This next post to the "common minke whale" blog comes at a time when the Icelandic minke whalers association are reporting that the first whaling vessel is getting ready to sail. Having set themselves a quota of 200 minke whales for this season we can only hope that the weather delayes their departure and that the whales get out of the whalers way ... and preferably come to Scottish (and associated) waters! For more on the story visit the WDCS website.
We're still waiting for our first minke of the season here on our field survey site in the north west corner of Scotland although we've heard reports that they've been sighted off the Isle of Mull and in the Moray Firth - so they're in the area!!
In the meantime, yet another good friend of WDCS, Marijke de Boer, tells us more about her work focusing on the minke whales in the central North Sea.
Minke whales in the Central North Sea
The Dogger Bank in the Central North Sea is an area characterised by frontal features and high productivity. This offshore bank is the area where Atlantic waters from the north meet and mix with waters from the English Channel. Relatively high primary production values have been reported although this productivity on a small-scale is patchy due to the complex hydrodynamics and the irregular occurrence of wind mixing.
The Dogger Bank is currently announced/proposed as a Special Area of Conservation (SAC) according to the Habitats Directive of the European Union. The Bank itself is a sandbank and offers a suitable sandeel habitat. Studies on fish, seabirds and cetaceans show the Bank has a high biodiversity.
Minke whales have mainly been reported to the north and west of the Dogger Bank with most survey work being carried out over the summer months when the weather is most suitable for dedicated research.
Recent survey work has now shown that the Bank is an important feeding habitat for minke whales in the spring time. The survey was carried out from 28 March to 2 July 2007 at a much finer scale than earlier studies in the region. A high density of whales was estimated by the researcher with a total of 77 sightings of minke whales comprising 130 individuals. The minke whales were temporarily congregating along this bank and were taking advantage of the local spring abundance of sandeels. The density found was higher than previous studies have suggested for the Central North Sea.
At present there are some threats to minke whales in these waters and an increased understanding of this species ecology is needed. The survey results correspond to recent observations of minke whale re-distribution within the North Sea and these may be related to a decline in sandeel availability elsewhere in the North Sea.
The offshore Dogger Bank is currently the last extensive sandeel fishing ground in the North Sea and concern has been raised regarding the effects of local sandeel depletion at the Bank on their predators and the North Sea ecosystem as a whole. Especially, when prey becomes less abundant elsewhere offshore banks may become increasingly important to minke whales within the North Sea. Minke whales may thus benefit from the designation of this area under the Habitat Direction, as an SAC.
M.N. de Boer. In press. Spring distribution and density of minke whale (Balaenoptera acutorostrata) along an offshore bank in the Central North Sea. Marine Ecology Progress Series.