Identification of pelagic eggs of marine fishes by rearing method

Pelagic fish eggs are usually fixed by formalin solution just after collection in the field. Most of these eggs are difficult to be identified to species, because only limited characters are available for identification and considerable changes in structures take place with fixation. In this study, species names of formalin fixed eggs were estimated by comparing their egg diameters and the diameter and number of oil globules with those of the fresh ones identified by the rearing method. Materials were collected in Wakasa Bay in May, August, and October, 1979–1982. Fresh eggs were classified into 40 species or types by the rearing method, but fixed eggs were divided into only 24 types. Comparison of fresh and fixed eggs revealed that 7 out of 24 types of fixed eggs were referable to species, and 13 types were composed of species groups. The rearing method is surely a useful step in indentifying species names and/or species types of fixed eggs.