Assessment of Atlantic wolffish population trends in the Maritimes Region

Abstract

Atlantic Wolffish was assessed as Special Concern by the Committee on the Status of Endangered Wildlife (COSEWIC) in 2000 and listed under the Species at Risk Act (SARA) in 2003 because of steep declines in abundance and area of occupancy over much of its range from the 1980s through the mid-1990s. Its status was re-assessed and confirmed by COSEWIC in 2012. No signs of population recovery were observed for the portion of the population occurring on the Scotian Shelf where abundance continued to decline. Data analyses were undertaken to examine recent trends in abundance and distribution of the portion of the Atlantic Wolffish population residing on the Scotian Shelf using data from Fisheries and Oceans Canada (DFO) research vessel and industry surveys, commercial landings, at-sea commercial fishing observations, and SARA logbooks. The Maritimes Region Ecosystem Summer Research Vessel (RV) survey has the longest time series and most comprehensive coverage of the Scotian Shelf. Other RV and fishing industry surveys overlap the Summer RV survey geographically and provide short time series for other seasons, depths, and gear types. Overall abundance of Atlantic Wolffish on the Scotian Shelf has decreased. Abundance of immature individuals peaked in the late 1990s–early 2000s, and has declined since 2010. Abundance of mature individuals has been declining since the 1980s. Total stratified biomass decreased 62% from 1970 to 2000, 69% from 2000 to 2010, and 23% from 2010 to 2021, an overall decrease of 91% over the survey period. Stratified area occupied declined 36% from 1970 to 2010, and 85% from 2010 to 2021 – an overall decline of 74%. Commercial fishery landings in 4X decreased rapidly in the early 2000s and have remained below 10 t over the past decade. Landings from 4VW and 5Z have been near zero since before 2000. While Atlantic Wolffish discards are observed in multiple fisheries, estimates of total discards were not determined. The contribution of discards to estimates of fishing mortality on Atlantic Wolffish from various fisheries has not been assessed. Given the data sources available, abundance of Atlantic Wolffish on the Scotian Shelf remains low. Mortality due to fishing has declined, based on declining commercial landings and observations by at-sea observers; however, population abundance has also continued to decline