Lateolabrax japonicus (Cuvier) is a common fish of Japan, sometimes ascending the river, attaining some 100 cm when full grown. The author operated artificial insemination of this fish on January 29, 1955, at Tamanoura, Goto Islands, Nagasaki Prefecture, and observed the egg development and hatched larvae. On the one hand I found floating eggs and larvae of this fish in the catches of tow-net and other fishing gears operated in Kyushu. According to the above mentioned catch records and the examination of the gonad condition of this fish, the spawning season seems to extended from November to March in Kyushu (Table 1, 3 and fig. 1). The egg is bouyant, colorless and spherical in shape, measuring 1.35-1.44 mm in diameter with a single light yellow oil-globule (rarely divided into 2 or 3) measuring 0.34-0.38 mm in diameter. The hatching took place in 4.5-5 days at the water temperature 11.0-16.2℃, and 4.0-4.5 days at 15.2-15.8℃ (Plate 10, figs. 1-9). The larva just hatched is 4.42-4.60 mm in total length, with the oil-globule situated in the anterior part of yolk, partly protruding from its surface. The myotome number is 19+18=37 (vertebral number of this fish is 18 +17-35) (Fig. 10). In a week the yolk and oil-globule was entirely consumed and reached 5.0-5.3 mm in total length. No remarkable change occurred during the course of yolk absorption (Fig. 11 and 12). The larvae, 5-15 mm in total length (Plate 11, figs. 1-5), live a pelagic life in coastal region. The big post-larvae or juveniles about 20 mm or more in total length (Figs. 6 and 7), are found from the bottom near shore, in the zostera zone of estuaries or in the tide pools, chiefly feeding upon copepods or small larval crustaceans (Table 4).
Mendeley出力
