Welcome to another “Wildlife of the Week”. Since our series has begun, what has been your favourite feature? Our feature today involves a Salish Sea species that is certainly more elusive to waters around southern Vancouver Island, but when seen, the sightings sure are amazing! Take a look at our photo; how many dolphins can you count just in this photo?
The Pacific White-Sided dolphin (Lagenorhynchus obliquidens) is a cetacean that is sure to charm and excite any audience with their fast and graceful swimming, acrobatics and occasional “superpods”! Both a predator and prey (the latter to Bigg’s Killer Whales), this dolphin must meet several demands in order to survive in the Salish Sea.
What is a species you would like to see featured on our next “Wildlife of the Week”? Comment below!
The Pacific White-Sided dolphin is both an active and agile cetacean, capable of swimming at high speeds. They are often uniquely known for their frequent “bow-riding” behaviour around ships. They are lively acrobats that may be witnessed leaping and porpoising above the surface. The species is not very large compared to some of its other cetacean relatives; measuring 5.5-8 feet long (just over 1- 2 metres) and weighing approximately 300-400 pounds maximum (136-181 kg).
Perhaps their most identifiable feature is their coloration pattern which displays a black ring around the eyes, black lips, a bright white belly and bands of cream and grey atop a dark black body. Their dorsal fin is majorly cream colored with a frontal outline of black. Based on the similar colors to that of a Killer Whale, Dall’s porpoise or Common Dolphin, some may mistake this dolphin for another species.
The melon area is round and the Pacific White-Sided dolphin has a blunt, short beak. The dorsal fin is broad, curved and short which is characteristic of many dolphins.
This extremely social species can be found usually in mid-latitude waters of the North Pacific, i.e. they are not observed in polar or tropic regions. They are a coastal and pelagic cetacean (less frequently seen very close to shore) with a wide range extending from Alaska down to the tip of Baja California, Mexico. They also live in waters around Asia, namely the Kuril Islands down to waters in Japan (Sea of Okhotsk, Sea of Japan) and waters south of Japan (Yellow and East China Seas).
This species of dolphin feeds on often small, oily and slippery prey; schooling fish such as sardines, hake and anchovies. They will though, prey on invertebrates such as squid. To aid the dolphin with their food, their teeth have evolved to be small and conical to catch and grasp. The animal can dive for its prey for up to six minutes at a time, working together as a cohesive unit to round up prey.
Pacific White-Sided dolphins are not very large at birth, a modest length of only 3-4 feet long. Like most cetaceans, calves rely on their mothers for an extended period of time after birth, and Pacific White-Sided dolphins will nurse for a year and a half! Mothers will typically have a calf every three years; reaching maturity at 8-11 years (males at 10), with both females and males living to about 40 years.
As mentioned, these animals are highly active out of the water- undertaking feats such as somersaulting, leaping or spinning. They are rarely seen alone, and their group numbers can range from ten(s) to thousands. They are a sought out prey item for Bigg’s (transient) Killer Whales, but are certainly a challenging prey item to subdue even for this equipped predator- due to their speed, agility and intelligence.
Pacific White-Sided Dolphins are at prominent risk for by-catch in fisheries and entanglement in fishing gear; reporting any entangled marine life to marine rescue authorities is an important behaviour in assisting these cetaceans and others.
If you are feeling confidence about your Pacific White-Sided dolphin knowledge, try out some further trivia below!
- How much food (in weight) does an average adult Pacific White-Sided dolphin eat? (ANS: 20 pounds).
- True or False? Female dolphins may be pregnant for about a year before their calf is born. (ANS: True. Gestation lasts 9-12 months).
- What is the nickname that this dolphin has earned based on its Latin scientific name? (ANS: “Lags”).
BONUS CHALLENGE:
In what method does the Pacific White-Sided dolphin eat their food (Hint: which way is the fish swallowed)? And why?
Fish are always swallowed whole, head-first, to prevent the spines from catching the dolphin’s throat.
To learn more about this special animal, read up on our References to learn more!
- “Pacific White-Sided Dolphin.” American Cetacean Society. https://www.acsonline.org/pacific-white-sided-dolphin.
2. “Pacific White-Sided Dolphin.” NOAA Fisheries. National Oceanic and Atmospheric Administration. U.S. Department of Commerce.. https://www.fisheries.noaa.gov/species/pacific-white-sided-dolphin.
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