Halibut: Atlantic

Halibut

Hirame

Atlantic halibut are the largest of the Atlantic flatfishes. They are widely distributed throughout the North Atlantic Ocean and parts of the Arctic Ocean at depths of 200-500 m. They grow relatively quickly and can live as long as 50 years, growing up to 320kg. However, individuals of this size have likely always been rare. Atlantic halibut are annual batch spawners and are able to release several batches of eggs in a single reproductive season, releasing up to 7 million eggs. Most individuals, however, produce considerably fewer eggs. Spawning occurs in Canadian waters in late winter and early spring. The diet of juvenile halibut (<30 cm) is composed of invertebrates such as krill, small crabs, and shrimp. Fish begin to make up a larger proportion of their diet until they reach approximately 70 cm after which time their diet shifts almost exclusively to other fishes.

In comparison to other commercially caught fish, biological traits of Atlantic halibut are moderately vulnerable to fishing pressure, as they mature at 12 years and can live up to 50 years old. The collapse of the American stocks and low abundance of the Gulf of St. Lawrence stock is evidence that this stock can be easily overfished if sustainable catch limits are not enforced. Atlantic halibut are considered to be “moderately” vulnerable to fishing pressure.

Atlantic Halibut in Canada are managed in several stock units. The Gulf of St. Lawrence population is extremely low compared to historical abundance, with stock status considered critical and no directed fishing occurring. The majority of the fishery is conducted in NAFO divisions 4V and 4W on the Scotian Shelf with some catch from the Southern Grand Banks. Catches peaked in 1984, and then declined. Abundance is low in these areas, compared to historical levels, but abundance seems to have stabilized.

In Atlantic Canada, halibut are directly targeted using longlines however many are also now taken incidentally as trawl bycatch. There is concern that the trawl fishery is resulting in high mortality of immature fish and because of population declines, this warrants a high conservation concern.

Based on the published literature noting the adverse effects of trawling on the various habitat types where halibut are found, as well as the significant amount of fishing effort along the continental shelf over the last 50 years, it is reasonable to assume that trawling has significantly altered or damaged a large portion of the seabed and the ecosystem. The degree of recovery from these actions is largely unknown and the effects of these fishing practices on habitats and ecosystems is ranked “severe”.

Management has been hindered by lack of long-term and relevant biological data and limited conservation measures were only implemented well after stocks fell to low levels. Stocks still at very low levels compared to estimated historical abundance. Currently, DFO cannot presently determine whether current catch levels are sustainable.

No.