The Davis Strait - DCE - Nationalt Center for Miljø og Energi

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West Greenland is an important foraging area where baleen whales target
dense patches of prey and the distribution of the whales is correlated with
certain prey items, such as capelin (Mallotus villosus), krill (Meganyctiphanes
norvegica and Thysanoessa sp.) and sandeels (Ammodytes sp.) (Heide-Jørgensen
& Laidre 2007, Laidre et al. 2010, Simon 2010). For instance, during a survey
focusing on the distribution of cetaceans, krill and capelin in September
2005, the overall distribution of fin, minke, humpback and sei whales was
strongly correlated with high densities of krill deeper than 150 m, with a
high density area within the assessment area and one south of the assessment
area (Laidre et al. 2010). Previous studies have shown how a sudden
shift in distribution of the prey resources may cause an equivalent shift in
the distribution of the whales (Weinrich et al. 1997). Therefore, changes in
prey distribution due to climatic changes may be an important link to predict
potential changes in distribution and abundance of baleen whales in the
assessment area and other areas in Greenland.
Besides prey, sea ice is a limiting factor for the northern distribution of fin
whales and this may also be true for other species of rorquals (Simon et al.
2010). Therefore, changes in sea ice coverage are likely to have an effect on
the distribution of baleen whales in the assessment area. In the following
text we will focus on the biology and occurrence of the different species of
baleen whales within the assessment area.
Fin whale, Balaenoptera physalus
The North Atlantic fin whales reach an average length of 19–20 m and an
average weight of 45–75 tonnes, which makes them the second largest animal
on the planet next to blue whales. Fin whales are found worldwide from
temperate to polar waters but are less common in the tropics. About 3,200
fin whales seasonally visit West Greenland waters (from Cape Farewell to
North of Disko Island) with an especially large abundance within the assessment
area along the 200 m contour (Heide-Jørgensen et al. 2008a, Laidre
et al. 2010). In Greenland, fin whales target prey such as sandeels, offshore
patches of krill and coastal aggregations of capelin (Kapel 1979). The strong
correlation between off shore krill abundance and high density of fin whales
indicates that the assessment area is an important fin whale feeding ground
(Laidre et al. 2010).
Fin whales are believed to migrate south to unknown breeding grounds during
winter, yet passive acoustic monitoring shows that fin whales are present
in Davis Strait until end December and the increased fin whale song
suggest that mating starts in October-November while the whales are still in
the assessment area (Simon et al. 2010). The Southward migration of the fin
whales coincides with the formation of sea ice, suggesting that ice coverage
is an important limiting factor for the northern distribution of fin whales
during winter (Simon et al. 2010).
In Greenland, fin whales are placed in the category of least concern on the
Greenland Red List due to the large abundance and signs of increase in the
North Atlantic (Boertmann 2007). However on a global scale the species is
considered as endangered as a result of a major decline in abundance of fin
whales due to whaling in the Southern hemisphere (IUCN 2008).
Minke whale, Balaenoptera acutorostrata
The minke whale is the smallest (about 7 m and 8 tonnes) and most abundant
baleen whale in Greenlandic waters. They migrate between low lati-