Updated assessment of Northern Wolffish, Spotted Wolffish, and Atlantic Wolffish related to population status, life history, and habitat

Abstract

An update of the 2014 assessment of wolffish was conducted to detect changes in population status, life history, habitat use, and fisheries interactions. The data used to assess changes in population status originate from numerous research vessel (RV) surveys with their own spatial and temporal coverage and constraints. Within all surveys, individual catches of wolffish were highly variable with a large number of zero catches resulting in very large confidence intervals around all indices of stock size. Since the last assessment, population status for all three wolffish species throughout Canadian Atlantic and Arctic waters remains largely unchanged and has shown little recovery. Increases in abundance have occurred since the late-1990s for Northern and Spotted Wolffish in Northwest Atlantic Fisheries Organization (NAFO) Divisions (Div.) 2H and 2J3K, where the majority of both populations reside. New parameters were estimated using models for age/length-at-maturity and growth. These parameter estimates were generally consistent with the range of values found in published studies. Wolffish are demersal fish species found over all bottom types. The three wolffish species occupy varying depth ranges in different regions. The majority of Northern Wolffish occur at depths down to 1,500 m. The majority of Spotted Wolffish and Atlantic Wolffish are restricted to depths less than 1,000 m, and inhabit nearshore waters seasonally. Wolffish thermal ranges vary among geographic regions. Spotted Wolffish have been observed more frequently at higher temperatures than Atlantic and Northern Wolffish where they co-occur. Current monitoring tools and programs are inadequate in most Canadian Atlantic and Arctic commercial fisheries to determine the scale of interactions, discard mortality, and total bycatch of wolffish by species.