Fróðskaparrit - 01.01.1998, Page 159

165
Long-term Fluctuations in Age and
Sex Composition of Pilot Whale Schools
in the Faroe Islands
Langtíðar broytingar í aldurs- og kynsmynstri hjá grind
Dorete Bloch
Føroya Náttúrugripasavn, FO-IOO Tórshavn, Faroe Islands
Phone: +298 31 85 88, fax +298 31 85 89, e-mail: doreteb@ngs.fo
Úrtak
Grindahagtølini vísa, at tey ár tá ið grindirnar eru
nógvar, eru tær eisini stórar, og føðin nógv. Hesi ár eru
fleiri kallfiskar og fleiri leiftrar í grindum, og størstu
kallfiskamir em smærri samanborið við ár við fáum
grindum.
Extended abstract
In the Faroe Islands the long-finned pilot
whale (Globicephala melas) has been taken
for food since the Norse settlement more
than 1,000 years ago and hunting statistics
are available back to 1584 and unbroken
from 1709. This whaling statistics include
some biological information in the form of
the total number of whales and their valua-
tion, in the old Norse value skinn. A skinn
is a weight value and one skinn is on aver-
age composed of 38 kg meat and 34 kg
blubber; the usable part of a pilot whale
contains 54% of the total body weight.
From the period 1821-1997 there exist
from 647 out of the 1.793 landed schools
containing 250.329 long-finned pilot wha-
les in total, the skinn value (533.389,875 in
total) of each single whale (from 90.498
whales). A change in the unit of skinn val-
ue about 1832 excludes the material 1709-
1831 from the calculations. Moreover, in-
formation about the skinn value and sex ex-
ist for 10,102 whales, of which 816 are
from 3 schools 1870-1871, the remaining
from 1964-1997. The skinn value, sex and
sexual status were available for 3,020
whales examined by the Faroese interna-
tional research programme 1986-1988.
Statistical analysis of these data showed
that many schools per year were connected
with many whales per year, while the skinn
measurements showed minimum values of
mean whale size (total annual number of
skinns / total annual number of whales) in
years with maximum number of pilot
whales landed. Estimation of a time series
of the sex distribution of the pilot whale
schools in the period 1832-1994 showed a
mean proportion of males of 29% and 71 %
for the females, correspondingly. Model-
ling the male/female part of the total num-
ber of whales landed 1832-1994 showed
that in peak periods the part of males was
Fróðskaparrit 46. bók 1998: 165-166