Research conducted by Dr. Natalia Botero-Acosta, Postdoctoral Researcher, Ocean Sciences, UC Santa Cruz / General Director, Macuáticos Foundation Colombia
The Gulf of Tribugá, located off the northern Pacific coast of Colombia, is an important breeding ground for humpback whales. Its waters are warm and the only boats operating in the region are small fiberglass vessels used for fishing and tourism. This acoustically pristine environment is important for mothers and calves; to avoid attracting predators, the whales will often exchange soft, whisper-like sounds, and calves will make gentle burps to signal their need for milk.
After a few months in the gulf, mother-calf pairs travel thousands of miles south to their feeding grounds in Antarctica. Researchers have noted, however, that fewer mother-calf pairs are evident in Antarctic feeding grounds than in Colombian breeding grounds. Satellite tags were deployed in the Gulf of Tribugá to learn more about migration patterns and threats faced by mother-calf pairs. During October 2023, three mothers were tagged, and their movements were tracked for several weeks.
Cruz (Gold): This mother, and by inference, her calf, traveled south to Chile. The whales initially followed the coastline but later shifted about 200 miles offshore in the Peruvian Pacific, possibly to avoid killer whales, which target calves.
Betty (Pink): This mother became entangled in fishing gear off the coast of Peru. Information about the entanglement came from the Peruvian fisherman who owned the net and returned the tag that is on display here. No information was received about the mortality of the mother or calf.
Eva (Blue): The satellite tag stopped transmitting at a similar time and place as Betty’s. While there is no confirmation of entanglement, the similar loss of signal would suggest this cause.
Among three tagged whales, the fact that one—and very likely two—whales experienced entanglement suggests this may be a widespread issue. Additional threats include an ongoing proposal to develop a major port in the Gulf of Tribugá, as well as rising ocean temperatures due to climate change. Evidence suggests that feeding areas near the poles, like Antarctica, are warming faster than other regions on the planet.
Below, Natalia discusses her experience witnessing a whale entanglement.
