Canary rockfish stock assessment 2022

The Canary Rockfish (CAR) stock assessment evaluates a British Columbia (BC) coastwide population harvested by two fisheries, one using combined bottom and midwater trawl gear and the other using non-trawl gear. Bottom trawl catches are predominant (83% by weight over the period 1996 to 2021), followed by midwater trawl (13%) and hook and line (4%). Analyses of biology and distribution did not support separate regional stocks for CAR. The CAR stock was assessed using an annual two-sex catch-at-age model, implemented in a Bayesian framework to quantify uncertainty of estimated and derived parameters. The analysis platform adopted was the National Oceanic and Atmospheric Administration’s (NOAA) Stock Synthesis 3. A base run that estimated natural mortality (M) and steepness (h) fit the available data credibly and was considered sufficient to model the population. This stock assessment was primarily informed by six CAR abundance series from fishery independent surveys, and a catch per unit effort (CPUE) abundance series. While the CAR survey abundance series had large relative errors, they did not contradict the commercial CPUE index series. Additionally, age frequency data from the commercial trawl fishery (36 years) and three survey series (23 years) were used. The median (with 5th and 95th percentiles) female spawning biomass at the beginning of 2023 (B2023) was estimated to be 0.78 (0.57, 1.05) of the equilibrium unfished female spawning biomass (B0). Also, B2023 was estimated to be 3.04 (1.92, 4.89) times the equilibrium female spawning biomass at maximum sustainable yield, BMSY. There was an estimated probability of 1 that B2023 > 0.4BMSY and a probability of 1 that B2023 > 0.8BMSY (i.e., of being in the Healthy zone). The probability that the exploitation rate in 2022 was below that associated with MSY was 1 for the combined commercial fisheries. Advice to managers was presented in the form of decision tables using the suggested reference points from Fisheries and Oceans Canada’s (DFO) Decision Making Framework Incorporating the Precautionary Approach (PA) (DFO 2009a). The decision tables provided ten-year projections across a range of constant catches up to 2000 tonnes/year. The recent five year (2017–2021) average catch was 789 t. The CAR stock was projected to remain above the limit reference point (LRP, 0.4BMSY) and upper stock reference (USR, 0.8BMSY) with a probability of >0.99 over the next 10 years at catch levels ≤1500 t/y. Catches ≤1250 t/y were predicted to keep the harvest rate below the harvest rate limit (uMSY) in 10 years with probability >95%. Reference points for long-lived, low productivity species are uncertain. Advice relative to MSY reference points was deemed appropriate for CAR; however, other B0 benchmark metrics were presented in the assessment document. It is recommended that a full re-assessment occurs in no more than 10 years, subject to the availability of new information. During intervening years, the trend in abundance can be tracked by commercial fishery CPUE and, less reliably (because of the high relative error), by the fishery independent surveys used in this stock assessment.

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