Seasonal Changes in the Food Intake of Captive Pacific White-Sided Dolphins (Lagenorhynchus obliquidens)

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.

Seasonal Resting Metabolic Rate and Food Intake of Captive Pacific White-Sided Dolphins (Lagenorhynchus obliquidens)

“…The same cannot be said for food intake, however, which is likely lower in captivity due to reduced levels of activity and possibly warmer water temperatures. Instead, seasonal changes in food intake in captivity and the wild are more likely due to physiological processes associated with key life history events (i.e., seasonality in estrous, calving, and lactation) and changes in the abiotic environment (e.g., Cheal & Gales, 1992;Kastelein et al, 2000;Piercey et al, 2013). We regret having to discard the metabolic data from one Pacific white-sided dolphin due to the presumed training effect, leaving us with data from only two individuals.…”

“…While seasonal changes in gross energy intake of mammals may be a response to seasonal changes in resting metabolism, it is also possible that they instead reflect parallel changes in prey availability (e.g., Fuglei & Øritsland, 1999), physiological shifts associated with different life history events, or changes in the physical environment (e.g., water temperatures; Piercey et al, 2013). Seasonal changes in feeding rates have been documented in small cetaceans housed in aquaria and have been linked to changes in pool temperature (Cheal & Gales, 1992;Kastelein et al, 2000), mating season (Kastelein et al, 1999), and changes in behavior or activity levels (Kastelein et al, 2003).…”