© Seaside AquariumA rare female northern right whale dolphin washed ashore on Manzanita Beach
The animals tend to live much further south and in deeper offshore waters, although they can range as far north as Alaska, Tiffany Boothe of the aquarium said.
Movements both north and south by the dolphins has been documented, marked by changes in water temperature. The whale dolphin moves south during colder water temperature periods and north during warmer water periods.
Boothe said that aquarium staff have only seen four of these unique dolphins since 1995, when the aquarium became involved with the Northern Oregon/Southern Washington Marine Mammal Stranding Network.
The northern right whale dolphin is known to travel in groups of up to 2,000, although they are more often is found in social groups of 200 or 300.
The largest threat to to these dolphins is from high-sea drift nets.
Unregulated until recently, drift nets are considered responsible for a 24 to 73 percent population decline. In Oregon and California, law requires fishing boats to a use pinger devices that deliver acoustic warnings into the water column to reduce cetacean by-catch.
The dolphin beached in Manzanita was picked up by the Seaside Aquarium and transferred to Portland State University where a necropsy was preformed, Boothe added. Preliminary results from the necropsy were inconclusive.
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