of the species’ range in the Aleutian Islands, now represent one of the few stable populations of Steller Sea Lions” (Cannings et al. 2005; NatureServe Canada). The Steller Sea Lion is thus considered to be a Canadian species of global conservation concern.

The Steller Sea Lion was red-listed in British Columbia by the provincial government in 1992, primarily on the basis of there being only three major breeding areas in British Columbia, the total population numbered only about 10,000, and the lack of recovery since cessation of the population culls (Cannings et al. 1999). Its Provincial Conservation Status has since been down-listed to a blue-listed species (B.C. Conservation Data Centre 2012). Blue-listed species are any indigenous species or subspecies considered to be of Special Concern in British Columbia. Taxa of Special Concern have characteristics that make them particularly sensitive or vulnerable to human activities or natural events. Blue-listed taxa are at risk, but are not Extirpated, Endangered or Threatened. Steller Sea Lions have a Provincial Status of S2S3B,S3N (2007) and a Conservation Framework (CF) Priority of 2 (B.C. Conservation Data Centre 2012). It is considered to be Imperilled to Vulnerable on the breeding grounds, and Vulnerable in the non-breeding season.

Top of Page

Habitat Protection and Ownership

The breeding rookeries at the Scott Islands, as well as several haulout sites within this archipelago, have also been designated as Ecological Reserves under the British Columbia Ecological Reserves Act. The rookery at Cape St. James was also once an Ecological Reserve, but became part of Gwaii Haanas National Park Reserve when it was created in 1987 under the federal National Parks Act. The Gwaii Haanas Park Reserve is co-managed by the federal government and the Haida Nation. In 2010, the Gwaii Haanas National Marine Conservation Area Reserve was established, which protects 3,500 km2 of marine waters surrounding the National Park Reserve. Thus 3 of the 5 existing breeding areas are protected (only Danger Rocks and Virgin Rocks are not). Extraction of resources is not permitted, and visitation is restricted through the issuance of permits.

The Oceans Act introduced in 1996 also provides protection for marine-mammal habitat by allowing for the creation of Marine Protected Areas to protect non-commercial species as well as threatened and endangered species. One of the first two pilot MPAs to be established on the Pacific coast of Canada was Race Rocks, in part because it was recognized as an important winter haulout for Steller and California sea lions.

Management of marine mammals in the waters adjacent to British Columbia is a US federal respon­si­­bility, and Steller Sea Lions are protected from disturbance and killing under the US Marine Mammal Protection Act of 1972 (MMPA). Due to the dramatic declines that have occurred in the Gulf of Alaska and Aleutian Islands, the western population of Steller Sea Lions is considered to be depleted under the MMPA, and was listed as endangered in 1997 under the U.S. Endangered Species Act (62 US Federal Register 24345, 5 May 1977). Although similar declines have not been observed south of Prince William Sound, the eastern population was listed as threatened in the US, primarily due to concerns that the declines would spread from the same causes with the same severity (which did not occur), and doubts about the then tentative evidence of genetic distinction between the two populations (also since shown to be unfounded). The US is considering removing the eastern population from the Endangered Species List due to continued population growth (NMFS 2012). The listings of the western population prompted a number of management actions to protect Steller Sea Lion critical habitat, including the creation of 3-nautical-mile no-entry zones around breeding rookeries, prohibition of groundfish trawling within 10-20 nm of certain rookeries, and spatial and temporal reallocation and in some cases closure of Walleye Pollock and Atka Mackerel (Pleurogrammus monopterygius) fisheries. A recovery plan for Steller Sea Lions was developed (NMFS 1992; NMFS 2008).

Top of Page

Acknowledgements and Authorities Contacted

Careful and thoughtful comments were provided by Jane Watson, Randall Reeves, Michael Kingsley, Hal Whitehead, Lisa Spaven, Christie Whelan, Justine Mannion, Caroline Girard, Helen Davis and Syd Cannings.

Top of Page

Information Sources

Aboriginal Traditional Knowledge Subcommittee of COSEWIC. 2011. ATK source report on Steller Sea Lion (Eumetopias jubatus). Committee on the Status of Endangered Wildlife in Canada, Environment Canada. Ottawa, ON. 43 pp.

Ainley, D.G., C.S. Strong, H.R. Huber, T.J. Lewis, and S.H. Morrell. 1981. Predation by sharks on pinnipeds at the Farallon Islands. Fisheries Bulletin 78:941-945.

Alaska Sea Grant. 1993. Is it food? Addressing marine mammal and sea bird declines. University of Alaska Sea Grant, 93-01. Fairbanks, AK. pp.

Alava, J.J., D. Lambourn, P. Olesiuk, M. Lance, S.J. Jeffries, F.A.P.C. Gobas, and P.S. Ross. 2012. PBDE flame retardants and PCBs in migrating Steller sea lions (Eumetopias jubatus) in the Strait of Georgia, British Columbia, Canada. Chemosphere 88: 855–864.

Allen, B.M., and R.P. Angliss. 2012. Alaska marine mammal stock assessments, 2011. National Marine Fisheries Service (NMFS) - Alaska Fisheries Science Center (AFSC). NOAA Technical Memorandum NMFS-AFSC-234. 288 pp.

Allen, J.A. 1880. History of North American pinnipeds, a monograph of the walruses, sea-lions, sea-bears, and seals of North America. U.S. Geol. Geogr. Surv. Terr., Misc. Publ. 12.

Allen, S.G., H. Nevins, D. Notthelfer, J. Pettee, D. Press, and S. Waber. 1999. ENSO effects on pinnipeds at Point Reyes [abstract]. Wildlife Society 6th Annual Confernce, 7-11 Sept 1999, Austin, TX.

Alverson, D. 1992. A review of commercial fisheries and the Steller sea lion (Eumetopias jubatus): the conflict arena. Reviews in Aquatic Sciences 6:203-256.

Andrews, R.D. 1999. Preliminary progress report of Steller sea lion (SSL) foraging ecology studies. Presentation to the Steller Sea Lion Research Peer Review Feeding Ecology Workshop Seattle, Washington, February 11-12, 1999. pp.

Andrews, R.D., D.G. Calkins, R.W. Davis, B.L. Norcross, K. Peijnenberg, and A.W. Trites. 2002. Foraging behavior and energetics of adult female Steller sea lions. pp. 19-22. In D. DeMaster and S. Atkinson (eds.). Steller sea lion decline: Is it food II?, University of Alaska Fairbanks, Alaska Sea Grant College Program (Report No. AK-SG-02-02), Fairbanks, AK.

B.C. Conservation Data Centre. 2012. B.C. species and ecosystems explorer. B.C. Ministry of Environment. Victoria, B.C. Web site: [accessed 03 Sept, 2012].

Baker, A.R., T.R. Loughlin, V. Burkanov, C.W. Matson, R.G. Trujillo, D.G. Calkins, J.K. Wickliffe, and J.W. Bickham. 2005. Variation of mitochondrial control region sequences of Steller sea lions: the three-stock hypothesis. Journal of Mammalogy 86:1075-1084.

Ban, S., J. Porter, M. Foreman, and A.W. Trites. 2003. Marine habitat characteristics of haulout sites used by Steller sea lions in British Columbia, Canada. in prep.

Ban, S., and A.W. Trites. 2007. Quantification of terrestrial haul-out and rookery characteristics of Steller sea lions. Marine Mammal Science 23:496-507.

Barrett-Lennard, L.G., K. Heise, E. Saulitis, G. Ellis, and C. Matkin. 1995. The impact of killer whale predation on Steller sea lion populations in British Columbia and Alaska. University of British Columbia, Fisheries Centre, 2204 Main Mall, Vancouver, B.C. V6T 1Z4. Unpublished Report. 77 pp.

Beach, R.J., A.C. Geiger, S.J. Jeffries, S.D. Treacy, and B.L. Routman. 1985. Marine mammals and their interactions with fisheries of the Columbia River and adjacent waters, 1980-82. U.S. Department of Commerce, NWAFC Processed Report. 85-04, 316 pp.

Benson, A.J., and A.W. Trites. 2002. Ecological effects of regime shifts in the Bering Sea and eastern North Pacific Ocean. Fish and Fisheries 3:95-113.

Bernard, D.R., S.J. Jeffries, G. Knapp, and A.W. Trites. 2011. An independent, scientific review of the Biological Opinion (2010) of the National Marine Fisheries Service Fisheries Management Plan for the Bering Sea/Aleutian Islands management areas. In Alaska Department of Fish and Game, Special Publication 11-16. Anchorage, AK. Alaska Department of Fish and Game, Special Publication 11-16. 136 pp.

Beverton, R.J.H. 1985. Analysis of marine mammal-fisheries interaction. pp. 3-33. In J. R. Beddington, R. J. H. Beverton and D. M. Lavigne (eds.). Marine mammals and fisheries, George Allen & Unwin, London, UK.

Bickham, J.W., J.C. Patton, and T.R. Loughlin. 1996. High variability for control-region sequences in a marine mammal: implications for conservation and biogeography of Steller sea lions (Eumetopias jubatus). Journal of Mammalogy 77:95-108.

Bigg, M.A. 1984. Sighting and kill data for the Steller sea lion (Eumetopias jubatus) and California sea lion (Zalophus californianus) in British Columbia, 1892-1982, with some records from Washington and southeastern Alaska. Nanaimo, BC. Can. Data Rep. Fish. Aquat. Sci. 460, 191 pp.

Bigg, M.A. 1985. Status of Steller sea lion (Eumetopias jubatus) and California sea lion (Zalophus californianus) in British Columbia. Can. Spec. Publ. Fish. Aquat. Sci. 77:1-20.

Bigg, M.A. 1988. Status of the Steller sea lion Eumetopias jubatus in Canada. Canadian Field Naturalist 102:315-336.

Bigg, M.A., G.M. Ellis, P. Cottrell, and L. Milette. 1990. Predation by harbour seals and sea lions on adult salmon in Comox Harbour and Cowichan Bay, British Columbia. Canadian Technical Report of Fisheries and Aquatic Sciences 1769:1-31.

Bowen, W.D. 1997. Role of marine mammals in aquatic ecosystems. Marine Ecology Progress Series 158:267-274.

Boyd, I.L., J.P.Y. Arnould, T. Barton, and J.P. Croxall. 1994. Foraging behaviour of Antarctic fur seals during periods of contrasting prey abundance. Journal of Animal Ecology 63:703-713.

Braham, H.W., R.D. Everitt, and D.J. Rugh. 1980. Northern sea lion decline in the eastern Aleutian Islands. Journal of Wildlife Management 44:25-33.

Brandon, E.A.A., R.W. Davis, S. Kanatous, D.G. Calkins, and T.R. Loughlin. 1996. Pup condition and growth rates in declining and stable populations of Steller sea lions in Alaska. In Steller sea lion recovery investigations in Alaska, 1992-1994. Alaska Department of Fish and Game, Division of Wildlife Conservation. Wildlife Technical Bulletin. 13, 62-68 pp.

Brenton, C.M. 1977. Inter and intraspecific behaviour of Eumetopias jubatus and Zalophus californianus on a winter haulout area. M.Sc. thesis, University of British Columbia, Vancouver, BC. 131 pp.

Brown, R.F., and S.D. Reimer. 1992. Steller sea lion counts in Oregon during June and July, 1975-1991. In-house Report, Nongame Wildlife Program, Oregon Department Fish and Wildlife, Newport, Oregon, 97365. 12 pp.

Brown, R.F. 1997. Pinnipeds in Oregon: status of populations and conflicts with fisheries, fish resources and human activities. In G. Stone, J. Goebel and S. Webster (eds.). Pinniped populations, East North Pacific: status, trends and issues, 127th Annual Meeting American Fisheries Society, 28 Aug 1997, Monterey, CA.

Burek, K.A., F.M.D. Gulland, G. Sheffield, E. Keyes, T.R. Spraker, A.W. Smith, D.E. Skilling, J. Evermann, J.L. Stott, and A.W. Trites. 2003. Disease agents in Steller sea lions in Alaska: a review and analysis of serology data from 1975-2000. Fisheries Centre Research Reports. 26 pp.

Burek, K.A., F.M.D. Gulland, G. Sheffield, K.B. Beckmen, E. Keyes, T.R. Spraker, A.W. Smith, D.E. Skilling, J.F. Evermann, J.L. Stott, J.T. Saliki, and A.W. Trites. 2005. Infectious disease and the decline of Steller sea lions (Eumetopias jubatus) in Alaska, USA: Insights from serologic data. Journal of Wildlife Diseases 41:512-524.

Burkanov, V.N. 2000. Steller's sea lion population status and dynamics in Russian waters in 1989-1999. Marine Mammals of the Holarctic Regions: Materials from International Conference, Archangelsk, Russia 21-23 September, 2000. Pages 56-65 (in Russian).

Calkins, D. 1985. Steller sea lion entanglement in marine debris. pp. 308-314. In R. S. Shomura and H. O. Yoshida (eds.). Proceedings of the workshop on the fate and impact of marine debris, NOAA-TM-NMFS-SWFC-54, Honolulu.

Calkins, D., E. Becker, T.R. Spraker, and T.R. Loughlin. 1994a. Impacts on Steller Sea Lions. pp. 119-139. Marine Mammals and the Exxon Valdez, Academic Press, Inc.

Calkins, D.G., and J.A. Curatolo. 1980. Marine mammals of Lower Cook Inlet and the potential for impact from outer continental shelf oil and gas exploration, development and transport. ADF&G Unpublished Report. 81 pp.

Calkins, D.G., and K.W. Pitcher. 1982. Population assessment, ecology and trophic relationships of Steller sea lions in the Gulf of Alaska. pp. 445-546. Environmental assessment of the Alaskan continental shelf: final reports of principal investigators, U.S. Dept. of Commer., N.O.A.A., Juneau, Alaska.

Calkins, D.G., and E. Goodwin. 1988. Investigation of the declining sea lion population in the Gulf of Alaska. Alaska Department of Fish and Game. Anchorage, Alaska. Unpublished Report. 76 pp.

Calkins, D.G., E. Becker, T.R. Spraker, and T.R. Loughlin. 1994b. Impacts on the distribution and abundance of Steller sea lions in Prince William Sound and the Gulf of Alaska. pp. 119-137. In T. R. Loughlin (ed.). Marine mammals and the Exxon Valdez, Academic Press, San Diego.

Calkins, D.G., and K.W. Pitcher. 1996. Steller sea lion movements, emigration and survival. pp. 34-40. Steller sea lion recovery investigations in Alaska, 1992-1994. (Pitcher, K. W. compiler). Wildlife Technical Bulletin No. 13, Alaska Department of Fish and Game, 333 Raspberry Road, Anchorage, AK 99518.

Calkins, D.G., E.F. Becker, and K.W. Pitcher. 1998. Reduced body size of female Steller sea lions from a declining population in the Gulf of Alaska. Marine Mammal Science 14:232-244.

Calkins, D.G., D.C. McAllister, K.W. Pitcher, and G.W. Pendleton. 1999. Steller sea lion status and trend in Southeast Alaska: 1979-1997. Marine Mammal Science 15:462-477.

Cannings, S., M. Anions, R. Rainer, and B.S. . 2005. Our home and native land: Canadian species of global conservation concern. NatureServe Canada, Ottawa, Ontario. 44 pp.

Cannings, S.G., L.R. Ramsay, D.F. Fraser, and M.A. Fraker. 1999. Rare amphibians, reptiles, and mammals of British Columbia. Wildlife Branch and Resources Inventory Branch, B.C. Ministry of Environment, Lands and Parks, Victoria, BC. 198 pp.

Committee on Taxonomy. 2012. List of marine mammal species and subspecies. Society for Marine Mammalogy. Web site: [accessed October 2012].

Daniel, R.G. 2003. The timing of moulting in wild and captive Steller sea lions (Eumetopias jubatus). M.Sc. thesis, University of British Columbia, Vancouver, British Columbia, Canada. 64 pp.

DeMaster, D., and S. Atkinson. (eds.). 2002. Steller sea lion decline: is it food II? University of Alaska Sea Grant, AK-SG-02-02 pp.

Duff, W. 1977. The Indian history of British Columbia, Vol. 1. The impact of the White man. Anthropology in British Columbia. Memoir No. 5. British Columbia Provincial Museum, Victoria, BC. 117 pp.

Edie, A.G. 1977. Distribution and movements of Steller sea lion cows (Eumetopias jubatus) on a pupping colony. M.Sc. thesis, University of British Columbia, Vancouver, British Columbia, Canada. 81 pp.

Elliot, H.W. 1882. The sea lion (Eumetopias stelleri). A monograph of the seal-islands of Alaska., U.S. Commission of Fish and Fisheries Spec. Bull., Govt. Printing Office, Washington D.C.

Engelhardt, F.R., J.R. Geraci, and T.G. Smith. 1977. Uptake and clearance of petroleum hydrocarbons in the ringed seal, Phoca hispida. Journal of the Fisheries Research Board of Canada 34:1143-1147.

Englehardt, F.R. 1987. Assessment of the vulnerability of marine mammals to oil pollution. pp. 101-115. In J. Kuiper and W. J. Van den Brink (eds.). Fate and effects of oil in marine ecosystems, Martinus Nijoff Publishers, Boston, MA.

Estes, J.A., M.T. Tinker, T.M. Williams, and D.F. Doak. 1998. Killer whale predation on sea otters linking oceanic and nearshore ecosystems. Science 282:473-476.

Fiscus, C.H. 1961. Growth in the Steller sea lion. Journal of Mammalogy 47:195-200.

Fisher, D.H. 1981. Studies on the biology of sea lions in British Columbia. National Geographic Society Research Report 13:215-219.

Fisher, R.A. 1958. The genetical theory of natural selection. Dover, New York, NY. 291 pp.

Fisheries and Oceans Canada. 2011. Management plan for the Steller sea lion (Eumetopias jubatus) in Canada [Final]. Species at Risk Act Management Plan Series. Fisheries and Oceans Canada. Ottawa. vi + 69 pp.

Ford, J.K.B., G.M. Ellis, L.G. Barrett-Lennard, A.B. Morton, R.S. Palm, and K.C. Balcomb III. 1998. Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters. Canadian Journal of Zoology 76:1456-1471.

Fowler, C.W., and T.R. Merrell. 1986. Victims of plastic technology. Alaska Fish Game 18:34-37.

Fowler, C.W. 1988. A review of seal and sea lion entanglement in marine fishing debris. National Marine Mammal Laboratory, Seattle, Washington. Unpublished Manuscript.

Fritz, L.W., R.C. Ferrero, and R.J. Berg. 1995. The threatened status of Steller sea lions, Eumetopias jubatus, under the Endangered Species Act: effects on Alaska groundfish fisheries management. Marine Fisheries Review 5:14-27.

Fritz, L.W., and R.C. Ferrero. 1998. Options in Steller sea lion recovery and groundfish fishery management. Biosphere Conservation 1:7-19.

Gelatt, T. & Lowry, L. 2012. Eumetopias jubatus. In: IUCN 2014. IUCN Red List of Threatened Species. Version 2014.1. Downloaded on 16 June 2014.

Gentry, R.L. 1970. Social behavior of the Steller sea lion. PhD thesis, University of California, Santa Cruz, California, USA. 113 pp.

Gentry, R.L. 1974. The development of social behavior through play in the Steller sea lion. Amer. Zool. 14:391-403.

Gentry, R.L., and J.H. Johnson. 1981. Predation by sea lions on northern fur seal neonates. Mammalia 45:423-430.

Geraci, J.R., and T.G. Smith. 1976. Direct and indirect effects of oil on ringed seals (Phoca hispida) of the Beaufort Sea. Journal of the Fisheries Research Board of Canada 33:1976-1984.

Geraci, J.R., and D.J. St. Aubin. 1980. Offshore petroleum resource development and marine mammals: a review and research recommendations. Marine Fisheries Review 42:1-12.

Gerlinsky, C.D., D.A.S. Rosen, and A.W. Trites. 2013. High diving metabolism results in a short aerobic dive limit for Steller sea lions (Eumetopias jubatus). Journal of Comparative Physiology B:DOI 10.1007/s00360-013-0742-7.

Ghai, R., and S.J. Insley. 2011. Probable effects of resident and transient killer whales (Orcinus orca) on the activity levels of Steller sea lions (Eumetopias jubatus) at Carmanah Point, British Columbia. Marine Mammal Science 27:E227-E233.

Gisiner, R.C. 1985. Male territorial and reproductive behaviour in the Steller sea lion, Eumetopias jubatus. Ph.D. thesis, University of California, Santa Cruz. 146 pp.

Gregr, E.J., and A.W. Trites. 2008. A novel presence-only validation technique for improved Steller sea lion Eumetopias jubatus critical habitat descriptions. Marine Ecology Progress Series 365:247-261.

Guénette, S., S.J.J. Heymans, V. Christensen, and A.W. Trites. 2006. Ecosystem models show combined effects of fishing, predation, competition, and ocean productivity on Steller sea lions (Eumetopias jubatus) in Alaska. Canadian Journal of Fisheries and Aquatic Sciences 63:2495-2517.

Guénette, S., S.J.J. Heymans, V. Christensen, and A.W. Trites. 2007. Ecosystem models of the Aleutian Islands and Southeast Alaska show that Steller sea lions are impacted by killer whale predation when sea lion numbers are low. pp. 150-154. In J. F. Piatt and S. M. Gende (eds.). Proceedings of the Fourth Glacier Bay Science Symposium, U.S. Geological Survey, Juneau, Alaska.

Hancock, D. 1970. California sea lion as a regular winter visitant off the British Columbia coast. Journal of Mammalogy 51:614.

Harding, L.E., and J.R. Englar. 1989. The Nestucca oil spill: fate and effects to May 31, 1989. Canada Environmental Protection Service, Pacific and Yukon. Regional Program Report (Vancouver): 89-01.

Harwood, J., and A. Hall. 1990. Mass mortality in marine mammals: its implications for population dynamics and genetics. Trends in Ecology and Evolution 5:254-257.

Hastings, K.K., L.A. Jemison, T.S. Gelatt, J. Laake, G. Pendleton, J.C. King, A.W. Trites, and K.W. Pitcher. 2011. Cohort effects and spatial variation in age-specific survival of Steller sea lions from southeastern Alaska. Ecosphere 2:111. doi:10.1890/ES11-00215.

Higgins, L. 1984. Maternal behavior and attendance patterns of the Steller sea lion in California. M.Sc. thesis, University of California, Santa Cruz pp.

Hood, W.R., and K.A. Ono. 1997. Variation in maternal attendance patterns and pup behaviour in a declining population of Steller sea lions (Eumetopias jubatus). Canadian Journal of Zoology 75:1241-1246.

Horning, M., and J.-A.E. Mellish. 2012. Predation on an upper trophic marine predator, the Steller sea lion: evaluating high juvenile mortality in a density dependent conceptual framework. PLoS ONE 7(1): e30173. doi:10.1371/journal.pone.0030173.

Hui, T.C.Y. 2011. Steller sea lions and fisheries: competition at sea? M.Sc. thesis, University of British Columbia, Vancouver, B.C. 114 pp.

Jameson, R.J., and K.W. Kenyon. 1977. Prey of sea lions in the Rogue River, Oregon. Journal of Mammalogy 58:672.

Jamieson, G.S., and P.F. Olesiuk. 2001. Salmon farm - pinniped interactions in British Columbia: an analysis of predator control, its justification and alternative approaches. Canadian Stock Assessment Secretariat, Research Document 2001/142. pp.

Jefferson, T.A., S. Leatherwood, and M.A. Webber. 1994. Marine mammals of the world, FAO species identification guide. United Nations Environment Program, Food and Agriculture Organization of the United Nations, Rome. 320 pp.

Johnson, S.R., J.J. Burns, C.I. Malme, and R.A. Davis. 1989. Synthesis of information on the effects of noise and disturbance on major haulout concentrations of the Bering Sea pinnipeds. Document submitted to Mineral Management Service, U.S. Department of Interior, contract no. 14-12-0001-30361. LGL Alaska Research Associates, 505 N. Lights Blvd., Suite 210, Anchorage AK 99503. pp.

Kajimura, H., and T.R. Loughlin. 1988. Marine mammals in the oceanic food web of the eastern subarctic Pacific Bull. Ocean Res. Inst. (Tokyo). Bull. Ocean Res. Inst. (Univ. Tokyo) 26:187-223.

Kastelein, R.A., N. Vaughan, and P.R. Wiepkema. 1990. The food consumption of Steller sea lions (Eumetopias jubatus). Aquatic Mammals 15:137-144.

Kenyon, K.W., and V.B. Scheffer. 1955. The seals, sea-lions and sea otter of the Pacific coast: descriptions, life history notes, photographs and drawings. U.S. Fish and Wildlife Service Circular No. 32.

Kenyon, K.W., and D.W. Rice. 1961. Abundance and distribution of the Steller sea lion. J. Mammal 42:223-234.

Kenyon, K.W. 1962. History of the Steller sea lion at the Pribilof Islands, Alaska. J. Mammal. 43:68-75.

Klimley, A.P., S.D. Anderson, P. Pyle, and R. Henderson. 1992. Spatiotemporal patterns of white shark (Carcharodon carcharias) predation at the South Farallon Islands, California. Copeia:680-690.

Klimley, A.P., B.J.L. Boeuf, K.M. Cantara, J.E. Richert, S.F. Davis, S.V. Sommeran, and J.T. Kelly. 2001. The hunting strategy of white sharks (Carcharodon carcharias) near a seal colony. Marine Biology 138:617-636.

Kooyman, G.L., R.L. Gentry, and W.B. McAlister. 1976. Physiological impact of oil on pinnipeds. Final Report, Research Unit 71 to US Dept Interior, Bureau of Land Management OCSEAP. 23 pp.

Kucey, L. 2005. Human disturbance and the hauling out behaviour of Steller sea lions (Eumetopias jubatus). M.S. thesis, University of British Columbia, Vancouver. 67 pp.

Kucey, L., and A.W. Trites. 2006. A review of the potential effects of disturbance on sea lions: assessing response and recovery. pp. 581-589. In A. W. Trites, S. K. Atkinson, D. P. DeMaster, L. W. Fritz, T. S. Gelatt, L. D. Rea and K. M. Wynne (eds.). Sea lions of the world, Alaska Sea Grant College Program, University of Alaska Fairbanks.

Lavigne, D.M., and O.J. Schmitz. 1990. Global warming and increasing population densities: a prescription for seal plagues. Marine Pollution Bulletin 21:280-284.

Lee, J.S., S. Tanabe, H. Umino, R. Tatsukawa, T.R. Loughlin, and D.C. Calkins. 1996. Persistent organochlorines in Steller sea lion (Eumetopias jubatus) from the bulk of Alaska and the Bering Sea, 1976-1981. Marine Pollution Bulletin 32:535-544.

Lewis, J.P. 1987. An evaluation of a census-related disturbance of Steller sea lions. M.Sc. thesis, University of Alaska, Fairbanks, AK. 93 pp.

Loughlin, T.R., D.J. Rugh, and C.H. Fiscus. 1984. Northern sea lion distribution and abundance: 1956-1980. J. Wildl. Manage. 48:729-740.

Loughlin, T.R., P.J. Gearin, R.L. DeLong, and R.L. Merrick. 1986. Assessment of net entanglement on northern sea lions in the Aleutian Islands, 25 June-15 July 1985. Alaska Fisheries Science Center. Seattle WA. NWAFC Processed Rep. 86-02. 50 pp.

Loughlin, T.R., A.S. Perlov, and V.A. Vladimirov. 1992. Range-wide survey and estimation of total number of Steller sea lions in 1989. Marine Mammal Science 8:220-239.

Loughlin, T.R., B.E. Ballachey, and B.A. Wright. 1996. Overview of studies to determine injury caused by the Exxon Valdez oil spill to marine mammals. Amer. Fish. Soc. Symp. 18:798-808.

Loughlin, T.R. 1997. Using the phylogeographic method to identify Steller sea lion stocks. pp. 159-171. In A. Dizon, S. J. Chivers and W. F. Perrin (eds.). Molecular genetics of marine mammals., Special Publication #3 of the Society for Marine Mammalogy.

Loughlin, T.R. 1998. The Steller sea lion: A declining species. Biosphere Conservation 1:91-98.

Loughlin, T.R., A.S. Perlov, J.D. Baker, S.A. Blokhin, and A.G. Makhnyr. 1998. Diving behavior of adult female Steller sea lions in the Kuril Islands, Russia. Biosphere Conservation 1:21-31.

Loughlin, T.R., and A.E. York. 2000. An accounting of the sources of Steller sea lion, Eumetopias jubatus, mortality. Mar. Fish. Rev. 62:40-45.

Loughlin, T.R. 2009. Steller sea lion. pp. 1107-1110. In W. F. Perrin, B. Wursig and H. G. M. Thewissen (eds.). Encyclopedia of marine mammals, Academic Press, San Diego.

Maniscalco, J.M., P. Parker, and S. Atkinson. 2006. Interseasonal and interannual measures of maternal care among individual Steller sea lions (Eumetopias jubatus). Journal of Mammalogy 87:304-311.

Maniscalco, J.M., K.R. Harris, S. Atkinson, and P. Parker. 2007. Alloparenting in Steller sea lions (Eumetopias jubatus): correlations with misdirected care and other observations. Journal of Ethology 25:125-131.

Marcotte, M.L. 2006. Steller Watch: timing of weaning and seasonal patterns in numbers and activities of Steller sea lions at a year-round haulout site in Southeast Alaska. MSc thesis, University of British Columbia, Vancouver, BC. 74 pp.

Martin, R.A. 2004. Northerly distribution of white sharks, Carcharodon carcharias, in the eastern Pacific and relation to ENSO events. Marine Fisheries Review 66:16-26.

Maschner, H.D.G., A.W. Trites, K.L. Reedy-Maschner, and M. Betts. 2013. The decline of Steller sea lions (Eumetopias jubatus) in the North Pacific: insights from indigenous people, ethnohistoric records and archaeological data. Fish and Fisheries:DOI 10.1111/faf.12038.

Mate, B.R. 1977. Aerial censusing of pinnipeds in the eastern Pacific for assessment of population numbers, migratory distributions, rookery stability, breeding effort and recruitment. Report to Marine Mammal Commission, contract no. MMC-75/01, Marine Mammal Commission, Washington D.C., Available Natl. Tech. Inf. Serv., Springfield, VA as PB 265-859. 67 pp.

Mate, B.R. 1985. Incidents of marine mammal encounters with debris and active fishing gear. pp. 453-457. In R. S. Shomura and H. O. Yoshida (eds.). Proceedings of the workshop on the fate and impact of marine debris, NOAA-TM-NMFS-SWFC-54, Honolulu.

Mathews, E.A., and M.D. Adkison. 2010. The role of Steller sea lions in a large population decline of harbor seals. Marine Mammal Science 26:803-836.

Mathisen, O.A., and R.J. Lopp. 1963. Photographic census of the Steller sea lion herds in Alaska, 1956-58. U.S. Fish and Wildl. Ser., Spec. Sci. Rep. Fish. 424:20.

McAlister, W.B., and M.A. Perez. 1976. Ecosystem dynamics, birds and marine mammals. Part I: Preliminary estimates of pinniped-finfish relationships in the Bering Sea. Northwest Fisheries Center, Alaska Fisheries Science Center. Seattle, WA. Final report for Environmental Assessment of the Alaskan Continental Shelf, RU-77. pp.

McKenzie, J., and K.M. Wynne. 2008. Spatial and temporal variation in the diet of Steller sea lions in the Kodiak Archipelago, 1999 to 2005. Marine Ecology Progress Series 360:263-283.

Merrick, R.L. 1987. Behavioral and demographic characteristics of northern sea lion rookeries. M.Sc. thesis, Oregon State University, Corvallis pp.

Merrick, R.L., T.R. Loughlin, and D.G. Calkins. 1987. Decline in abundance of the northern sea lion, Eumetopias jubatus, in Alaska, 1956-1986. Fisheries Bulletin 85:351-365.

Merrick, R.L., R. Brown, D.G. Calkins, and T.R. Loughlin. 1995. A comparison of Steller sea lion, Eumetopias jubatus, pup masses between rookeries with increasing and decreasing populations. Fishery Bulletin 93:735-758.

Merrick, R.L. 1997. Current and historical roles of apex predators in the Bering Sea ecosystem. Journal of Northwest Atlantic Fishery Science:343-356.

Merrick, R.L., and T.R. Loughlin. 1997. Foraging behavior of adult female and young-of-year Steller sea lions in Alaskan waters. Canadian Journal of Zoology 75:776-786.

Milette, L.L., and A.W. Trites. 2003. Maternal attendance patterns of lactating Steller sea lions (Eumetopias jubatus)from a stable and a declining population in Alaska. Canadian Journal of Zoology 81:340-348.

Miller, W., and J.E. Miller. 1848. Translation of G.W. Steller. 1751. Habits and characteristics of sea lions. In D. S. Jordan (ed.). The fur seals and fur-seal islands of the North Pacific Ocean, Part 3. Mem. Imp. Academy Sciences in St. Petersburg for the year 1849, Government Printing Office, Washington, D.C.

Morton, A.B. 1990. A quantitative comparison of the behaviour of resident and transient forms of the killer whale off the central British Columbia coast. Report of the international Whaling Commission, Special Issue 12:245-248.

Newcombe, C.F., and W.A. Newcombe. 1914. Sea-lions on the coast of British Columbia, Report of the Commission of Fisheries for 1913. 131-139 pp.

NMFS (National Marine Fisheries Service). 1992. Recovery Plan for the Steller sea lion (Eumetopias jubatus). Prepared by the Steller Sea Lion Recovery Team for the National Marine Fisheries Service, Silver Spring, Maryland. 92 pp.

NMFS (National Marine Fisheries Service). 2008. Recovery plan for the Steller sea lion (Eumetopias jubatus). Revision. National Marine Fisheries Service, Silver Spring, MD. 325 pp.

NMFS (National Marine Fisheries Service). 2012. Draft status review of the eastern distinct population segment of Steller sea lion (Eumetopias jubatus). Protected Resources Division, Alaska Region, National Marine Fisheries Service, 709 West 9th St, Juneau, Alaska 99802. 106pp + Appendices pp.

O'Corry-Crowe, G., B.L. Taylor, T. Gelatt, T.R. Loughlin, J. Bickham, M. Basterretche, K.W. Pitcher, and D.P. DeMaster. 2006. Demographic independence along ecosystem boundaries in Steller sea lions revealed by mtDNA analysis: implications for management of an endangered species. Canadian Journal of Zoology 84:1796-1809.

O'Daniel, D., and J.C. Schneeweis. 1992. Steller sea lion, Eumetopias jubatus, predation on Glaucous-winged gulls, Larus glaucescens. Canadian Field Naturalist 106:268.

Olesiuk, P.F., and M.A. Bigg. 1988. Seals and sea lions in British Columbia. Department of Fisheries and Oceans Special Publication. 12 pp.

Olesiuk, P.F., D. Burles, G. Horonowitsch, and T.G. Smith. 1993. Aerial censuses of pinnipeds in the Queen Charlotte Islands, 1 July - 1 August, 1992. Canadian Manuscript Report Fisheries and Aquatic Sciences 2217.

Olesiuk, P.F. 2004. Status of sea lions (Eumetopias jubatus and Zalophus californianus) wintering off southern Vancouver Island. National Marine Mammal Peer Review Committee Working Paper No. 2004-03. pp.

Olesiuk, P.F., D.G. Calkins, K.W. Pitcher, W.L. Perryman, C. Stinchcomb, and M. Lynn. 2008. An evaluation of Steller sea lion (Eumetopias jubatus) pup counts from 35mm oblique photographs. Canadian Stock Assessment Secretariat Research Document 2008/64.

Olesiuk, P.F. 2011. Abundance of Steller sea lions (Eumetopias jubatus) in British Columbia. Canadian Science Advisory Secretariat Research Document 2010/000:1-43.

Olesiuk, P.F., S.J. Jeffries, M.M. Lance, A.W. Trites, P.J. Gearin, K. Miller-Saunders, A. Tabata, S.D. Riemer, and D.M. Lambourn. 2011. Prey requirements and salmon consumption by Steller sea lions (Eumetopias jubatus) in southern British Columbia and Washington State. Canadian Science Advisory Secretariat Research Document 2010/XXX:104 pp., unpublished manuscript.

Orr, R.T., and T.C. Poulter. 1967. Some observations on reproduction, growth, and social behavior in the Steller sea lion. Proceedings of the California Academy of Science 35:193-226.

Parker, P., J.T. Harvey, J.M. Maniscalco, and S. Atkinson. 2008. Pupping-site fidelity among individual Steller sea lions (Eumetopias jubatus) at Chiswell Island, Alaska. Canadian Journal of Zoology 86:826-833.

Pascual, M.A., and M.D. Adkinson. 1994. The decline of the Steller sea lion in the northeast Pacific: demography, harvest or environment. Ecol. Appl. 4:393-403.

Pauly, D., V. Christensen, J. Dalsgaard, R. Froese, and F. Torres Jr. 1998. Fishing down marine food webs. Science 279:860-863.

Perez, M.A., W.B. McAlister, and E.E. Mooney. 1990. Estimated feeding rate relationship for marine mammals based on captive animal data. National Marine Fisheries Service. NOAA Technical Memorandum. NMFS F/NWC-184, pp.

Perez, M.A. 1994. Calorimetry measurements of energy value of some Alaskan fishes and squids. U.S. Dep. Commer. NOAA Tech. Memo. NMFS-AFSC-32, 32 pp.

Phillips, C.D., J.W. Bickham, J.C. Patton, and T.S. Gelatt. 2009a. Systematics of Steller sea lions (Eumetopias jubatus): subspecies recognition based on concordance of genetics and morphometrics. Occasional Paper of the Museum of Texas Tech University 283:1-15.

Phillips, C.D., R.G. Trujillo, T.S. Gelatt, M.J. Smolen, C.W. Matson, R.L. Honeycutt, J.C. Patton, and J.W. Bickham. 2009b. Assessing substitution patterns, rates and homoplasy at HVRI of Steller sea lions, Eumetopias jubatus. Molecular Ecology 18:3379-3393.

Phillips, C.D., T.S. Gelatt, J.C. Patton, and J.W. Bickham. 2011. Phylogeography of Steller sea lions: relationships among climate change, effective population size, and genetic diversity. Journal of Mammalogy 92:1091–1104.

Pike, G.C. 1958. Food of the northern sea lion. Fisheries Research Board of Canada, Progress Report of the Pacific Coast Biological Station. 112, 18-20 pp.

Pike, G.C., and B.E. Maxwell. 1958. The abundance and distribution of the northern sea lion (Eumetopias jubata) on the coast of British Columbia. Journal of the Fisheries Research Board of Canada 15:5-17.

Pitcher, K.W. 1981. Prey of the Steller sea lion, Eumetopias jubatus, in the Gulf of Alaska. Fishery Bulletin 79:467-472.

Pitcher, K.W., and F.H. Fay. 1982. Feeding by Steller sea lions on harbor seals. The Murrelet 63:70-71.

Pitcher, K.W., D.G. Calkins, and G. Pendleton. 1998. Reproductive performance of female Steller sea lions: an energetics-based reproductive strategy? Canadian Journal of Zoology 76:2075-2083.

Pitcher, K.W., P. F. Olesiuk, R. F. Brown, M. Lowry, J. Sease, W. Perryman, C. Stinchcomb, and L. Lowry. 2003. Status and trend of the eastern population of Steller sea lions. Marine Sciences in the Northeast Pacific Symposium, 13-17 January, 2003, Anchorage, Alaska.

Pitcher, K.W., P.F. Olesiuk, R.F. Brown, M.S. Lowry, S.J. Jeffries, J.L. Sease, W.L. Perryman, C.E. Stinchcomb, and L.F. Lowry. 2007. Abundance and distribution of the eastern North Pacific Steller sea lion (Eumetopias jubatus) population. Fishery Bulletin 105:102-115.

Porter, B. 1997. Winter ecology of Steller sea lions (Eumetopias jubatus) in Alaska. M.Sc. thesis, University of British Columbia, Vancouver, British Columbia, Canada. 84 pp.

Raum-Suryan, K., and K.W. Pitcher. 2000. Trip report: brand resights of Steller sea lions within Southeast Alaska and northern British Columbia from 19 June - 10 July, 2000. Unpubl. Report. Available form Alaska Department of Fish and Game, 333 Raspberry Road, Anchorage, Alaska.

Raum-Suryan, K.L., K.W. Pitcher, D.G. Calkins, J.L. Sease, and T.R. Loughlin. 2002. Dispersal, rookery fidelity, and metapopulation structure of Steller sea lions (Eumetopias jubatus) in an increasing and a decreasing population in Alaska. Marine Mammal Science 18:746-764.

Raum-Suryan, K.L., L.A. Jemison, and K.W. Pitcher. 2009. Entanglement of Steller sea lions (Eumetopias jubatus) in marine debris: Identifying causes and finding solutions. Marine Pollution Bulletin 58:1487–1495.

Rehberg, M.J., and J.M. Burns. 2008. Differences in diving and swimming behavior of pup and juvenile Steller sea lions (Eumetopias jubatus) in Alaska. Canadian Journal of Zoology 86:539-553.

Rehberg, M.J., R.D. Andrews, U.G. Swain, and D.G. Calkins. 2009. Foraging behavior of adult female Steller sea lions during the breeding season in Southeast Alaska Marine Mammal Science 25:588-604.

Repenning, C.A. 1976. Adaptive evolution of sea lions and walruses. Syst. Zool. 25:375-390.

Rice, D.W. 1998. Marine mammals of the world: systematics and distribution. Special Publication of the Society of Marine Mammalogy. 231 pp.

Roffe, T.J., and B.R. Mate. 1984. Abundances and feeding habits of pinnipeds in the Rogue River, Oregon. J. Wildl. Manage. 48:1261-1274.

Rosen, D.A.S., and A.W. Trites. 1999. Metabolic effects of low-energy diet on Steller sea lions, Eumetopias jubatus. Physiological and Biochemical Zoology 72:723-731.

Rosen, D.A.S., and A.W. Trites. 2000a. Assessing the role of nutritional stress in the decline of wild populations: a Steller case of scientific sleuthing. pp. 182-186. In C. L. K. Baer (ed.). Proceedings of the Third Comparative Nutrition Society Symposium, No. 3, Pacific Grove, California, August 4-9, 2000.

Rosen, D.A.S., and A.W. Trites. 2000b. Pollock and the decline of Steller sea lions: testing the junk-food hypothesis. Canadian Journal of Zoology 78:1243-1258.

Rosen, D.A.S., and A.W. Trites. 2000c. Digestive efficiency and dry matter digestibility of Steller sea lions fed herring, pollock, squid, and salmon. Canadian Journal of Zoology 78:234-239.

Rosen, D.A.S., and A.W. Trites. 2004. Satiation and compensation for short-term changes in food quality and availability in young Steller sea lions (Eumetopias jubatus). Canadian Journal of Zoology 82:1061-1069.

Rosen, D.A.S. 2009. Steller sea lions Eumetopias jubatus and nutritional stress: evidence from captive studies. Mammal Review 39:284-306.

Rowley, J. 1929. Life history of sea lions on the California coast. Journal of Mammalogy 10:1-36.

Sandegren, F.E. 1970. Breeding and maternal behaviour of the Steller sea lion (Eumetopias jubatus) in Alaska. MSc thesis, University of Alaska, Fairbanks, Alaska, USA pp.

Sandegren, F.E. 1976. Courtship display, agonistic behavior and social dynamics in the Steller sea lion. Behaviour 57:136-158.

Scammon, C.M. 1874. The marine mammals of the northwestern coast of North America. Dover Publ. Edition (1968), New York, NY. 312 pp.

Scheffer, V.B. 1964. Hair patterns in seals (Pinnipedia). Journal of Morphology 115:291-304.

Schusterman, R.J., F. Balliet, and S.S. John. 1970. Vocal displays underwater by the grey seal, the harbor seal and the Steller sea lion. Psychol. Sci. 18:303-305.

Sease, J.L., R.F. Brown, V.N. Burkanov, D.G. Calkins, P.F. Olesiuk, and A.E. York. 1999. Range-wide survey of Steller sea lions in 1994. NMML, Unpublished Report.

Sease, J.L., and C. Stinchcomb. 2003. 2002 Surveys of Steller Sea Lions in Alaska. Marine Sciences in the Northeast Pacific Symposium, 13-17 January, 2003, Anchorage, Alaska.

Shima, M., A.B. Hollowed, and G.R. VanBlaricom. 2000. Response of pinniped populations to directed harvest, climate variability, and commercial fishery activity: a comparative analysis. Reviews in Fisheries Science 8:89-124.

Sigler, M.F., L.B. Hulbert, C.R. Lunsford, N.H. Thompson, K. Burek, G. O’Corry-Crowe, and A.C. Hirons. 2006. Diet of Pacific sleeper shark, a potential Steller sea lion predator, in the north-east Pacific Ocean. Journal of Fish Biology 69:392–405.

Sinclair, E.H., and T.K. Zeppelin. 2002. Seasonal and spatial differences in diet in the western stock of Steller sea lions (Eumetopias jubatus). Journal of Mammalogy 83:973-990.

Smith, T.G., and J.R. Geraci. 1975. The effect of contact and ingestion of crude oil on ringed seals in the Beaufort Sea. Beaufort Sea Tech. Rep. No. 5, 66 pp.

Snyder, G.M., K.W. Pitcher, W.L. Perryman, and M.S. Lynn. 2001. Counting Steller sea lion pups in Alaska: an evaluation of medium-format, color aerial photography. Marine Mammal Science 17:136-146.

Spalding, D.J. 1964. Comparative feeding habits of the fur seal, sea lion and harbour seal on the British Columbia coast. Fisheries Research Board of Canada Bulletin 146:1-47.

Springer, A.M., J.A. Estes, G.B. van Vliet, T.M. Williams, D.F. Doak, E.M. Danner, K.A. Forney, and B. Pfister. 2003. Sequential megafaunal collapse in the North Pacific Ocean: An ongoing legacy of industrial whaling? Proceedings of the National Academy of Sciences of the United States of America 100:12223-12228.

St. Aubin, D.J. 1990. Physiologic and toxic effects on pinnipeds. pp. 103-127. In J. R. Geraci and D. J. S. Aubin (eds.). Sea mammals and oil: confronting the risks, Academic Press, San Diego, CA.

Stewart, B.S., and P.K. Yochem. 1987. Entanglement of pinnipeds in synthetic debris and fishing net and line fragments at San Nicolas and San Miguel Islands, California, 1978-1986. Marine Pollution Bulletin 18:336-339.

Stroud, R.K. 1978. Causes of death and pathological findings in marine mammals along the Oregon coast. MSc thesis, Oregon State University, Corvalis, OR. 65 pp.

Swain, U., and D.G. Calkins. 1997. Foraging behaviour of juvenile Steller sea lions in the northeastern Gulf of Alaska: diving and foraging trip duration. pp. 92-106. Steller sea lion recovery investigations in Alaska, 1995-1996, Alaska Department of Fish and Game, Division of Wildlife Conservation. Alaska Department of Fish and Game, 333 Raspberry Road, Anchorage, Alaska 99518-1599, U.S.A.

Swain, U.G. 1999. Steller sea lion foraging studies in Southeast Alaska during 1998. Presentation to the Steller Sea Lion Research Peer Review Feeding Ecology Workshop Seattle, Washington, February 11-12, 1999. pp.

Thorsteinson, F.V., and C.J. Lensink. 1962. Biological observations of Steller sea lions taken during an experimental harvest. Journal of Wildlife Management 26:353-359.

Tollit, D.J., A.D. Schulze, A.W. Trites, P.F. Olesiuk, S.J. Crockford, T.S. Gelatt, R.R. Ream, and K.M. Miller. 2009. Development and application of DNA techniques for validating and improving pinniped diet estimates. Ecol. Appl. 19:889-905.

Trillmich, F., and K. Ono. (eds.). 1991. Pinnipeds and El Niño: responses to environmental stress. Springer-Verlag, New York. 293 pp.

Trites, A.W., and P.A. Larkin. 1992. The status of Steller sea lion populations and the development of fisheries in the Gulf of Alaska and Aleutian Islands. Fisheries Centre, University of British Columbia. Vancouver. 134 pp.

Trites, A.W., and P.A. Larkin. 1996. Changes in the abundance of Steller sea lions (Eumetopias jubatus) in Alaska from 1956 to 1992: How many were there? Aquatic Mammals 22:153-166.

Trites, A.W. 1997. The role of pinnipeds in the ecosystem. pp. 31-39. In G. Stone, J. Goebel and S. Webster (eds.). Pinniped populations, eastern north Pacific: status, trends and issues, New England Aquarium, Conservation Department, Boston.

Trites, A.W., V. Christensen, and D. Pauly. 1997. Competition between fisheries and marine mammals for prey and primary production in the Pacific Ocean. Journal of Northwest Atlantic Fishery Science 22:173-187.

Trites, A.W., and D. Pauly. 1998. Estimating mean body masses of marine mammals from maximum body lengths. Canadian Journal of Zoology 76:886-896.

Trites, A.W., P. Livingston, M.C. Vasconcellos, S. Mackinson, A.M. Springer, and D. Pauly. 1999a. Ecosystem considerations and the limitations of ecosystem models in fisheries management: Insights from the Bering Sea. pp. 609-619. Proceedings of Ecosystem Considerations in Fisheries Management. 16th Lowell Wakefield Fisheries Symposium and American Fisheries Society joint meeting. Anchorage, Alaska, USA. September 30 - October 3, 1998, College Sea Grant Program.

Trites, A.W., P.A. Livingston, S. Mackinson, M.C. Vasconcellos, A.M. Springer, and D. Pauly. 1999b. Ecosystem change and the decline of marine mammals in the eastern Bering Sea: testing the ecosystem shift and commercial whaling hypotheses. Fisheries Centre Research Reports. 7(1), 106 pp.

Trites, A.W., and B.T. Porter. 2002. Attendance patterns of Steller sea lions (Eumetopias jubatus) and their young during winter. Journal of Zoology, London 256:547-556.

Trites, A.W., and C.P. Donnelly. 2003. The decline of Steller sea lions in Alaska: a review of the nutritional stress hypothesis. Mammal Review 33:3-28.

Trites, A.W., B.P. Porter, V.B. Deecke, A.P. Coombs, M.L. Marcotte, and D.A.S. Rosen. 2006. Insights into the timing of weaning and the attendance patterns of lactating Steller sea lions (Eumetopias jubatus) in Alaska during winter, spring, and summer. Aquatic Mammals 32:85-97.

Trites, A.W., D.G. Calkins, and A.J. Winship. 2007a. Diets of Steller sea lions (Eumetopias jubatus) in Southeast Alaska, 1993-1999. Fishery Bulletin 105:234-248.

Trites, A.W., V.B. Deecke, E.J. Gregr, J.K.B. Ford, and P.F. Olesiuk. 2007b. Killer whales, whaling, and sequential megafaunal collapse in the North Pacific: a comparative analysis of the dynamics of marine mammals in Alaska and British Columbia following commercial whaling. Marine Mammal Science 23:751-765.

Trites, A.W., A.J. Miller, H.D.G. Maschner, M.A. Alexander, S.J. Bograd, J.A. Calder, A. Capotondi, K.O. Coyle, E.D. Lorenzo, B.P. Finney, E.J. Gregr, C.E. Grosch, S.R. Hare, G.L. Hunt, J. Jahncke, N.B. Kachel, H.-J. Kim, C. Ladd, N.J. Mantua, C. Marzban, W. Maslowski, R. Mendelssohn, D.J. Neilson, S.R. Okkonen, J.E. Overland, K.L. Reedy-Maschner, T.C. Royer, F.B. Schwing, J.X.L. Wang, and A.J. Winship. 2007c. Bottom-up forcing and the decline of Steller sea lions (Eumetopias jubatus) in Alaska: assessing the ocean climate hypothesis. Fisheries Oceanography 16:46-67.

Trites, A.W., and D.G. Calkins. 2008. Diets of mature male and female Steller sea lions (Eumetopias jubatus) differ and cannot be used as proxies for each other. Aquatic Mammals 34:25-34.

Trites, A.W., and A.P. Coombs. 2010. Summer haulouts are breeding sites: redefining the reproductive strategy of Steller sea lions. Fisheries Centre Working Paper 2010-11, The University of British Columbia (PDF; 787 KB), Vancouver, B.C., Canada. 16 pp.

Vania, J.S., and E. Klinkhart. 1967. Sea lions. Marine mammal report. Vol. VIII. Alaska Department of Fish and Game. Juneau. Federal Aid in Wildlife Restoration Annual Projects Segment Report. 5 pp.

Vania, J.S. 1972. Sea lion pelage study. Alaska Department of Fish and Game, Federal Aid in Wildlife Restoration Projects W-17-3 and W-17-4, Job 9.1R, Anchorage. 12 pp.

Wada, K. 1998. Steller sea lions: present status of studies of migratory ecology, and conflict between fisheries and conservation in Japan. Biosphere Conservation 1:1-6.

Wilke, F., and K.W. Kenyon. 1952. Notes on the food of fur seal, sea-lion, and harbor porpoise. Journal of Wildlife Management 16:396-397.

Wilson, K., L. Fritz, E. Kunisch, K. Chumbley, and D. Johnson. 2012. Effects of research disturbance on the behavior and abundance of Steller sea lions (Eumetopias jubatus) at two rookeries in Alaska. Marine Mammal Science 28:E58-E74.

Winship, A.J., A.W. Trites, and D.G. Calkins. 2001. Growth in body size of the Steller sea lion (Eumetopias jubatus). Journal of Mammalogy 82:500-519.

Winship, A.J., A.W. Trites, and D.A.S. Rosen. 2002. A bioenergetic model for estimating the food requirements of Steller sea lions (Eumetopias jubatus) in Alaska, USA. Marine Ecology Progress Series 229:291-312.

Winship, A.J., and A.W. Trites. 2003. Prey consumption of Steller sea lions (Eumetopias jubatus) off Alaska: How much prey do they require? Fishery Bulletin 101:147-167.

Withrow, D.E. 1982. Using aerial surveys, ground truth methodology, and haul out behavior to census Steller sea lions, Eumetopias jubatus. MSc thesis, University of Washington, Seattle, Washington, USA pp.

Wolfe, R.J. 1997. The subsistence harvest of harbor seal and sea lion by Alaska natives in 1996. Final report for year five subsistence study and monitor system (no. 50ABNF400080). Alaska Dept. Fish and Game, Division of Subsistence, Juneau, Alaska. Technical Paper No. 241. 69 pp.

Wolfe, R.J., and L.B. Hutchinson-Scarbrough. 1999. The subsistence harvest of harbor seals and sea lions by Alaska Natives in 1998. Alaska Dept. Fish and Game, Division of Subsistence, Juneau, Alaska. Juneau, Alaska. Technical paper no. 250. pp.

York, A.E. 1994. The population dynamics of northern sea lions, 1975-1985. Marine Mammal Science 10:38-51.

York, A.E., J.R. Thomason, E.H. Sinclair, and K.A. Hobson. 2008. Stable carbon and nitrogen isotope values in teeth of Steller sea lions: age of weaning and the impact of the 1975-1976 regime shift in the North Pacific Ocean. Canadian Journal of Zoology 86:33-44.

Top of Page

Biographical Summary of Report Writer

Dr. Andrew Trites is a Professor and Director of the Marine Mammal Unit at the UBC Fisheries Centre, and is Research Director of the North Pacific Universities Marine Mammal Research Consortium. He is also a Research Associate at the Vancouver Aquarium, a member of the Marine Mammal Specialist Group for the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), and a member of the PICES Advisory Panel on Marine Birds and Mammals. Dr. Trites has been studying marine mammals in the North Pacific for over 30 years. His research involves captive studies, field studies and simulation modelling. He trains graduate students and collaborates with researchers specializing in such disciplines as nutrition, ecology, physiology, anthropology and oceanography.

Top of Page

Collections Examined

None.

Top of Page

Personal Communications

Peter Olesiuk, Fisheries and Oceans Canada, Nanaimo, BC

Stephen Raverty, Animal Health Centre, B.C. Ministry of Agriculture, Food and Fisheries, Abbotsford, British Columbia

Top of Page

Appendix 1. Number of non-pup Steller Sea Lions counted during province-wide breeding season surveys during 1971-2010. (Data from DFO.)

Number of non-pup Steller Sea Lions counted during province-wide breeding season surveys during 1971-1998. (Data from DFO.)
Site NameType28 June-
30 June 1971
29 June-
03 July 1973
27June-
30 June
1977
28 June-
01 July
1982
29 June-
03 July
1987
28 June-
03 July
1992
28 June-
01 July 1994
29June-
04 July 1998
CARMANAH PTW/Y0NS181170146103150255
PACHENA PTW/Y00000000
WOUWER ISLW/Y00000000
MARA ROCKW/Y0(NS)03004187
LONG BEACHY39426510262231344298535
PEREZ ROCKSY--------
RAPHAEL PTW000000580
FERRER PTW--------
BARRIER ISLSYNSNS105153149274290843
O'LEARY ITSW/Y331NS2008560811474
SOLANDER ISLW/Y0310051419179
CAPE SCOTTW0(NS)10142680
MAGGOT ISLR418416627442550511371245
BERESFORD ISLY716241001241641195
SARTINE ISLR628616879806600575343262
TRIANGLE ISLR5503755703761057160316262540
ASHBY POINTW/YNS82412103226225
BUCKLE GROUPW/Y?-------(NS)
MILLER GROUPW/Y--------
VIRGIN ROCKSY/R31720562190229157131168
PEARL ROCKSY100812762312812698199
GOSLING ROCKSY106NS3717913572192133
MCINNES ISLY196NS4500109241163
STEELE ROCKYNSNS85150735137227
ASHDOWN ISLW(NS)(NS)0NSNS25NS0
ISNORY-------0
JOSEPH ISL?--------
N DANGER RKSR148347230288339301309583
BONILLA ISLY2915833321919265272303
WARRIOR ROCKSY?????4162282
CHERNEY ISLW/Y-------0
ROSE SPITW/Y-------0
REEF ISLY2071058836482489538216
SKEDANSW0(NS)0450000
JOYCE ROCKS?--------
CAPE ST. JAMESR6315497826981021867797763
S TASU HDY76NS27811726380196285
MORESBY ITSW(NS)(NS)(NS)(NS)0311565
CONE HDW/Y(NS)(NS)(NS)(NS)070211
JOSEPH ROCKSY408NS399366309327397601
LANGARA ISLW/Y6NS033NS0217
ANTHONY ISLY????44279617359
GARCIN ROCKSY/R-------0?
Miscellaneous-1-212453
Number Counted-46173208521947136109737680919818
Missed (sites)-272(3)831(9)0(0)13(1)13(1)2(1)13(1)0(0)
Total Estimated-48894039521947266122737881049818

Top of Page

Number of non-pup Steller Sea Lions counted during province-wide breeding season surveys during 2002-2010. (Data from DFO.)
Site NameType02 July-
06 July
2002
01 July-
03 July
2006
01 July-
09 July
2008
26 June-
03 July
2010
CARMANAH PTW/Y237247162514
PACHENA PTW/Y04453166
WOUWER ISLW/Y3144889
MARA ROCKW/Y296264376514
LONG BEACHY7143888295367
PEREZ ROCKSY0353466321
RAPHAEL PTW0000
FERRER PTW01620
BARRIER ISLSY58554210511284
O'LEARY ITSW/Y214100
SOLANDER ISLW/Y187876320632
CAPE SCOTTW0000
MAGGOT ISLR456590362286
BERESFORD ISLY14713397153
SARTINE ISLR268379264231
TRIANGLE ISLR2995357636454621
ASHBY POINTW/Y519786541479
BUCKLE GROUPW/Y?4720461
MILLER GROUPW/Y00151140
VIRGIN ROCKSY/R419516595533
PEARL ROCKSY467449247263
GOSLING ROCKSY160257308439
MCINNES ISLY2581236139
STEELE ROCKY10192194173
ASHDOWN ISLW(NS)0017
ISNORY72290109
JOSEPH ISL?010030128
N DANGER RKSR592375652527
BONILLA ISLY215692282508
WARRIOR ROCKSY58849811141106
CHERNEY ISLW/Y1930244508
ROSE SPITW/Y025313257
REEF ISLY3700194316
SKEDANSW0000
JOYCE ROCKS?002364
CAPE ST. JAMESR98210948111077
S TASU HDY1514798251
MORESBY ITSW2100
CONE HDW/Y131278597
JOSEPH ROCKSY696770511339
LANGARA ISLW/Y348421898
ANTHONY ISLY313513473186
GARCIN ROCKSY/R329261305565
Miscellaneous-32849208
Number Counted-12121157211506117996
Missed (sites)-0(0)0(0)0(0)0(0)
Total Estimated-12121157211506117996

NOTE: Sites were classified as R-rookeries, Y-year-round haulouts, and W-winter haulouts, although in some cases sites used appeared to change over the course of the study period. NS denotes the site was not surveyed and animals likely missed, and (NS) denotes the site was not surveyed but it was not expected that any animals were missed based on the preceding and proceeding surveys. The "?" denotes that the site was not known to exist, and could have been overlooked in previous years. The estimated number of animals missed (and the number of missed sites) is given near the bottom of the table.

Top of Page

Appendix 2. Number of Steller Sea Lion pups counted during province-wide breeding season surveys from 1971-2010. (Data from DFO.)

Number of Steller Sea Lion pups counted during province-wide breeding season surveys from 1971-1998
Site Name28 June-
30 June 1971
29 June-
03 July 1973
27June-
30 June
1977
28 June-
01 July
1982
29 June-
03 July
1987
28 June-
03 July
1992
28 June-
01 July 1994
29 June-
04 July 1998
MAGGOT ISL1741881471711781077472
SARTINE ISL16327330940917625362148
VIRGIN RKS00002000
TRIANGLE ISL1811891401853054766301211
N DANGER RKS869364745414884144
CAPE ST. JAMES337272303404367484333484
GARCIN RKS--------
Miscellaneous00024034
Total BC941101596312451084146811862073
FORRESTER ISLNS2371NS21202073326120732364

Top of Page

Number of Steller Sea Lion pups counted during province-wide breeding season surveys from 2002-2010. (Data from DFO.)
Site Name02 July-06 July 200201 July-03 July 200603 July-07 July 200827June-02 July 2010
MAGGOT ISL76623656
SARTINE ISL146178101104
VIRGIN RKS15595154
TRIANGLE ISL2199267425503776
N DANGER RKS219403216272
CAPE ST. JAMES635723900846
GARCIN RKS--104217
Miscellaneous6236560
Total BC3281411840675485
FORRESTER ISL30573429NS4036

Top of Page