Some reproductive aspects of female bullet tuna, Auxis rochei (Risso), from the Turkish Mediterranean coasts

Abstract

The study aims to investigate some reproductive properties of bullet tuna (Auxis rochei) in Turkish waters. A total of 216 bullet tunas, 110 males (50.93%) and 106 females (49.07%), from the Turkish Mediterranean coasts were sampled monthly between December 2008 and December 2009. The sex ratio was 1:1.04. A total of 106 ovaries were obtained from the females, and these ovaries were histologically examined to determine the reproductive conditions and developmental stages of oocytes. The gonado-somatic index (GSI) values calculated for females indicated that spawning generally occurred between May and September. The most intensive spawning period was observed between June and August. A total of 40 females collected between May and September were sexually mature.