Marine Conservation, Science and Research

Osa Conservation Supports Research in Golfo Dulce: A Humpback Whale Hotspot

These three photos show a baby Humpback whale next to its resting mama – TOP: nursing; MIDDLE: breathing; and BOTTOM: spyhopping

A variety of whale species may be found in the eastern Pacific Ocean off the coast of Costa Rica, including Byrde’s whale (Balaenoptera edeni), Fin whale (Balaenoptera physalus), Sperm whale (Physeter macrocephalus) and Killer whale (Orcinus orca). But the most commonly seen whale inside the Golfo Dulce is the Humpback whale (Megaptera novaeangliae), a species that annually migrates from colder feeding grounds near the magnetic poles to warmer equatorial breeding and birthing grounds.

In fact, the area around the Osa Peninsula is a really special place for Humpbacks — it is the only known place in the world where the migration paths of whales from both the northern and southern hemispheres cross over. Because the Arctic and Antarctic seasons are opposing, Humpbacks from the North Pacific Ocean spend time inside the Golfo Dulce during January and February while Humpbacks from the Southern Ocean normally arrive during July and August. That means whales are coming and going from the gulf throughout much of the year.

We logged 25 Humpbacks during our surveys, mostly mothers with young calves. The whales were often seen traveling up into the embayment, possibly seeking sanctuary from the open sea. We even witnessed a baby Humpback nursing — an experience Jorge and I will never forget! That sighting plus birthing events reported to us during both seasons suggest that embayment may even be a haven for Humpback nativity. Isn’t that remarkable? Indeed, the more we learn about the role the Golfo Dulce plays in the whales’ ecology, the more important it appears.

It is incredible to think how far Humpback whales travel to visit the Golfo Dulce and we can only hope the calm gulf waters will always offer those gentle titans safe retreat at the end of their long journey.

Brooke Bessesen conducted Marine research at the Osa in 2010 and 2011 as a recipient of the Greg Gund Memorial Fellowship. Check out her Golfo Dulce report on our website.