MORPHOLOGICAL VARIABILITY OF ROUND GOBY, NEOGOBIUS MELANOSTOMUS (PALLAS, 1814) OF THE MIDDLE PART OF DNIPRO BASIN

Abstract

The morphological variability of male (n = 94) and female (n = 122) of Round Goby, Neogobius melanostomus (Pallas, 1814) of the middle part of Dnipro basin was analyzed. It was proved that within the samples studied the young immature fish with the length range from 37 to 70 mm mostly dominate. At that SL of males (39–70 mm; М = 54.14 mm) is bigger than of females (37–62 mm; М = 51.5 mm). It is shown that among the studied fish 5 (5.32 %) males of 52–70 mm standard length and 21 (17.21 %) females of 46–60 mm standard length reached the puberty and were ready to reproduce. Among 122 females with hardroe 7 (5.74 %) zooids of 46–58 mm standard length were detected at the 4^th puberty stage, 2 (1.24 %) fish of 50 and 56 mm standard length – at the 3^rd stage, 12 (9.84 %) fish of 45–60 mm standard length – at the 2^nd stage, 9 (7.38 %) fish of 46–64 mm standard length – at the 1^st stage. It was detected that the variability of linear body sizes of Round Goby is described by the first factor (F₁), the residual variance of which is 77.8 % in females and 82.7 % in males, the proportion variability – F₂ (2.64 %) і F₃ (4.50 %). It is shown that linear body sizes (the length and the absolute values of 17 plastic charactristics) male and female of Round Goby are differentiated into two size groups: small (in male SL = 48.4 mm, in females SL = 45.3 mm) and large (in male SL = 59.8 mm in females SL = 55.2 mm) fish. It was proved that males are significantly larger than females in both groups. The intersex distinctions due to body proportions of Round Goby are missing. Only large fish have relative length of the snout in males (30.92 %) which is higher (t = 2.76; P < 0.01), than in females (29.79 %). Sex differences in the formation of body proportions of Round Goby were found.