Biology and effects of cartilaginous fishes on fisheries in the Sagami Bay

相模湾软骨鱼类的生物学及其对渔业的影响

基本信息

批准号：
14560163
负责人：
TANIUCHI Toru
金额：
$ 2.56万
依托单位：
Nihon University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

The total number of 21 species of cartilaginous fishes were collected from the depth below 150 m in the Sagami Bay during the course of the present study. Three triakid species were provided by fishermen. Among those species, most abundant species was Squalus mitsukurii, making up 69% of the total catch of 442 specimens captured by R/V Enoshima-maru belonging to Kanagawa Prefectural Fisheries Research Center. Other species constituted less than 10 % of the total.Shortspined dog fish, S.mitsukurii, ranged from 150 m to 550 m in depth, mainly between 300-400 m. Trend of catch per unit efforts (CUPUE) using hooked rates expressed by number caught per hundred hooks and unit net length, indicates that they made seasonally vertical migration and go into deep waters during warm seasons while they inhabit shallower depth during cold seasons. However, they were not caught in mid-winter in the coastal waters while they are captured in the seamount near the entrance of Tokyo Bay., suggesting hori … More zontal migration within the bay as well. Segregation by sizes and sexes were also suggested, judging from scarcity of males and small specimens in the catch. Predation by S.mitsukurii on commercially important fishes distributed in the Sagami Bay was also investigated using stomach contents analysis and tooth scars of damaged fishes. As a result, it is concluded that about 8 % of fishes caught by vertical loglines suffered from predation by S.mitsukurii. Age and growth studies were also conducted using annuli marked on second dorsal fin spines. Growth curves were close to those presented by the past studies in offshore area of Choshi while quire different from those in Ogasawara and Seamount of Hancock... Reproductive studies of S.mitsukurii indicate that reproductive strategy is a little different from that obtained from Choshi area. Stomach contents analysis reveals that there seemed to be a little different between regions in Sagami Bay but totally S.mitsukurii are an exclusive picivore as reported by other studies in other regions. Feeding status of seven species was analyzed using stable isotope ratio of nitrogen and carbon. C-N maps indicated that differences between species are rather smaller than differences between habitats. They also differed according to growth stage. Less

在本研究过程中，渔民在相模湾150 m以下的深度收集了总共21种软骨鱼类，其中最丰富的物种是鲫鱼。神奈川县水产研究中心所属的 R/V Enoshima-maru 捕获的 442 种标本中，占总捕获量的 69% 其他物种不足。占总数的 10 %。短刺犬鱼 S.mitsukurii 的深度范围为 150 m 至 550 m，主要在 300-400 m 之间。单位努力捕获量 (CUPUE) 的趋势，使用以每百个鱼钩捕获的数量表示的上钩率。和单位净长，表明它们进行季节性垂直迁移，在温暖的季节进入深水区，而在寒冷的季节栖息在较浅的深度，但没有被捕获。仲冬时分，它们在东京湾入口附近的海山中被捕获，这表明从雄性和小型鱼类的稀缺性来看，海湾内也存在按体型和性别进行隔离的情况。还通过胃内容物分析和受损鱼类的牙齿疤痕调查了 S.mitsukurii 对分布在相模湾的具有商业价值的鱼类的捕食情况。结果得出的结论是，大约 8 种。垂直线捕获的鱼类遭受 S.mitsukurii 捕食的百分比也使用第二背鳍棘上标记的环进行了生长曲线接近铫子近海地区的过去研究。与小笠原和汉考克海山的情况不同...对S.mitsukurii 的繁殖研究表明，其繁殖策略与铫子地区获得的繁殖策略略有不同。相模湾地区之间略有不同，但正如其他地区的其他研究报告的那样，S.mitsukurii 完全是一种独特的食肉动物，使用氮和碳的稳定同位素比图分析了七个物种的摄食状况，表明了不同地区之间的差异。物种之间的差异比栖息地之间的差异要小得多。