The spawning and early life history of \u22Buri\u22, Japanese yellow tail, Seriola quinqueradiata Temminck et Schlegel

From the 14th of April to the 19th of May, 1954, the authors expect Uchida stayed at the fishing-ground of the \u22Otosi-ami\u22, a kind of trap-nets, on the coast of Mesima Island, one of the Danjyo Islands, some 90 nautical miles southwest of Nagasaki City with the main purpose of researching for the spawning and early life history of \u22Buri\u22, or Japanese yellow tail, Seriola quingeradiate Temminck et Schlegel, together with other fishes. The ripe \u22Buri\u22 caught there during that period ranged from 4 to 12 kg in body-weight. No difference was found in external features between female and male of the ripe \u22Buri\u22. From the examination of the ripe gonads of both sexes, the ripe \u22Buri\u22 seems to spawn several times in one spawning-season (Fig. 2). The weight of the ripe gonad exceeds 10 % of the body-weight. The number of ovarian eggs was enumerated as. from 550,000 to 1,600,000. The artifical insemination was executed. The fertilized egg is buoyant and spherical in shape, measuring 1.19 to 1.27 mm in diameter, with an oil-globule. Faint alveolar structure appears in the yolk. The development of the egg is figured in Plate 18. The incubation period was about 50 hours at the temperature changing from 18.0 to 24.0℃. During the staying period, 408 eggs of \u22 Buri\u22 were collected from the vicinity of the Danjyo Islands with the surface tow-net. The water temperature there ranged from 19.0 to 22.0℃, and the specific gravity of sea water was 23.5=δ15. The newly hatched larvae ranged from 3.42 to 3.48 mm in total length (Pl. 18, P). The larvae were kept in a glass-jar for three days, and grew to 3.85 mm in total length and nearly consumed the yolk (Pl. 18, R). Later growing stages up to 34.0 mm in total length, are figured in Plate 19.農林省農林漁業試験研究補助金による「重要魚類の発生過程に関する研究」の一部として内田の計画および指導により, 道津・水戸・中原は昭和29年4月14日から同年5月19日までの36日間, 長崎県五島列島福江島の西南約40浬に位置する男女群島女島にある大洋漁業株式会社定置漁業部の女島共同漁場ブリ落網の漁場現場に滞在し, 落網漁獲物の調査を主とし, それに次に述べる各種の調査方法も併せて用い, 男女群島周辺水域の魚類調査を行つた. この調査期間中に採集した魚類は魚卵, 仔・稚魚を包めて八十余種であつたが, 本報告では調査の主目的であつたブリの産卵および初期生活史について, 女島で得た資料と内田が旧朝鮮総督府水産試験場に在職していた時以来集積してきた資料とに基づいて述べる