Gulf of St. Lawrence Herring

Atlantic herring are an abundant and highly migratory pelagic fish that inhabit the Gulf of St. Lawrence (GSL). In the northern GSL, they are managed and assessed as two discrete stocks; one along the west coast of Newfoundland (NAFO division 4R) and another on the north coast of Quebec (NAFO division 4S).

However, herring schools undertake extensive annual migrations between feeding, spawning and overwintering areas which are poorly understood. There is some evidence from mark-recapture studies and commercial fishery data that mixing occurs between the herring stocks in 4R and eastern 4S. Biological differences were also observed between the herring inhabiting the eastern and western regions of 4S, suggesting that 4S may comprise two separate stocks.

Stock assessment relies on the assumption that stock units are closed, and that no mixing occurs between units. When this assumption is violated, the results of stock assessments may be inaccurate, which can confound management strategies. This project is funded by the DFO Competitive Science Research Fund (CSRF) and will address this knowledge gap by employing acoustic telemetry to determine the seasonal movements and distribution patterns of the herring stocks within 4RS.

The lack of information on stock structure has been identified as the main source of uncertainty at the last 4S herring stock assessment. The overall objective of the project is to use acoustic telemetry to monitor the spatial and temporal movement patterns of the Atlantic herring stocks in the northern GSL in relation to fishery management areas (i.e., NAFO divisions 4R and 4S). Specific objectives are: 1.

Provide a detailed description of the seasonal migratory patterns of Atlantic herring in the northern GSL; 2. Determine the degree of mixing between herring stocks along the lower north shore of Quebec (eastern region of NAFO division 4S) and the proximal west coast of Newfoundland (NAFO division 4R); 3. Determine the degree of mixing between herring stocks in the eastern and western regions of NAFO division 4S; 4.

Provide new information to DFO biologists and resource managers on herring stock structure in the northern GSL to improve the accuracy of stock assessments and their use in fishery management.