EnglishBy Jason G. Goldman
Humpback whales can be found throughout the world’s oceans, from the iciest waters of Antarctica, to the balmy seas surrounding Hawaii, and everywhere in between. While the males are best known for their soulful songs that can be heard perhaps hundreds of miles away, the concert singers of the sea are also responsible for some of the longest migrations in the world.
The whales gorge on krill and small fish in the frigid poles throughout the summer. Then, following a migration of up to 25,000 kilometers (nearly 16,000 miles), they spend the winters in the tropics where they breed and give birth.
During those migrations, humpback whales seem to prefer hugging the coastline in fairly shallow waters. This probably helps older whales to protect the babies from predators like killer whales, though it undoubtedly made it easier for whalers in the last several centuries to kill some 90 percent of the world’s humpback population. Now that whales are generally well protected from anthropogenic slaughter, they have become more easily spotted when they gather in tropical regions each winter.
Central America’s Pacific coastline offers the perfect setting for whales (and people) to spend their winters since the waters are warm and the risk of predation is low.
A California Connection
Those whales that spend their summers near California, Oregon, and Washington have often been spotted wintering off the coast of Central America, some 6000 kilometers to the south. These whales form a unit known as the “Central American Distinct Population Segment,” and number around six hundred. It’s a fairly small, understudied population of whales that, while still recovering from centuries of persecution at the hands of whalers, continues to face a moderate risk of predation.
But these whales – especially those that winter in Nicaraguan waters – have a secret. Most whales focus their energy during the winter on breeding and giving birth. They can avoid spending time hunting for food because they spent the long summer building up fat reserves that can fuel them through the winter. But a team of researchers recently observed humpback whales feeding there. They say it’s the first formal scientific documentation of the behavior, in this area, by this population.
In addition to humpback whales, the biologists recorded frigatebirds, pelicans, and several types of dolphins feeding alongside them. The aggregation of so many predators in a relatively small area suggests that there is also quite a lot of prey available for them, likely due to a coastal upwelling that occasionally occurs off the coast of Nicaragua, where nutrient rich waters from the ocean depths rise to the surface.
Because the humpbacks here and around the world are still recovering from centuries of persecution, it’s impossible to know what this new finding represents. It isn’t clear whether this is a new phenomenon or whether the population simply needed to recover to a certain size before anybody would notice.
If it is truly a new feeding ground, then it could be that climate change has driven a shift in the geographic availability of food for humpback whales, and they are simply following the fish; or it could be that increasing humpback whale populations, facing a shortage of food in traditional hunting areas, have been forced to alter their survival strategies by foraging in new places and at a different times of the year.
Clearly, more information is needed to understand the origin of these unusual feeding behaviors. Whatever the reason, Nicaragua is in a unique position to protect the whales’ and their habitat, which may require a different set of management strategies than other, nearby countries. It is likely that much of the protection for whales in this region will come directly from the voluntary efforts of small-scale fishermen and women, working in collaboration with Paso Pacífico.
A Visitor from the South
Meanwhile, most of the Southern Hemisphere humpbacks that spend their summers foraging in the frigid waters of the Antarctic Peninsula overwinter in Costa Rica and Panama.
But new research suggests that they may be starting to pop up further north, in Nicaraguan seas. Between 2015 and 2018, a team of researchers photographed humpback whales nearly one hundred times off the coast of San Juan del Sur, Nicaragua. One of the whales was matched to a photo taken 257 days earlier in Antarctica, a distance of some 10,000 kilometers. It’s the northernmost record of a Southern Hemisphere humpback whale ever spotted overwintering in Central America.
Nobody knows whether the two populations of whales, both of which take advantage of Central American coastal habitats, ever meet up to trade genetic or cultural information. So far, it would seem unlikely. That’s because the North American whales overwinter between January and April, during the boreal winter. The Antarctic whales don’t cruise north until it becomes winter in the Southern Hemisphere, between July and October.
Because the tropics are generally pleasant all year long, this habitat can host both groups of animals during each of their respective winters.
Header: A humpback whale seen in Los Cóbanos, El Salvador. Taken by Daniel Boyano S. Used under CC BY-NC-SA 2.0.