Development of a stock-specific management procedure for snow crab fishery in the Sea of Japan using conditioned surplus production models in a data-moderate situation

A management procedure (MP) automatically calculates an acceptable biological catch from input data, and its performance is quantitatively evaluated by closed-loop simulations of population dynamics with their uncertainties (operating models). In snow crab in the Sea of Japan, an MP based on survey biomass estimates was adopted by stakeholders, rather than a generic MP recommended for data-moderate Japanese stocks. This was done without quantifying its performance owing to data and resource limitations. This study evaluated the performance of the existing MPs and modified the generic MP through closed-loop simulations with state–space surplus production models (SSPMs) conditioned with actual data. The survey-based MP generally worked well to achieve sustainable catch and biomass but tended to be sensitive to the bias in biomass estimates. The modified MP can be more robust to the bias than the survey-based MP with higher catches than the generic MP. This study demonstrates that, although continuing efforts of collecting composition data are inevitable, SSPM could be used as the conditioned operating models even in data-limited situations to sufficiently represent the stock status and its uncertainty.