A data-limited approach for assessing Octopus mimus Gould, 1852 (Cephalopoda: Octopodidae) in the northern zone of Chile

Resumen: In northern Chile, Octopus mimus sustains small-scale fisheries from Arica (18°28’ S) to Huasco (28°33’ S), yet stock assessment remains a challenge owing to data limitations. This study applied a data-limited approach, recognizing that stock assessment is a continuum from status classification analysis to quantitative models, improving data analysis. We used landings records (1979–2022) and applied maximum catch benchmarks, structural time-series analysis, and catch-only models to infer stock conditions. A spatiotemporal Bayesian hierarchical CPUE model produced a standardized abundance index for 2001–2022. These data informed JABBA, a Bayesian surplus production model that revealed a consistent overfished status. Although signs of overfishing have persisted, a notable decline in fishing mortality was observed by 2022. Despite the elevated uncertainty in recent years, retrospective analysis confirmed the robustness of the model. While our approach assumes fixed reference points, the observed structural shifts in landings suggest a potential decline in productivity during the cold period after 1998, which would affect either the carrying capacity or growth rates, warranting further investigation. This study highlights the utility of robust data-limited tools for managing small-scale fisheries under uncertainty.