Pacific white-sided dolphin
Lagenorhynchus obliquidens

Also known as Lags from their scientific name, these high-spirited dolphins are the most acrobatic of B.C.’s commonly seen cetaceans.

Description

Sleek, smartly marked and tirelessly playful, the Pacific white-sided dolphin can be easy to identify. That’s because it throws itself out of the water so often that it leaves little doubt about its identity. The body is black on the back, with striking light gray flanks and a pearl-white belly. Two gray stripes run along the entire length of the back. These markings, which some people liken to suspenders, are easily seen from above when the dolphin is riding bow waves. The dolphin has a short snout, or beak, and long curved pectoral flippers. Its black and grey dorsal fin is tall and curved. When fully grown, the Pacific white-sided dolphin is about 2.5 metres long and weighs up to 180 kilograms.

Range

Pacific white-sided dolphins are perhaps the most abundant dolphin in the North Pacific. They are found from the southern tip of Baja, Mexico as far north as the Aleutian Islands of Alaska. They are seen year-round in some areas. It was once thought that Pacific white-sided dolphins stayed mainly offshore, but in recent years, large groups have been seen more and more in protected waters such as Johnstone and Queen Charlotte Straits off northeastern Vancouver Island.

Behaviour

Seeing Pacific white-sided dolphins in the wild can put a smile on anyone’s face. They are very social, normally travelling in groups of 20 to several hundred. In one group seen far offshore there were an estimated 6,000 dolphins! Large groups are often noticeable from quite far away. As they race through the water, their dorsal fins kick up a splash called a rooster tail. Pacific white-sided dolphins are eager surfers and seldom pass up a chance to ride a bow or stern wave. They have even been seen to abandon a meal to race over to a passing boat. Fast, powerful swimmers, they cartwheel and somersault with almost reckless abandon. Once, one accidentally leapt 3 metres onto the deck of a moving research ship! Pacific white-sided dolphins not only enjoy each other’s company, they also like to travel with other types of whales and dolphins. They have been seen with northern right whale dolphins, Risso’s dolphins, and humpback and gray whales, among others. Even seals and sea lions can be playmates.

Very little is known about the life history of the Pacific white-sided dolphin. Studies are now underway to learn more about their biology. It is likely that calves are born in summer or early fall. Newborns are about 95 centimetres long. Pacific white-sided dolphins are very ‘talkative’ animals. Using air trapped in their blowholes, they make a variety of very high-pitched squeals, whistles and whines. These noises are most likely used to communicate with each other. Pacific white-sided dolphins also use clicking sounds, known as echolocation, to find their way around and to catch their food. They eat squid and small schooling fish, such as lanternfish, herring, hake, and anchovies. They use their small, pointed teeth to capture their prey, which they usually swallow whole.

Status

The Pacific white-sided dolphin is widespread throughout its range and does not appear to be at risk. Recent surveys off the coast of Washington State and Oregon estimated that there were about 38,000 in those waters. It is unknown how many there are in B.C. There are some signs that Pacific white-sided dolphins are becoming more common in inshore waters.