Grey seals and cod
DFO has conducted extensive scientific research, in collaboration with independent scientific experts and the fishing industry, to improve our understanding of the complex relationships between grey seals and other components of the Atlantic coastal ecosystem, including Atlantic cod.
While much research remains to be done, the lack of cod recovery in the southern Gulf of St. Lawrence appears to be due to high mortality among larger cod. Predation by grey seals may account for up to 50 percent of this natural mortality, making them a major factor limiting the recovery of this cod stock. The Department continues to study the interaction between grey seals in Quebec and Atlantic Canada and this information will be used to inform management of both the seal harvest and the cod fishery.
How much cod do grey seals eat?
The Department has conducted numerous studies on grey seal diet using several different methods, including stomach content, scat and fatty acid analyses. The proportion of cod in a seal's diet varies widely between locations, seasons, and individuals. Based on data from a number of studies using traditional methods (i.e., scat and stomach/intestine content analyses) a single adult grey seal can eat as much as two tonnes of prey per year and cod can represent between 10 and 50 percent of its diet.
What is DFO doing to help cod stocks recover?
The Department has made many changes over the past several years to the management measures in place for both cod and other fisheries that incidentally catch cod. Some of these changes include:
- gear modifications to limit the bycatch of cod;
- implementing maximum incidental catch of cod (by percentage or weight) in other fisheries;
- closing certain fishing areas when cod are spawning or where juvenile fish are known to be found;
- limiting participation in some fisheries to fixed gear only (no trawling)
- fishing gear restrictions that limit the harvest of small fish;
- increase at-sea observer coverage in fisheries;
- mandatory dockside monitoring for virtually all groundfish landings; and
- continued investments in scientific research programs.
The Department is focused on a balanced approach that will take into consideration the health of Atlantic cod stocks and the grey seal population, for the benefit of important marine ecosystems and the fishing communities that depend on them.
Is DFO planning to conduct a grey seal cull?
There are currently no plans to conduct a program for the removal of grey seals. In considering any actions, the Department will consult with scientific experts and affected stakeholders to ensure that any measures put forward are achievable, humane and responsible, and that they will have a tangible, long-term impact on the recovery of important fish stocks, without compromising the sustainability of the grey seal population.
Related Scientific Journal Articles
- Feeding by grey seals on endangered stocks of Atlantic cod and white hake
- Seal–cod interactions on the Eastern Scotian Shelf: Reconsideration of modelling assumptions
- Seals, cod and forage fish: A comparative exploration of variations in the theme of stock collapse and ecosystem change in four Northwest Atlantic ecosystems
- Covariation between grey seal (Halichoerus grypus) abundance and natural mortality of cod (Gadus morhua) in the southern Gulf of St. Lawrence
- Date modified: