What Are the Differences Between a Male & a Female Harbor Porpoise?

The harbor porpoise, also known as "sea pig," "herring hog" and "common porpoise," bears the scientific name of Phococena phococena. The porpoise species are related to whales (cetacean), and the harbor porpoise is the smallest among the 80 known whale types. As the name indicates, they live mostly near the coastline (harbors) in waters that are less than 492 feet deep. They are found in cold and temperate waters of the north Atlantic, north Pacific and Black Sea. The male is called a "bull," the female a "cow" and their young a "calf." It is difficult to differentiate between the male and female harbor porpoise, as their physical appearance is almost identical.

  1. About the Species

    • Porpoises are called "puffer pigs" by fishermen in Canada and New England because their name is derived from "porcus," which means "pig" in Latin. The word from which their name was derived is porco-piscus (proco meaning pig, and piscus meaning fish). Though porpoises live mostly in estuaries and harbors, they do live in deeper seas, such as in Georgia Strait where the waters are more than 400 meters deep. The porpoises have the shortest life span among the cetacean whale family, about 20 to 24 years. Only 5 percent live more than 12 years, mostly due to disease and accidents with fishing gear. Porpoises do not splash when they surface. They arch their back and roll from beak to fluke. By nature they are shy mammals that prefer to stay away from humans and boats, unlike dolphins --- a species with which they often confused. They normally live in groups of two to five animals of mixed sexes.

    Female Harbor Porpoise

    • The female harbor porpoise reaches sexual maturity at 3 to 4 years of age. The gestation period is 11 to 12 months, and the litter consists of one calf. The mother porpoise nurses her calf up to 12 months. The female can grow to a length of 4.6 to 6.2 feet and weigh a maximum of 167 lbs.

    Male Harbor Porpoise

    • The male porpoise reaches sexual maturity at about 4 to 5 years of age and grows to a length of 4.6 to 6.2 ft and weighs about 134 pounds. The males compete with each other during the mating season not by fighting but by producing enormous amount of sperm. An amazing fact about the harbor porpoise is that the male testes can grow up to 6 percent of its body weight.

    Differences Between the Genders

    • The only outward physical difference between the genders is that the female whale is larger than the male --- but this difference is small and not very helpful in differentiating between the genders. The best way to distinguish between a male and female is by observing the genital slit. In the female harbor porpoise, this is situated close to the tailstock, right at the base of the belly. For the male, the genital slit is just at the base of the belly below the navel. The best time to identify male from female is during mating season (late summer to early fall) when it is easy to mark the male by his testes, which are remarkably big.