Dall's porpoise

How it lives

Typical life span is 15 to 20 years, and NOAA gives up to 22. They reach maturity at about 3 to 5 years. Pregnancy lasts 11 to 12 months, a calf is born mostly in summer, and females calve about every 3 years. Groups are usually 2 to 10 animals, and larger groups of hundreds are reported now and then. They are fast swimmers, with a speed near 35 mph (about 56 km/h) reported by the US National Park Service, and they often come to ride the bow wave of boats. Transient killer whales prey on them.

Where it goes

Dall's porpoise lives in cold North Pacific water, from the California and Mexico border north to the Bering Sea and west to the Sea of Okhotsk and Sea of Japan, mostly where water is deeper than about 600 ft (180 m) and cooler than 18 C. In Kenai Fjords National Park it is seen in cool, glacier-fed water. Wikipedia lists separate Japan and Okhotsk groups of migrants, so some animals move seasonally in the western Pacific. I did not find detailed movement data for the eastern Pacific.

We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.

Populations

Wikipedia puts the total at over one million animals. Recent regional estimates it lists: California, Oregon and Washington 25,800 (surveys 2008 to 2014), Alaska 83,400, British Columbia about 5,000. NOAA lists about 100,000 for the US West Coast stock, 83,000 for Alaska, 104,000 around Japan and 554,000 in the Sea of Okhotsk. These figures come from different surveys and methods, so they do not match exactly. NOAA calls it reasonably abundant but says trend data are insufficient, and Wikipedia reports no evidence of a range-wide decline. Threats include fishing-gear entanglement and hunting in Japan, where the 2023 quota was 8,535 and 109 were taken, down from a peak above 45,000 in 1988. It is listed on CMS Appendix II.