Growth and reproduction properties of the poor cod, Trisopterus capelanus (Lacepède, 1800) (Gadidae) in the Edremit Bay, Northern Aegean Sea, Turkey

Abstract

Age, growth, gonadosomatic index and condition factor of poor cod, Trisopterus capelanus were evaluated from 593 specimens collected in Edremit Bay, the northern Aegean Sea between the years of March 2015 and February 2016 by the hauls of trawls. Total length ranged between 10.7-19.8 cm and 9.6-17.0 cm while weight varied between 9.34-95.59 g. and 8.13-51.45 g. in females and males. The male and female ratio was 1:0.42 (M:F) in the favor of males. The von Bertalanffy growth equations (in length) were found as Lt= 23.5 (1-e -0.52(t+0.50) for all individuals. Length-weight relationships were found to be W=0.0089L3.0665 (R2=0.9299), W=0.0112×L2.9655 (R2=0.9125), and W=0.0087L3.0692 (R2=0.9347) for females, males and combined sexes, respectively. As the determination b values are not statistically significant from 3 (t test, p>0.05), isometric growths were observed for all samples. The condition of the fish increased during autumn. A long spawning season (about 4-5 months) in late winter-early spring occured in the population. Analysis of the diet composition showed that poor cod is carnivourus and the food composition of T. capelanus consists of mostly crustaceans as Alpheus glaber and Liocarcinus sp. Poor cod has an economic value for Turkish Seas and it is also important in the view of biodiversity.