Research Document 2023/065
An Assessment of Newfoundland and Labrador Snow Crab (Chionoecetes opilio) in 2020
By Pantin, J., Coffey, W., Mullowney, D., Baker, K., 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), and oceanographic surveys are used to inform trends in biomass, recruitment, production, and mortality over the time series. Due to the COVID-19 pandemic, there was no spring multispecies trawl survey and at-sea observer coverage was very poor in 2020. Snow Crab landings declined to a 25-year low of 26,400 tonnes (t) in 2019, but increased slightly to 29,100 t in 2020. Fishing effort decreased to under 2.5 million trap hauls per year in 2020, the lowest level in two decades. Overall fishery catch per unit effort (CPUE) was at a time-series low in 2018, but returned to near the time‑series average in 2020. There have been modest increases in the trawl exploitable biomass index over the past three to four years and the index was nearing the time-series average in 2020. Meanwhile, the trap survey exploitable biomass index declined by nearly 60% in 2017 and 2018 to a time-series low. This index has increased during the past two years, but remains below the time-series average. Overall recruitment into the exploitable biomass increased in 2020, nearing the time-series average. Total mortality in exploitable crab has decreased in all ADs in recent years, but remains highest in AD 2HJ and lowest in AD 3LNO Offshore. Exploitation rate indices (ERIs) were near time-series lows in all ADs in 2020, except AD 2HJ, where it remained high at around 50%. Elements of the Precautionary Approach (PA) Framework presented in this assessment are tentative. Limit Reference Points (LRPs) have been established by a peer-reviewed Science process, but Upper Stock References (USRs) and Harvest Control Rules (HCRs) remain under development. In 2021, with status quo landings, all ADs are projected to be above the LRPs of the PA Framework. There are indications that several ecosystem-related factors may be encouraging both short- and long‑term growth of the stock, including cool bottom water temperatures in previous years (2012-17) and a slight decline in predation in most areas. Furthermore, there are signals of increased abundances of pre-recruit and small-sized crab, indicating a positive outlook for the next two to four years if fishing pressure levels allow the crab to recruit into the exploitable biomass. A sharp decline in male size-at-maturity (i.e., terminal molt size) in most ADs in recent years, and persisting in ADs 2HJ and 3K in 2020, could dampen short-term prospects for recruitment into the exploitable biomass.
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