The first data on the population parameters and morphometry of Mesogobius batrachocephalus (Pallas 1814) (Family: Gobiidae) in the southern Black Sea

Abstract

Knout goby, Mesogobius batrachocephalus Pallas, 1814, which belongs to Gobiidae, inhabits in the Black Sea, Sea of Azov, the Caspian Sea and the rivers that flow in these three seas. The major population parameters and morphometry of Mesogobius batrachocephalus from the coasts of the southern Black Sea were investigated in this study. A total of 641 individuals were sampled between January 2019 and December 2019 between the depths of 2 to 120 m depth by using a trammel net with a mesh size of 17-24 mm. The average length and weight values were calculated as 23.1 cm (5.3-34.0) and 130.1 g (1.34-377.54) respectively. The male to female ratio of the population was found as 1:0.91 (P>0.05). Age of sampled 641 individuals varies between zero and seven. For all the sampled individuals, the von Bertalanffy growth parameters were calculated as; L∞ = 38.2 cm, k = 0.245 year-1 and t0 = -1.873 year and the length-weight relationship was found as W = 0.0058 TL3.148. Total mortality (0.481), natural mortality (0.466), fishing mortality (0.015), growth performance index (2.55) and condition factor (0.913) were calculated. The maximum value of gonadosomatic index was reached in March. Average relative fecundity was found to be 118.3 eggs per g (78.9-234.5), while the average diameter of the eggs was found as 2733.0 µm ±221.18 (2287.1-3097.8). This study provides the first data on the population parameters and the morphometry of Mesogobius batrachocephalus. These data could contribute to the establishment of a sustainable management plan for fisheries resources in the Black Sea.