Morphometric Differences between Two Smelt Species, Hypomesus japonicus (Brevoort, 1856) and H. nipponensis (McAllister, 1963) (Pisces: Osmeridae) from The Northwestern Part of the Sea of Japan

Abstract

Two smelt species that inhabit the northwest of the Sea of Japan, Hypomesus japonicus and H. nipponensis (family Osmeridae), which are both currently referred to as Japanese smelt, have been studied in order to clarify the taxonomic value of morphometric characters. Variations between individuals of these species have been revealed using a multivariate analysis of their morphometric characters and indices. The results of the analysis show that H. japonicus is distinguished from H. nipponensis both by the previously known characters (the eye diameter is smaller and the vertical through the beginning of the dorsal fin is closer to the head than that through the beginning of the pelvic fins) and by a greater height of the dorsal and adipose fins in the former species as defined in the paper. Within the species H. japonicus, the individuals sampled from Olga Bay are most similar morphologically to those from the coastal waters off the village of Terney. In contrast, the individuals of this species from the coastal waters off Russky Island and from Olga Bay manifest the greatest differences.