さあ！諸君！捕鯨問題だ！

＜Bottlenose dolphins＞
Two morphological forms of this species occur along the
coast of southern Japan: a spotted form of smaller body
size found along the coast of the Ryukyu Islands; and an
unspotted type of greater body size found in all Japanese
waters (Uchida, 1982).

Although both forms may occur in Ryukyu waters, most
appear to be unspotted. This form, occurring off Iki Island,
has an ovulation rate and a testis weight at the attainment
of sexual maturity which are different from those of the
same form in the lzu and Taiji waters. This is thought to
indicate the presence of different stocks in the two areas
(Kasuya, unpublished).

Miyashita (1993) confirmed that this species occurs in a
broad area in the western North Pacific west of 180°E, and
between 23° and 42°N. However, out of six individuals
radio-tagged and released at Taiji (Tanaka, 1986), four
remained within 30 n.miles, one moved to 50 n.miles away
and then returned to coastal waters, and only one reached
90 n.miles offshore. This suggests infrequent mixing of
coastal and offshore individuals. This is further supported
by a gap in distribution between 142° and 145°E. It seems
likely, therefore, that there are offshore and coastal stocks
of the unspotted form.

The abundance was estimated at 35,046 in the East
China Sea (Miyashita, 1986) and 168,791 in the wesrern
North Pacific between 23° and 42°N and west of 180°E
(Miyashita, 1993); 36,791(CV = 0.25) were found west of
145°E and north of 30°N.

The catch of this species in the drive fishery was low until
the 1970s, but has increased recently to between 200 and
1 ,600 per year (Table 12). The drive fishery at Taiji and the
crossbow fishery at Nago have contributed to this change.

ソース 　 REP. INT. WHAL. COMMN 43, 1993 　 p．451
KISHIRO & KASUYA: JAPANESE DRIVE FISHERIES