大西洋主に東部水域産のビンナガの外部形態による系統群解析

抄録

The Atlantic albacore, Thunnus alalunga (BONNATERRE), is distributed abundantly almost all the round. The author gives morphometrical analysis on this fish from six areas (Fig. 1), which seems the first contribution in this field of fishery biology.
Data used in this report are shown in Table 1. Specimens from northeastern (Sample A) and from southeastern (Sample B) Atlantic are measured as soon as possible by the author on board the research vessel, Shoyo Maru, from September 1960 to February 1961, Certain portions on body are measured in mm. using slide calipers as proposed by MARR and SCHAEFER (1949). These specimens from the six localities are compared each other by stations on the nine relative lengths to body length (Fig. 2).
The results get here are summarized as follows:
1) The specimens from the same area (Sample A) show some sexual differences in head and pectoral lengths. It may be said, however, such differences are not significant, as compared with the local ones, as suggested already by SCHAEFER (1948) and KUROGANE (1960).
2) The local differences between specimens of the northeastern and southeastern areas may be obviously recognized.
The northeastern specimens have shorter head, more front fins of the 1st and 2nd dorsals, anal and pelvic than do the southeastern ones (Table 4, Fig. 4).
3) In comparison with the western Atlantic fish, the eastern ones have longer head, more hear pelvic, and more front 1st and 2nd dorsals (Fig. 5). It must be noted here that these differences can be due to seasonal or technical variations.
4) The morphometrical evidences here obtained show that in the eastern Atlantic at least two populations may be found, while the western population can not be discussed.