Fróðskaparrit - 01.01.1992, Side 17

THEINTERNATIONAL RESEARCH .. .
21
significantly different from the average,
one showing a higher growth rate (Sandur,
110986) and two showing lower growth
rates (Hvannasund, 220187; Vágur,
230187).
Female pilot whales off the Faroes were
found to grow longer than those off
Newfoundland (Sergeant, 1962a; Kasuya
et al., 1988) and Iceland (Sigurjónsson et
al., 1993) but with similar body lengths to
those stranded on the British coast (Martin
et al., 1987). The longer females and pro-
tracted growth pattem off the Faroes may
be explained by the favourable feeding pos-
sibilities in these waters, or may point to
the existence of more than one stock in the
North Atlantic. Overall there are many sim-
ilarities in growth pattems, mortality and
survival throughout the North Atlantic,
especially in the northeast.
Age, growth and morphometric studies
of Califomian short-finned pilot whales are
currently being carried out, based on
strandings from 1960 to 1990. Com-
parative studies between those pilot
whales, Japanese short-finned pilot whales
and North Atlantic long-finned pilot
whales are landed (Lockyer, pers. comm.).
Bloch, D. In prep. The social structure in schools of
long-finned pilot whales off the Faroe Islands with
remarks on the occurrence of fighting marks.
Bloch, D. and Lockyer, C. 1989. Age related parameters of
the pilot whale off the Faroe Islands. Preliminary resu-
lts. Paper SC/41/SM15 presented to the IWC Scientific
Committee, May 1989 (unpublished). 1-20.
Bloch, D., Lockyer, C. and Zachariassen, M. In press. Age
and growth parameters of the long-finned pilot whale
off the Faroe Islands. Rep.int.Whal.Commn (Special
Issue 14).
Lockyer, C., Desportes, G. and Waters, T. 1987.
Preliminary studies of pilot whales from Faroese waters
since 1986: Age determination. IWC Doc. Paper
SC/39/SM16 presented to the IWC Scientific Commit-
tee, May 1987 (unpublished). 1-9.
Martin, A.R. and Rothery, P. In press. Reproductive para-
meters of female long-finned pilot whales
(Globicephala melas) around the Faroe Islands.
Rep.int.Whal.Commn (Special Issue 14).
Reproductive parameters
The analysis of the data on female repro-
duction raised some analytical problems.
The dataset and the methods of analysis as
they stand to date have not allowed a choice
to be made between a unimodal and a
bimodal pattem of breeding. However, the
estimate of some of the parameters is sensi-
tive to this choice. Some of the results
given here are, thus, preliminary and sub-
ject to changes.
Females reached sexual maturity between 5
and 15 years of age, at a mean age of 8.7 yrs
and a mean length of 378.5cm and a weight
ranging between 524 and 620 kg, 600 kg in
mean.
Males reached puberty later, between 11
and 18 years, at a mean age of 14.3 yrs, a
mean length of 493.8 cm and a weight
ranging between 1.0 and 1.5 tonnes, in
mean 1.277 kg. The testes became fully
histological mature some years later at a
mean age of 17.3 yrs and males might
become socially mature, i.e. mate success-
fully, only some years later maybe at
around 25yrs of age.
The average rate of ovulation was pre-
dicted to be one corpus every 4 years.
However, examination of ovaries showed