Science Advisory Report 2019/035

Assessment of the Atlantic Mackerel stock for the Northwest Atlantic (Subareas 3 and 4) in 2018

Summary

• Reported commercial landings in Canadian waters have decreased significantly in recent years. Between 2005 and 2013, they decreased from 54,726 t to 8,674 t before reaching a record low of 4,272 t in 2015. Preliminary landings in 2017 and 2018 were 9,430 t and 10,499 t.
• The TAC was reached for the first time in 2016. The TAC increased from 8,000 t to 10,000 t in 2017 and was surpassed in 2018.
• Total landings in US waters (commercial and estimated recreational and discards) also decreased significantly in recent years. In 2016 and 2017 landings were 10,277 t and 11,230 t. Based on the 2017 American assessment of the NW Atlantic stock, mackerel were determined overfished and overfishing is occurring.
• Preliminary analyses on otolith stable isotopes as well as a synthesis of tagging data suggest that a large proportion of Northern contingent (Canadian) Atlantic mackerel are caught in US fisheries. As such, estimates of removals of Northern contingent mackerel in US waters are now explicitly accounted for in this stock assessment.
• Preliminary genetic analyses of mackerel caught in Northeast Newfoundland, the Gulf of St. Lawrence, and Europe suggest that nearly all genotyped adult mackerel caught in Northeast Newfoundland have a Northwest Atlantic genetic signature. This concords with information from previous tagging studies.
• Preliminary analyses suggest that mackerel recruitment and condition are negatively influenced by warming temperatures and the reduced availability of their preferred prey.
• Since 2005, the spawning stock biomass index has declined and is now approximately one twentieth of the levels observed in the 1980s.
• The current age structure is truncated compared to the pre-2000 period and is now dominated by one year class. The 2015 year class represented 75% of declared landings by weight in 2018.
• A revised catch-censored statistical catch-at-age model was developed to include unaccounted for Canadian catch as well as US catch of Northern contingent mackerel.
• According to the consensus model, the current estimate of the 2016 spawning stock biomass is 59% of the LRP compared to 77% in 2018. The estimated 2018 fishing mortality was 1.13 (exploitation rate of 68%). Recruitment levels in 2017 and 2018 are at all-time lows.
• Short-term projections under different harvest control rules indicated that, with increasing TACs from 0 to 10,000 t, the probability of exceeding the LRP by 2021 decreased from 68 to 48%, and the probability of stock growth by 2021 decreased from 78 to 49%.
• A draft Management Strategy Evaluation (MSE) was peer-reviewed. Scientific review resulted in suggestions to add trade-offs to management objectives, to improve operating models, and to develop quantitative metrics for strategy evaluation. These steps would provide an improved basis to select Management Procedures to attain specific objectives (including rebuilding) for the stock under key uncertainties.

This Science Advisory Report is from the March 5-7, 2019 on Assessment of Atlantic Mackerel in Subareas 3-4. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Complete document (PDF, 1,287 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.