Initial investigations of a sex-specific stock assessment model for Dissostichus eleginoides in Division 58.5.2

Following the recommendations of the 2023 independent review of CCAMLR toothfish assessments, this paper presents an investigation into a fitting sex-specific stock assessment model to Patagonian toothfish (Dissostichus eleginoides) in Division 58.5.2. Using an iterative model fitting approach showed that inclusion of sex-specific growth provided the largest change to B_0, B₂₀₂₄ and spawning stock biomass status. This however also coincided with generally poorer fits of the stock assessment model, likely due to the large uncertainty associated with female growth estimates (CV = 0.208). A sensitivity run using a halved CV (0.104) for female growth resulted in better stock assessment fits to the input data. Given this sensitivity to the uncertainty associated with input parameters, we recommend further work is needed before a sex-specific model is used for catch setting advice.