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

从铫子、小笠原群岛、马赛场和汉考克海山采集了三栗角鲨标本，研究其年龄、生长、繁殖和食性。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，各区域的成熟时的大小和年龄也有很大差异。抱子长度和精巢重量随成熟期的开始而迅速增加。窝仔数和每雌大卵数随母体大小的增加而增加，且区域间差异较大。然而，这一物种似乎拥有一个统一的生殖策略，因为这种差异是由成熟时的大小差异引起的。胃内容物分析表明，该物种是食鱼的。不同地区的猎物种类不同，本文对三种小型水鲨的繁殖和食性进行了研究。雌性在成熟时的大小和最大大小方面均优于雄性。每只雌性动物的大卵子数量似乎表明了真实的窝仔数，而不是表观窝仔数。这些物种没有明确的生殖周期。这三个物种表明空胃的发生率很高。胃内容物重量占总重量的比率通常小于3%。在铫子海域采集了2种蓝鳍鲨，对其繁殖和食性进行了研究。两个物种表现出在成熟时的大小和最大长度的差异不大。一个明确的生殖周期没有found.Analysis的饮食组成显示重叠在更高类别的食物，但这两个物种似乎避免了竞争的猎物，改变发生率和不同的猎物种类。

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.