Les stocks de hareng Atlantique (Clupea harengus) sur la côte ouest de Terre-Neuve (Division 4R de l'OPANO) en 2019

Abstract

This document presents the data and methods used to assess the status of the Northwest Atlantic Fisheries Organization (NAFO) 4R spring and fall spawning herring stocks. Based on preliminary data, herring catches totalled 7,418 t in 2018 and 15,806 t in 2019, with an annual total allowable catch of 20,000 t. The fishery experienced difficulties due to weather, changes in herring distribution and management measures. The proportion of landings composed of the spring spawning stock increased from 1.5% in 2014 to 24.5% in 2019. Catches of spring spawning herring were dominated by the 2013 cohort. Fall spawning herring age 11+ have dominated the landings since 2014. The 2008 cohort contributed to the fishery in recent years, but has been less important to the fishery than the previous 2000 year-class. Evidence from scientific sampling and the fishery indicates above average presence of young fish in recent years. Both of these stocks show a general downward trend in mean weight-at-age for ages 3+ beginning in the early 1980s, and a downward trend in condition since the early 2000s associated with changes in zooplankton abundance, phenology and community structure. The biomass of herring estimated from the 2019 fall acoustic survey was 47,522 t and 68,796 t for spring and fall spawning herring, respectively. There is evidence of changes in catchability of the acoustic survey in recent years indicating that the survey may not consistently provide a reliable index of abundance. Further investigation of the assessment model used as the basis of the advice confirmed existing concerns over model sensitivity to time-varying survey catchability and other input assumptions (constant natural mortality), and the inability to reliably estimate recruitment. As a result, the model was rejected as the basis of the advice. A review of the assessment framework for 4R herring is recommended. The available evidence up to 2019 (commercial catch-at-age, age and length at maturity, abundance of young fish, low exploitation rate in 2019) indicate that current harvest levels do not pose significant risk to herring stocks in 4R in the short term. This conclusion should be revisited following a review of the assessment framework.