Cetacean sigthings in North Sea

Original provider:
Marijke N. de Boer

Dataset credits:
Marijke N. de Boer

Abstract:
Minke whales and other marine mammals were recorded in the central
North Sea in an area characterised by frontal features and high productivity
northeast of the Dogger Bank (4677 km2). Survey efforts were carried
out from 28 March to 2 July 2007, at a finer scale than in earlier studies in
the region, using 2 vessels as platforms of opportunity and a dedicated line-
transect survey vessel following distance sampling methods. The high
density of whales indicated that this offshore bank slope is an important
spring habitat for minke whales in the North Sea. In total, 77 sightings of
minke whales comprising 130 individuals were recorded. The peak density
of minke whales was estimated to be 0.029 whales km–2 (minimum
estimate, 95% CI: 0.012 to 0.070) in May. During peak abundance, the minke
whales temporarily congregated in the area, suggesting that the whales
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. The results correspond to recent observations of minke
whale redistribution within the North Sea, and these may be related to a
decline in sandeel availability elsewhere in the North Sea. Offshore banks
that aggregate prey may therefore become increasingly important feeding
habitats for minke whales and other top predators in the North Sea. The
observed habitat preference of minke whales along this offshore bank
appeared to be similar to that observed in coastal areas, and this suggests
some degree of generality regarding the preference for this type of habitat.