Stock status update of Atlantic Halibut (Hippoglossus hippoglossus) on the Scotian Shelf and Southern Grand Banks in NAFO Divisions 3NOPs4VWX5Zc for 2023

Abstract

Atlantic Halibut (Hippoglossus hippoglossus) is the largest of the commercial flatfishes and ranges widely over Canada's east coast. The management unit definition, Northwest Atlantic Fisheries Organization (NAFO) divisions 3NOPs4VWX5Zc, is based largely on tagging results that indicate that Atlantic Halibut move extensively throughout the Canadian North Atlantic with smaller fish moving further than larger fish. The Atlantic Halibut fishery was unregulated until a total allowable catch (TAC) was implemented in 1988 and a legal size limit (≥ 81 cm total length) was fully established in 1995. The Fisheries and Oceans Canada (DFO) Maritimes Summer Ecosystem Research Vessel (RV) Survey provides an index of abundance for incoming recruitment for the stock. An Industry-DFO Halibut Longline Survey (Fixed Station Halibut Survey) on the Scotian Shelf and southern Grand Banks (NAFO Divs. 3NOPs4VWX5Zc) was initiated in 1998 to provide an index of exploitable Atlantic Halibut. In 2017, a new Stratified Random Industry-DFO Halibut Longline Survey (hereafter referred to as the Stratified Random Halibut Survey) was initiated extending the longline survey into areas and depths that were not well sampled by the Fixed Station Halibut Survey. One hundred fixed stations continued to be fished to calibrate the 153-station Stratified Random Halibut Survey and provide an index for TAC advice (DFO 2020). A new assessment model was adopted in 2022 to inform Resource Management of the status of the Halibut resource and closed-loop simulation was used to evaluate harvest control rules (Johnson et al. 2024). Harvest level advice will be based on the exploitable biomass index from the Stratified Random Halibut Survey (Figure 1). The abundance index from the DFO Summer Ecosystem RV Survey (NAFO Divs. 4VWX) is monitored as an index of recruitment. DFO Resource Management asked Science to update the Atlantic Halibut stock status and provide 2024–2025 TAC advice based on the articulated harvest control rule adopted at the Scotia-Fundy Groundfish Advisory Committee (SFGAC) meeting in March 2022. This Science Response Report results from the regional peer review of December 6, 2023 on the Update of Stock Status for Atlantic Halibut in 3NOPs4VWX5Zc.