Additional analyses on the stock assessment of northeastern Atlantic porbeagle (Lamna nasus) using the Spict Surplus Production Model
In 2022, ICES and ICCAT aimed to jointly assess the northeast Atlantic porbeagle stock, which was last assessed in 2009. The SPiCT runs used the 3 indices reviewed by the Working Group on Elasmobranch Fishes (WKELASMO), and included the historical Spanish longline index that was used in the 2009 assessment. The proposed SPiCT run uses all available indices of abundance. Comparisons were made between the proposed SPiCT run and JABBA run applying similar model settings. Both models indicated that the northeast porbeagle stock is still overfished, but experiencing very low fishing mortality at present. However, those results differ in the level of depletion, SPiCT results being slightly more pessimistic compared to the JABBA results, likely due to the assumptions of process error, the variance of indices, and structural model estimation, among others. It is suggested that integrating both model results will provide a more comprehensive evaluation of the stock assessment uncertainty for providing management advice. It is recommended to reactive monitoring programs to confirm the recovery trends of the stock.