Research Document 2019/003

An Assessment of Newfoundland and Labrador Snow Crab (Chionoecetes opilio) in 2017

By Mullowney, D., Baker, K., Coffey, W., Pedersen, E., Colbourne, E., Koen-Alonso, M., and N. Wells

Abstract

The status of the Snow Crab (Chionoecetes opilio) resource surrounding Newfoundland and Labrador (NL) in Northwest Atlantic Fisheries Organization (NAFO) Divisions (Divs.) 2HJ3KLNOP4R is assessed using a variety of metrics. Data from multi-species bottom trawl surveys conducted during fall in Divs. 2HJ3KLNO and spring in Divs. 3LNO and Subdiv. 3Ps are examined to provide information on trends in biomass, recruitment, production, and mortality over the time series. Multi-species trawl survey indices are compared with other relevant indices toward inferring changes in resource status for 2018 and beyond. These other indices are derived utilizing data from harvester logbooks, at-sea observers, the dockside monitoring program (DMP), and inshore and offshore trap surveys, as well as oceanographic surveys. Snow Crab landings most recently peaked at 53,500 t in 2009 and have since gradually declined to 34,000 t in 2017, their lowest level in two decades. Fishery catch per unit effort (CPUE) was at a two-decade low in 2017 with most divisions at or near historical lows. Despite a modest increase in 2017, the trawl survey exploitable biomass index has remained at its lowest observed level for the past three years. Meanwhile, the trap survey index has been at its lowest observed level in the past two years. Overall recruitment into the exploitable biomass has been very low in recent years and survey data suggest recruitment available to the 2018 fishery will remain low in most divisions. However, survey and environmental data suggest modest increases in recruitment could occur in some divisions over the next 2-4 years. Total mortality in exploitable crab has increased to be at or near time-series highs in recent years in all divisions. Status quo removals would maintain two-year average exploitation rate indices near or above long-term median levels in all divisions. New time-series highs would occur in Divisions 3L Inshore, 3LNO Offshore, and 4R3Pn. The relatively low level of residual biomass (old-shelled adult crab) at all sizes in all divisions in recent years is concerning given it is generally associated with low CPUE and high levels of discards in the fishery. Increasing recruitment potential in some divisions, coupled with a low residual biomass, suggests that wastage of soft-shelled pre-recruits could become more problematic if high levels of exploitation are maintained in the fishery in the next few years.

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