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Atlantic Herring (Clupea harengus) in Northwest Atlantic Fisheries Organization (NAFO) Division 4T, referred to as the southern Gulf of St. Lawrence (sGSL), consists of two spawning components, spring spawners and fall spawners. This document presents the most recent information on trends in abundance, distribution, and harvest for the spring and fall spawning Herring components in NAFO Division 4T. This includes catch-at-age and catch-per-unit-effort (CPUE) indices, fisheries-independent acoustic indices, experimental gillnet survey indices, mesh selectivity, fishery-dependent acoustic indices and catches in the multi-species bottom trawl survey of the sGSL. The data and indices are reported for the sGSL for the spring spawners, and regionally-disaggregated (North, Middle, and South regions) for the fall spawners where applicable. Spring spawners were assessed using a statistical catch at age (SCA) model that allowed for time-varying catchability to the gillnet fishery and time-varying natural mortality. The model estimated that spawning stock biomass (SSB) has been in the critical zone of the Precautionary Approach framework since 2002. The SSB median estimate in April 1 2022 is estimated to be 28,835 tons (t); 62% of the limit reference point (LRP = 46,340 t). Under current low recruitment and high natural mortality conditions, this stock is not expected to recover in the short or the long term. Reducing fishing mortality will have marginal effects on the projected SSB trends. By 2027, the probability of exceeding the LRP was not more than 20% at all catch levels, with SSB values ranging between 32,500 and 35,400 t. Fall spawners were assessed as regionally-disaggregated populations using a SCA model that allowed for time-varying catchability to the gillnet fishery and time-varying natural mortality. Estimated SSB has been declining in all three regions in recent years and is currently in the Cautious Zone of the Precautionary Approach framework. At the target catch level in 2021 (~12,000 t), the probabilities of a 5% increase in SSB by 2024 are all under 40%. Long-term projections show a continuous decline of SSB, however the probability of moving into the Critical Zone (under the LRP) by 2027 was 0% at all catch levels. As a consequence of low productivity and high natural mortality, exploitation of this stock should assert caution until high recruitment is observed for consecutive years. [ABSTRACT FROM AUTHOR]

Individuals must reproduce to survive and thrive from generation to generation. In fish, the fecundity of individuals and estimates of total reproductive output are critical for evaluating reproductive success and understanding population dynamics. Estimating fecundity is an onerous task; therefore, many populations lack contemporary estimates of fecundity and size-fecundity relationships. However, reproductive dynamics are not static in time; therefore, it is important to develop contemporary fecundity estimates to better inform conservation and management action. To highlight the importance of contemporary fecundity estimates, we examined the fecundity of southern Gulf of St. Lawrence (sGSL) spring and fall spawning Atlantic herring in 2022, developed size-fecundity models, and compared these to historical fecundity estimates and models. Our results suggest that the average fecundity of sGSL spring and fall herring has undergone a substantial temporal decline of approximately 47% and 58%, respectively, since the 1970s and 1980s. The size-fecundity relationships for fall spawning herring have shifted, with fish of a given size exhibiting lower fecundity in 2022 compared to the 1970s. Alternatively, the size-fecundity relationships for spring spawning herring have remained relatively static. Furthermore, simulations highlighted a substantial reduction in potential reproductive output in 2022 compared to 1970 of approximately 32% and 68% for spring and fall spawners, respectively, based on a fixed number of mature females, which may have negative implications for stock rebuilding. Overall, our study provides support for periodic estimates of fecundity in fish populations to better understand temporal changes in reproductive and population dynamics., (© 2024 His Majesty the King in Right of Canada. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of Fisheries Society of the British Isles. Reproduced with the permission of the Minister of Fisheries and Oceans Canada.)

The abundance of top predators in the southern Gulf of St. Lawrence, Canada, has fluctuated dramatically in recent decades. The associated increase in predation and its effect on the lack of recovery of many fish stocks in the system generates the need for a better understanding of predator-prey relationships and the implementation of an ecosystem approach to fisheries management. This study used stomach content analysis to further describe the diet of Atlantic bluefin tuna in the southern Gulf of St. Lawrence. Teleost fish largely dominated the stomach contents in all years. Previous studies established that Atlantic herring was the main component of the diet by weight, whereas herring was almost absent from the diet in this study. A shift in the diet of Atlantic bluefin tuna has been observed, as it now feeds almost exclusively on Atlantic mackerel. The estimated daily meal varied between years, ranging from 1026 g per day in 2019 to 2360 g per day in 2018. Daily meals and daily rations were calculated and showed substantial year-to-year variation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2023. Published by Elsevier Ltd. All rights reserved.)