Fróðskaparrit - 01.01.1991, Page 51

STUDIES ON THE LONG-FINNED PILOT WHALE
55
the presence of nematodes also from the
cephalopods in the stomachs.
Number and size of corpora: Ovaries from
158 females were examined in detail. The
corpus luteum supporting the pregnancy
had an average diameter of 41.7 x 41.0 x
40.9 mm (range 8-139 mm, N = 46), and
weighed on average 48.2 + 3.6 g (range:
5.8-88.3 g, N = 38). The c. lutei regressed
during lactation to c. albicantia with a di-
ameter as low as 4x3 mm. The maximum
number of corpora counted on one ovary
was 10, compared with 15 on both, and on
average, mature females contained 5.5 t
0.3 corpora (N=117). Due to the incom-
plete readings of the teeth of older whales, it
is not possible to state conclusively from this
material that all the corpora resulted in
calves or that abortions had occurred in be-
tween. But further studies, recording up to
25 corpora in a single female, conclude that
not all ovulations are followed by pregnan-
cy, since some mature females contained a
larger number of corpora than would be
possible for the number of calves actually
born, according to the mother’s age (Martin
and Desportes, in prep), and since twins oc-
cur only very rarely.
There was a linear correlation (N = 69;
r = 0.57; t = 4.83) between the number of
ovarian corpora and the female body length
(Fig. 11).
From some schools, some of ovaries exa-
mined contained none follicles and only cor-
pora albicantia indicating that the females
were senescent (table 9): in this material spe-
cifically this was 3 whales from 2 different
schools. The lengths of these females were
442-480cm, they contained 8-9 corpora
each, and two of them were 17 and 24 years
old.
Food and feeding
The first study of Faroese pilot whale feed-
ing was based on the examination of 55
stomachs sampled in August and Septem-
ber, 1984 from this material (Desportes,
1985). Additional data was provided by
Moore et al (1978; 1979), and by this investi-
gation.
The long-finned pilot whale appeared to
eat mainly squid in the Faroese area with the
favorite prey being Todarodes sagittatus.
Some other species found in lower frequen-
cy and in much lesser quantity in the
stomachs were:
Gonatus fabricii, Desportes (1985), Moore
et al (1978; 1979), and present data,
Eledone sp., Desportes (1985),
Teuthowenia, Taonius, Histioteuthis spp.,
determined by M. Clarke, Plymouth, pre-
sent data, plus undetermined species, pre-
sent data.
Fish represented in the stomachs were
Blue Whiting (Micromesistius poutassou)
and Cod (Gadus morhua), present data. It
seems that the pilot whale becomes very ex-
clusive in the summertime around the
Faroes, when T. sagittatus is very abundant,
despite the great abundance of other prey.
In Desportes (1985) among 3 species found,
T. sagittatus had a percentage in frequency
of 100%, and in number of 96%. But in
wintertime, when T. sagittatus was absent
from Faroese waters, a greater number of
species (8), including fish, were found for
which the percentage in number was more
equal.
This feeding behaviour fits well with the
later findings from the Faroes (Desportes