Age, growth, reproduction and mortality of Mediterranean sand smelt Atherina hepsetus (Atherinidae) from the Crimea region (the Black Sea)

Abstract

Sex ratio, size and the age structure, growth, dynamics of gonadosomatic indices and mortality were analyzed for the Mediterranean sand smelt Atherina hepsetus collected in the Crimean coastal area. Overall, 3193 specimens were examined between 2011 and 2021 years. The total sex ratio in the A. hepsetus catches was balanced (1.03:1), but it differed in the older age groups, where females predominate. The maximum total length of females was 15.8 cm, of males was 15.6 cm; its weight was 26.6 g and 23.6 g, respectively. The maximum age for both sexes was 4 years. There was not any statistical difference in sizes and growth between sexes. The values of the parameters of the Bertalanffy equation were calculated: in females, the asymptotic length was 15.94 cm, the asymptotic weight was 25.98 g, the growth constant was 0.53 year −1; for males — 15.90 cm, 24.47 g, and 0.55 year −1, respectively. The exponent values of the length–weight relationships in females was 3.09, in males – 2.96. The growth performance index in females was 2.13, for males — 2.14. Spawning period falls in March–July with the peak in April. The total and fishing mortality rates for both sexes were 1.52 year −1, 1.07 year −1 and 0.45 year −1, respectively; the exploitation ratio was 0.30, that indicated a low fishing pressure. It has been found that Atherina hepsetus from the Crimean waters differs from the Mediterranean Sea populations for the largest sizes and the highest growth rate.