Harbor Porpoise (Phocoena phocoena)

Harbor Porpoise on the Ledge: This small cetacean species actually overwinters in the waters of the Ledge. Sightings on Jeffreys typically start in the early fall (often September), and decrease again in May. This appears to be an important winter habitat for the species. In the 1980s and early 1990s there appeared to be a high incidental take of porpoises in winter gillnet fisheries. Use of pingers, to warn porpoises of the net, and decreases in gillnet effort due to overfishing appear to have helped solve the problem for now. Size: 4-5 feet as adults Weight: approximately 200 pounds Distinctive Characteristics: A short, stocky body with a triangular dorsal fin in the middle of the back. Diet: A combination of fish and squid, often herring, cod, and sole. Distribution: Summer habitat appears to be in the northern Gulf of Maine and the Bay of Fundy. Harbor Porpoises are also found in the Gulf of St. Lawrence; it is unclear if this is the same breeding population or not. During the winter, porpoises move south to waters off of New England to the mid-Atlantic. Despite their name, they often occur in deep waters. However, in recent winters, some porpoises have been sighted regularly in Boston Harbor! Life History: Mating occurs from March through July, and calves are born after an 8-10 month gestation period. Calves are approximately 2 ∏ feet and 15-20 pounds at birth. Sexual maturity is reached at four years, and females calve every other year. Social Organization: Harbor porpoises are typically sighted in small groups of 3-15 animals, but aggregations of more animals than that in an area are not uncommon. It is unknown if these are stable groups or not. Population Status: In the North Atlantic, harbor porpoises have been thought to be declining because of incidental catches in fishing gear. One recent estimate indicated that if current catches continue, the stock will become extinct in 100 years. The National Marine Fisheries Service had proposed threatened status for the population, but withdrew the proposal in January 1999, hoping that new regulations would eliminate the decrease in the population. However, they may reconsider it in the year 2000. The best estimate of the population in October 1998 is 54,300 (minimum is 48,200). Other Sites: Link #1    Link #2    Link #3