Biological aspects of bullet tuna (Auxis rochei Risso, 1810) landed in Towo’e Market Tahuna Indonesia

Abstract

The bullet tuna (Auxis rochei Risso 1810) is one of the species of neritic tuna that lives in tropical and subtropical coastal waters. Research on the biological aspects of the bullet tuna in Indonesian waters is very important considering the limited information on this species. The purpose of this study is to analyze size structure, length-weight relationship, sex ratio, length at first maturity and length at first capture. A total of 1353 bullet tuna was randomly collected during February-November 2017 at Towo’e Market Tahuna North Sulawesi. The study was conducted by observation and enumeration. The results showed that the bullet tuna landed in Towo’e Market had a length ranging from 19-29 cmFL with an average size of 23.34 cmFL. The LW relationship indicates a positive allometric condition. The sex ratio of male and female bullet tuna showed an unbalanced condition with the ratio of females and males being 1: 0.97. Lm was 22.82 cmFL and Lc was 23.32 cmFL. This condition indicates that most of the bullet tuna caught are already spawning, so caution is needed in their utilization because it can prevent the recruitment pattern of the bullet tuna.