Stock and risk assessment of bigeye tuna (Thunnus obesus) in the Indian Ocean by Age-Structured Production Model (ASPM

We applied an Age-Structured Production Model (ASPM) to assess the status of the bigeye tuna stock (Thunnus obesus) in the Indian Ocean using 61 years of data (1952-2012). The assessment results suggested that MSY=120,500 tons (catch in 2012=99,899 tons) and the SSB ratio (2012) is near the MSY level (1.10), while F ratio (2012) is much lower than the MSY level (0.42). The results suggested that the bigeye stock is in the healthy condition and the projection based on the current catch level (99,899 tons) suggest that the current level can increase the stock from 2013 and after.