STOCK ASSESSMENT OF THE SOUTHERN INDIAN OCEAN ST. PAUL AND AMSTERDAM ROCK LOBSTER STOCKS USING BAYESIAN STATE-SPACE SURPLUS PRODUCTION MODEL

Bayesian state-space surplus production models were fitted to Amsterdam and St. Paul rock lobster (Jasus paulensis) catch and CPUE data using the open-source stock assessment tool JABBA. The results of the reference case models indicated that MSY estimates lied between 182 and 258 tons for Amsterdam and 208 and 352 tons for St. Paul rock lobster. Stock status trajectories for both rock lobster stocks started from an underexploited state and moved from of a period of unsustainable fishing in the beginning of the 1980s. Both stocks recovered in the 1990s leading to a > 95% and > 85% probability of stocks biomass in 2019/2020 being above level that produce MSY and fishing mortality rates below sustainable exploitation levels for Amsterdam and St. Paul respectively. Finally, based on the sensitivity analysis, all alternative scenarios combined lead to a 95% and 89% probability that the stock of Amsterdam and St. Paul were below sustainable bounds