Pacific White-Sided Dolphin
Lagenorhychus obliquidens
A student web page designed by Michelle Hubbard

Socialization and Reproduction:
The Pacific White-Sided Dolphin lives in coastal waters off the B.C. coast in the Northern Pacific. These lively animals are generally found in large herds, sometimes as big as several thousand individual animals. These herds are generally the largest in September and October, averaging about 115 individuals, whereas in the winter months the herds are usually only 35 members large (though this is still a large group). Herd size peaks in the fall because this time of year is breeding season for these animals. Once they reach a length of 1.8m (6 ft) Pacific White Dolphins begin reproducing and have a gestation period (pregnancy) of 10-12 months. At birth, these marine mammals are about 1m (3 ft) in length.

Appearance and Behaviour:
Pacific White-Sided Dolphins are usually 2.1m to 2.4m (7-8ft) and weigh 90 to 140 kg. These robust animals are mostly black with a gray and white dazzle pattern, short thick beaks, and curved dorsal fins. However, they can usually be recognized from a distance by there playful behaviour. White-sides (or lags as they are often called) are extremely acrobatic and social animals. They love to perform somersaults and cart wheels and even swim along on their backs. They truly appear to be awaiting applause! In fact, one lag even jumped onto the deck of a ship, which was 3m (10ft) above the water. This animal was quickly thrown back into the ocean by the amused crew! Pacific White Sided dolphins have been observed swimming and/or feeding in the company of many other marine mammals, including the Northern Right Whale and Risso's dolphin, just to name a few.

Feeding and Predation:
Lags are carnivorous and feed primarily on squid, herring, sardines, hake, and anchovies. Their primary cause of death at present is human activity; they often become entangled in fishing nets which prevents them from coming up for air. These animals also fall victim to killer whales, and the occasional shark.

Communication:
Like all dolphins, Pacific White Sides use sonar (a series of rapid clicks) for communication and to locate objects, such as prey and obstacles. Dolphins are thought to be extremely intelligent, in fact some scientists say they are as intelligent as humans. However, measuring intelligence is not an easy task so this is a difficult comparison to make. In fact we often end up measuring how similar animals are to humans, rather than their absolute intelligence. The vocabulary of these animals is incredibly diverse and includes squeaks, squawks, groans, rattles and clicks. They are also able to mimic the sounds of other animals, and they can be trained to perform according to human vocal instruction.

Questions and answers about dolphins and toothed whales

 to marine biodiversity index