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bende måde. Det er blevet dokumenteret, at nogle individer
opholder sig i Diskobugten i mindst 56 dage. Samtidig er
det ved hjælp af fotoidentifikation vist, at nogle individer
kommer til Diskobugten i successive år.
Summary
The bowhead whale Balaena mysticetus is an ice-adapted
baleen whale living in the Arctic waters all year round. Dis-
ko Bay is the primary bowhead whale aggregation area off
western Greenland. The whales stay in the area from late
January to early June.
Disko Bay is thought to act as a mating ground for bow-
head whales in winter. High densities of zooplankton in the
spring also make Disko Bay an important feeding ground.
In the beginning of June, the bowhead whales usually
leave Disko Bay, and satellite tracking has shown that the
migration goes through the pack ice in Baffin Bay to sum-
mer aggregation areas in eastern Canadian waters.
Besides satellite tracking, sampling of biopsies has pro-
vided important knowledge of the bowhead whales visiting
Disko Bay. Genetic data indicate that the number of bow-
head whales in the population aggregating in Disko Bay is
1,410 and that the majority of these are females.
Bowhead whales have numerous white scars, useful for
identification of the individual whales. The scars can be a
result of contact with ice, killer whale attacks, collisions
with ships, or entanglement in ropes and nets. However, new
wounds can be acquired and old scars disappear, making
the use of scars as an identification mark problematic.
Resightings of bowhead whales have shown that the scars
persist for years. The rate of accumulation of marks also
appears to be low. As the bowhead whales in Disko Bay are
adults, the markings have had time to accumulate.
The usefulness of white scars for recognition of the in-
dividual bowhead whales has been demonstrated in several
surveys, based mostly on aerial photographs. This study
used photographs taken from a boat, and it aims to deter-
mine the potential of boat-based photo-identification to pro-
vide knowledge on the residence time and site fidelity of the
bowhead whales in Disko Bay.
All ID photographs were taken in Disko Bay in the vi-
cinity of Qeqertarsuaq on Disko Island, western Greenland.
The field work was conducted in the spring of 2010 and
2011. The photographs were taken from a small open boat
with an outboard engine or from the R/V Porsild using a
Nikon D-200S camera with a 70-300 mm Nikkor lens. The
ID photos did not focus on a specific region of the whale,
so when possible, several photographs of the whale were
taken to cover as many angles and as much of the whale as
possible. The photographs were subsequently examined for
individual whales which were photographed several times
within the two seasons.
Twelve individuals were recognised on different days
within a season, and the results show that at least some indi-
viduals stay in the Disko Bay area for at least 56 days.
In addition, three individuals were photographed in both
2010 and 2011. This demonstrates that at least some bow-
head whales appear in Disko Bay in successive years.
This study has shown that boat-based photo-identifica-
tion is a usable method to conduct non-invasive investiga-
tions of bowhead whales, and it demonstrates the applica-
bility of ID photos taken from a boat for recording residence
time and interannual site fidelity of bowhead whales.
Noter
1. M.P. Heide-Jørgensen, K.L. Laidre, M.V. Jensen, L.
Dueck, L.D. Postma: Dissolving stock discreteness with
satellite tracking: Bowhead whales in Baffin Bay: Marine
Mammal Science , 2006, 1/22, p. 34-45, p. 35.
2. D. Rugh, H. Braham, G. Miller: Methods for photographic
identification of bowhead whales, Balaena mysticetus: Ca-
nadian Journal of Zoology, 1992, 70, p. 617-624.
3. O. M. Tervo: Acoustic behaviour of bowhead whales Bala-
ena mysticetus in Disko Bay, Western Greenland. PhD thesis,
University of Copenhagen, 2011. pp. 132.
4. Fotoidentifikationsprojektet “Boat based photo-identifica-
tion of bowhead whales ( Balaena mysticetus) in Disko Bay,
Greenland” var mit bachelorprojekt (biologi, Københavns
Universitet). Som led i projektet var jeg i det tidlige forår
2011 på Arktisk Station, Københavns Universitet, i Qeqer-
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