Cusk

At a glance

A slow-moving and sedentary fish, the cusk is a member of the cod family. Over only three generations, cusk populations in the Gulf of Maine and the southeastern Scotian Shelf have declined by nearly 90 percent, mainly due to commercial fishing.

About the cusk

Essentially northern, deep-water fish, cusk are relatively slow-growing and late-maturing. Males reach sexual maturity at around five years of age; females at seven. Spawning usually occurs in May to August on the Scotian Shelf, but may be as early as April in the Gulf of Maine. Females are thought to lay up to 100,000 eggs at a time.

Little is known about the diet of cusk in Canadian waters. However, studies have shown that the fish favour marine invertebrates, such as crab, shrimp and krill, and occasionally other fish.

How to recognize a cusk

A cusk has an elongated body, a large head and a wide mouth. Several rows of sharp teeth line the fish’s jaws, and a single barbel—or whisker—adorns the lower jaw. Body colouring varies from reddish- to greenish-brown shading to cream or white on the belly.

Jeffrey C. Domm

Where cusk live

In Canada, cusk are found primarily in the Gulf of Maine and on the southeastern edge of the Scotian Shelf. The fish seem to prefer water that is more than 200 metres deep, sometimes swimming to depths of 600 metres. Cusk inhabit areas with a hard, rocky sea floor. They are occasionally found over gravel and mud, but rarely over sand.

Why it’s at risk

According to COSEWIC, cusk populations in the Gulf of Maine and the southeastern Scotian Shelf have declined by 90 percent since 1970. Although cusk has not been commercially fished since 1999, the biggest threat to cusk populations still comes from fishing. Cusk is caught as bycatch mainly by longline fisheries for other groundfish such as cod and haddock.

What’s being done

The cusk is designated as threatened by COSEWIC, but was not listed under Species at Risk Act (SARA).

There has not been a directed commercial fishery for cusk since 1999; however, it is caught as bycatch in other groundfish and invertebrate fisheries. DFO has implemented a cap of 750 tonnes on the bycatch of cusk by commercial groundfish gear fisheries.

The restrictions in groundfish fisheries are monitored by at-sea observers to ensure that the fishing rules are followed and by independent monitors at dock-side who verify the weights by species of fish when vessels offload their catches.

DFO is committed to increasing scientific research on cusk to better understand and track the current status of the species. DFO is also working with the fishing industry to develop and implement a conservation strategy.

Cooperative efforts focus on the gathering of information to determine the biological status of cusk stocks; investigating the potential for survival after release from fishing gear; developing and testing modifications to fishing gear to reduce bycatch; and other measures to significantly reduce the bycatch of cusk.

What can you do?

Cusk populations will get the protection they need only if all Canadians work together to reduce threats. Find out more about cusk and be aware of human-induced threats. Do your best to reduce these threats wherever possible to better protect the cusk’s critical habitat. Get involved with the Habitat Stewardship Program for Species at Risk(HSP) or another conservation organization.