Fraser’s dolphins in the Caribbean: Social island hoppers

New study from the Caribbean Cetacean Society reveals that one of the ocean’s least-studied dolphins has found a stronghold in the island chain stretching from Grenada to Anguilla

Have you heard of Fraser’s dolphins?

Fraser’s dolphin (Lagenodelphis hosei) wasn’t formally described until 1956, and scientists didn’t actually see one alive in the wild until 1971. These medium-sized dolphins usually live far offshore in tropical waters, making them especially hard to study. But the Lesser Antilles represents a remarkable exception to this pattern.

From 2021 to 2024, researchers with the Caribbean Cetacean Society surveyed nearly 30,000 kilometers of ocean, from Grenada in the south to Anguilla in the north. They found that Fraser’s dolphins were the second most frequently encountered species in the region and that they typically travel in large groups averaging about 112 individuals.

In the Caribbean, they island hop, looking for deep water canyons and continental slopes

Using advanced habitat modeling, the researchers found that Fraser’s dolphins prefer waters between 500 and 1,750 meters deep, especially near steep underwater continental slopes and canyons. The Caribbean side of the Lesser Antilles forms an almost continuous ribbon of ideal habitat for them. This is perhaps not too surprising, since they are deep divers that feed on squid, lanternfish, hatchetfish, viperfish, and shrimp.

By identifying individual dolphins from unique markings on their dorsal fins (known as photo identification), the team tracked 10 dolphins over nearly two and a half years. Seven of them were spotted around different islands, traveling an average of 105 kilometers between sightings, with one dolphin making an impressive 229-kilometer journey from Martinique to the southern Grenadines.

These movements suggest that the entire Lesser Antilles arc acts as one connected home for Fraser’s dolphins, with few barriers between islands. What makes this even more remarkable is how rare these dolphins are elsewhere in the Caribbean. Surveys in places like Curaçao, Aruba, and the Dominican Republic did not record a single sighting. This suggests that the Lesser Antilles population may be uniquely isolated.

The social butterflies of the Caribbean

An impressive 83% of sightings involved these dolphins swimming alongside other species, a much higher rate than any other dolphin in the region. They were often seen in mixed groups with pantropical spotted dolphins, pilot whales, bottlenose dolphins, spinner dolphins, sperm whales, and melon-headed whales.

This pattern is not unique to the Caribbean; similar associations have been observed from the Philippines to Dominica. In fact, researchers think these partnerships help the dolphins find food more efficiently, either by following other species to feeding grounds or by teaming up during hunts. In some cases, mixed groups have even been observed feeding together at the surface. We wrote a whole story about mixed-species associations, if you would like to know more about them.

Conservation Challenges Across Borders

The dolphins’ wide-ranging movements make conservation especially challenging. They face threats from ship strikes, fishing gear entanglement, chemical pollution, and small-scale hunting around St. Vincent and St. Lucia, where an estimated 100–700 small cetaceans are killed each year.

Because these dolphins move freely across borders, one protected in a marine sanctuary may later face danger in another jurisdiction. Thus, safeguarding them effectively will require close cooperation among all the territories and nations of the Lesser Antilles.

This study provides the first clear picture of Fraser’s dolphins in the Caribbean, showing that while they’re rare elsewhere, the Lesser Antilles offers vital habitat for what may be a unique, isolated population. Their close ties with other dolphin and whale species reveal how interconnected the region’s marine life is: protecting them means protecting the whole community. As climate change and human pressures grow, long-term monitoring like this is key to understanding and safeguarding these animals across borders.

Sources and Further Reading

• The study we cover here: Bernier, L., González, R. P., Hassall, C., Teillard, V., & Bernus, J. (2025). Characterizing Fraser’s Dolphin (Lagenodelphis hosei) in the Lesser Antilles: Distribution, Movements, and Co‐Occurrence With Other Cetacean Species to Inform Conservation Strategies in the Caribbean. Marine Mammal Science, e70039.
• Fielding, R., & Kiszka, J. J. (2021). Artisanal and aboriginal subsistence whaling in Saint Vincent and the Grenadines (Eastern Caribbean): History, catch characteristics, and needs for research and management. Frontiers in Marine Science, 8, 668597.
• Kiszka, J. & Braulik, G.T. (2018). Lagenodelphis hosei. The IUCN Red List of Threatened Species 2018: e.T11140A50360282. https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T11140A50360282.en. Accessed on 16 October 2025.
• Louella, M., & Dolar, L. (2009). Fraser’s dolphin: Lagenodelphis hosei. In Encyclopedia of marine mammals (pp. 469-471). Academic Press.
• Witte, R. H., van Buurt, G., Debrot, A. O., Bermudez-Villapol, L. A., & Simal, F. (2012). First record of Fraser’s dolphin Lagenodelphis hosei for the Dutch Caribbean. Marine Biodiversity Records, 5, e46.