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.