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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 off 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. [ABSTRACT FROM AUTHOR]

Killer whales (Orcinus orca) have strong social matrilineal bonds and form groups and long‐lasting associations, but little is known about their population or social structure in an equatorial setting such as the waters around the Galápagos Islands. Using 91 encounters and identification photographs from 1991 to 2017, we identified 64 killer whales of which 18 individuals were locals with high resighting rates. Group size was small, ranging from 1 to 15 animals, with 69% of the groups containing four or fewer animals. Using social network analysis (SOCPROG 2.7) whales grouped into three distinct units and one loose association with frequent exchange between different groups. One male–male unit showed a strong association (association strength = 0.55). Overall, associations lasted over at least 3 years. Our data give first evidence of a loose social organization of Galápagos killer whales, similar to fission‐fusion societies. [ABSTRACT FROM AUTHOR]

Latitudinal preferences within the breeding range have been suggested for Breeding Stock G humpback whales that summer in different feeding areas of the eastern South Pacific. To address this hypothesis, humpback whales photo-identified from the Antarctic Peninsula and the Fueguian Archipelago (southern Chile) were compared with whales photo-identified from lower latitudes extending from northern Peru to Costa Rica. This comparison was performed over a time span that includes 18 austral seasons. A total of 238 whales identified from the Antarctic Peninsula and 25 whales from the Fueguian Archipelago were among those photo-identified at the breeding grounds. Our findings showed that humpback whales from each feeding area were resighted unevenly across the breeding grounds, which suggests a degree of spatial structuring in the migratory pathway. Humpback whales that feed at the Antarctic Peninsula were more likely to migrate to the southern breeding range between northern Peru and Colombia, whereas whales that feed at the Fueguian Archipelago were more likely to be found in the northern range of the breeding ground off Panama. Further photo-identification efforts and genetic sampling from poorly sampled or unsampled areas are recommended to confirm these reported connectivity patterns. [ABSTRACT FROM AUTHOR]