The diets of humpback whales (Megaptera novaeangliae) on the shelf and oceanic feeding grounds in the western North Pacific inferred from stable isotope analysis

Abstract

Humpback whales feed on a variety of prey, but significant differences likely occur between regional feeding grounds. In this study, the diets of humpback whales were analyzed by comparing stable isotope ratios in animal tissues at three humpback whale feeding grounds in the Russian Far East: Karaginsky Gulf, Anadyr Gulf, and the Commander Islands. Anadyr Gulf is a neritic zone far from a shelf break, Karaginsky Gulf is a neritic zone close to a shelf break, and the Commander Islands represent an open oceanic ecosystem where whales feed off the shelf break. Samples from the Commander Islands had the lowest mean δ13C and δ15N values (mean ± SE: δ13C = −18.7 ± 0.1, δ15N = 10.4 ± 0.1) compared to the samples from Karaginsky Gulf (δ13C = −17.2 ± 0.1, δ15N = 12.7 ± 0.2) and Anadyr Gulf (δ13C= −17.8 ± 0.1, δ15N = 14.0 ± 0.4). The samples from Anadyr Gulf had the highest δ15N values, while the samples from Karaginsky Gulf had the highest δ13C values. Both δ13C and δ15N values differed significantly among all three areas. Our data support the hypothesis that humpback whales tend to feed on fish in neritic areas and on plankton in deep oceanic waters.

Trophic Ecology of Humpback Whales (Megaptera novaeangliae) in the Magellan Strait as Indicated by Carbon and Nitrogen Stable Isotopes

“…The present work is one of the first efforts to study the trophic ecology of the Southeast Pacific humpback whale population. Previous studies in the Northern Hemisphere have reported that whale skin isotopic ratios during the feeding season are between -16 and -19‰ for δ 13 C and from 12 to 15‰ for δ 15 N (e.g., Gendron et al, 2001;Jaume, 2004;Witteveen et al, 2011;Filatova et al, 2013;Ryan et al, 2013). This study reveals that the mean isotopic ratios for whale skin for the years 2011 and 2012 are within similar ranges to those from the Northern Hemisphere.…”

High-Resolution AMS14C Dates for the Par-Tee Site (35CLT20) and Prehistoric Whale Hunting on the Oregon Coast

“…AMS 14 C measurements of purified bone collagen from the humpback whale phalanx produced an age of 2120±15 14 C yr BP (PSU-5971/UCIAMS-137937) and stable isotope values consistent with an omnivorous marine mammal (δ 13 C: –15.2‰ VPDB; δ 15 N: 14.7‰ Atm N 2 ). Correcting and calibrating this date is more complicated than the procedures used for the elk bone harpoon date, in part because the migration and feeding patterns of humpback whales takes them through waters of differing 14 C age (Calambokidis et al 2001; Straley et al 2009; Filatova et al 2013). We used two methods to estimate the reservoir offset (ΔR) in the whale bone.…”

Feeding of humpback whales in low latitudes of the Southeast Pacific Ocean

“…Genetic analysis demonstrated finer site fidelity between two different feeding sites spaced 500 km apart in the Russian Pacific [18]. In addition, humpback whales showed different feeding strategies in the two feeding sites, as near Karaginsky Island they foraged on schooling fishes and around the Commander Islands they foraged on euphausiids [19].…”