Age, growth, and reproductive biology of Atlantic bonito ( Sarda sarda Bloch, 1793) from the Turkish coasts of the Black Sea and the Sea of Marmara

Abstract

This study aims to investigate some biological characteristics of Atlantic bonito, Sarda sarda Bloch, 1793, from the Turkishcoasts of the Black Sea and the Sea of Marmara. A total of 212 S. sarda (100 females, 89 males, and 23 undetermined) were sampledmonthly between May 2011 and September 2012. Te sex ratio (♂/♀ ) was 0.89; females prevailed but not statistically signifcantly soFork lengths of all sampled individuals ranged from 17.7 to 63.0 cm. Te length weight relationship for all individuals was calculatedas W = 0.01 L3.085. Te ages of the fsh ranged from 0+ to 2+. Growth parameters calculated according to the von Bertalanfy growthequation were L∞ = 69.565 cm, k = 0.439, t0 = 1.327 for females; L∞ = 74.603 cm, k = 0.364, t0 = 1.518 for males; and L∞ = 67.883cm, k = 0.463, t0 = 1.220 for both sexes. One hundred ovaries were obtained from the females, and these ovaries were histologicallyexamined to determine the reproductive conditions and developmental stages of oocytes. Te gonadosomatic index values calculatedfor females indicated that spawning generally occurred between May and August. Te most intensive spawning period was observed inJune and July. Te length at frst maturity was estimated to be 42.5 cm for females and 36.8 cm for males.