Atlantic wolffish (Anarhichas lupus) COSEWIC assessment and status report 2012: chapter 3

COSEWIC
Executive Summary

Atlantic Wolffish
Anarhichas lupus

Wildlife Species Description and Significance

The Atlantic Wolffish, Anarhichas lupus, is a large-bodied, bottom-dwelling fish with prominent canine-like teeth. It has dark bars on its body that distinguish it from the other wolffish species. This species is taken as bycatch in a wide range of fisheries and was of commercial interest in the 1990s. A very limited commercial fishery persists, with the largest catches reported off Nova Scotia and south of Newfoundland.

Distribution

The Atlantic Wolffish inhabits northern regions on both sides of the North Atlantic and in the Arctic. In Canadian waters, it is distributed from the Canadian portion of the Gulf of Maine to offshore of Baffin Island, including the Bay of Fundy, Scotian Shelf, Grand Banks off Newfoundland, Gulf of St. Lawrence, northeastern Newfoundland and the Labrador Sea. It is most abundant off northeastern Newfoundland, on the Labrador Shelf and in the southern Grand Banks off Newfoundland. Although there is evidence of genetic differentiation in parts of its range, the information available to date does not support a division of the species into separate designatable units.

Habitat

The eggs of Atlantic Wolffish are deposited in crevices on rocky bottoms. The larvae are planktonic before becoming established on the bottom. Juveniles and adults are found primarily in the waters of the continental shelf on rocky or sandy bottoms. The fish tolerate a broad temperature range (from -1.5°C to 13°C), although they concentrate in a narrower range and water temperature is thought to be a major factor determining habitat selection.

Biology

The size at which 50% of females reach sexual maturity is 51.4 cm in the northern part of the range and 68.2 cm in the south. The age at which 50% of the female population reaches sexual maturity is between 8 and 15 years. These population parameters are based on old data as no recent estimates are available.

Wolffish have internal fertilization. Spawning is thought to occur in the fall and the eggs are guarded by the male until they hatch. Females spawn multiple times over their lifetime and egg production is low. Larvae hatch at a length of over 20 mm and remain near the bottom until the yolk sac is absorbed. Adults can reach up to 152 cm in length. Generation time is estimated to be 15 years for this species. Adults are fairly sedentary but juveniles are capable of wide dispersal. This species feeds primarily on invertebrates and, to a lesser extent, fish. Although juvenile wolffish have been found in the stomachs of seals and carnivorous fish species, larger individuals probably have few predators.

Population Sizes and Trends

The total number of Atlantic Wolffish in Canadian waters has been estimated at 49 million, including about 5 million mature individuals. There have been declines in both abundance and area occupied over most of its range since the 1970s or 1980s until the mid-1990s. Since then there has been a significant upward trend in abundance and distribution over much of its range, including the waters off the southern Labrador Shelf, which is the historical stronghold of this species. In contrast, adults (but not juveniles) on the Scotian Shelf have continued to decline in abundance and range size.

In the Gulf of Maine outside Canadian waters, the Atlantic Wolffish is at the southern limit of its range and is generally rare and unlikely to provide a source of fish that could rescue adjacent Canadian waters. Off western Greenland, its population is estimated at several million and on the Flemish Cap, abundance was estimated at over 10 million in 2006.

Threats and Limiting Factors

Commercial fishing (directed and bycatch) has been a threat to this species. Recorded catches were relatively high in the 1970s, but declined considerably in the 1990s in Canadian waters due to the closure of several groundfish fisheries. Climate change and its effects on water temperatures may also affect the distribution and abundance of this species.

Protection, Status and Ranks

The Atlantic Wolffish was first assessed as Special Concern by COSEWIC in November 2000 and was subject to a Management Plan. The status was confirmed in 2012 by COSEWIC. It is also listed as likely to be designated threatened or vulnerable under Quebec’s Act Respecting Threatened or Vulnerable Species (Loi sur les espèces menacées ou vulnérables; R.S.Q., c E-12.01). A petition to list Atlantic Wolffish under the US Endangered Species Act was not accepted. Canada’s small marine protected areas network protects fish in a very small proportion of their range, and some areas are currently subject to a closure to bottom-trawling.

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