Stock status update of 4VWX herring for the 2023 fishing season

Abstract

Maritimes Fisheries and Oceans Canada (DFO) Resource Management has requested that DFO Science conduct a stock status update of the Northwest Atlantic Fisheries Organization (NAFO) Divisions 4VWX Atlantic Herring (Clupea harengus) (henceforth referred to as 4VWX Herring) in support of decision-making for the 2023 fishery. The last full assessment of 4VWX Herring was conducted in March 2022 (DFO 2022a). As defined in the Terms of Reference, the objectives for this update were as follows: Evaluate the indicators and assess the fishery with respect to the Limit Reference Point (LRP) for Southwest Nova Scotia/Bay of Fundy spawning component (SWNS/BoF). Update and review information on the other spawning components (Offshore Scotian Shelf, Coastal Nova Scotia, Southwest New Brunswick migrant juvenile fishery). Update and evaluate the candidate Management Procedures (MPs) on the Reference Set of Operating Models for the SWNS/BoF component. Advise on the probability of rebuilding above the LRP over the projection period for each candidate MP for the SWNS/BoF component. Assess whether exceptional circumstances are triggered for the SWNS/BoF component. Estimate Tmin, where Tmin is the time SWNS/BoF herring would take to rebuild above the LRP with a high probability in the absence of fishing (F=0). Estimate the Probability of Preventable Decline from Year 3 to Year 8 in the projections for each MP. The biological and fishery information for 4VWX Herring forms the basis for establishing harvest levels for the 2023 fishery, as required in the Integrated Fisheries Management Plan (IFMP). An assessment of biological and fishery information for 4VWX Herring is provided in this Science Response. For the SWNS/BoF spawning component of 4VWX Herring, an assessment framework was conducted using a Management Strategy Evaluation (MSE) from 2019 to 2022 (Singh et al. 2020, Carruthers et al. 2023, Barrett In press). The stock status of the SWNS/BoF component is estimated by comparing the 3-year moving average of the acoustic index of spawning stock biomass for German Bank and Scots Bay to the Limit Reference Point defined in terms of the acoustic index (LRP, Clark et al. 2012), and also accounts for turnover of spawners at these grounds (DFO 2018). This science advice uses the 2022 assessment framework to identify candidate MPs that have a high probability of rebuilding the SWNS/BoF component above the LRP, evaluate trade-offs among other management objectives, and assess whether exceptional circumstances are triggered. This advice builds on the advice from 2022 (DFO 2022a) after which an MP was not selected. For other spawning components of 4VWX Herring, indicators of relative status and landings are reported herein based on methodologies presented in the 2018 stock assessment (DFO 2018). This Science Response Report results from the regional peer review of April 3, 2023, on Update of Stock Status for Herring in Northwest Atlantic Fisheries Organization Fishing Areas 4VWX.