SOME BIOLOGICAL ASPECTS OF SKIPJACK TUNA (Katsuwonus pelamis LINNAEUS, 1758) DI PERAIRAN TOLI-TOLI WATERS, CENTRAL SULAWESI

Abstract

Skipjack tuna (Katsuwonus pelamis) was one of the export commodities, where the demand tends to increase. The high level of skipjack tuna exploitation leads to overfishing, so sustainable fisheries management was required. The objective of the research was to study the several aspects of biology including of length of weight relationship, sex ratio maturity stage, gonad somatic index (GSI), Length at first capture and length at first maturity. The research was conducted in February - December 2015 in Toli-toli, Central Sulawesi. The results showed that the skipjack  tuna growth pattern was allometrically positive, where growth weight was faster than the length increase. The  length of the first time capture skipjack tuna of pole and line was bigger than length at first maturity, it means the mostly skipjack tuna caught have already spawned. The spawning season was occur throughout the year with spawning peaks in April and September, fecundity ranging from 450,570 - 1,707,390eggs.