日本産ナマコ類の水産学的・分類学的研究における最近の動向

抄録

In this review, studies on the growth of the Japanese sea cucumber Apostichopus japonicus are summarized. All the recent studies referred have been using the new method of estimation of body size of A. japonicus from only one simultaneous measurement of body length and breadth taken from living animals. There were differences in individual growth rates (uneven growth) of A. japonicus seedlings in a tank, which was mainly due to the unevenness in the amount of food for each individual in the tank. However, such uneven growth may not occur in nature. In their natural habitat, juveniles grew up well and were uniform in their size within the same year-group, revealed by the cohort study of juvenile sea cucumber from an intertidal habitat in the Hirao Bay, Yamaguchi. The artificially-reared seedlings released in an artificial habitat also grew up well and uniform in their size within the same year-group, revealed in the Funka Bay, Hokkaido. In the nursery habitats of juvenile sea cucumber, the origin of the natural food resources was also investigated based onδ¹³C andδ¹⁵N plots of juveniles’ tissue samples, and their potential food sources. The recent studies on the inventory surveys and taxonomy of the Japanese holothurians were also summarized.