Pacific White-Sided Dolphin

Often called “lags”, derived from their scientific (Genus) name, Pacific white-sided dolphins are often very energetic and acrobatic. They are robust with short beaks and a sharply hooked dorsal fin, and have unique coloring with light gray thoracic sides and white underbellies.


Pacific white-sided dolphins are found in the North Pacific, from Baja, California north to the Gulf of Alaska, and south to Japan.  They are occasional visitors to our inland waters.  They will enter the Strait of Juan de Fuca and may sometimes head up to the Strait of Georgia, but rarely visit Puget Sound.


Pacific white-sided dolphins have dark gray backs with striking light “suspender stripes” running from their forehead to the base of their tail.  Their dorsal fins have a two-tone pattern of dark gray with a light gray trailing edge.  Their dark gray pectoral fins or flippers are curved. 

Pacific white-sided dolphins feed mainly on squid and small schooling fish like anchovies, herring, sardines and hake. 

Sexual maturity is reached at about 6 ft (1.8 m) and their gestation period is 9 to 12 months.

Social Structure and Behavior

Pacific white-sided dolphins are often found in large herds of hundreds and even thousands, and may be found traveling with other dolphin species such as Risso’s and Northern right whale dolphins.  They are fast and playful and will often bow-ride vessels or large whales.

Current and Historical Threats

The most significant threat to Pacific white-sided dolphins are drift and gill nets.  They are also preyed upon by transient killer whales.


Jefferson, T. A., et al. 2008, Marine Mammals of the World: A Comprehensive Guide to their identification. Academic Press.

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Adult ♂ : 8 ft (2.5 m)

Adult ♀ : 7.5 ft (2.3 m)

Birth Length :3 ft. (0.9 m)


Adult ♂ : 300 lbs (135 kg)

Adult ♀ : 300 lbs (135 kg)

Birth Weight : 30 pounds (15 kg)

Life Expectancy

40+ years


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