Thank you very much, Mr. Chair.
I am a professor and Canada Research Chair in Fisheries Ecology at the Université du Québec à Rimouski. In 2008, I defended a doctoral thesis on the ecology of the larval stage of mackerel in the Southern Gulf of St. Lawrence, with particular emphasis on the environmental factors that regulate the survival of larvae and that are therefore responsible for the replenishment of adult stocks.
I then worked regularly on this species and participated in Fisheries and Oceans Canada’s stock assessments. I therefore believe that I have the knowledge required to comment on the ecology of the species in the context of fisheries management.
Contrary to the assessment of a number of forage species stocks in Canada, mackerel stock assessment is based on a reliable survey of adult abundance, derived from egg abundance in the egg‑laying area in the Southern Gulf of St. Lawrence. Because mackerel may alter its migration based on temperature, it is important to periodically check whether a substantial proportion of egg‑laying is occurring outside of the survey area. Over the past few years, the survey has been extended on an ad‑hoc basis to a number of areas such as the west coast of Newfoundland and the Scotian shelf, but the amount of egg‑laying outside the Gulf has always been considered negligible in calculating abundance, which has always been considered reliable.
The critical state of the stock can be attributed to two key factors: one is very high mortality in adults and the other is a low survival rate for the larvae.
Regarding mortality in adults, we estimate that, despite the substantial reduction in commercial catches in the past 20 years, when the quota went from 75,000 tonnes to just 4,000 tonnes, mortality remained too high to promote stock growth. In addition to high fishing pressure, natural mortality due to predatory fish such as bluefin tuna increased in the Gulf of St. Lawrence. There is also an indication that the stock in the Southern Gulf of St. Lawrence is suffering from other predators, such as grey seals, of which there are 16 times more now than there were in the 1960s. Predation has therefore increased a great deal since the early 2000s.
Finally, recent studies looking at the origin of mackerel caught during the winter fishery in the U.S. showed that a significant proportion of the fish caught in the U.S. are originally from the Gulf of St. Lawrence stock. This is therefore another source of mortality that is difficult to estimate at this time.
In addition to the high mortality in adults, the decline in mackerel abundance can be explained by a decline in recruitment since the 2010s. This decline in recruitment has been traced back to environmental conditions that have become unfavourable for larvae. During the first weeks of life, the survival of the larvae depends directly on their ability to successfully feed on their main prey: zooplankton.
With the rapid increase in temperature in the Gulf of St. Lawrence, there has been a change in the development period of the mackerel’s main prey, as they now develop earlier in the season, while the mackerel’s egg‑laying period has not changed. As a result, the emergence of larvae and prey production are no longer at the same time and place, leading to recruitment failure in the past few years. The stock recovery rate will depend largely on the return to colder conditions that would promote the survival of larvae and recruitment. However, short‑term climate projections unfortunately do not point to a return to these types of favourable conditions in the near future.
Now, here are some recommendations.
The first is to maintain fishing activity at as low a level as possible until signs of a recovery in the adult stock are observed.
The second is to establish a strategy to more accurately measure mortality resulting from fishing, including baitfishing in regions where it is not mandatory to report catches, and the winter fishery in the U.S.
The third is to establish a joint management plan with the U.S., given the presence of mackerel from the Gulf of St. Lawrence in their winter fishery.
The last is to use alternative baits from the highly abundant species in the Gulf of St. Lawrence, such as redfish, until the mackerel population recovers.
Thank you, Mr. Chair.