ベーリング海および北太平洋北部から得られたボウズギンポZaprora silenusの仔稚魚
1981 年 28 巻 3 号 p. 313-318
詳細
1981 年 28 巻 3 号 p. 313-318
Development and distribution of larval zaprorid fish, Zaprora silenus Jordan, from the Bering Sea and around the Aleutian Islands are described.A total of 31 specimens of larvae, ranging in body length from 12.0 to 36.2mm, were collected with a 1.3-m ring net at 12 stations from June to August, 1971-1979.
Zaprora silenus is characterized by the dense pigmentation of black and brown stellate melano-phores which are found on the sides of the body through the larval period.The anus is located a little behind the middle of the body.Larvae were classified in three developmental stages: larval, prejuvenile, and juvenile stages.These included nine specimens excluding the minimum larva which was immeasurable, ranging in body length from 12.0 to 17.3mm, 10 specimens from 17.5 to 24.0mm, and 11 specimens from 26.9 to 36.2mm, respectively.In the larval stage of 17.3mm in length the body is surrounded by the fin fold, and the notochord is slightly flexed and 16 rays appear in the caudal area.Melanophores are present in the fin fold of the anal fin area.In the early prejuvenile stage the caudal elements are well developed.In the late stage the notochord is fully flexed and the caudal fin is formed.Although the full number of rays for each fin is present, the dorsal and anal fins still connect with the caudal fin.Several pigment bands appear on the dorsal and anal fins.In the juvenile stage each fin is completed and body proportions become constant.Seven to eight bands of pigment appear on the dorsal and three bands on the anal fin.
Two larvae were taken in the Pacific side of the Aleutian Islands, south of the Amchitka and Atka Islands.In the Bering Sea two specimens were collected north of the Tanaga and Adak Islands, and 25 specimens were captured above the 30m layer in the slope region at depths of 150 to 3000m from Unalaska Island to the Pribilof Islands.Two larvae were also collected in the basin area (latitude 58°N).The distributional pattern suggests that Zaprora silenus is planktonic during the larval and juvenile stages in the upper layer within the Alaskan Stream and the Bering Slope Current.
