On the Spawning of Ilisha elongata (BENNETT) in the Mouth of the River Kin, Western Korea

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No clupeoid fish of Japan has yet been known to spawn in the river. In the lowermost part of the River Kin which discharges into the Yellow Sea, a considerable amount of Ilisha elongata is captured in June. In this season the fish comes from the sea into the lower part of the river for spawning, gravid with matured reproductive elements. The spawning ground extends from the river mouth to about 15 km upward. The salinity at. the river mouth was 23.7‰ at the high tide and about 12.0‰ at the low (June 23, 1937). The egg is pelagic, sphe-rical in shape, and measures 2.22 to 2.48 mm in diameter. The perivitell:ne space is large. The yolk is 1.71 to 1.87 mm in diameter, transparent and vesicular structure, provided with a single yellowish oil-globule measuring 0.38 to 0.42 mm (Fig. 2, a). The newly hatched larva, 51 mm in total length, retains the oil-globule at the posterior end of the ellipsoid yolk-sac. The anus opens under the 40th myotome. Melanophores are found on the dorsal side of the head and nape, on the dorsal half of the oil-globule and in front of the rectum (Fig. 2, b). The number of the myotomes was enumerated as 39+19=58 in a larva of 2 days old. Hat-ching seems to take place about 30 hours after being spawned at temperatures ranging from 23° to 26°C.
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