This paper presents an updated stock assessment for the Patagonian toothfish (Dissostichus eleginoides) fishery of the Kerguelen Island EEZ, CCAMLR Division 58.5.1. It includes commercial fishery data up to the end of the season 2021/2022. The updated assessment model is based on the best available data and includes abundance estimates from random stratified trawl surveys (POKER, 2006, 2010, 2013 and 2017), longline tag-release and tag-recapture data from 2007 to 2022 and priors and estimates on model parameters such as life traits (e.g. growth, maturity and natural mortality). It also uses commercial data that account for fish removals (fishing mortality and depredation) and support the estimation of year class strength (YCS) and selectivity functions.
Compared to the previous assessment that was presented to WG-FSA 21 (Massiot-Granier et al., 2021), this assessment accounts for (1) updated catch and biological data (2021/2022), (2) updated age data from aa ongoing 4-year otolith reading program, (3) updated priors on YCS and period of estimation (4) and updated depredation rate. All model runs were conducted using CASAL 2.30 2012-03-21 rev. 4648, that was agreed on by WG-SAM-14.
This paper also includes comparison of outputs from integrated stock assessment using CASAL and Casal2 with similar parametrization, weighting and settings. The comparison showed strong consistency between the two models.
The updated model leads to a lower estimate of the virgin spawning stock biomass SSB0 than in 2021 with an estimate of 224 760 tons (95% CI:206 390 – 249 520). The estimate of the current SSB status of the stock is 66.3% (95% CI: 63% - 70,3%) and the current catch limit (CL) of 5020 tons meets the CCAMLR decision rules.