Atlantic wolffish (Anarhichas lupus) COSEWIC assessment and status report 2012: chapter 6

Wildlife Species Description and Significance

Name and Classification

Class: Actinopterygii

Order: Perciformes

Family: Anarhichadidae

Latin name: Anarhichas lupus (Linnaeus 1758)

Common names:
English – Atlantic Wolffish
Also: Striped Wolffish, Catfish, Ocean Whitefish
French – Loup atlantique
Also: Loup de l’Atlantique, poisson-loup, loup de mer à peau mince, chat de mer, blennie-loup

Morphological Description

Members of the family Anarhichadidae are large marine fish that get their common name from their large conical canine-like teeth. There are three species of wolffish in the Canadian Atlantic and adjacent Arctic waters: the Atlantic Wolffish (Anarhichas lupus), which is the subject of this report, and the Spotted (Anarhichas minor) and Northern Wolffish (Anarhichas denticulatus).

The Atlantic Wolffish has an elongate body with large pectoral fins, and a large head with a rounded snout (Figure 1). It can reach a length of over 150 cm and a weight of 24 kg. In common with all wolffish species, it has prominent canine-like teeth in the front of the jaws, and flattened, grinding (vomerine) teeth behind. Wolffish species are distinguished from other fish by a continuous dorsal fin and the absence of pelvic fins. This species varies in colour from slate blue to dull olive green to reddish brown, and there are dark transverse bars on the body (Whitehead et al. 1986, Scott and Scott 1988).


Figure 1. Atlantic Wolffish (Anarhichas lupus) and distinguishing morphological features. Photo credit: C. Nozères, Department of Fisheries and Oceans.

Photo of the Atlantic Wolffish, lateral view (see long description below).
Description of Figure 1

Photo of the Atlantic Wolffish, lateral view, with arrows pointing to two distinguishing morphological features: the large pectoral fin and dark bars on the body. The species has an elongate body and a large head with a rounded snout. The dorsal fin is continuous and pelvic fins are absent. The individual shown here is a dark olive green on the upper two-thirds of the body, which is marked by about nine dark transverse bars. The underside is grey.

The Atlantic Wolffish can be distinguished from the other two wolffish species of the northwestern Atlantic by the 9 to 13 irregular and broken dark transverse bars on its body, some of which extend onto the dorsal fin. As well, its musculature is firm, not jelly-like as in the Northern Wolffish, and the grinding teeth on the vomer[1] extend to the rear of the mouth, farther back than the palatine teeth do[2] (Barsukov 1959 in Whitehead et al. 1986, Kulka et al. 2007). The position of these vomerine teeth can be used to distinguish between the three wolffish species.

Population Spatial Structure and Variability

Dispersal by eggs is not possible because eggs are deposited on the bottom (Keats et al. 1985, Scott and Scott 1988), and the larvae stay close to the nest (Bigelow and Schroeder 1953). However, the larvae can rise to near surface waters where they may disperse (Kulka et al. 2004), though they are negatively buoyant and sink to the bottom when they stop swimming (Mokness and Pavlov 1996), which could limit dispersal. Adults are generally considered sedentary (see section “Dispersal and Migration”).

Genetic differences among the three species of wolffish of the northwestern Atlantic were evaluated on the basis of their mitochondrial DNA genomes (Johnstone et al. 2007, McCusker and Bentzen 2010a) and nuclear genetic markers (McCusker et al. 2008, McCusker and Bentzen 2010a). These studies showed that the three wolffish species in the Atlantic are distinct from each other, with the Atlantic Wolffish more closely related to the Spotted Wolffish than to the Northern Wolffish.

McCusker and Bentzen (2010b) used microsatellites and amplified fragment length polymorphism (AFLP) markers to study the population genetic structure of Atlantic Wolffish throughout its North Atlantic range, including six areas within Atlantic Canada (Table 1). Genetic differentiation was weak to non-existent across much of the trans-Atlantic range of the species; however, sample locations in Atlantic Canadian waters were significantly differentiated from all locations elsewhere across the species’ range (Table 2). In addition, there were significant genetic differences among some locations within Atlantic Canada, particularly between the Grand Banks and other locations to the south and west (Table 2).

Table 1. Atlantic Wolffish sample details for microsatellite analysis in McCusker and Bentzen (2010b).
Label Location NAFO/ICES Years n
SS-02 Scotian Shelf 4VWX 2002 75
SS-04 Scotian Shelf 4VWX 2004 79
SG Southern Gulf of St. Lawrence 4T, 4Vn 2002, 2004 64
NG Northern Gulf of St. Lawrence 4RS 2004 63
SNF Southern Newfoundland 3OP 2002, 2003 74
SGB SE Grand Banks 3N 2001–2003 64
NGB NE Grand Banks 3L 2001–2003 68
WG West Greenland 1ABCDE 2004 83
EG East Greenland XIVb 2004 44
I-02 Iceland Va 2002 96
I-04 Iceland Va 2004 94
Sp Spitsbergen IIa2 2004 34
Bar Barents Sea IIa2 2004, 2005 111
NS North Sea IVb 2002, 2004 66
R-05 Rockall Bank VIb2 2005 34
R-06 Rockall Bank VIb2 2006 75
Table 2. Atlantic Wolffish Fst microsatellite analysis in McCusker and Bentzen (2010b). Location names correspond to Table 1.
  SS-02 SS-04 SG NG SNF SGB NGB WG EG I-02 I-04 Sp Bar NS R-05 R-06
SS-02   0.124 0.058 0.027 0.602 0.005 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
SS-04 0.002   0.206 <0.001 0.609 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
SG 0.001 0.002   <0.001 0.468 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
NG 0.005 0.006 0.011   <0.001 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
SNF -0.002 -0.001 0 0.007   0.004 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
SGB 0.002 0.007 0.011 0.007 0.003   0.404 <0.001 <0.001 <0.001 <0.001 0.003 <0.001 <0.001 <0.001 <0.001
NGB 0.008 0.01 0.02 0.01 0.008 -0.001   0.003 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
WG 0.019 0.02 0.031 0.016 0.019 0.007 0.004   0.819 0.248 0.1 0.277 0.074 0.002 <0.001 <0.001
EG 0.02 0.026 0.036 0.021 0.022 0.011 0.009 -0.001   0.504 0.732 0.463 0.738 0.307 <0.001 <0.001
I-02 0.016 0.02 0.03 0.015 0.018 0.007 0.007 0 -0.001   0.973 0.153 0.251 0.002 <0.001 <0.001
I-04 0.015 0.021 0.03 0.015 0.018 0.006 0.006 0.001 0 -0.002   0.181 0.348 0.109 0.001 <0.001
Sp 0.018 0.021 0.032 0.014 0.017 0.007 0.008 0 -0.002 0.003 0.003   0.487 0.303 0.008 <0.001
Bar 0.016 0.021 0.032 0.013 0.018 0.008 0.007 0.002 0 0.002 0.001 -0.002   0.098 <0.001 <0.001
NS 0.017 0.022 0.033 0.013 0.02 0.012 0.01 0.005 0.001 0.003 0.002 0 0   <0.001 <0.001
R-05 0.025 0.03 0.037 0.027 0.026 0.016 0.019 0.005 0.005 0.008 0.005 0.005 0.007 0.008   0.72
R-06 0.027 0.032 0.035 0.027 0.029 0.019 0.022 0.011 0.01 0.01 0.008 0.012 0.013 0.01 0  

Designatable Units

Although the results of McCusker and Bentzen (2010b) provide evidence for the existence of two or three genetically distinguishable populations of Atlantic Wolffish in Atlantic Canada, there is no evidence that these populations meet any of the COSEWIC ‘significance’ criteria needed for them to merit recognition as distinct DUs. For example, there is no evidence of distinct evolutionary lineages, adaptive genetic differences, distinctly different environments, or major spatial disjunctions that could be interpreted as evidence of significance. Accordingly, Atlantic Wolffish in Atlantic Canada are treated as a single designatable unit.

Special Significance

Atlantic Wolffish can occur in fairly dense concentrations and were of commercial interest in the 1990s. A small fishery for this species has persisted on the south coast of Newfoundland. Both Newfoundland and Maritimes Regions allow bycatch of this species to be landed. They can be filleted and sold fresh or frozen. The skin of these species can also be tanned and marketed. However, a large directed commercial fishery for these species is not currently possible due to the lack of sufficient concentrations. In 2008, their landings in Newfoundland totalled 7,743 kg for a landed value of $2,653 (Fisheries and Oceans Canada 2010). This species is popular with recreational divers.

This species is caught in mixed fisheries or as bycatch in many other fisheries such as Atlantic Halibut, Hippoglossus hippoglossus, Atlantic Cod, Gadus morhua, and Yellowtail Flounder, Limanda ferruginea (Kulka et al. 2007, Fisheries and Oceans Canada 2011). The largest catches are reported off the southern coast of Newfoundland and in Nova Scotia. In Newfoundland, landings have been recorded for all wolffish species combined. It is legal to land Atlantic Wolffish as this is not prohibited by the status of “Special Concern” on SARA Schedule 1.

The ecological role of the Atlantic Wolffish is difficult to assess owing to lack of available information. They feed on a variety of invertebrates and fish, and their larvae and juveniles are believed to be subject to predation by several species of fish.

1 The vomer is a single, median bone that forms the inferior and posterior portion of the nasal septum.

2 Palatine teeth are those that grow on the sides of the palate towards the centre of the jaw, rather than on the dental arch.

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