6th World Fisheries Congress, Edinburgh, United Kingdom, 7 - 11 May 2012, pp.159
The study aimed to identify the age and growth parameters as well as some reproductive properties of little tunny (Euthynnus alletteratus) and bullet tuna (Auxis rochei) in Turkish waters in the last decade. The fish were caught from the north-eastern Mediterranean Sea between November 2002 and December 2009. During the study period, a total of 96 little tunny and 216 bullet tuna were sampled. The fork length values for little tunny were between 43-87 cm, and for bullet tuna were between 34 and 48. Age and growth were estimated by assessing seasonally bands formed on the first dorsal spines of 96 little tunny and 150 bullet tuna specimens. Little tunny samples were estimated to be between 1 and 6 years old, and bullet tuna samples were between 1 and 5 years old. Von Bertalanffy growth parameters were estimated for all individuals. For little tunny, the von Bertalanffy growth parameters for both sexes and all years combined were L∞=83.720 cm, k=0.385 years-1 and to=-1.678 years. For bullet tuna, these parameters were L∞=57.388 cm, k=0.181 years-1 and to=-4.155 years. The ovaries obtained from the females of little tunny (60 samples) and bullet tuna (106 samples) were histologically examined to determine the reproductive conditions and developmental stages of oocytes. The gonado-somatic index (GSI) values calculated for females indicated that the spawning period for both species was observed between May and September. The most intensive spawning period for little tunny was between July and August. This period for bullet tuna was between June and August.