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| Ecology and Behavior |
| This may be the fastest swimmer of all small cetaceans, at least for short bursts. When swimming rapidly, Dall's slice along the surface, producing a characteristic roostertail of spray. At other times, the animals move slowly and roll at the surface, creating little or no disturbance. They are avid bowriders, moving back and forth with jerky movements, and often coming from seemingly nowhere to appear at the bow of a fast-moving vessel. Breaching, porpoising, and other kinds of aerial behavior, are extremely rare in this species. Dall's porpoises are found mostly in small groups of 2-12, although aggregations of up to several thousand have been reported. Groups appear to be fluid, often forming and breaking up for feeding and playing.
Most Dall's porpoise calves are born in spring and summer, and there is great geographic variation in age and length at sexual maturity among populations. |
| Feeding and Prey |
| Dall's porpoises are apparently opportunistic feeders, taking a wide range of surface and midwater fish and squid, especially lanternfish and gonatid squid. Occasional krill, decapods, and shrimps found in stomachs are not considered normal prey. |
| Threats and Status |
| Dalls porpoise is one of the primary species taken directly by Japanese fishermen for human consumption. Porpoises are harpooned as they ride the bow waves of catcher boats, and in the recent years the annual catch has been as high as 40,853 (1988). In addition, Dalls porpoises have been taken incidentally in large numbers in several North Pacific driftenet fisheries, although several of these fisheries are now defunct. Smaller incidental catches occur in several fisheries using gillnets and trawls in US and Canadian west coast waters. Environmental contaminants are also thought to be a threat, and high levels of organochlorines may reduce testosterone levels in males and reduce calf survival, thereby influencing reproduction.
Lower Risk/Conservation Dependent (IUCN); Not Listed (ESA). |
| References |
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ESCORZA TREVINO, S., AND A. E. DIZON. 2000. Phylogeography, intraspecific structure and sex-biased dispersal of Dall's porpoise, Phocoenoides dalli, revealed by mitochondrial and microsatellite DNA analyses. Molecular Ecology 9:1049-1060.
FERRERO, R. C., AND W. A. WALKER. 1999. Age, growth, and reproductive patterns of Dall's porpoise (Phocoenoides dalli) in the central North Pacific Ocean. Marine Mammal Science 15:273-313.
HOUCK, W. J., AND T. A. JEFFERSON. 1999. Dall's porpoise Phocoenoides dalli (True, 1885). Pp. 443-472 in S. H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Vol. 6 The second book of dolphins and the porpoises. Academic Press.
JEFFERSON, T. A. 1988. Phocoenoides dalli. Mammalian Species 319:7 pp.
JEFFERSON, T. A. 2002. Dalls porpoise Phocoenoides dalli. Pp. 308-310 in W. F. Perrin, B. Würsig and J. G. M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.
MIYASHITA, T., AND T. KASUYA. 1988. Distribution and abundance of Dall's porpoise off Japan. Scientific Reports of the Whales Research Institute 35:107-128.
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| Relevant OBIS-SEAMAP Datasets (# sets:
45) |
| Aerial Surveys of Marine Birds and Mammals in Support of Oil Spill Response and Injury Assessment |
| MMS Aerial Surveys for Seabirds and Mammals, Oregon and Washington |
| MMS Central/Northern California High-altitude mammals |
| MMS Central/Northern California Low-altitude birds and mammals |
| MMS High Altitude Survey for Mammals, Southern California |
| MMS Low Altitude Survey for Mammals, Southern California |
| MMS Oregon/Washington Marine Mammal Surveys |
| MMS Oregon/Washington Miller Freeman Cruise (Birds) |
| MMS Seabird Ecology Study |
| MMS Ship Transect Survey for Mammals and Seabirds, Southern California Bight |
| MMS Surveys in the Southern California Bight |
| NMML 1999 Bering Sea Shelf Cetacean Survey |
| NMML 2000 Bering Sea Shelf Cetacean Survey |
| NMML Harbor Porpoise Aerial Survey, Alaska Peninsula, Replicate 1, 1992 |
| NMML Harbor Porpoise Aerial Survey, Alaska Peninsula, Replicate 2, 1992 |
| NMML Harbor Porpoise Aerial Survey, Bristol Bay, Replicate 2, 1991 |
| NMML Harbor Porpoise Aerial Survey, Bristol Bay, Replicate 3, 1991 |
| NMML Harbor porpoise Aerial Survey, Kodiak Island, Replicate 1, 1992 |
| NMML Harbor Porpoise Aerial Survey, Kodiak Island, Replicate 2, 1992 |
| NMML Harbor Porpoise Aerial Survey, Kodiak Island, Replicate 3, 1992 |
| NMML Harbor Porpoise Aerial Survey, SE Alaska, Replicate 1, 1993 |
| NMML Harbor Porpoise Aerial Survey, SE Alaska, Replicate 2, 1993 |
| NMML Harbor Porpoise Aerial Survey, SE Alaska, Replicate 3, 1993 |
| NMML Harbor Porpoise Vessel Survey, SE Alaska, Fall 1991 |
| NMML Harbor Porpoise Vessel Survey, SE Alaska, Fall 1992 |
| NMML Harbor Porpoise Vessel Survey, SE Alaska, Fall 1993 |
| NMML Harbor Porpoise Vessel Survey, SE Alaska, Spring 1991 |
| NMML Harbor Porpoise Vessel Survey, SE Alaska, Spring 1992 |
| NMML Harbor Porpoise Vessel Survey, SE Alaska, Spring 1993 |
| NMML Harbor Porpoise Vessel Survey, SE Alaska, Summer 1991 |
| NMML Harbor Porpoise Vessel Survey, SE Alaska, Summer 1992 |
| NMML Harbor Porpoise Vessel Survey, SE Alaska, Summer 1993 |
| NMML Killer Whale Vessel Survey, Alaska Peninsula, 1992 |
| NMML Killer Whale Vessel Survey, Alaska Peninsula 1993 |
| NMML Killer Whale Vessel Survey, Bering Sea, 1992 |
| NMML Killer Whale Vessel Survey, Bering Sea, 1993 |
| NMML Killer Whale Vessel Survey, Kodiak Island, 1993 |
| NMML Killer Whale Vessel Suvey, Kodiak Island, 1992 |
| NMML Small Cetacean (coastal) Aerial Survey 1997, Gulf of Alaska |
| NMML Small Cetacean (coastal) Aerial Survey 1998, Gulf of Alaska |
| NMML Small Cetacean (coastal) Aerial Survey 1999, Gulf of Alaska |
| SWFSC Cetacean Sightings during a Marine Mammal Survey in the Eastern Tropical Pacific (1508) |
| SWFSC Marine Mammal Survey of the California Coast (1426) |
| SWFSC Oregon, California and Washington Line-Transect Experiment (Orcawale) (1604) |
| SWFSC Oregon, California and Washington Line-Transect Experiment (Orcawale) (1605) |
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