Reproductive Biology of little tunny, Euthynnus alletteratus (Rafinesque 1810) in the Eastern Coast of Alexandria, Egypt

Abstract

Reproductive biology of Euthynnus alletteratus was described based on 628 fishes that were collected from Abu Qir landing site between October 2006 and September 2007. Only 146 specimens were sexually distinguished (102 females, 44 males) and the others were immature. The sex ratio was estimated as M: F 1:2.3. Size at first sexual maturity was estimated as 42cm. Spawning season was investigated based on monthly observation of gonadal maturity stages and gonad-somatic index (GSI). The spawning season extends from June to August with a highest GSI value in June.The fork length (FL)–gutted weight (GW) relationship was estimated as GW=0.052 FL2.639 for combined sexes. Condition factor (K) was calculated using the gutted weight of all samples (regardless of sex) with an average of 1.3. Management plan is important to overcome the high percentage of immature fishes in the catch off Alexandria water. Extending closed season to July and increasing the length at capture to 44cm are important for enhancing the chance of spawning at least once during its life.