Studies of minke whale (Balaenoptera acutorostrata) ecology in the northeast Atlantic: Description of the 1993 scientific catch operations and preliminary results from stomach analyses and resource surveys

摘要

Ecological studies of the Northeast Atlantic minke whale(Balaenoptera acutorostrata), initiated in 1992, were continued in 1993.The field work was carried out in spring (15 April-15 May),summer (15 June-12 July) and autumn (25 August-20 September)using four chartered small-type whaling vessels which operatedin four selected subareas. To ensure random sampling of whales,stringent sampling procedures, where the vessels searched forwhales along predetermined transects within each subarea, wasapplied. Concurrent with the sampling of minke whales, estimatesof potential prey abundance were carried out using accoustics andtrawls. A total of 69 whales were shot; 5, 35 and 29 in spring,summer and autumn, respectively. Preliminary results from thestomach analyses indicate a diet where fish play a very prominentrole. Diet varied between both periods and areas. Gadoid fishspecies dominated the spring diet. In summer and autumn the dietin the northmost areas (Spitsbergen and Bear Island) wasprimarily characterized by the presence of krill, to a much lesser extent by capelin. This is consistent with an increase inkrill and severe decrease in capelin availability in these areasin 1993. In the coastal areas of North Norway, herring is thedominant planktivorous fish, and was also the most important fooditem for the whales both in summer and autumn. To some extent,however, the herring was accompanied by some gadoid speciesduring summer. Whale consumption of 0-group fish were observedto be rather limited. Along with material necessary for the studyof condition and diet, sampling was also carried out for a numberof other studies included in the framework of the Norwegianscientific catch program.