Ecotype and geographical variation in carbon and nitrogen stable isotope values in western North Pacific killer whales (Orcinus orca). Issue 3 (2nd April 2020)

• Record Type: Journal Article
• Authors: Borisova, Ekaterina A.; Filatova, Olga A.; Fedutin, Ivan D.; Tiunov, Alexei V.; Shpak, Olga V.; Hoyt, Erich
• Is Part Of: Marine mammal science. Volume 36:Issue 3(2020)
• Page Start: 925
• Page End: 938
• Publication Date: 2020-04-02
• Subjects: ecotypes -- feeding ecology -- geographical variation -- killer whale -- North Pacific -- Orcinus orca -- stable isotopes; Marine mammals -- Congresses; Marine mammals -- Periodicals; Marine mammals, Fossil -- Periodicals; Mammifères marins -- Périodiques; 599.5
• DOI: 10.1111/mms.12688
• Languages: English
• ISSNs: 0824-0469

Abstract

Abstract: Killer whales are top predators in marine trophic chains, and therefore their feeding preferences can substantially affect the abundance of species on the lower trophic levels. Killer whales are known to feed on many different types of prey from small fish to large whales, but a given killer whale population usually focuses on a specific type of prey. Stable isotope analysis is widely used to study whale diets, because direct observations are often impossible. Killer whale feeding habits in the western North Pacific are poorly studied, and the large‐scale stable isotope analysis provides a unique opportunity to gain insights into the trophic links of this top predator. In this study, we compare the δ 13 C and δ 15 N stable isotope values from killer whale skin samples obtained in different areas of the western North Pacific from fish‐eating (R‐type) and mammal‐eating (T‐type) killer whale ecotypes. The effect of ecotype was highly significant: both carbon and nitrogen stable isotope values were lower in R‐type whales than in T‐type whales. The geographical variation also affected killer whale stable isotope values due to both the differences in killer whale diet and the variation in baseline stable isotope values across the study areas.