Fróðskaparrit - 01.01.1992, Blaðsíða 9

THE INTERNATIONAL RESEARCH ...
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from NASS-89. The smearing method 2 of
Buckland and Aganuzzi (1988) and a haz-
ard-rate model (Buckland, 1985; 1987)
were used, and different stratification fac-
tors were analysed. This analysis led to an
estimate of 778,000 pilot whales in the cen-
tral and eastem North Atlantic (cv=0.295,
95% CI 442,000-1,370,000). The Scientific
Committee of the Intemational Whaling
Commission endorsed this figure at its 44th
Annual Meeting in Glasgow, June 1992.
Both sets of analysis emphasised the
potential biases resulting from the difficul-
ty in estimating the number of schools and
their size, in a loose aggregation of pilot
whales.
Bloch, D., Gunnlaugsson, T., Hoydal, K. and Sigurjónsson,
J. 1989. Distribution and abundance of pilot whales
(Globicephala melas) in the Northeast Atlantic in
June-August 1987 based on shipboard sightings sur-
veys. Paper SC/41/SM10 presented to the IWC Scien-
tific Committee, May 1989 (unpublished). 1-16.
Buckland, S.T., Cattanach, K.L., Gunnlaugsson, T., Bloch,
D., Lens, S. and Sigurjónsson, J. 1992. Abundance and
distribution of long-finned pilot whales in the North
Atlantic, estimated from NASS-87 and NASS-89 data.
Paper SC/44/SM19 presented to the IWC Scientific
Committee, June 1992 (unpublished). 1-17.
Buckland, S.T., Cattanach, K.L., Gunnlaugsson, T., Bloch,
D., Lens, S. and Sigurjónsson, J. In press. Abundance
and distribution of long-finned pilot whales in the North
Atlantic, estimated from NASS-87 and NASS-89 data.
Rep.int.Whal.Commn (Special Issue 14).
Gunnlaugsson, Th. and Sigurjónsson, J. 1990. NASS-87:
Estimation of whale abundance based on observations
made on board Icelandic and Faroese survey vessels.
Rep.int.Whal.Commn 40: 571-580.
Joyce, G.G., Desportes, G. and Bloch, D. 1990. The Faroese
NASS-89 Sightings Cruise. Paper SC/42/Ol 1 presented
to the IWC Scientific Committee, May 1990 (unpub-
lished). 1-10.
Joyce, G.G., Desportes, G. and Bloch, D. 1991. The Faro-
ese NASS-89 Sightings Cruise. Rep.int.Whal.Commn
41:592.
Long-term analysis ofcatch series
The catch series go back to 1584 and are
unbroken from 1709 onwards. They
revealed a periodic occurrence of long-
finned pilot whales in Faroese waters, with
a period of c. 120yrs and two main peaks
around 1710-1730 and 1830-1850. Catch
series analysis did not reveal any strong
periodic signals and the time series model
(ARIMA) explains 32% of the variance.
Data series which could explain the long
term trends and year-to-year variations
were long-term climatic series, data on the
prey species, Todarodes sagittatus and the
blue whiting Micromesistius poutassou and
experiences from sightings. Similarities
between three sets of time series are
analysed: Pilot whale and Bottle nose
whale, Hyperoodon ampullatus, catch
series, temperature series from Greenland
and a temperature series from the Faroes. A
shift in the correlation between series
appeared around 1890. There is evidence of
a long term stability, and catch levels expe-
rienced historically did not seem to affect
numbers caught subsequently.
Abundance of whales was positively
related to abundance of squid, blue whit-
ing, herring, cod and seabirds (Alcidae), all
positively correlated with sea-surface tem-
perature. Certain weather and main current
conditions on the Faroe Plateau also influ-
enced the abundance of whales.
There was seasonal variations in the
abundance of pilot whales, with a peak in
July-August (21% and 28% of the catch)
and a valley in February-March (2% and
2%). The geographical (North-East vs.
South-West bays) and the seasonal