COSEWIC Assessment and Update Status Report on the Spring Cisco Coregonus sp. in Canada - 2009

Table of Contents

List of Figures

List of Tables


Spring Cisco Coregonus sp.

Photo of a Spring Cisco Coregonus species.

Endangered 2009

COSEWIC -- Committee on the Status of Endangered Wildlife in Canada

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. 2009. COSEWIC assessment and update status report on the Spring Cisco Coregonus sp. in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 33 pp..

Previous report:

Hénault, M. and R. Fortin. 1992. COSEWIC status report on the Spring Cisco Coregonus sp. in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 11pp.

Production note:

COSEWIC acknowledges Audrey Sanfaçon and Louise Nadon for writing the update status report on Spring Cisco, Coregonus sp. in Canada, overseen and edited by Robert Campbell, Claude Renaud, and Eric Taylor, Co-chairs, COSEWIC Freshwater Fishes 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 Website

Également disponible en français sous le titre Évaluation et Rapport de situation du COSEPAC sur le cisco de printemps Coregonus sp. au Canada - Mise à jour.

Cover Photo:
Spring Cisco - Michel Hénault, biologist.

© Her Majesty the Queen in Right of Canada, 2009.
Catalogue No.CW69-14/576-2009E-PDF
ISBN978-1-100-12938-9

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COSEWIC Assessment Summary

Assessment Summary - April 2009

Common name: Spring Cisco
Scientific name: Coregonus sp.
Status Endangered: Reason for designation This species, known from only one small lake in southwestern Quebec, has undergone a drastic decline in abundance over the past 15 years (3 generations). The decline may be related to a combination of factors including habitat degradation and loss resulting from urban and agricultural development, the introduction of non-native species (e.g. Rainbow Smelt and Atlantic Salmon), and climate change.
Occurrence: Quebec
Status history: Designated Special Concern in April 1992. Status re-examined and designated Endangered in April 2009. Last assessment based on an update status report.

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COSEWIC Executive Summary

Spring Cisco Coregonus sp.

Species information

Spring Cisco (Coregonus sp.) may represent a valid taxon that has not yet been described. The single Canadian population of this taxon was first discovered in May 1981 when ready-to-spawn or partially spawned individuals were collected. Spring Cisco spawn between mid-May and early June. They are closely related to fall-spawning Cisco, Coregonus artedi, which are more widely distributed. However, Spring Cisco is shorter in length, has a smaller head and a narrower and shorter caudal peduncle. The anal fins contain 11 rays for Spring Cisco and between 12.1 to 12.5 rays for fall-spawning C. artedi. The number of gill rakers on the first gill arch is the most distinctive morphological criterion. Spring-spawning ciscoes have an average of 42.7-gill rakers as opposed to 50.5 for fall-spawning ciscoes in surrounding lakes.

The complete reproductive isolation of the Spring Cisco from C. artedi and the morphological differences observed support genetic distinctiveness. Being the only known existing spring-spawning population of Cisco in North America, the Spring Cisco of Lac des Écorcesmeets the COSEWIC criteria for eligibility as an evolutionarily unique designatable unit.

Distribution

Spring Cisco occurs only in Lac des Écorces in the Laurentides Region, Quebec, (46°31'48" N, 75°25'03" W).

Habitat

Lac des Écorces has a flow rate of approximately 20 m/sand minimum dissolved oxygen concentrations of 1.3 and 1.9 mg/L. Summer and fall water temperatures rise well above the preferential temperature of ciscoes (< 12°C), which distinguishes its thermal environment from that of the fall-spawning cisco. In summer, the fish stay in the colder waters of the hypolimnion while the epilimnion can reach temperatures as high as 25°C. In other lakes, the water remains at 4°Cthroughout most of the hypolimnion. During spawning, spawners congregate in pools at depths of 20 to 30 metres, where temperatures are below 6°C. The high temperatures in the hypolimnion of Lac des Écorces in summer and fall may be the reason for the shift in the spawning period, in that they allow for rapid growth of larvae before winter.

Biology

Spring Cisco reach sexual maturity at three years of age, and few individuals survive beyond eight years. Oocyte maturation begins in the fall, continues at a slower rate over the winter, and peaks between mid-May and early June. The egg development rate increases as the temperature rises; however, temperatures of 10°C or higher are lethal to the eggs.

Larvae are first observed in late July, and hatching continues during the month of August. Spring Cisco larvae develop in truly marginal environmental conditions, which can be harmful. Although the cause of the shift in the spawning period remains unknown, temperature seems to play a critical role in gonad development, which, in this case, is potentially inhibited by the high summer and fall temperatures of the hypolimnion.

Population sizes and trends

According to experimental fisheries conducted since 1981, the number of Spring Cisco catches per unit time and average length are declining. These reductions may be due to several factors, such as water quality, habitat degradation or introduction of predators and competitors. The small number of specimens captured makes it difficult to draw reliable conclusions on the population size, trend and average length. It is known, however, that at the age of three years, the average total lengths are slightly below those of cisco populations in the same watershed.

Limiting factors and threats

The recent colonization of Lac des Écorces by Rainbow Smelt observed in 1999 may have a negative effect on the Spring Cisco population. Given that the preferred habitat of Rainbow Smelt overlaps with that of both adult and larval ciscoes, competition and predation can be expected. Spring Cisco are also vulnerable to habitat degradation, which has been observed in Lac des Écorces for a number of years. Cisco inhabits clear, well-oxygenated waters and such conditions are also required for egg and larval development.

Special significance of the species

Many members of the genus Coregonus are at risk or have become extinct. Traditional taxonomic methods may fail to recognize units below the species level; however COSEWIC may designate units below the species level where the conservation of morphologically and ecologically distinct populations is critical to the preservation of unique evolutionary variants. Spring Cisco play an important role in the food chain in that they are the main prey of several species of sport fish that occur in Lac des Écorces.

Existing protection or other status designations

Although no measures have been taken to specifically protect Spring Cisco, it has been designated a species of Special Concern by COSEWIC (April 1992) and it appears in Schedule 3 of the Species at Risk Act. The Spring Cisco is considered rare and imperilled in Quebec (S2S3).

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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.

Definitions (2009)

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)*
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)**
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)***
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.

* Formerly described as "Vulnerable" from 1990 to 1999, or "Rare" prior to 1990.
** Formerly described as "Not In Any Category", or "No Designation Required."
*** 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.

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


COSEWIC Assessment and Update Status Report on the Spring Cisco Coregonus sp. in Canada – 2009

Species Information

Name and classification

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Salmoniformes
Family: Salmonidae
Subfamily: Coregoninae
Scientific name: Coregonus sp.
Common name:
English:
Spring Cisco
French: cisco de printemps

The single population of Spring Cisco of Lac des Écorces, whose spawning period has undergone a shift from fall to spring, is very likely associated with the Cisco, Coregonus artedi already present in the watershed. For many years, the taxonomic history of the Cisco (C. artedi Lesueur, 1818) has been debated and still requires resolution (Clarke 1973; Scott and Crossman 1998; Turgeon and Bernatchez 2003). Given the high plasticity of the species, a large number of synonyms and subspecies were described until 1970, when McPhail and Lindsay (1970, cited in Scott and Crossman 1998) suggested a more general approach, i.e., to consider the cisco as a species group, known as “Coregonus artedi” complex. This implies that there is not one clearly defined species, but rather a number of divergent evolutionary phenotypes.

The complex currently has seven extant taxa (an eighth, Deepwater Cisco (C. johannae) is extinct): Blackfin Cisco (C. nigripinnis), Shortjaw Cisco (C. zenithicus), Shortnose Cisco (C. reighardi), Kiyi (C. kiyi), Bloater (C. hoyi), Nipigon Cisco (C. nipigon) and Cisco (C. artedi) [Nelson et al. 2004]. Bernatchez et al. (1991) and others (Bodaly et al. 1991; Turgeon and Bernatchez 2003) indicated that Least Cisco (C. sardinella), Bering Cisco (C. lauretta) and Arctic Cisco (C. autumnalis), all referred to as northwest taxa, belong to a separate lineage.

Turgeon and Bernatchez (2003) proposed that the phylogenetic status of the continental populations does not make it possible to unambiguously identify them as separate taxa, and that the continental ciscoes all be recognized as C. artedi. They (Turgeon and Bernatchez 2001a, b, 2003) hypothesized that ciscoes are undergoing a process of evolutionary divergence, which would explain why morphological analyses demonstrating that polymorphism exists lack parallel genetic delineation.

Turgeon and Bernatchez’s (2003) proposed delineation of C. artedi sensu lato has not been largely accepted as the study is viewed as incomplete. Not all of the species of the so-called complex were included, nor were many of the lakes (Nelson et al. 2004). Nelson et al. (2004), the accepted authority for recognized taxa of freshwater fishes (COSEWIC 2007a), accept that postglacial reticulate evolution combined with independent evolution of similar phenotypes has occurred. However, they (Nelson et al. 2004) do not regard the six other extant species as conspecific with C. artedi, stating that more detailed scientific studies are required before any conclusions linking the other species with C. artedi can be made, and the existing specific status holds for the seven species.

In this report, the cisco that spawns in spring in Lac des Écorces will be referred to as Coregonus sp. or Spring Cisco, which may represent a taxon waiting to be described. Fall-spawning individuals of C. artedi of any body of water are herein referred to as Cisco (cisco de lac in French). The latter is also described as lake Herring, Tullibee, Freshwater Herring, Ciscoe, Blueback, Sand Herring, Shallow Water Cisco, Grayback Tullibee, Common Cisco, Bear Lake Herring, Blueback Tullibee and Herring-salmon.

At the time of the discovery (May 1981) of the spring-spawning cisco in Lac des Écorces, Pariseau et al. (1983) advanced the hypothesis of an allopatric population that was in the process of speciation. This hypothesis is favoured despite the collection of some fall-spawning individuals in 1981 (n= 3) and 1987 (n= 10). Hénault and Fortin (1989, 1992) maintained that they cannot draw any conclusions as to the existence of a sympatric population due to the small number of individuals collected and the absence of distinctive characteristics in these specimens from those caught upstream from Lac des Écorces. They prefer to refer to a downstream migration of mature individuals, which is insufficient to maintain a contemporary sympatric population. They suggested the idea that the two populations co-existed in the past, and then began competing for food resources. Availability of appropriate food is considered to be a limiting resource in adult ciscoes that may potentially lead to reproductive isolation between sympatric ecotypes (Chouinard and Bernatchez 1998).

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Morphological description

Spring Ciscoes captured in Lac des Écorces meet the usual criteria for the identification of Cisco such as large iridescent scales with an overall silvery coloration, a laterally flattened body, a distinctly forked caudal fin and small dorsal adipose fin (Scott and Crossman 1998; Pariseau et al. 1983; Bernatchez 2000). Spring Cisco can measure up to 360 mm in length, even though the average total lengths of spawners caught between 1983 and 2004 (n= 145) in Lac des Écorcesgenerally vary between 201.3 mm and 296 mm(MRNF, unpubl. data). In addition, in the closed position, the lower jaw of its terminal mouth slightly protrudes beyond the upper jaw (Pariseau et al. 1983) (Figure 1).

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Figure 1. Spring Cisco (Coregonus sp.) from Lac des Écorces and a fall-spawning cisco (Coregonus artedi) from a nearby lake (Marquis). Both specimens are of the same length (top). The lower enlargement highlights the differences in the heads of the two forms. Adopted from Hénault and Fortin (1993).

Two photos showing a Spring Cisco Coregonus species from Lac des Écorces and a fall-spawning cisco Coregonus artedi

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Pariseau et al. (1983), Hénault (1987) and Hénault and Fortin (1989) presented a detailed discussion of the meristic and morphometric differences of the Spring Cisco phenotype relative to fall-spawning individuals found in Lac des Écorces and surrounding lakes (McGregor, Petit Lac Kiamika, Marquis, Rochon, Saint-Paul, and Kiamika Reservoir). Even though spring-spawning cisco is considered allopatric, some fall-spawning individuals were collected in 1981 (n= 3) and 1987 (n= 10). In their experimental fishery of July 1981, Hénault and Fortin (1989) collected three specimens at gonad maturity stage IV. Two specimens had fall-spawning attributes and one fit the spring population. Hénault also collected 19 fish with fall-spawning characteristics in 1987.

Hénault (1987), Hénault and Fortin (1989, 1993) have used morphometric measurements to demonstrate the main differences. The cephalic structures are significantly smaller for Spring Cisco males than for fall-spawning males (n= 17 spring and n= 15 fall ciscoes). The Spring Cisco also has a slightly deeper body and a narrow, shorter caudal peduncle. In addition, there are significantly fewer rays: 9.9 dorsal rays for the Spring Cisco (n= 45) and between 11-11.1 rays for fall spawners of Lac des Écorces and surrounding lakes. The anal fin contains 11 rays (n= 45) for spring individuals and between 12.1 and 12.5 rays (n= 66) for fall spawners (Hénault 1987). Hénault and Fortin (1993) also found that there is no overlap in the frequency distribution of the gill rakers on the inferior part of the gill arch. The spring specimens were also appreciably longer (maximum length = 270 mm in fall spawners vs 360 mm in spring spawners).

The number of scales on the lateral line is also decidedly lower on the Spring Cisco, 72 (n= 45) compared to 74-79 (n= 66). However, the average number of gill rakers on the first gill arch is the most obvious morphological distinguishing feature. The Spring Cisco has an average of 43 gill rakers (n= 45), whereas fall-spawning individuals from the same watershed have an average of 50.5 (n= 66) (Pariseau et al. 1983; Hénault 1987). This suggests a difference in diet and the possible use of a different trophic niche (Hénault 1987; Hénault and Fortin 1989, 1992; Turgeon and Bernatchez 2003). The higher number of gill rakers suggests specialized feeding on zooplankton, whereas the prey of individuals with fewer gill rakers is probably more abundant and more specific in terms of size (Bernatchez 2005). A smaller number of gill rakers also suggests more rapid development under higher temperature conditions (Pariseau et al. 1983).

The number of gill rakers has been one of the principal morphological characters used in taxonomic identification of whitefish and has been shown to be genetically determined (Svärdson 1970). Gill raker number in coregonids can show striking adaptive radiation, either in the absence of other species or as a result of character displacement in the presence of different species (Lindsey 1981). They have also been used to indicate the occurrence of species pairs in other systems (Bodaly et al. 1992; Bernatchez et al. 1999). Etnier and Skelton (2003) tested the validity of gill raker counts in a study on the differentiation of three species of cisco (n= 655) from Lake Saganaga at the Minnesota/Ontario border. The purpose of the study was to taxonomically distinguish Coregonus nipigon, formerly included in the C. artedi complex by McPhail and Lindsay (in Scott and Crossman 1998). They found that gill raker counts, lateral-line scale counts, body shape and vertebral counts are the criteria that differentiate C. nipigon, from other ciscoes and thus suggested that it may be a species in its own right. Similarly, Hénault and Fortin (1993) suggest that these same criteria separate the Spring Cisco from C. artedi.

The morphological variation described above can be attributable to the local environmental conditions during development (Hénault and Fortin 1992; Turgeon and Bernatchez 2003). The morphological analysis of cisco from 34 lakes in Canada showed the presence of many morphotypes distributed relatively homogeneously. In most cases, the differences related to diet, habitat and reproductive season are thought to be closely tied to local environmental conditions (Turgeon and Bernatchez 2003). These authors also report that the divergence in the number of gill rakers is accompanied by a genetic divergence attributed to natural selection.

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Genetic description

Very few genetic studies have been undertaken on Spring Cisco. An analysis of mitochondrial markers and microsatellites, as a function of the geographic range of 34 cisco populations, including the spring-spawning cisco of Lac des Écorces, indicated distinct genetic compositions, with different but overlapping distributions (Turgeon and Bernatchez 2001a, b, 2003). Genetic differentiation was higher in representatives of the same taxon from different lakes than in sympatric stocks from a given lake. It appears that continental ciscoes are in the process of evolutionary diversification. From this perspective, Spring Cisco of Lac des Écorces belongs to an eastern population and does not appear to have originated from a distinct lineage.

Given the low level of intraspecific and interspecific genetic variation in the genus Coregonus, its phylogenetic history is difficult to resolve. Todd (1981) observed that, despite the lack of genetic diversity among species of ciscoes from Lake Superior (Bloater, Cisco, Kiyi, and Shortjaw Cisco), there was a high level of phenotypic diversity. He found that, since it was not possible to differentiate stocks by electrophoresis, phenotypic characteristics seem to be the best descriptors of the various populations and are the result of environmentally induced local adaptations. Phenotypic differences and reproductive isolation are thought to be the result of the heterogeneity of food resources, the environment and competition for resources (Hjelm and Johansson 2002; Bernatchez 2005).

A change in the spawning period has been observed previously in other populations in the genus Coregonus. The Shortjaw Cisco (from fall to spring) and the Shortnose Cisco (from spring to fall) are North American examples (Smith 1964; Scott and Crossman 1998; COSEWIC 2003). The former is Threatened (May 2003), and the latter Endangered (May 2005). Vendace (C. albula) is also known for its spring-spawning populations in Finland (Airaksinen 1968 ), and Sweden (Svärdson 1979 ). DNA imprints of such a phenomenon have not been revealed in the Spring Cisco population of Lac des Écorces and the phenomenon remains poorly documented to date. According to Bernatchez (2005), phenotypic and ecological divergences and reproductive isolation in coregonines are the direct result of a process of natural selection induced by their environment.

The difficulties in attempting to genetically define specific relationships within families such as the C. artedicomplex means that researchers often have to revert to the basic concepts of taxonomy (Taylor 1999; Schluter 2000). Moreover, in temperate environments associated with postglacial lakes, it is common to find morphologically, genetically or ecologically distinct sympatric populations (Taylor 1999; Lu et al. 2001). Such complexes are believed to form a large part of our biodiversity.

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Designatable units and eligibility

Hénault (1987) first introduced Spring Cisco as a candidate for COSEWIC consideration, and highlighted the urgency of protecting the species. Hénault and Fortin (1992, 1993) reiterated the Spring Cisco’s North American uniqueness, and its vulnerability as an ecotype, as Lac des Écorcesfaces increasing disturbances. COSEWIC, in its 1992 assessment, accepted the Spring Cisco as an undescribed species in recommending a status of Special Concern at the species level.

Although the species was not reported in the lake prior to 1981 (Hénault and Fortin 1993), it has undoubtedly existed there for a considerable period of time as demonstrated by the extent of divergence from C. artedi in nearby lakes. This endemic population is unique to North America, and meets the COSEWIC Eligibility Criteria (COSEWIC 2007a) since it is morphologically, ecologically and possibly genetically distinct, is the sole representative of the form in North America, and is restricted to the Great Lakes-Upper St. Lawrence National Freshwater Biogeographic Zone of Canada. The complete reproductive isolation of the Spring Cisco from C. artedi (see Biology), and the morphological differences observed, support genetic distinctiveness.

The lack of a formal species description does not prohibit assessment of status since the form consists of a single population endemic to Lac des Écorces. Where taxonomic status remains uncertain, as in the case of Spring Cisco, a population may be recognized as a designatable unit (DU) if it has attributes that make it “discrete” and evolutionarily “significant” relative to other populations (COSEWIC 2007b). In other words where “the putative unit has a distinctive and rare trait or traits (behaviour, life history, physiology, morphology) that represent(s) local adaptation and identifies the unit as not being ecologically interchangeable with other known putative designatable units within the species, and is an irreplaceable component of Canada’s biodiversity” (Taylor 2005; COSEWIC 2007a).

According to Taylor (1999) and Turgeon and Bernatchez (2003), populations that are morphologically, ecologically and genetically distinct should be given priority conservation status because traditional taxonomic methods make it difficult to designate and recognize units below the species level. The complete reproductive isolation of the Spring Cisco from C. artedi supports the hypothesis of an undescribed species (McAllister 1990). Morphological differences (see Morphological description above), such as the inferior number of rays on unpaired fins, and the smaller gill raker count support genetic distinctiveness.

Thus, the Spring Cisco is a valid designatable unit, eligible for assessment of status under the COSEWIC guidelines. The form consists of a single population endemic to the lake, located in the Great Lakes-Upper St. Lawrence Biogeographic Zone, and as such is the sole global representative of the form.

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Distribution

Global range

This species is a Canadian endemic.

Canadian range

There is only one known Spring Cisco population in Canada situated in Lac des Écorces(46°31'48" N, 75°25'03" W, Figure 2, Figure 3) in the Laurentides Region (Quebec). Although experimental fisheries have been conducted in several adjacent lakes (Lacs Petit, Gauvin, Kiamika, Marquis, McGregor, Rochon and Saint-Paul), no Spring Cisco catches have been reported (Pariseau et al. 1983; Hénault 1987). Likewise, surveys in Lake Chandos, near Havelock, Ontario (see Hénault and Fortin 1993) indicated that the cisco present in this lake spawns in the fall (McAllister and Campbell unpubl. data). Aggregations of cisco at the outlet creek to Gillies Lake on the Bruce Peninsula of Ontario were also thought to be indicative of spring-spawning behaviour, but this remains to be verified. However, it may be similar to the situation in Chandos Lake where aggregations of fish in the spring are probably related to water conditions and food availability, as no ciscoes in spawning condition were found (McAllister and Campbell unpubl.data). Todd (1981) also observed spring-spawning of Coregonus artediin Lake Superior, but the phenomenon has not been reported since.

Lac des Écorces has an area of 658 ha (6.58 km²), and a perimeter of 25 km. The known distribution of this species, therefore, is restricted to approximately 6.58 km². Its extent of occurrence would therefore be limited to the actual surface area of the lake, but if calculated according to the COSEWIC guidelines (i.e., using the minimum convex polygon method, see COSEWIC 2007) would be approximately 20 km². The distribution of the fish in the lake is unknown, but the area of occupancy (at a scale relevant to the ecology of the species) would be approximately equal to the surface area of the lake ( 6.58 km²) since it appears that a large part of the lake, at least in terms of surface area, is utilized when all stages are included (see Habitat requirements below). The index of area of occupancy, as defined in the COSEWIC guidelines, using 1 x 1 km²grid cells overlaid on the lake, was estimated at 20 km², and 28 km², using a 2 X 2 km grid (see COSEWIC 2008).

The lake has a flow rate of approximately 20 m/sec, hence a theoretical turnover of about seven times a year. Its average depth is 13 m and the maximum depth is 38 m(Pariseau et al. 1983). Lac des Écorces is fed by the Kiamika River, which drains the Kiamika Reservoir.

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Figure 2. Range of Spring Cisco of Lac des Écorces.

Map showing the range of the Spring Cisco of Lac des Écorces.

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Figure 3. Location of Lac des Écorcesand nearby lakes mentioned in the text that do not contain spring-spawning ciscoes.

Map showing the location of Lac des Écorces and nearby lakes mentioned in the text that do not contain spring-spawning ciscoes.

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Habitat

Habitat requirements

Adult habitat

The Spring Cisco prefers cool, well-oxygenated waters, and performs daily vertical migrations to meet its environmental requirements (Hénault and Fortin 1991; Hénault and Fortin 1993). Although areas of anoxia were identified in 1992, the waters throughout Lac des Écorcesare well oxygenated year round. A physicochemical study conducted in September 2005 showed dissolved oxygen levels of 8.8 mg/l at the surface and 5.6 mg/L at a depth of 32 m. Ongoing surveys, since 1968 to date, include information on physicochemical parameters in Lac des Écorces (as well as lakes Rochon, Gauvin, Kiamika, and Saint-Paul); however, the data have yet to be summarized and statistically analyzed, but appear to support this condition of annual oxygenation (Hénault, pers. comm. 2008; MRNF, unpubl.data).

The preferred water temperature of Spring Cisco seems to be 12°C and below. During summer warming, the adults migrate to the hypolimnion, which ranges from 2.8° to 7.8°C, until the water in the epilimnion cools (MRNF, unpubl. data). The thermal behaviour of the water body is similar to that of a river (Pariseau et al.1983). The waters in the hypolimnion warm up quickly in the summer (7.8°C) and remain warm until the end of fall, whereas in the nearby lakes the water temperature remains at 4° C. The relatively warm hypolimnion temperatures in Lac des Écorces distinguish the thermal environment of the Spring Cisco from that of the fall-spawning ciscoes in surrounding lakes. According to Hénault and Fortin (1991), this phenomenon influences gonad development.

Spawning habitat

Spring Cisco use deeper zones located between 20 and 30 m (Pariseau et al. 1983; Hénault and Fortin 1991). This adaptation, possibly attributable to the shift in the spawning period from fall to spring, allows normal incubation of the eggs during the high summer temperatures. Eggs were collected from a steeply sloped site below 20 m depth with a mud substrate, but it is difficult to draw any conclusions regarding the nature of their requirements with a small sample (n= 14 in 1991) (Hénault and Fortin 1991). It is possible to state, however, that Spring Cisco spawning habitat must be well oxygenated and have a temperature of less than 5°-6°C (Hénault and Fortin 1992). During the spawning period, fertile females (stage V) are distributed throughout the water column, whereas the males are found near the bottom (Hénault and Fortin 1991).

Colby and Brooke (1973) found that in laboratory conditions, a temperature of 5.6°C is optimal for incubation of the eggs. The survival rate decreases rapidly as the temperature rises, and is nil at 10°C for both Ciscoes and Spring Ciscoes (Scott and Crossman 1998; Pariseau et al. 1983). By September, Spring Ciscoes behave like fall-spawning individuals in occupying the entire water column (Hénault and Fortin 1991). The concentration of dissolved oxygen does not appear to be a limiting factor since the concentration of oxygen in Lac des Écorces is high year round (MRNF, unpubl.data).

Early life stage habitat

Given the small number of larval Spring Ciscoes collected in Lac des Écorces (n= 6 in 1984, n= 3 in 1987), it is difficult to describe their ecology (Hénault and Fortin 1991). The same authors claimed that, given the already high water temperatures at the time of hatching in August, special adaptations are involved. When larvae were collected in August 1987, the water temperature at the surface was 22°C. However, the lack of catches in the first metre suggests that larvae avoid this section of the water column. The authors advanced the hypothesis of daily vertical migrations.

Details on the early life stages of Spring Cisco are limited, but several laboratory experiments were conducted on Cisco. Fry (1937, cited in McCormick et al. 1971), also observed that Cisco larvae left the epilimnion when it reached a temperature of 20°C. The upper temperature limit tolerated by juveniles 48 mm in length is believed to be 19.8°C, when acclimated to a temperature of 3°C under experimental conditions. Edsall and Colby (1970) reported a lethal temperature of 19.8°C following acclimation to 2°C, although juveniles can tolerate temperatures as high as 26°C when acclimated to 12.5°C and over. McCormick et al. (1971) added that the optimal temperature for juvenile growth is between 13° and 18°C, but according to Kerr and Grant (1999), the preferred temperature is between 7° and 10°C. Optimal temperature varies depending on habitat and food resources. When food resources are scarce, the optimal growth temperature falls (McCormick et al. 1970).

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Trends

Aquatic habitat within the lake has undergone many disturbances over the last 50 years leading to significant habitat degradation, and possibly habitat loss. The shoreline has been rapidly developed for the construction of homes and/or cottages, and the waters impacted by the leaching of chemicals and organic wastes from agriculture and livestock production. The lake was once considered mesotrophic (Bergeron and Vincent 1973), but now tends to eutrophic conditions (Hénault and Fortin 1993) as a result of increased nutrient loads from urban and agricultural practices, and the introduction of exotic species such as Eurasian Water Milfoil (Myriophyllum spicatum).

The tendency to eutrophication may also be related to climate change and global warming. Most models indicate that the fastest and most profound effects will be experienced in northern latitudes, and that boreal forests and wetlands may be the most vulnerable (Woodwell et al. 1995). Environmental monitoring studies from across the Boreal Shield ecozone suggest that dramatic changes to primary productivity, carbon storage, hydrology, and fish habitat have already occurred, and may lead to malfunctioning of Shield communities and ecosystems (Schindler 1998). Ice studies of Boreal Shield lakes in Ontario demonstrate a shift to shorter periods of ice cover in the 1970s and 1980s followed by year-to-year variability (Urquizo et al. 2000). Schindler et al. (1990) noted that annual air temperature increased by 1.6°C, precipitation declined by 40%, and evapotranspiration increased by nearly 50% in the same area between 1970 and 1990. Other changes include: decreased stream flows resulting in up to 40% decreases in transportation of dissolved organic carbon and phosphorus (Dillon and Molot 1997); decreased phytoplankton abundance in lakes with lowered phosphorus content; increased transparency caused by reduced dissolved organic carbon, which permits deeper penetration of UV-B radiation; increased use of thermal refuges by cold-adapted fishes such as lake trout; deepening of the thermocline resulting in reduced habitat for cold-adapted invertebrates and fishes; increased acid deposition in snow during the winter, and decreased pHfollowing the spring thaw, acidification of streams as a result of low water levels in catchment areas, which facilitated the oxidation of sulphur to sulphates (Schindler et al. 1990; Snucins and Gunn 1995; Dillon and Molot 1997; Schindler 1998).

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Protection/ownership

Most of the foreshore and shoreline areas of the lake are under private ownership; however, provisions for habitat protection exist under appropriate sections of the federal Fisheries Act(R.S. 1985, c. F-14). The species and its habitat are also afforded some degree of protection under the Quebec Environment Quality Act (R.S.Q., c. Q-2) and the Regulation Respecting Wildlife Habitats of the Act Respecting the Conservation and Development of Wildlife(R.S.Q., c. C-61.1). Authority for the application and enforcement of the Policy for Protection of Rivers, Littoral Zones and Flood Plains (Quebec Ministry of Sustainable Development, Environment and Parks) is delegated to the municipalities.

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Biology

Reproduction

Unlike Cisco, which spawn in the fall, Spring Cisco spawn from the second half of May to early June (Pariseau et al.1983; Hénault 1987; Hénault and Fortin 1992, 1993). Initiation of gametogenesis in coregonines seems to be related to temperature (Scott and Crossman 1998) and to the decline in the photoperiod (Hénault and Fortin 1991). In Spring Cisco of Lac des Écorces, oocyte maturation begins in the fall, slows down over the winter, and levels off in the spring just prior to the spawn. Judging from the stage of development of the eggs collected in 1984, fertilization took place between May 10 and June 7 (Hénault and Fortin 1991).

Hepatic mass seems generally to be the most highly correlated predictor of fecundity; this is not characteristically the case in the genus Coregonus (Hénault and Fortin 1991). Female fecundity varies as a function of total length and ranges from 29,400 to 74,900 eggs/kg, for females measuring between 220 and 265 mm.

Depending on the temperatures at depths of 30 m, the equation model of Colby and Brooke (1973) corresponded to an incubation period of 72 days (for 50% hatch) for the Spring Cisco, although incubation can last between 76 and 92 days in other cisco populations (Anderson and Smith 1971; Scott and Crossman 1998; Hénault and Fortin 1991). During embryonic development, cisco eggs are vulnerable to predation, sedimentation and dissolved oxygen levels in the water (Colby and Brooke 1980).

Despite a significant sampling effort by Hénault and Fortin (1991) in 1984 and 1987, only nine Spring Cisco larvae were collected, the first of which was detected near the end of July. Daily vertical migration could account for the small sample size and all samples being caught at night. Specific data on Spring Cisco larvae behaviour are not available. It is known, however, that upon hatching, cisco larvae begin to feed and swim to the surface of the water to fill their swim bladder with atmospheric O2. This is a critical stage in their survival, which then depends on food availability.

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Diet

Pelagic cisco larvae are planktivorous and feed almost exclusively on copepods and cladocerans (Anderson and Smith 1971; Scott and Crossman 1998). This close relationship between zooplankton availability and larval survival was demonstrated in Lake Superior (Anderson and Smith 1971; McCormick et al. 1971).

Pelagic adults are plankton feeders, but consume a wide variety of prey, such as insects, eggs, small fishes and crustaceans, depending on the season (Scott and Crossman 1998; Kerr and Grant 1999; Bernatchez 2000). The analysis of the stomach contents of Spring Cisco captured in September 2005 (n= 7) revealed that insects comprise 18% of their diet, benthos 36% and zooplankton 45% (MRNF, unpubl.data).

Growth

In Lac des Écorces, cisco larvae develop in marginal environmental conditions (see Habitat above) and are vulnerable to temperature variations. However, in addition to avoiding the top metre of water, cisco larvae are more tolerant than adults of temperature variations in their environment, which can sometimes reach values that are close to the lethal temperature of 26°C (Edsall and Colby 1970). On the basis of an examination of scales, the authors (Hénault and Fortin 1989; Hénault and Fortin 1991) concluded that there is a significant lag in growth at the end of the first year of life: 50-58 mm versus 106-130 mm in individuals from Lake McGregor, which is located 100 kmsouth of Lac des Écorces.

At three years, the age at which sexual maturity is reached, average total lengths (220-265 mm) tended to be slightly below those of Cisco populations in the same watershed (245-285 mm) [Hénault and Fortin 1989; Hénault and Fortin 1991]. Despite this lag, which is made up over the years, the authors (Hénault and Fortin 1989; Hénault and Fortin 1991) concluded that the growth of specimens from Lac des Écorces is considered normal for fishes from small lakes.

The oldest specimen collected was an 11 year-old female, although the average age was five years and few specimens live longer than 8 years (Hénault and Fortin 1991).

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Dispersal/migrations

During the summer, the Spring Cisco is usually found throughout the lake in the hypolimnion where they move about daily in search of food (Hénault and Fortin 1993). In autumn, they are found throughout the lake at depths of 12 m or more. In the spring, during spawning, they have been captured at various sites around the principal basin of the lake at depths of 20 to 30 m over a soft, muddy substrate (Hénault and Fortin 1993).

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Predation/interspecific interactions

In 1984, 22 fish species occurred in Lac des Écorces, including Northern Pike (Esox lucius), Walleye (Sander vitreus), Yellow Perch (Perca flavescens), Lake Whitefish (Coregonus clupeaformis), Smallmouth Bass (Micropterus dolomieu), Pumpkinseed (Lepomis gibbosus), Brown Bullhead (Ameiurus nebulosus), White sucker (Catostomus commersonii), Muskellunge (Esox masquinongy), Lake Trout (Salvelinus namaycush), and Brook Trout (Salvelinus fontinalis) (MRNF, unpubl.data; Bernatchez 2000; M.-A. Montpetit, pers. comm. 2005). Spring Cisco was the main prey of several of these piscivorous species including Northern Pike, Walleye, Smallmouth Bass, Muskellunge, Lake Trout and Brook Trout (Bernatchez 2000). At least two other species, known to have a predator-prey relationship, have since been added to the list, Rainbow Smelt (Osmerus mordax) and Atlantic Salmon (Salmo salar). These two species were introduced into the Kiamika Reservoir, located upstream from Lac des Écorces, in the early 1990s. The presence of Rainbow Smelt was confirmed in 1999, when three dead fish were found in Lac des Écorces. In 2004 and 2005, a spawning site was identified at the mouth of Gauvin Creek, a tributary of Lac des Écorces.

The introduction of Rainbow Smelt resulted in changes in predator-prey relationships in this fish community. The experimental fishery of September 1992 and 2005 in Lac des Écorces indicated an increase in the catch per unit effort (CPUE) from 3.3 to 6.8 and from 25.1 to 35.3 for Walleye and Yellow Perch, respectively (MRNF, unpubl. data). An interaction with the recent colonization of Rainbow Smelt may be a factor in this increase. The analysis of the stomach contents of Walleye (n= 68) in the 2005 sample revealed the presence of Rainbow Smelt in the stomachs of 58% of the individuals (MRNF, unpubl.data), and 0% individuals had Yellow Perch. Therefore, it appears that the abundance of Yellow Perch is increasing as a result of the decline in predation on this species, and could, therefore, become a significant predator of newly hatched cisco larvae during their vertical migration. One fish larva (difficult to identify but resembling to a cisco larva) was found in the stomach of a Yellow Perch captured on September 22, 2005. A Yellow Perch was caught in 2008 with eggs in its mouth that were not identified as to species, but were thought to be Spring Cisco eggs. In addition, the stomach contents of all Lake Whitefish (Coregonus clupeaformis) collected in May 1983 and 1984 contained a large number of cisco eggs (Hénault and Fortin 1991).

Lac des Écorces has been stocked a number of times in an effort to improve the sport fishery. In 1988, 1990, 1991 and 1992, it was stocked with Brook Trout, and in 1960, with Walleye, which still occur in the lake. In the early 1990s, the Kiamika Reservoir (Figure 2) located upstream from Lac des Écorces was stocked with Atlantic Salmon and Rainbow Smelt. Experimental fisheries conducted in 1992 and 2005 showed that Lake Trout have all but disappeared from the lake, and that catches by anglers are considered marginal, although Lake Trout are still found at the base of the dam and upstream from the Kiamika Reservoir (Hénault and Fortin 1993; M.-A. Montpetit, pers. comm. 2005; MRNF, unpubl.data).

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Adaptability

The shift in the spawning period of Spring Cisco can be directly attributable to environmental conditions, particularly the high summer and fall temperatures of the hypolimnion of Lac des Écorces (Hénault 1987; Hénault and Fortin 1991, 1992, 1993). As reported by several authors, water temperature plays a critical role in gonad development, which can be inhibited by high temperatures (e.g., John and Hasler 1956; Okuzawa et al. 1989; Strussmann and Nakamura 2002; Lim et al. 2003). Temperatures in the hypolimnion are very cold in the winter (2.8°C in January 1968), rise quickly in the summer (9°C in June 1968) and fall late in the autumn (5.6°C in November 1968) (MRNF, unpubl.data).

It is not likely the thermal variation in Lac des Écorces is a result of manipulation of flow regimes. The current dam at the outlet of the lake (Reno Dam), and the barrier at the outlet of Lac Kiamika (Barrage Kiamika) creating the Kiamika Reservoir were both completed in 1952 and 1954 respectively. However, early barriers at both locations date back to at least 1914, and have undergone various modifications over the years to control flooding (M. Hénault. pers. comm.. 2009). Although all dams alter all monthly flow rate characteristics to a greater or lesser extent, the extent of such modifications is variable. Smaller watersheds, such as the Kiamika, demonstrate less variability since there is less effect on small watersheds, and most changes are observed in the winter and early spring (Lajoie et al.2007). Moreover, the type of thermal variation in Lac des Écorces appears to be unique to the lake, and is seldom seen in other lakes in the Kiamika River watershed downstream of the reservoir (Hénault and Fortin 1993). Furthermore, the extent of divergence from C. artedi in nearby lakes has led to reproductive isolation of the Spring Cisco from C. artedi(see Biology), which would indicate that the unique temperature regimes of the lake are long-standing.

The shift of the spawning period has resulted in the larvae hatching primarily in July and August when there is a reduction in the preferred habitat of Spring Cisco and Rainbow Smelt due to the temperature preference of these species. At this time they occur in the basin of the lake, under the thermocline. Given the knowledge on the predator-prey relationship of Rainbow Smelt, predation on larval coregonines exists, and the impact of Rainbow Smelt on Spring Cisco larvae in deep zones seems to be a real and serious concern.

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Population Sizes and Trends

Search effort

Experimental fisheries conducted in adjacent lakes and elsewhere have failed to verify the presence of this species at any of the nearby lakes or other locations (see Distribution; Pariseau et al. 1983; Hénault 1987 Hénault and Fortin 1993; McAllister and Campbell unpubl. data). Experimental fisheries have been conducted in Lac des Écorces periodically since 1983 using experimental gill net sets at standard locations (Table 1).

Table 1: Catch per unit effort of Spring Ciscoes from Lac des Écorces between 1983 and 2008
YearDateStationCPUE (n/hour)NumberHours FishedRemarks
Total
0.03
1
34.7
 
1981May 22
3
6.8
77
11.5
experimental gill net
1983May 5
1
4.8
30
6.3
gill net (30 m X 2 m X 5 cm stretch measure mesh)
1983May 18
2
3.9
68
17.3
Fisheries in night (experimental net)
1983May 18
2
11.7
203
17.3
gill net (30m X 2 m X 5 cm stretch measure mesh)
1983June 7
2
0.4
6
17.0
gill net (30m X 2 m X 5 cm stretch measure mesh)
1983June 7
1
4.6
79
17.0
Fisheries in night (experimental net)
Total
5.2
386
74.9
 
1984May 24
1
29.2
175
6.0
gill net (30m X 2 m X 5 cm stretch measure mesh)
1984June 10
1
5.8
13
2.3
gill net (30m X 2 m X 5 cm stretch measure mesh)
Total
22.8
188
8.25
 
1987May 20
1
15.2
41
2.7
Experimental net
1987May 20
1
11.1
30
2.7
?
Total
13.1
71
5.4
 
1994May 18
1
13.4
51
3.8
Brook Trout experimental net
1994May 18
2
7.8
31
4.0
Brook Trout experimental net
Total
10.5
82
7.8
 
1997May 28
1
10.8
42
3.9
Brook Trout experimental net
1997May 28
2
0.0
0
3.8
Brook Trout experimental net
Total
5.5
42
7.7
 
2003May 21
1
3.4
12
3.5
Brook Trout experimental net
2003May 21
2
0.0
0
3.42
Brook Trout experimental net
2003May 29
1
6.7
32
4.75
Brook Trout experimental net
2003May 29
2
3.2
14
4.42
Brook Trout experimental net
Total
3.6
58
16.09
 
2004May 17
1
0.0
0
3.5
Brook Trout experimental net
2004May 17
2
4.8
14
2.9
Brook Trout experimental net
2004May 27
1
1.2
5
4.1
Brook Trout experimental net
2004May 27
2
1.6
6
3.7
Brook Trout experimental net
Total
1.8
25
14.2
 
2008May 14
1
0.0
0
4.60
Lake Trout experimental net
2008May 14
1
0.2
1
4.70
Brook Trout experimental net
2008May 14
2
0
0
4.5
Lake Trout experimental net
2008May 14
2
0
0
4.6
Brook Trout experimental net
2008May 23
1
0
0
4
Lake Trout experimental net
2008May 23
1
0
0
4.10
Brook Trout experimental net
2008May 23
2
0
0
4.10
Lake Trout experimental net
2008May 23
2
0
0
4.10
Brook Trout experimental net

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Abundance

Experimental fisheries conducted for over 25 years in Lac des Écorces, using CPUE as an index of abundance, suggest that the population has been in decline since 1987; based on available data, there is a high probability that the population has experienced a decline in excess of 50% over the last three generations) between 1994 and 2008 (Figure 4), to a point an order of magnitude below that of the initial 1983 effort. At the same time, the numbers of fish caught has also decreased while fishing effort has not. No surveys were conducted in 2006 and 2007, but the 2008 survey yield only a single specimen despite an almost tripling of sampling effort.

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Figure 4. Catch per unit effort of Spring Ciscoes from Lac des Écorces between 1981 and 2008.

Chart showing catch per unit effort of Spring Ciscoes from Lac des Écorces between 1981 and 2008.

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Over a period of 21 years, the average length of ciscoes decreased from 240 mm to 205 mm (Figure 5). Minimum and maximum sizes of the specimens captured are much closer to the mean, which reflects homogeneity in size, and possibly in year classes, indicating that the number of older, sexually mature fish adults is declining.

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Figure 5. Average length of mature spring-spawning ciscoes captured in May from 1983 to 2008 in Lac des Écorces. A Student's t-test for small and independent samples was used to compare the average length, lighter area at the top of each bar is one standard deviation.

Chart showing the average length of mature spring-spawning ciscoes captured in May from 1983 to 2008 in Lac des Écorces.

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There are a number of factors that may explain the decline in catches and average size. The recent introduction of Rainbow Smelt may be causing a reduction in cisco recruitment quality and growth. The decline observed in Figure 4 may also be explained by competition for food resources among adult ciscoes and the resulting reduction in growth. It has also been observed that the size of ciscoes decreases as their density increases (Aku and Tonn 1997), but this does not appear to be the case in Lac des Écorces. Strong year classes are typical of coregonines and are often correlated with environmental fluctuations (Anderson and Smith 1971; Bowen et al. 1991; Aku and Tonn 1997).

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Rescue effect

Not applicable - the species is endemic to Lac des Écorces.

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Limiting Factors and Threats

Lac des Écorces has undergone many disturbances over the last 50 years. The waters are considered mesotrophic but there are several references to its tendency towards eutrophic conditions (Bergeron and Vincent 1973; Hénault and Fortin 1993). The rapid development of its shorelines for the construction of homes or cottages, and the leaching of chemicals and organic wastes from agriculture and livestock production are cause for concern. Until 1995, the municipalities of Lac-des-Écorces and Chute-Saint-Philippe discharged their untreated wastewater into the Kiamika River, the main tributary of Lac des Écorces. Since then, the wastewater has undergone primary municipal treatment, and is still discharged into the river (M.-A. Montpetit, pers. comm. 2005). However, there remain a number of cattle and pig farms along the banks of the Kiamika, and nearly 1000 ha adjoining the river are used for grain production.

Eutrophication of lakes through sewage disposal from lakeshore cottage developments is a major concern throughout the Boreal Shield (Urquizo et al.2000). Sewage effluents contribute to the addition of materials that are usually not present, or present in lower amounts, including metals, organic chemicals and suspended sediments. At toxic levels these can inversely impact the biota by killing them, weakening them, or interfering with their ability to feed and/or reproduce (Quebec Biodiversity Website 1999). Cottage owners also tend to create “clean shorelines” by removal of macrophyte communities that provide critical rearing and/or feeding habitat for aquatic invertebrates and fishes. Removal of shoreline vegetation has been shown to lead to declines in local macrophyte populations, disruptions in aquatic food chains and declines in populations of Northern Pike and prey species such as Yellow Perch and Pumpkinseed (Urquizo et al. 2000).

No information is available to assess possible changes in the Lac des Écorces ecosystem as a result of the recent period of climatic warming; however, warming of the lake waters may not be as much of a challenge for the Spring Cisco as for C. artedi(Hénault, pers. comm.2008). On the other hand, other factors such as deepening of the thermocline or reductions in dissolved organic carbon and phosphorus could negatively impact the species through habitat loss and/or degradation. The issue of habitat loss and degradation appears to be more likely the result of environmental (climate) change superimposed on other factors associated with urbanization, agricultural practices, and introductions of exotic species. Elsewhere in Quebec, 30 of the 217 known populations of the southern subspecies of Arctic Char (Salvelinus alpinus oquassa) have been lost due to such a combination of factors, as well as over-fishing (J. Reist, DFO, pers. comm. 2007).

The change in fish community and the eutrophication of Lac des Écorces and throughout the entire watershed may represent threats for Spring Cisco. The recent introduction of Rainbow Smelt represents a potential hazard in several respects. The interaction between these two species may result in competition for food resources and in predator-prey relationships (Scott and Crossman 1998; Etnier and Skelton 2003). There is a strong likelihood that Rainbow Smelt will have an impact on young cisco (Hrabik et al. 1998) or eggs (Evans and Loftus 1987) [see Predation/interspecific interactions above]. Food web shifts can be expected, leading to restructuring of the fish community (Loftus and Hulsman 1986; Evans and Loftus 1987).

An inversely proportional relationship between Rainbow Smelt and cisco was observed in lakes Simcoe and Superior suggesting competition for food resources among fishes under one year old (Anderson and Smith 1971; Evans and Waring 1987). In an attempt to conserve the latter, Evans and Loftus (1987) went so far as to recommend excluding Rainbow Smelt from small lakes.

According to Evans and Loftus (1987), there is a close interaction between Lake Trout and Smelt, since the achievement of a long-standing equilibrium, based on a predator-prey relationship, has regularly been observed. Lake Trout in Lac des Écorces underwent a serious decline as a result of the degradation of water quality in the lake, and this is also believed to have had an overall impact on the new community dynamics. One would expect that smelt populations would increase following the decline of lake trout, and this in turn would have a negative impact on young cisco, which seems to be the case as the number of cisco has declined concomitant with the introduction of Rainbow Smelt and the decline in numbers of Lake Trout. Following the stocking of Lake Trout to Lake Simcoe, Yellow Perch, Cisco and Rainbow Smelt populations all declined due to predation (Evans and Waring 1987). Moreover, a 40-year study has found that in the presence of these two prey species, young Lake Trout will feed on Rainbow Smelt; whereas, cisco is a preferred prey of older individuals (Mason et al. 1998).

There are indications that Walleye populations are also in decline, but further research is required to substantiate this. If the Walleye population collapses, perch will probably become the dominant predator in the lake, and may already be making an impact on cisco populations. Further study in 2009 may help to shed some light on this.

The Spring Cisco is also vulnerable to habitat degradation. Shoreline development, various forms of pollution, and the proliferation of vegetation can contribute to the eutrophication of the river or stream (Hénault and Fortin 1992). Increased nutrient loads contribute to the decline in oxygen levels in the cold, deep waters in which the species occurs in the summer. In Lac des Écorces, there are only two pools that exceed 20 m in depth. The number and quality of spawning sites can potentially constitute a limiting factor. Oxygen depletion in the hypolimnion can, in fact, be the cause of catastrophic mortalities for ciscoes (Scott and Crossman 1998). The preservation of these sites is critical to the survival of Spring Cisco. However, physicochemical data from 2005 indicate that dissolved oxygen levels are still considered adequate for salmonids even in the deep zone (MRNF, unpubl.data).

Bergeron and Vincent (1973) reported significant growth of aquatic plants in the bays of Lac des Écorces. In 2006, the vegetation was still abundant and Eurasian Water Milfoil (Myriophyllum spicatum), an invasive exotic species, has now colonized the sites.

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Special Significance of the Species

Eight species of ciscoes have been designated at risk by COSEWIC (COSEWIC 2007c), with several members of the genus Coregonus being designated extinct or at risk. These taxa reflect the precarious situation of several North American cisco populations.

Ciscoes play an important ecological role in terms of the fish population dynamics of Lac des Écorces. Predatory sport species that occur in the lake, such as Northern Pike, Walleye and Brook Trout, feed heavily on cisco. According to Hazel and Fortin (1986), Yellow Perch is the most important prey in mesotrophic lakes dominated by percids, followed by cisco.

Spring Cisco would be an excellent candidate for testing and determining the process of natural selection, thereby recognizing the importance of morphotypes to the potential adaptability of a species.

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Existing Protection or Other Status Designations

Following the study published by Hénault and Fortin (1992), Spring Cisco was designated Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 1992. Since 2003, the Spring Cisco has been listed under Schedule 3 of the Species at Risk Act (SARA). The Spring Cisco is considered rare and imperilled in Quebec (S2S3) and has a global rank of G5T3Q (abundant), but the Lac des Écorces population is unique despite the taxonomy being unresolved.

Spring Cisco habitat is also protected at the federal level under the Fisheries Act (R.S. 1985, c. F-14). The species and its habitat are also afforded some degree of protection under the Quebec Environment Quality Act (R.S.Q., c. Q-2) and the Regulation Respecting Wildlife Habitats of the Act Respecting the Conservation and Development of Wildlife (R.S.Q., c. C-61.1).

Authority for the application and enforcement of the Policy for Protection of Rivers, Littoral Zones and Flood Plains(Quebec Ministry of Sustainable Development, Environment and Parks) is delegated to the municipalities.

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Technical Summary

Coregonus sp.

Spring Cisco – Cisco de printemps
Range of Occurrence in Canada: Quebec–Canadian Endemic

Demographic Information

Generation time (average age of parents in the population): 5 yr
Observed, percent reduction in total number of mature individuals over the last 15 years (3 generations): > 50%
Projected or suspected percent reduction in total number of mature individuals over the next 15 years (3 generations): Unknown
Suspected or observed percent reduction in total number of mature individuals over any 15 year (3 generations) period, over a time period including both the past and the future: Not Applicable
Are the causes of the decline clearly reversible? No
Are the causes of the decline understood? No
Have the causes of the decline ceased? No
Observed trend in number of populations: Stable
Are there extreme fluctuations in number of mature individuals? Unknown
Are there extreme fluctuations in number of populations? No

Extent and Area Information

Estimated extent of occurrence: 6.58 km²
Are there extreme fluctuations in extent of occurrence? No
Area of occupancy (AO): 6.58 km²
Index of Area of Occupancy (IAO)
1 X 1 km overlaid grid: 20 km²
2 X 2 km overlaid grid: 28 km²
Observed, inferred, or projected trend in area of occupancyPossible decline
Are there extreme fluctuations in area of occupancy? No
Is the total population severely fragmented? No
Number of current locations: 1
Trend in number of locations: Stable
Are there extreme fluctuations in number of locations? No
Trend in [area and/or quality] of habitat: Decline

Number of mature individuals in each population

PopulationN Mature Individuals
Total:Unknown
Number of populations (locations):1

Threats (actual or imminent threats to populations or habitats)

Actual: Stable - introduction of competing or predatory species (Rainbow Smelt, Atlantic Salmon).
Imminent: eutrophication, degradation of the water quality of Lac des Écorces and of the spawning habitat.
Potential: increase in water temperatures as a result of global warming.

 

Rescue Effect (immigration from an outside source)None–Canadian Endemic
Status of outside population(s)? None known
Is immigration known or possible No
Would immigrants be adapted to survive in Canada?
Is there sufficient habitat for immigrants in Canada?
Is rescue from outside populations likely? No

Quantitative Analysis

No data

Current Status

Nature Conservancy Ranks (NatureServe 2007)
Global – G5T3T5Q Rounded T4
National (Canada) –NNR
Regional – QC S2S3

Wild Species 2005 (Canadian Endangered Species Council 2006)
Not Listed

Province – Imperilled

COSEWIC – Endangered (April 1992)

SARA – Schedule 3

Status and Reasons for Designation

Status: Endangered
Alpha-numeric code: A2bce; B1ab(iii,v)+B2ab(iii,v)
Reasons for Designation: This species, known from only one small lake in southwestern Quebec, has undergone a drastic decline in abundance over the past 15 years (3 generations). The decline may be related to a combination of factors including habitat degradation and loss resulting from urban and agricultural development, the introduction of non-native species (e.g. Rainbow Smelt and Atlantic Salmon), and climate change.

Applicability of Criteria

Criterion A (Declining Total Population): Meets Endangered A2bce. An index of population size has shown that the population has decreased by over 50% over the past three generations. The reduction does not appear to have ceased and the causes are not fully understood, and may not be reversible, but may be related to a number of factors including habitat degradation resulting from urban and agricultural practices as well as climate change, and the introduction of exotic species.
Criterion B (Small Distribution, and Decline or Fluctuation): Meets Endangered B1ab(iii,v)+B2ab(iii,v). The species exists in only 1 location with an EO and AO < 20 km², where quality of habitat and number of individuals has demonstrated continuing decline over the past 3 generations.
Criterion C (Small Total Population Size and Decline): Not Applicable – Population size, although undoubtedly small and in serious decline, is unknown.
Criterion D (Very Small Population or Restricted Distribution): Meets Threatened D2, known from only 1 location with an AO of < 20 km².
Criterion E (Quantitative Analysis): Not Applicable – No data.

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Acknowledgements and Authorities Consulted

The authors wish to thank Michel Hénault for so generously sharing his knowledge. Without him, very little information would be available on the Spring Cisco. The authors also thank Marc-Antoine Montpetit of the municipality of Lac-des-Écorces for providing them with valuable information on fishing activities in Lac des Écorces. They also would like to thank Claude Renaud, Daniel Banville, James D. Reist, Lara Cooper, Karine Picard, Marthe Bérubé as well as Fisheries and Oceans Canada, the Ministère des Ressources Naturelles et de la Faune and the Canadian Wildlife Service for providing them with resources and constructive comments.

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Information Sources

Airaksinen, K.J. 1968. Preliminary notes on the winter-spawning vendance (Coregonus albula L.) in some Finnish lakes. Annales Zoologici Fennici 5(3): 312-314.

Aku, P.M.K., and W.M. Tonn. 1997. Changes in population structure, growth, and biomass of cisco (Coregonus artedi) during hypolimnetic oxygenation of a deep, eutrophic lake, Amisk Lake, Alberta. Canadian Journal of Fisheries and Aquatic Sciences 54:2196-2206.

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Biographical Summary of Report Writers

Louise Nadon completed a bachelor’s degree in biology (ecology) at the University of Quebec in Montreal and graduated, in 1997, with a master’s degree in renewable resources from the University of Quebec in Chicoutimi. Her thesis focused on feeding habits and growth of landlocked Atlantic Salmon (Salmo salar) in Lac St-Jean. Until 1997, she worked as a contractual biologist for the government and with various engineering firms. She worked on a variety of projects such as environmental impact assessments, studies concerning the management of wild furbearers as well as the development of an aquatic wildlife direction in an ecotoxicology laboratory, which was developed for bioessays on zooplankton, algae and fish. Since 1997, she has been in charge of sport fishing management for the Wildlife Section of the Ministry of Natural Resources and Wildlife after being involved in the field of wildlife habitats and studying the impacts of logging on aquatic fauna.

Audrey Sanfaçon graduated in 2000 with a bachelor’s degree in biology (wildlife management) from the University of Quebec in Rimouski. Since then, she has been working on several research projects in Canada and the United States. She worked on wildlife research contracts as a biologist for the Provincial Museum of Alberta, the North Carolina State University, the University of Arizona, and the Washington State Department of Fish and Wildlife. She presently works and studies at the University of Quebec in Chicoutimi as a research assistant at the Department of Fundamental Sciences.

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Collections Examined

None.