Studies on growth, reproduction and food habits of demersal sharks.

从长溪、小川群岛、马赛巴和汉考克海山采集了三岛角鱼的标本，以揭示其年龄、生长、繁殖和食物习性。使用第二背鳍进行年龄测定。因此，观察到生长参数的差异。同样，不同地区的体型和成熟年龄也有很大差异。附子长度和睾丸重量随着成熟度的增加而迅速增加。产仔数和单雌大卵数随亲本大小的增加而增加，且地区间差异较大。然而，该物种似乎拥有一种统一的生殖策略，因为差异源于成熟时大小的不同。胃内容物分析表明，该物种是食鱼性的。猎物种类因地区不同而不同。为了阐明繁殖和食性的某些方面，我们对3种小型棘鲨进行了调查。雌性在成熟期的体型和最大体型上均优于雄体。每只雌性的大卵子数似乎表明了真实的产仔数，而不是表观产仔数。推测这些物种没有明确的繁殖周期。这三个物种的空胃发生率都很高。胃内容物重量占总重量的比例通常不到3%。重要的食物是鱿鱼和鱼。为了研究繁殖和食物习性，在楚市采集了两种弯吻鲨。两个物种在成熟时的大小和最大长度上几乎没有差异。没有发现明确定义的繁殖周期。对食物组成的分析表明，在较高种类的食物中存在重叠，但这两个物种似乎通过改变出现百分比和取食不同的猎物物种来避免竞争猎物。

Specimens of Squalus mitsukurii were collected from Choshi, the Ogasawara Islands, Masseiba, and Hancock Seamounts to reveal age, growth, reproduction and food habits. Age determination was undertaken using the 2nd dorsal fin. As a result differences in growth parameters were observed. Similarly, size and age at maturity differed greatly by regions. Clasper lengths and testis weights showed a rapid increase with the onset of maturity. Litter size and the number of large ova per female increased with the size of the parent and showed a large difference among regions. However, this species seemed to possess an united reproductive strategy since the difference arose from differences in the size at maturity. Stomach content analysis revealed that this species was piscivorous. Prey species were different by regions.Three species of small Aqualoids sharks were investigated to elucidate some aspects of reproduction and food habits. Females showed predominance over males in the size at maturity and the maximum size. The number of large ova per female appeared to indicate true litter size rather than apparent litter size. It is conjectured that these species showed no well defined reproductive cycle. The three species indicated high percentage occurrence of empty stomachs. Ratios of stomach content weight to total weight were usually less than 3 %. Important diets were squids and fishes.Two species of scyliorhinid sharks were collected from Choshi to study reproduction and food habits. Both species showed little differences in the size at maturity and the maximum length. A well defined reproductive cycle was not found. Analysis of diet compositions showed overlapping in higher category of food but the two species seemed to avoid competition for prey by changing percentage occurrence and feeding on different prey species.