Pacific White-sided Dolphin, Largenorhynchus obliquidens

Pacific White-sided Dolphin, Largenorhynchus obliquidens. Underwater photograph taken in coastal waters off Kona, Hawaii, September 2015. Photography and identification courtesy of Bob Hillis, Ivins, Utah.

The Pacific White-sided Dolphin, Largenorhynchus obliquidens (Gill, 1865), is a member of the Delphinidae Family of Oceanic Dolphins. They robust in stature but have a sleek profile with an exceedingly small beak. The have large flippers and the dorsal fin is large and falcate (sickle shaped). Dorsally they are dark in color transitioning to light gray mid-flank and white ventrally. The caudal fin and leading edge of the dorsal fin is dark gray and the rear two-thirds of the fin is light gray. The pectoral fins are low on the body and white. They have a wide dark gray oblique bar that extends from the crown to the anus. The upper jaw has a dark band that runs to the eyes and continues as a black line to the flippers. When viewed from above, the white above the eye on both sides, looks like suspenders.

Pacific White-sided Dolphins reach 2.5 m (8 feet 2 inches) in length and 200 kg (440 lbs) in weight. They are gregarious and active and usually found in large groups and often mixed in with other dolphins and whales. They are known to ride the bow wakes of boats and they are curious animals that are drawn to stopped boats and swimmers. These dolphins are opportunistic predators, primarily eating small, schooling, fish and squid.  In turn they are preyed upon by Killer Whales. They are primarily found in temperate waters of the north Pacific Ocean. They venture into the tropics along the coasts of Asia and in Mexican coastal waters along the coast of Baja south to the greater Cabo San Lucas area, Baja California Sur and throughout the Sea of Cortez.

From a conservation perspective the Pacific White-sided Dolphin is currently considered to be of Least Concern with stable, widely distributed populations. Historically they have been targeted by Asian fishermen and they are killed as by-catch in fishing nets.

Synonyms include Delphinus longidens, Largenorhynchus longidens, and Largenorhynchus ognevi.