Southern Gulf of St. Lawrence (NAFO Division 4TVn) fall spawning Atlantic Herring (Clupea harengus) stock assessment to 2023

Abstract

Status The Spawning Stock Biomass (SSB) of the southern Gulf of St. Lawrence (NAFO division 4TVn) fall spawning Atlantic Herring has been in the Cautious Zone of the Precautionary Approach (PA) Framework since 2017. As of 2022 and 2023, SSB of fall spawning Atlantic Herring has (100% probability) remained in the Cautious Zone. Trends Fall spawning Atlantic Herring has experienced declining SSB over the past decade, with declines continuing steadily over the past few years, except for 2023 where a slight increase in SSB was observed. Recruitment of fall spawning Atlantic Herring has been declining since 2006 to reach the lowest level of the time series in 2019. Recruitment has since increased and there was evidence of a notable recruitment event in 2022. Starting in 2010, natural mortality estimates for older ages of fall spawning Atlantic Herring sharply increased up to mid-2010s, then slightly decreased and remained at high levels. Ecosystem and Climate Change Considerations Higher water temperatures, poor food quality and high predator abundance likely have negative implications for Atlantic Herring size-at-age, fecundity and overall abundance. Stock Advice Under current conditions of high natural mortality, declines in weight-at-age, and low recruitment, the probabilities that SSB of fall spawning Atlantic Herring will increase by 2025 range from 48 to 53% across all considered catch options (2 to 18 kilotonnes). At all catch options, there is no chance that the SSB will decline into the Critical Zone by 2029. In light of recent stock trends and environmental conditions, caution should be taken when interpreting SSB projections for fall spawning Atlantic Herring as they suggest unrealistically optimistic trends. Therefore, stock advice should focus on 2023 SSB estimates rather than projections and a framework review should be conducted for this stock.