Stock identification study on elasmobranchs

利用形态、生态和遗传特征，对棘鳃类，特别是三种鲨鱼进行了种群鉴定研究。关于斑角鱼，根据从7个地区采集的1,514个标本，对种群鉴定进行了广泛的研究。通过典型相关分析检测不同产地间的形态差异。在年龄和生长方面也观察到了地理差异，表现出向北方地区生长和寿命增加的趋势。在Lenngth出生时也观察到了类似的趋势。长度和成熟年龄随纬度的增加呈增加的趋势。产仔数随母鱼长的增加而增加，东京湾产仔数最少，台湾产仔数最多。然而，青森的繁殖周期似乎与其他地方有很大不同。饮食习惯也显示出地理差异，显示出胃内容物重量占总重量的比例向南增加。因此，有人认为日本各地至少有五种斑点角鱼。对采自世界7个地区的133个标本进行了形态特征和遗传特征的种群研究。观察到不同地区的真皮小齿以及胸鳍和尾鳍的形状有显著的差异，导致地中海、南非和日本和澳大利亚三个群体的分离。在基因上，日本、澳大利亚和南非三个群体被区分开来。出于这些原因，物种复合体被分为四个组，日本、澳大利亚、地中海和南非。首次对太平洋大洋白鳍鲨的年龄、生长和繁殖进行了研究，获得了该鲨种群的基本信息。

Stock identification studies on elasmobranchs, particularly three species of sharks, were conducted using morphological, ecological, and genetic characters. Regarding starspotted dogfish Mustelus manazo, extensive study on stock identification was carried out based upon 1,514 specimens collected from seven localities. Morphological differences between localities were detected by canonical correlation analysis. There were also observed geographical differences in age and growth, showing trend of increase of growth and longevity toward the northern locality. The similar trend was also observed in lenngth at birth. Length and age at maturity showed a tendency of increase with latitude. Litter size showed an increase with parent length and the smallest number in Tokyo Bay at the same length whereas largest in Taiwan. However, the reproductive cycle in Aomori seemed to be quite different from other localities. Food habits also revealed geographical variations, demonstrating an increase in the ratio of stomach content weight to total weight toward south. As a result, it is suggested that there are at least five stocks of the starspotted dogfish around Japan. Regarding shornose spurdog Squalus megalops, paopulation studies were conducted using morphological and gentic characters based upon 133 specimens collected from seven localities in the world. Significant differences were observed in shape of dermal denticles and pectoral and caudal fins between localities, resulting in the separation of three groups, the Mediterranean, South Africa, and Japan and Australia. Genetically, three groups, Japan, Australia and South Africa were distinguished. For these reasons, the species complex was divided into four groups, Japan, Australia, the Mediterranean and South Africa. Regarding the oceanic whitetip shark Carcharhinus longimanus, age, growth and reproduction were elucidated in the Pacific Ocean for the first time and fundamental information on stocks of the shark was obtained.