Wednesday, 24 November 2010 14:04
Skipjack are a surface–schooling tuna which are easily distinguished from other species of tuna due to their small size, small dark pectoral fins and three to six distinct dark longitudinal lines (stripes). It is found year-round concentrated in warmer tropical waters of the WCPO, with that distribution expanding seasonally into subtropical waters to the north and south. Skipjack are caught mainly on the surface by purse seine and pole-and-line gear and are used for producing canned tuna.
The typical capture size for skipjack is between 40 and 70cm, corresponding to fish between one and three years of age, with very few captured fish exceeding 80cm. However, rare records of skipjack over 100cm and weighing more than 30kg have been reported historically.
Skipjack tuna is a fast growing species (reaching 42-45cm within its first year), are relatively short-lived (few live longer than 3 - 4 years) and mature early (~ 1 years of age). These biological characteristics promote rapid turnover in skipjack populations.
Skipjack are also highly fecund and can spawn year round over a wide area of the tropical and subtropical Pacific. Environmental conditions are believed to significantly influence recruitment and can produce widely varying recruitment levels between years.
In the Western and Central Pacific Ocean (WCPO), the biomass of skipjack tuna is very large and estimated to exceed that of the other three main tuna species combined. It is assumed that skipjack in the WCPO is a separate population (for stock assessment and management purposes) to those in the eastern Pacific.