Indicators of stock status for skipjack tuna in the Indian Ocean

Fully quantitative stock assessments for skipjack tuna are difficult to conduct and as
such alternative methods of investigating current stock status are required. Fishery
Stock status indicators have been constructed from total catch, average weight and
catch rates from the purse seine fisheries of France and Spain as well as Maldivian
baitboat (when possible) have been investigated to infer stock status . In order to
investigate current status in relation to historic levels, upper and lower limit reference
levels have been advocated including both 5th and 95th percentiles as well as a
standard deviation multiplier that incorporates 90% of the data series. These rough
indicators can be difficult to interpret and are sometimes potentially contradictory. The
indicators in this study provide some evidence that the SKJ population may be
experiencing increasing pressure, although further analysis is required. These
indicators provide a potential tool for applying empirical harvest control rules for
fisheries management.