Pantropical Spotted Dolphin, Stenella attenuata
Pantropical Spotted Dolphin, Stenella attenuata. Underwater photograph taken in coastal waters off Kona, Hawaii, September 2015. Photography and identification courtesy of Bob Hillis, Ivins, Utah.
Pantropical Spotted Dolphin, Stenella attenuata (Gray, 1846), is a member of the Delphinidae Family of Oceanic Dolphins that is known in Mexico as delphi’n manchado and delphi’n pintado. They are slender in stature with fairly long, slender beaks. The dorsal fin is relatively small and fairly falcate (concave posteriorly). The back “cape” is dark gray, as are the fins; ventrally they are light gray; the adults y are covered with varying amounts of whitish spots, however, some may lack spots completely. Most specimens will also display a white tip on their beak that looks like a golf ball. Many individuals will have light colored scars from Cookie-cutter Sharks.
Pantropical Spotted Dolphins reach a maximum length of 2.57 m (8 feet 5 inches) and 118 kg (260 lbs) in weight. They can be found from the surface to depths up to 345 m (1,125 feet). They are gregarious and reside in schools of hundreds or thousands individuals spread out over large areas of ocean. Usually they segregate themselves into smaller groups within the school, based on age and sex. They are often associated with schools of tuna and the Spinner Dolphin, Stenella longirostris. These dolphins are known for leaping high out of the water a behavior that is thought to help them rid themselves of parasites. Their prey includes several species of fish, cephalopods, and crustaceans. Most hunting occurs at night when their prey ascends toward the surface with feeding occurring in the first 46 m (150 feet) of the water column. In turn they are preyed upon by large sharks, Killer Whales, and False Killer Whales. They have life spans of up to 46 years.
Pantropical Spotted Dolphins are found off shore found worldwide, in tropical and warmer temperate seas. There are currently three recognized subspecies of Pantropical Spotted Dolphins and all three have been recorded in Tropical Eastern Pacific waters. The Coastal or Inshore Spotted Dolphin (Stenella attenuate graffmani [Perrin, 1990]) is the most common subspecies found along the Baja Peninsula. It ranges along a narrow 200 km wide strip along the coast from Magdalena Bay, Baja California Sur to Peru. They are also found in the southern Sea of Cortez, including the East Cape Region.
From a conservation perspective the Pantropical Spotted Dolphin is currently considered to be of Least Concern with stable, widely distributed populations.
The Pantropical Spotted Dolphin is difficult to identify and as a result there are more than 2 dozen synonyms for this species.