Benchmark Workshop for selected elasmobranch stocks (WKELASMO)

• Main Author: ICES
• Format: Article in Journal/Newspaper
• Language: English
• Published: ICES 2022
• Subjects: Northeast Atlantic; Porbeagle
• Online Access: https://archimer.ifremer.fr/doc/00810/92233/98236.pdf; https://doi.org/10.17895/ices.pub.21025021; https://archimer.ifremer.fr/doc/00810/92233/

A Benchmark Workshop for selected elasmobranch stocks (WKELASMO) was convened to eval-uate the appropriateness of data and methods to assess and provide short-term forecast of four stocks: Porbeagle in the Northeast Atlantic (por.27.nea), thornback ray in the Bay of Biscay (rjc.27.8), undulate ray in the Channel (rju.27.7de), and cuckoo ray in western waters (rjn.27.678abd). For porbeagle in the Northeast Atlantic, the workshop (and the reviewers from the stock iden-tity working group (SIMWG)) considered that there is not enough evidence to split the stock despite genetic analysis and mark-recapture data indicating a possibility of two components. A SPiCT assessment using reported landings since 1926, three commercial indices and one recon-structed survey, was accepted and the forecast settings agreed, leading the stock into category 2. The stock is estimated to be harvested largely below FMSY (F/FMSY = 0.02), and the biomass, while increasing, remains below MSY-Btrigger (B/BMSY = 0.43). The 35th percentile of the catches at Ftarget is 324 tonnes. Members of WKELASMO from the International Commission for the Conservation of Atlantic Tunas (ICCAT) provided additional assessments using JABBA and SPicT, both using a Fox model. Results were very similar and gave the same perception as the final accepted SPiCT as-sessment. For thornback ray in the Bay of Biscay, a synthesis of work on stock boundaries within Sub-area 8 was presented, indicating that this species in this area may be considered to comprise of two stocks: 8.abd and 8.c. The workshop (and the review from SIMWG) agreed to follow this conclusion. • Thornback ray in divisions 8.abd: a Bayesian state-space biomass production model in-cluding Close kin mark-recapture (CKMR) results was accepted as the basis of the assess-ment and forecast, leading the stock into category 2. The stock is estimated to be exploited close to FMSY, and Biomass close to BMSY. The forecast at FMSY provides catches (35th percentile) 34% lower than the previous advice. • Thornback ray ...