Eastern North Pacific Blue Whale Migration

node · earth · Northeast Pacific, from the Gulf of Alaska to the eastern tropical Pacific

The best-resolved blue whale migration anywhere: summer and autumn feeding in the California Current, then a southward movement in winter to waters off Baja California, into the Gulf of California, and out to the Costa Rica Dome in the eastern tropical Pacific. It was reconstructed from satellite telemetry rather than from sightings - Argos tags were attached to 159 whales, mostly off California in late summer, between 1993 and 2007, of which 92 tracks ran longer than seven days, and a wider programme tagged 171 animals between 1993 and 2008. The Gulf of California was confirmed as a wintering ground when five whales tagged in 1999 spent the winter there. The timing of arrivals suggests the Costa Rica Dome functions as a calving and breeding area, which is an inference from movement, not a direct observation of calving.