Information about blue whales (Balaenoptera musculus) in the Eastern Tropical Pacific is scarce. Only a few whales have been seen in recent decades. Molecular research, photo ID and acoustic studies suggest a degree of connectivity between Chilean and Antarctic blue whales in potential breeding areas of the coast of Peru and the Galapagos, and also between blue whales of the Costa Rica Dome and Northern Hemisphere population feeding off the coast of California, though potential breeding areas are still unknown. With opportunistic sighting records in the Galapagos, group size and year-round distribution were documented during a 17-year period from 2001 to 2018. Sightings slightly increased during this period and 50% of the whales seen were singletons. Whales were seen year-round. Most sightings occurred during the austral winter (82%), while calf sightings occurred from June to September. With the remaining 18% of sightings in the austral summer, we propose there is geographical overlap between equatorial Galapagos and Northern Hemisphere blue whales. One blue whale was identified in the Galapagos during February 2009, resighted in the Costa Rica Dome during January 2014, and sighted again in the Galapagos during May 2016, when whales from the Southern Hemisphere could already be present. Our data strongly suggest there is a non-migratory blue whale population and a degree of overlap between the North and Southeast Pacific blue whale populations in the Galapagos.
Denkinger, J., A.B. Douglas, D. Biggs, R. Sears, M. Narvaez, and D. Alarcon. 2023. Year-Round Presence of Northern and Southern Hemisphere Blue Whales (Balaenoptera musculus) at the Galapagos Archipelago. Journal of Cetacean Research and Management 24: 63-76. doi: 10.47536/jcrm.v24i1.387Download PDF
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