A few years ago, I sailed north from Port Hardy to Prince Rupert on the Queen of the North. It was a night sailing in November and the evening was exceptionally clear, with a full moon. The old teak fixtures in my cabin rattled continuously making sleep impossible, so I went out for a night stroll on the deck. Just then, I noticed several splashes in the water, breaking up the path of reflected moonlight. I soon realized that this was a pod of Pacific white sided dolphins, riding the bow wake of the ship.
The Dolphins kept up to us with ease and often leapt clear out of the water just for the joy of it. It was a special moment, and I have always recalled the beauty of the evening and the thrill of seeing the dolphins.
The Pacific white-sided dolphin is the most frequently encountered dolphin of our province, seen regularly along the Inside Passage, the Strait of Georgia, and the Strait of Juan de Fuca. Limited to the temperate waters of the north Pacific, the dolphins range from Alaska south to Baja, Mexico and over to Japan. These fast, energetic swimmers are known for their playful acrobatics. They leap, flip, somersault and belly flop, occasionally jumping so far out of the water that they have been known to land on the decks of ships. Highly social creatures, dolphins typically travel in groups of 10 to 100, though herds of more than 2000 have been spotted. They enjoy approaching other marine mammals too, such as whales, seals and sea lions.
Dolphins, porpoises and whales are mammals known as Cetaceans. Like Killer Whales, Pacific white-sided dolphins belong the dolphin family or Delphinidae. They are often nicknamed ?lags? due to their long-winded latin name, Lagenorhynchus olbiquidens.
Pacific white-sided dolphins have distinctive markings, with a black back, light grey sides, and a white belly. They also have "suspenders", two white stripes that extend from head to tail (most clearly visible from above). Lips and beak are black, and eyes are dark. Flippers are curved, and blunt tipped, and the two-toned dorsal (back) fin is hooked with a dark leading edge. When dolphins speed through the water, their dorsal fins create a splash called a "rooster tail".
Adults average 2.3 metres long, and weigh up to 180 kilograms, and most live from 30 to 40 years. Dolphins are perfectly adapted to their environment. They have strong eye muscles and can change the shape of their eye lens to focus in air and water. Dolphins also have a highly developed sense of hearing, and are very vocal animals, communicating with high-pitched squeals using air trapped in their blowholes. Clicking sounds are used for echolocation, helping dolphins navigate and locate prey.
Dolphins feed on creatures such as hake, anchovies, squid and sardines. They grip prey with their teeth, and swallow it whole, head first. Dolphins have few predators, but transient Killer Whales will sometimes prey upon them.
It is hard to imagine how such active animals sleep. Scientists believe that dolphins are able sleep with half a brain. One half of the brain is awake while the other half sleeps, then the sides switch. Dolphins function normally during this time, and the half-brained sleeping prevents drowning.
Pacific white-sided dolphins mate in late summer or early fall. After close to 12 months gestation, calves 1 metre long are born. Females generally give birth every three to four years, and nurse calves for over a year after birth. Between 1978 and 1990 it is estimated that as many as 89, 000 Pacific white-sided dolphins were killed in Asian driftnet fisheries. Fortunately, these fisheries were discontinued after a United Nations resolution in 1992. Today, the dolphins are not considered to be a species at risk, and populations appear stable though exact numbers are unknown.
The discovery of teeth in ancient First Nations middens suggests that dolphins have been around for thousands of years. Despite this, Pacific white sided dolphins were absent from coastal BC between 1915-1984. The temporary absence of the dolphins has yet to be understood, but it believed that a change in ocean temperature (partly a result of oceanographic events like El Nino), and corresponding shifts in prey distribution might have affected the dolphins.
Pacific white-sided dolphins are a joy to watch, and their social, playful behaviour makes them particularly endearing to humans. A safe way to view dolphins, whales and other marine mammals is to take a whale watching tour.
Make sure to read our story on Orca Whale watching in BC, British Columbia.