Grey Seals and Cod

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The northwest Atlantic grey seal population has seen a thirty-fold increase since the 1960s. The most recent population assessment from 2010 estimates the population at 349,000 seals.

Fisheries and Oceans Canada 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. As part of the Science Advisory Process in October 2010, a peer-review working group concluded that predation by grey seals was the greatest contributor to increased mortality in large southern Gulf of St. Lawrence cod.  At the same meeting, it was concluded that, while grey seal predation on cod is important on the Scotian Shelf, it explained less than 25% of the cod mortality, whereas it could account for around 50% in large cod in the southern Gulf.

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 content analyses) the average proportion of cod in the diet of northwest Atlantic grey seals can be estimated at about 10 percent, but could be lower or as high as 50 per cent, depending on where and when the samples are collected.

A few studies using a new method, fatty acid analysis, have found lower proportions of cod in the grey seal diet in some areas. There are biases associated with both fatty acid analysis and traditional methods that need to be considered, and further discussion is needed as to how results from these different methods can best be interpreted.

It is important to keep in mind that even in areas where the proportion of cod in the diet of seals is low, the total amount of cod consumed may still be high, given the abundance of seals and the amount of fish consumed by each animal.

What is DFO doing to help cod stocks recover?

The Department has made many changes overs 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 fishing areas when cod are spawning or where juvenile fish are known to be found and the creation of no-trawling areas;
• fishing gear restrictions that limit the harvest of small fish;
• doubling of at-sea observer coverage in most fisheries;
• mandatory dockside monitoring of almost all groundfish landings; and
• significant investment in scientific research programs.

We are 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 seal cull on Sable Island?

There are currently no plans to conduct a program for the removal of grey seals on Sable Island.

In considering any future action, 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.