The word “Porpoise” is derived from the Latin words for pig, “Porcus” and fish “piscis.” But just what do we know about these little “pig-fish” we see rolling at the surface or riding our bow wakes?
I’m Sunny Rice for the Petersburg Marine Mammal Center.
Two types of porpoise frequent the waters around Petersburg – the shy harbor porpoise and the more gregarious Dall’s porpoise.
Similar in coloration to the killer whale, the Dall’s porpoise has a mostly black body with white flanks and belly and white tips on the dorsal fin and flukes. They average about 6 feet long and 300 pounds, and generally live about 16 years. Like other dolphins and porpoises, these animals feed on a diet of small schooling fish.
Dall’s porpoises are often quite playful. They are commonly seen riding the bow waves of moving boats, darting quickly from side to side. Dall’s porpoises are extremely fast swimmers, cruising at speeds up to 35 mph. While their coloration is somewhat similar to the Pacific White-Sided Dolphin, a Dall’s porpoise can be distinguished by the rooster-tail spray it creates when it quickly, but barely, breaks the surface to breathe.
Unlike their dolphin cousins, Dall’s porpoises rarely leap completely free of the water.
Harbor porpoise are smaller – only about 5 feet long and 120 pounds. Their small size is one of their main identifying characteristics. A harbor porpoise’s dorsal fin is solid grey or black, as compared to the black and white fin of the Dall’s. Harbor porpoises are also more solitary – you’ll usually only see them alone or in small groups. They are unlikely to approach vessels as they roam shallow waters in their home ranges, which can be thousands of square miles. Consider yourself lucky if you see a harbor porpoise or two briefly rolling at the surface to take a breath.
And while the name porpoise is derived from the Latin for “pig-fish,” you can be sure they don’t taste as good as a nice slab of bacon.
