The eastern North Pacific is home to 8 species of dolphin (including orcas/killer whales), 3 of which have been recorded by our hydrophones. Many eastern North Pacific dolphin species prefer deep, offshore waters, and so have not come within range of our hydrophones.

Pacific White-sided Dolphins

Pacific white-sided dolphins are very social and gregarious. They travel in groups of 10 to 100 individuals, and have even been seen in groups of over 2000. They often spend time with other marine mammal species, including Steller sea lions, Dall’s porpoises, resident orcas and humpback whales in coastal British Columbia, and Risso’s dolphins, northern right whale dolphins and short-finned pilot whales offshore. They are opportunistic predators; they eat at least 13 different prey species in British Columbia, and eat 60 different fish and 20 different cephalopod species worldwide. They often work together to catch their prey by co-ordinating their efforts to corral or heard schools of fish. They are very active, and often approach boats to bow ride.

Male pacific white-sided dolphins are larger than females, and can grow up to 2.5 m long and weigh 198 kg. Females can grow to be 2.3 m long and weigh up to 145 kg. Pacific white-sided dolphins can live for more than 40 years. They live only in the cool, temperate waters of the North Pacific. Their predators include humans, sharks and Bigg’s orcas. Their threats include anthropogenic noise, bycatch in trawls and gillnets, pollution, high power sonar, and the Japanese harpoon and drive fisheries.

Short-Beaked Common Dolphin

Short-beaked common dolphins are very active and acrobatic. They often breach, and bow-ride on the waves produced by boats and large whales. They are very vocal, and can sometimes be heard above the water surface. They travel in large groups of hundreds of individuals, although groups as small as 10 and as large as 10,000 individuals have been seen. They are often seen with other cetaceans, such as striped dolphins and pilot whales. They can weigh up to 200 kg, grow up to 2.3 m long, and live for about 35 years. They are deep divers, and can dive as deep as 200 m.

Short-beaked common dolphins prefer warm-temperate and tropical coastal waters. Our observatory is towards the northern edge of their habitat where these dolphins are rare. They are hunted in Russia and Japan, and by nations bordering the Mediterranean and the Black Sea. Humans are their only confirmed predators, although they may also be preyed upon by Bigg’s orcas and sharks. Their threats include overfishing, hunting by humans, and bycatch in longlines, driftnets, gillnet and trawls. 

Striped Dolphin

Striped dolphins are acrobatic and very social. They can jump over 7 m, and live in tight, cohesive groups of 25 to 100 individuals. They rarely associate with other marine mammal species, although they can occasionally be seen with short-beaked common dolphins. Striped dolphins eat a wide variety of fish and cephalopods. They are very deep divers, and can dive down to 700 m in search of prey.

These dolphins can live for up to 58 years. Males can grow up to 2.7 m long and weigh 160 kg. Females are smaller than males, growing up to 2.4 m long and weighing up to 150 kg. They prefer warm, tropical, offshore waters, and are rarely seen as far north as our observatory. Striped dolphins are preyed upon by humans, sharks, and orcas, and may be attacked by false killer whales, pygmy killer whales and pilot whales. Their threats include pollution, overfishing, fishing bycatch, and hunting by humans in Japan, the Caribbean and Sri Lanka.

Northern Right Whale Dolphin

The northern right whale dolphin is one of few dolphin species without either a dorsal fin or dorsal ridge, and the only dolphin species in the Pacific with this trait. Its scientific name, Lissodelphis borealis, derives from the Greek words for “smooth” and “dolphin,” referring to its slender, streamlined body, and the Latin word for “northern.” These dolphins are very gregarious, and have been seen in groups as large as 2,000-3,000 individuals. They typically travel in groups of 5 to 200 individuals, and are often seen with other cetaceans, including Pacific white-sided dolphins and short-finned pilot whales. They often “porpoise” when they travel, meaning that they frequently leap forward out of the water. Air has lower resistance than water, and porpoising allows these dolphins to increase their speed of travel without increasing their effort. Northern right whale dolphins can reach 35kmph for short bursts, and can travel 7m over the ocean surface in a single bound. Although they occasionally bow-ride, they generally avoid boats.

Northern right whale dolphins can live 42 years or more. They grow to be 2-3 m long and can weigh 60-100 kg. Males are larger than females. They can dive as deep as 200 m in search of food, and often eat lanternfish and squid. They are found across the Pacific Ocean between 31°N and 51°N. Their threats include pollution, bycatch in driftnets, gillnets and purse seines. They are sometimes killed directly in the Japanese Dall’s porpoise harpoon drive fishery.

Risso’s Dolphin

The Risso’s dolphin is a cosmopolitan species, living in all oceans between 60°N and 60°S. They are gregarious, and are often seen with other dolphin species, including bottlenose dolphins, Pacific white-sided dolphins, and northern right whale dolphins. They travel in groups of 3 to 30 individuals, and sometimes form superpods of several thousand. Recent research suggests that individuals within Risso’s dolphin groups may be related.

Risso’s dolphins are born a uniform, light grey colour and darken to a brownish-grey as they age. Most are covered with white scars, which may be from other dolphins, squid, parasites, etc. Scarring can be so extensive that the entire body may appear to be white. Risso’s dolphins have no upper teeth, and have only 7 or fewer pairs of lower teeth. Risso’s dolphins primarily eat squid, although they have been known to eat a number of fish species as well. They grow up to 3.8 m long and can weigh up to 500 kg, although 300 kg is more typical. Male Risso’s dolphins are slightly larger than females. Their lifespan is not known with certainty, but is at least 20 years.

Risso’s dolphins prefer offshore, warm-temperate and tropical waters. They can dive as deep as 300 m, and often hunt at night when squid have migrated closer to the surface. Humans are their only known predator. Risso’s dolphins are hunted in Japan, Sri Lanka, Indonesia, the Lesser Antilles and the Solomon Islands. Other threats to Risso’s dolphins include pollution and bycatch in gillnets, longlines and trawls.

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