FEEDING RATE AND DAILY ENERGY INTAKE OF DALL'S PORPOISE IN THE NORTHEASTERN SEA OF JAPAN
Abstract: We examined thirty stomachs of Dall's porpoises (Phocoenoides dulli) 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 morn...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.602.9482 http://polaris.nipr.ac.jp/~penguin/polarbiosci/issues/pdf/1998-Ohizumi.pdf |
| Summary: | Abstract: We examined thirty stomachs of Dall's porpoises (Phocoenoides dulli) 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, Univ. Tokyo, 1974) reported that digestion time was eight hours from full stomach to empty on captive Tursiops gilli and Delphinus 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 x 2418) 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 27.2 MJ for a 108 kg Dall's porpoise from prey energy density, weight contribution rate of prey and 5 % feeding rate. This is close to 25.5 MJ of the daily energy requirement calculated by the allometric method using body weight. key words: Dall's porpoise, Phocoenoides dailli, feeding rate, energy intake, stomach contents |
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