Rough-toothed dolphin in Los Cabos

How to recognize it

A medium-sized, dark-gray dolphin with a conical head: the forehead slopes smoothly into a fairly long beak, with no crease between them. The lips and throat are white or pinkish, and the belly usually has white or pinkish blotches and spots. A narrow dark cape runs along the back from the blowhole to the dorsal fin. The dorsal fin is tall and the flippers are large and set well back. Up close, the 20 to 27 teeth in each row show fine vertical wrinkles.

Biology

Rough-toothed dolphins live in deep oceanic water in tropical and warm temperate seas, from about 40°N to 35°S. In the eastern Pacific they range from southern Baja California south to Colombia and Ecuador, and in Mexico there are records from the Pacific coast of Baja California and Baja California Sur, the Gulf of California, Sonora and Nayarit. Groups usually hold 10 to 20 animals, often swimming in tight subgroups, and they often travel with other species such as short-finned pilot whales, bottlenose dolphins, spotted dolphins and spinners.

They eat squid and fish, and observations in the eastern Pacific and Hawaii suggest they may specialize in large mahimahi (dorado). They can stay underwater for up to 15 minutes and can live 36 years or more, maturing at 10 to 14 years. When travelling fast they often skim along the surface with the chin and head out of the water.

Seeing them from the boat

Rough-toothed dolphins are an occasional, offshore sighting around Cabo. CONANP lists them among the marine mammals of the Cabo San Lucas protected area, and they have stranded in Baja California Sur, but they live in deep blue water and their small groups are easy to miss. You are most likely to meet them far out, often near floating debris.

Dorado fishermen have a reason to look twice: these dolphins hunt big mahimahi, and they like the same floating logs and debris. Enjoy them from the boat, keep lines and baits away from them, don’t chase or split up a group, and never feed them or try to swim with them.

Rules & conservation

Don't confuse it with

The bottlenose dolphin has a short, thick beak with a clear crease where it meets the rounded forehead, and no white lips or belly blotches. The spinner dolphin is smaller and slimmer, with a needle-thin beak, and spins as it leaps. The common dolphin has a crisscross hourglass pattern of tan and gray on its sides. The pantropical spotted dolphin is spotted, with a white-tipped beak. Risso’s dolphin has no beak at all and a pale, heavily scarred body.

Questions

By Max VargasTop Anglers, Cabo San Lucas · international judge at big game fishing world championships · reviewed October 2026

Sources

• NOAA Fisheries: rough-toothed dolphin
• FAO Marine Mammals of the World: Steno bredanensis
• Pitman & Stinchcomb 2002, rough-toothed dolphins as predators of mahimahi (Pacific Science)
• ASCOBANS: Steno bredanensis
• Villegas-Zurita 2015, first record of Steno bredanensis off Oaxaca (Therya)
• Félix, Castro & Platt 2026, first rough-toothed dolphin record for mainland Ecuador (Mammalia aequatorialis)
• Mammals of Texas (Texas Tech): rough-toothed dolphin
• Quadratín: 2015 stranding at Bahía de Ulloa, BCS
• Quadratín: 2014 stranding at El Mogote, La Paz
• CONANP 2023: Estudio Previo Justificativo, APFF Cabo San Lucas
• NOM-059-SEMARNAT-2010, 2019 annex (DOF)
• Ley General de Vida Silvestre (Cámara de Diputados)
• Código Penal Federal (Cámara de Diputados)

Top illustration: Top Anglers. Photos: iNaturalist contributors, credited on each photo.