FEEDING RATE AND DAILY ENERGY INTAKE OF DALL'S PORPOISE IN THE NORTHEASTERN SEA OF JAPAN (19th Symposium on Polar Biology)

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We examined thirty stomachs of Dall's porpoises (Phocoenoides dalli) collected on board a hand harpoon fishery vessel in the Sea of Japan off Hokkaido in May 1995 Maximum ratio of stomach content weight to body weight of the sated animals (MRSCW, 1 68%) was recorded early in the morning, and average of the ratio decreased in the daytime T TOBAYAMA (Studies on the feeding habits of the little toothed whales. Ph. D. thesis, Umv Tokyo, 1974) reported that digestion time was eight hours from full stomach to empty on captive Tursiops gilli and Delphmus delphis The eight hour digestion profile was almost middle of the possible digestion time range found in this study. Assuming that the digestion time was eight hours, maximum daily digestible food intake was estimated at 5.04% (MRSCW×24/8) of body weight. This value is between the feeding rate indirectly obtained from the biological concentration rate of mercury in the wild Dall's porpoise (2-3%), and that directly measured from a captive porpoise (12 5%) Daily intake of energy was calculated as 27 2MJ for a 108kg Dall's porpoise from prey energy density, weight contribution rate of prey and 5% feeding rate. This is close to 25 5MJ of the daily energy requirement calculated by the allometnc method using body weight.
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