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Photo By: Tim Melling
Photo By: Tim Melling

Pacific White-Sided Dolphins

Pacific White-Sided dolphins are one of the favorite mammals to encounter on the ocean for both tourists and nature enthusiasts around Vancouver Island. They are usually viewed in schools of 50-100 or more in a pod around the north eastern part of Vancouver Island. They are very playful, curious creatures often jumping along behind boats passing by.
Where to view Pacific White-sided dolphins on Vancouver Island? Johnstone Strait going north to the Queen Charlotte Islands where you will see the greatest concentration of dolphins.

History in British Columbia
Pacific White-sided dolphins were considered primarily a pelagic species until the mid 1980’s when they became common sights in the coastal waters on the north-eastern side of Vancouver Island and north to Queen Charlotte Strait. Estimated numbers for British Columbia usually range somewhere around 25,000, however since dolphins are social with a strong attraction to vessels it is hard to determine accuracy. Pacific White-sided dolphins can move from off shore to inshore and back several times during summer months depending on feed and other unknown factors. In British Columbia waters dolphins feed on salmon, herring, pilchards, anchovies, needlefish, squid, shrimp, Pollock, sablefish, rock cod and other small fish. Large groups of dolphins can feed cooperatively together or they may split up and feed in smaller groups depending on the menu.

Taxonomy
Males weigh up to 200 kg (440 lb) with males reaching 2.5 m (8.2 ft) and females weigh up to 150 kg (330 lbs) and 2.3 m (7.5 ft) in length. Pacific White-sided dolphins are very close in size to other dolphins found around the world. Dolphins identifies themselves by a unique name-whistle. Underwater microphones capture continuous chatter between dolphins as they travel along in groups. Pacific White-sided dolphins are very social and are usually seen in groups up to 100 but have also been seen in supergroups up to a few thousand. They are also social with other aquatic species and have been seen with resident Orca whales, Dall’s porpoise, and Steller Sealions.

Mating and Life Cycle
Females reach sexual maturity at 7-9 years and males around 10 years. Gestation usually lasts about 12 months. Calves are usually born during the summer, weigh about 15 kg (30lbs) and are about 1 meter in length and are nursed from 8-10 months.. Females usually have a calving interval from 4 to 5 years. Life expectancy is usually around 40 years or more.
Predators and Threats

Both Bigg’s (transient) killer whales and sharks are known to eat dolphins. Killer whales pods have been seen driving groups of dolphins into small coves and making a bloody feast though this is not common. During the 80’s as many as 90,000 Pacific White-sided dolphins were killed by Japanese, Korean and Taiwanese driftnet fisheries. In a 1992 United Nations resolution these fisheries were discontinued. In the late 1990’s the use of underwater deterrent devices by the salmon farms correlated with the decline of dolphins in the Broughten Archipelago. These devices are now banned.