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Abstract: The Pacific white-sided dolphin (Lagenorhynchus obliquidens) is one of the most abundant apex predators in the North Pacific Ocean, but little is known about how much food they consume and whether their food requirements vary seasonally. We attempted to address these two issues using the feeding records of five Pacific white-sided dolphins housed at the Vancouver Aquarium. These individuals consumed an average of 7.9 kg ± 0.35 (± SE) of fish and squid per day (~11,000 kcal day-1), which equated to ~7% of their body mass and an annual mean intake of 2,880 kg ± 131.8 (± SE) per dolphin (N = 5). Patterns of food consumption and seasonal changes were assessed using long-term feeding records (1977 to 2001) from a single adult female, and were found to be highest in terms of biomass and calories in late December, and about 15% less in late May and early June. Seasonal pool temperatures (range 6.5 to 21.5º C) were inversely related to food intake and accounted for part of the variation, suggesting that seasonal cues other than temperature triggered the changes in food consumption. Amounts of prey consumed by Pacific white-sided dolphins are undoubtedly higher in the wild than in captivity due to relative differences in their respective behaviors in the two environments. However, relative seasonal changes in energy requirements are likely to be independent of living conditions and have implications for estimating the energy requirements of Pacific white-sided dolphins in the wild.
Key Words: season, Pacific white-sided dolphin, Lagenorhynchus obliquidens, cetacean, captive, food intake
Document Type: Research article
Page Numbers: 211-220