Seasonal variation in body condition and muscular lipid contents in northeast atlantic minke whale,Balaenoptera acutorostrata

Anatomical measurements and muscle samples for lipid content analysis from 225 minke whales, Balaenoptera acutorostrata, were sampled during scientific whaling operations in Norwegian and adjacent waters in 1992–1994. Data collected were sorted into three seasons and three areas. A linear regression analysis was used to investigate the relationship between total body length and muscle/ blubber weight. To test whether there was significant differences between areas and/or seasons an ANCOV A-analysis was used. A condition index originally developed for fish based on muscle/ blubber weight was fitted to test the usefulness for minke whales. The regression analysis on Intransformed data revealed that both muscle and blubber weight vs total body length were linear. A seasonal weight increase was found and was mainly due to increase in blubber weight. The condition index based on blubber weight and total body length was found useful for minke whales. Blubber thickness increases during the feeding season both on the ventral and dorsal side of the whales. Visceral fat also shows a seasonal increase. The results from the biochemical analysis revealed that there are variable amounts of lipid stored in different muscular groups. Generally there is a seasonal increase in lipid, most clear shown by increase in lipid stored in the muscular group behind the dorsal fin.