Research Document 2024/055
Assessment of Newfoundland and Labrador Snow Crab (Chionoecetes opilio) in 2021
By Pantin, J.R., Coffey, W., Mullowney, D., Baker, K.D., Cyr, F., and Koen-Alonso, M.
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 at the Assessment Division (AD) level using a variety of metrics. Data from multispecies bottom trawl surveys, inshore and offshore trap surveys, harvester logbooks, at-sea observers, the Dockside Monitoring Program (DMP), as well as oceanographic surveys are used to inform trends in biomass, recruitment, production, and mortality over the time series. There was no spring or fall multispecies trawl survey in AD 3LNO Offshore in 2021 and there was reduced coverage in the fall trawl survey in ADs 2HJ and 3K. Analyses were undertaken to investigate the impact of reduced coverage in 2HJ3K, and comparative modelling was conducted to investigate exploitable biomass estimates for AD 3LNO Offshore in the absence of trawl survey data. Snow Crab landings declined to a 25‑year low of 26,400 tonnes (t) in 2019, but have increased since to around 38,000 t in 2021, while effort increased slightly to near 3 million trap hauls. Overall fishery catch per unit effort (CPUE) was at a time-series low in 2018 but has greatly increased since then and was above the time-series average level in 2021. The overall exploitable biomass has increased in both trawl and trap surveys during the past four years from historic lows. However, this increase has not been seen in AD 2HJ. Total mortality in exploitable crab has decreased in all ADs in recent years. It remains highest in AD 2HJ. There is no updated total mortality estimate for AD 3LNO Offshore in 2021. Exploitation rate indices (ERI) were near time-series lows in all ADs in 2021, except AD 2HJ. With status quo removals in 2022, ERI is expected to decrease or remain low in all ADs, except 2HJ, where it would be over 60%. Elements of the Precautionary Approach (PA) Framework presented at the time of this assessment were tentative. Limit Reference Points (LRPs) have been established by a peer-reviewed Science process, but Upper Stock References (USRs) and Harvest Control Rules (HCRs) remained under development at the time of the assessment. In 2022, with status-quo removals, all ADs are projected to be in the healthy zone of the provisional PA Framework, except AD 2HJ, which is projected to be in the cautious zone. Pre-recruit abundance indices suggest favourable prospects for recruitment into the exploitable biomass over the next two to four years, however multiple streams of evidence suggest further improvements may be limited. A sharp decline in male size-at-maturity (i.e., terminal molt size) occurred in most ADs in recent years, and persisted in AD 2HJ in 2021, which could dampen short-term prospects for recruitment into the Snow Crab exploitable biomass.
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