Exploratory assessment of ling (Molva molva) in ICES subareas 3, 4 6-9, 12 and 14 with the Stochastic Surplus Production model in Continuous Time (SPiCT): Working Document presented to the ICES Working Group on the Biology and Assessment of Deep Sea Fisheries Resources (WGDEEP) 30 April-6 May 2025, Thorshavn, Faroe Islands

We applied the stochastic surplus production model in continuous time (SPiCT; Pedersen and Berg, 2017) to the ling stock in ICES subareas 3, 4, 6-9, 12 and 14 using abundance indices derived from the ICES DATRAS survey dataset and Norwegian commercial catch per unit effort (CPUE). The trawl survey index included seven bottom trawl surveys, all using use a common sampling gear (GOV) and survey protocols coordinated under the ICES International Bottom Trawl Survey Working Group (IBTSWG), and was standardized using the Vector Autoregressive Spatio-Temporal model, (VAST, Thorson and Barnett, 2017). We constructed five trial model configurations with different combinations of indices and catch year range, and ran each under a range of SPiCT settings with varying priors. We identified model configurations that met all of the criteria for acceptance set out by ICES and which remained stable under a wide range of SPiCT settings. We recommend that this model should be taken forward for further robustness testing and development in the context of an ICES benchmark and considered for use in the future assessment of the stock