Morphological Variability of the Smelts (Osmeriformes: Osmeridae) of the Russian Far East

Abstract

This paper presents the first study comparing the smallmouth smelts – the Japanese smelt Hypomesus nipponensis McAllister, 1963, the pond smelt H. olidus (Pallas, 1814), the marine smelt H. japonicus (Brevoort, 1856) – and the Asiatic smelt Osmerus dentex Steindachner et Kner, 1870 with the use of the variance of fluctuating asymmetry, the coefficient of variation, and the mean values of characters of these species. The comparison showed that the Asiatic smelt was characterized by the largest sum of dispersions of all characters, while the marine smelt had the smallest sum, which was obviously associated with more stable conditions of embryonic and early postembryonic development of the marine smelt. Japanese and pond smelts were similar in coefficients of variation for all traits. The Asiatic smelt displayed the maximum sum of coefficients of variation of all characters; while the marine smelt had the minimal sum of coefficients of variation of the characters, which may indicate relative morphological stability of this species in the range of its occurrence. A greater variability of smelts spawning in fresh water is in good agreement with the conclusion of G.V. Nikolsky et al. that the variability of traits in freshwater fish species is higher than in marine fish species. According to the average values for the characters, the four species of smelts differed only in the number of rays in the pectoral fins, while the minimum value was typical of the pond smelt, and the maximum value – for the marine smelt. The Japanese (24) and pond (26) smelts showed the minimum differences from other species, and the marine and Asiatic smelts – maximum differences (28).