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Lifetime coastal and oceanic foraging patterns of male Guadalupe fur seals and California sea lions
Author(s) -
AuriolesGamboa David,
Szteren Diana
Publication year - 2020
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/mms.12649
Subject(s) - oceanography , sea lion , foraging , isotope analysis , predation , δ13c , δ15n , geology , stable isotope ratio , environmental science , ecology , biology , physics , quantum mechanics
Carcasses of adult and subadult male Guadalupe fur seals (GFSs) are beached on Isla Magdalena, representing about 73% of all GFSs beachings since 2003. Analysis of carbon and nitrogen stable isotopes in dentin collagen from male GFSs was used in an attempt to distinguish animals from two possible locations of origin: the oceanic Guadalupe Island (GI) and the coastal San Benito Islands (SBI). Samples of conterminous and contemporary California sea lions (CSLs) were included as representative of coastal predators. Two distinct groups of GFSs were evident based on δ 13 C values: coastal GFSs with higher δ 13 C values than CSLs, and oceanic GFSs with lower δ 13 C values than CSLs. Significant temporal trends were observed in the δ 15 N values; values for oceanic GFSs and CSLs increased annually (0.082‰ and 0.089‰, respectively), while those for coastal GFS decreased annually by 0.183‰. The isotopic segregation of oceanic and coastal GFS males, presumably from GI and SBI respectively, has been present at least since the mid‐1990s. This segregation may be due to dissimilar ingestion of prey from oceanic vs . coastal origin prior to their seasonal co‐occurrence in the Gulf of Ulloa.