The Rough Toothed Dolphin (Steno bredanensis) is a large dolphin common on our Niihau Boat Tours from Kauai. They can be playful when they’re in the mood, but can also be shy and reclusive. When feeding, they will avoid our vessel by diving. We have seen populations of several hundred individuals spread out over a 15 mile swath across the Kaulakahi channel (this channel separates the islands of Kauai and Niihau). Rough Toothed Dolphins are a deep water species dolphin rarely found in waters less than 1000 meters in depth.
The characteristic feature of the Rough Toothed Dolphin is its conical shaped head and slender nose. The flippers are set back further along the body than other similar dolphins. At sea this dolphin may be confused with the Spinner, Spotted and Bottle Nose Dolphins.
The lips, throat and belly are pink-white. The flanks are a light grey and the back and dorsal fin a much darker grey. The dolphin grows up to about 2.5m in length and weigh about 150kg (330 lbs) when mature.
Like most dolphin species, this is a social animal. Groups sizes are commonly as large as fifty, though we’ve occasionally seen much larger groups. The Rough Toothed Dolphin has not been observed to bow-ride but will “skim” – swim with their heads and chin above the surface of the water.
Although a small number of individuals have been harpooned by Japanese whalers and others have been caught in seine nets by trawlers fishing for tuna, this is one species whose population is not currently believed to be threatened by human activities.
See Wikipedia, “Rough-toothed Dolphin”, http://en.wikipedia.org/wiki/Rough-toothed_Dolphin