Fróðskaparrit - 01.01.1991, Page 50

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STUDIES ON THE LONG-FINNED PILOT WHALE
months in Frazer and Huggett (1959), 15.5
months in Sergeant (1962), whereas Harri-
son calculated 9-12 months (1949: 250). As-
suming a gestation time of 15.5 months, this
examination will show birth times from ear-
ly October to late November, June, August
and mid January, i.e. nearly all year, as
pointed out by Miiller (1884: 23) who said
that »the pilot whale breeds all year because
the same amount of calves and pregnant fe-
males are always found«. Harrison (1949:
250) concluded the same as Míiller. Des-
portes (1982) also agreed with this hypothe-
sis, but suggested peaks of birth frequency
in August and conception in April respec-
tively, and the present material did not indi-
cate otherwise. This was also confirmed in
further examinations by Desportes et al (in
print).
The percentage of pregnant females ap-
peared to vary from 8-35%, and the largest
number of pregnant females was found in
September. It must be mentioned that 2 fe-
males in this material were found to be
simultaneously pregnant and lactating (Fig.
4).
Twins: Miiller (1882; 1884) mentioned once
seeing a pair of fully developed twin foe-
tuses, and in the Húsavík catch from August
31, 1958, one pair of male twins of 38cm
each was found (Table 3).
Duration of suckling: The reproductive
stage of all females was examined in two
schools: Fuglafjørður , August 21, 1984 and
Klaksvík, January 29, 1985 (Table 8). There
were 10 (28%) and 5 (31%) lactating females
respectively. Each lactating female presuma-
bly suckled her own calf only. By counting
the number of shortest newborns and lactat-
ing females, the calves suckled to a length of
about 300 cm (1.5-2 years). This was in ac-
cordance with the data from New Found-
land (Sergeant, 1962: 39), but was a slightly
longer suckling time than was estimated by
Desportes (1982; 1983). Another method to
calculate the suckling time is: no. of lactat-
ing x gestation time: pregnant females
(Kasuya and March, 1984). Based on a
gestation period of 15.5 months, the data
from 3 schools (Table 8) gives a suckling
time of: (21:13) x 15.5 = 25.1 months, i.e.
also about 2 years, which agrees with the
first calculation.
Suckling time and cephalopod marks: The
marks made by cephalapods are mostly
placed around the mouths, although they
can also be found elsewhere, especially on
the belly. These marks have been examined
before by Fjeldstrup (1887) and Jensen
(1916).
One school consisting of 73 whales from
Vestmanna, July 17, 1984, was examined
for cephalopod marks. From this school the
skinn values rather than the length were ob-
tained. Only three whales had no cephalo-
pod marks at all. Of three newborns of a
value of 1, 1, 1 /2 skinn, two had no marks,
but the third had marks, which would indi-
cate that newborns begin to eat cephalopods
soon after birth. There was, peculiarly, one
6-skinn female without any visible marks.
From three other schools 55 stomachs
were examined (Desportes, 1985: 167), and 7
young 1-2 skinn animals of 186-256cm con-
tained milk in their stomachs, the largest
also beaks from cephalopods. This suggest-
ed that newborns ate cephalopods at the
same time as they were suckling, as was also
shown by Desportes (1985) when examining