魚類学雑誌
Online ISSN : 1884-7374
Print ISSN : 0021-5090
ISSN-L : 0021-5090
チクゼンハゼの生態・生活史
道津 喜衛
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ジャーナル フリー

1957 年 6 巻 4-6 号 p. 97-104

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Paleatogobius uchidai TAKAGI is a small goby, some 35mm in total length, resembling to the gobies of the Genus Chaenogobius GILL: C. castanea (O'SHAuGHNESSY), C. heptacanthus (HILGENDORF), etc. (Fig. 1). It lives a bottom lif e on sandy mud bottom of estuaries in Kyushu, Japan (Fig. 2).
The sex-dimorphism is slightly observed in the form of genital papillae.The mature female fish are generally larger than the male. The black nuptial coloration appears in the mature female fish only on the ventral ahd anal fins, just as was reported in the gobies of the Genus Chaenogobius: C. castanea, C. heptacanthus, etc. (KINOSHITA, K. 1936, DÔTU, Y. 1954). The ripe ovary contained two groups of the eggs: the mature yellow one, 0.69-0.89 mm in egg-diameter, and the inmature translucent one, 0.14-0.34mm in diameter.The number of the mature ovarian eggs of one individualwas enumerated as 158-430 in eight specimens with the total legth 27-45 mm (Table 1). The ripe testis is thin and translucent band-form with a small appendant organ at its posterior end (WEISEL, G. F. 194 ). The spawning season seemed to extend from January to March in Fukuoka City and its vicinity. The spawning occurred in the ordinal habitat of the adult, as in the estuary of the River Kanakuzu in Fukuoka City. In the same place Chaenogobius castanea also spawned in same manner (Fig. 2; DÔTU, Y. 1954). The parent fish utilized vacant living holes of a kind of shrimp, Upogebia major DE HAAN, for its spawning room. Openings of the numerous holes were exposed all over the flat at ebb tide. The holes were short vertical ones, about one centimetre in diameter and about twenty centimetres long. The spawned eggs were deposited on the inner wall of the hole about five centimetres deep from the opening. The male parent fish was guarding the eggs in the hole until the eggs hatched out. The number of one brood was enumerated as 114-174 in five cases. The water-temperature at the spawning ground was 9.6-14.5°C in the spawning season. The fertilized egg is demersal and adhesive, with a large perivitelline space and a bundle of adhesive filaments at its basal end. The egg is club-shaped, 2.40 mm in long axis and 0.84 mm in short axis, with a shallow depression circling near the top (Fig. 3, Fig. 4). This egg resembles to that of C. castanea in shape, but smaller.
The newly hatched larva is 4.3mm in total length (Fig. 5 A). The postlarvae under 10mm in total length were not yet collected. The postiarvae, 10-15mm in total length, were collected with drawing-nets in Fukuoka Bay from May to July (Fig. 5 B C). These larvae supposedly live a swimming life in the bay. The last postlarvae, over 15 mm in total length, were found already entering into the bottom life at the estuary where the adult fish lived (Fig. 2; Fig. 5 D E). The gut-contents of the postlarvae, supposedly carrying a swimming life, consisted chiefly of planktonic Copepods, whereas that of the adult consisted of worms, young fish, and organic detritus (Fig. 5 F).
The examination of the size-frequency of the collected specimens, over 450 individuals, collected from Fukuoka City and its vicinity shows preliminary that this goby attalns 26-31 mm in total length, and becomes mature in a year; in two years it willattain 31-37mm. The largest specimen examined is a female fish, 52mm in total length.

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