Understanding the feeding ecology of minke whales, Balaenoptera acutorostrata, in Korean Seas using trophic lipid markers

Abstract

In order to understand the feeding ecology of minke whales Balaenoptera acutorostrata in East/Japan Sea, lipid biomarkers (e.g. fatty acids, sterols, compound-specific stable isotope ratio) were analyzed in blubber tissues of by-caught minke whales and their potential preys (i.e. anchovy Engraulis japonica, krill Euphausia pacifica). Lipid contents of minke whales blubber ranged from 68 to 81% of wet weight with a dominance of triacylglycerols (TG) (accounting for 96 to 98% of total lipids). No difference in lipid contents and class compositions was found, but fatty acid 9FA) composition was different between the inner (near muscle) and outer layer (near skin) of the blubber. Higher saturated fatty acids (SAFA) were found in the inner layer (22.94 to 25.24 % of total fatty acids) than in the outer layer (20.43 to 20.95 % of total fatty acids). However, polyunsaturated fatty acids (PUFA), especially 22:6(n-3) and 20:5(n-3) known as FA trophic markers, were found in higher concentrations in the outer layer than in the inner layer, and also appeared in higher concentrations in the potential preys analyzed (anchovy and krill). The result of this study confirms that lipid trophic markers combined with compound-specific stable isotope ratio could be a useful chemical tracer to track the feeding history of minke whales.