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Long-finned pilot whale (Globicephala melas): tissue lipid profiles
thesisposted on 2023-05-26, 13:35 authored by Andrea WaltersAndrea Walters
Blubber and muscle samples were collected from 63 long-finned pilot whales, Globicephala melas, involved in a single mass stranding event on the east coast of Tasmania (Reban Beach) in October 1998. This is the first time that aspects of the foraging ecology and body condition of a complete group of pilot whales have been reported from the Southern Hemisphere. Individuals ranged in total length from 236 to 548 cm. Blubber thickness ranged from 30.7 to 74.0mm and blubber lipid content from 34.6 to 87.9%. No relationship was found between blubber lipid content and blubber thickness, sex or reproductive state. Both whole depth blubber samples, and blubber separated into three distinct layers were analysed.. Lipid content in muscle from a subsample of adult males, was found to be significantly different that found in blubber. Muscle lipid content was significantly less variable than blubber lipid content, and ranged from 1.2 to 13.2% (and on average comprised 3.3 ± 3.7% by weight of lipid). The lipid composition of the blubber was dominated by triacylglycerol (TAG). In comparison, muscle was comprised primarily of TAG (57.3 ± 18.4%) and polar lipid (PL; 38.8 ± 16.8%). The FA composition of the blubber was dominated by high levels of long-chain monounsaturated fatty acids (LC-MUFA) (53.2 ± 3.7%) and low levels of polyunsaturated fatty acids (PUFA; 5.9 ± 1.7%). Principal Components Analysis (PCA) revealed no differences in FA composition of blubber between male and female pilot whales, nor between non-lactating and lactating females. PCA did, however, reveal clear separation between juveniles and adults, demonstrating significant differences in fatty acid (FA) composition between age groups. FA driving the age separation were 18:1ω9, 16:1ω7 and 16:0. Both lipid content and composition did not vary significantly throughout the vertical aspect of the blubber layer in adult male pilot whales. A repeated measures ANOVA demonstrated no significant differences in the FA composition across blubber layers indicating little differential deposition of FA components within the inner, middle or outer portions of the blubber layer. The diet of Globicephala melas was investigated by comparing signature fatty acid data of potential prey to fatty acid profiles of both blubber and muscle tissue. Discriminant Function Analysis for 18 prey species grouped into squid, fishes and crustaceans, showed pilot whales grouping more closely with all fish (predominantly myctophids) and three species of squid which feed on myctophids.
Department/SchoolInstitute for Marine and Antarctic Studies
PublisherUniversity of Tasmania