In 1998, researchers photographed and collected DNA from a female pygmy blue whale off the coast of the Galapagos Islands. Eight years later, another team did the same with a similar-looking whale in the waters off Chile. Turns out, it was the same whale.
Here’s Annick Laurent, for Science:
That means Isabela (named after the lead author’s daughter to represent hope for future preservation efforts) migrated a minimum of 5200 km, the longest recorded latitudinal migration made by any Southern Hemisphere blue whale on record. The findings suggest Chile’s and the Galapagos’ blue whale aggregations are connected, meaning those feeding in the Gulf of Corcovado off Chile may be breeding in the Tropical Eastern Pacific.
It’s a new migration record for blue whales. But the observation is important for another reason. Researchers know enough about other species of big, baleen whales to hypothesize that blue whales migrate seasonally, but for a long time direct evidence for this had been lacking. As the researchers—who were led by Juan Pablo Torres-Florez, of the Federal University of São Carlos—note, in the latest issue of Marine Mammal Science:
There is unequivocal evidence for this migration pattern in humpback whales, Megaptera novaeangliae and some indications of a similar migration in ﬁn whales, Balaenoptera physalus; thus, it has been argued by analogy that the pattern holds also for blue whales. However, information about migratory movements is still speculative for blue whales and mostly inferred by indirect methods such as genetics and acoustic.
The observation of a single whale in two far-flung locations is not enough to declare the Eastern Tropical Pacific a breeding destination for the eastern South Paciﬁc population of blue whales. However, the researchers do say that Isabella provides “the ﬁrst direct evidence of a possible migratory destination for these whales.”
Contact the author at email@example.com. Top Photo: Top–Isabela’s dorsal fin, as photographed in waters west of the Galapagos (Credit: Paula Olson | NOAA), in 1998; bottom–Isabela’s dorsal fin, off the coast of Chile, in 2006 (Credit: Rodrigo Hucke-Gaete/Blue Whale Center).