Harbor Porpoise

 

Status
MMPA - Harbor porpoises, like all marine mammals, are protected under the MMPA.

Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Phocoenidae
Genus: Phocoena
Species: phocoena

Species Description
Harbor porpoises have a small, robust body with a short, blunt beak. Harbor porpoise males reach average lengths just over 5 ft (1.5 m) while females are slightly larger with average lengths of 5.5 ft (1.7 m). The average adult harbor porpoise weighs between 135 and 170 lbs (61-77 kg).

Mid-way down the body sits a medium-sized triangular dorsal fin. The back of the animal is dark gray while the belly and throat are white. There is a dark gray chin patch and also intermediate shades of gray along the sides of the animal.

Harbor porpoises are non-social animals usually seen in groups of 2 to 5 animals. When surfacing for air, they do not splash; they roll from beak to fluke and arch their backs. Little information is known about their social behavior.

Females reach sexual maturity at 3-4 years and may give birth every year for several years in a row. Gestation lasts for 10-11 months and lactation lasts for 8 to 12 months. The harbor porpoise lifespan is about 24 years.

They feed on demersal and benthic species, mainly consisting of schooling fish (e.g., herring and capelin) and cephalopods.

Habitat
Harbor porpoises inhabit northern temperate and subarctic coastal and offshore waters. They are commonly found in bays, estuaries, harbors, and fjords less than 650 ft (200 m) deep.


harbor porpoise range map
Harbor Porpoise Range Map
(click for larger view PDF)




Distribution
Harbor porpoises have a discontinuous distribution. In the North Atlantic, they range from West Greenland to Cape Hatteras, NC (but do not enter Hudson Bay), and from the Barents Sea to West Africa. In the North Pacific, they are found from Japan (34°N) north to the Chukchi Sea and from Monterey Bay, CA to the Beaufort Sea.

Population Trends
There are 10 stocks of harbor porpoises in U.S. Waters: Bering Sea, Gulf of Alaska, Gulf of Maine-Bay of Fundy, Inland WA, Monterey Bay, Morro Bay, Northern California-Southern Oregon, Oregon-Washington Coastal, San Francisco-Russian River, and Southeast Alaska. NMFS Stock Assessment Reports (SARs) include estimated population sizes for the 10 U.S. stocks and are summarized below. Population trends for all of the U.S. stocks are currently unknown.

Stock

Estimated Abundance

Reference*

Bering Sea

66,078

SAR 2006

Gulf of Alaska

41,854

SAR 2006

Gulf of Maine-Bay of Fundy

89,054

SAR 2007

Inland WA

10,682

SAR 2006

Monterey Bay

1,613

SAR 2004

Morro Bay

1,656

SAR 2004

Northern California-Southern Oregon

17,763

SAR 2002

Oregon-Washington Coastal

37,745

SAR 2006

San Francisco-Russian River

8,521

SAR 2004

Southeast Alaska

17,076

SAR 2006

* NMFS Stock Assessment Reports (SARs) for the Harbor Porpoise

Threats
The primary threat to harbor porpoises is "bycatch" in fishing gear, specifically in gillnets and trawls. In Canada, harbor porpoises are also incidentally taken in herring weirs.

Conservation Efforts
In 1996, NMFS convened two "take" reduction teams (TRT) to mitigate bycatch of harbor porpoises in gillnet fisheries: the Gulf of Maine Harbor Porpoise TRT and the Mid-Atlantic TRT. The Gulf of Maine TRT addresses gillnet fisheries in waters from Maine through Rhode Island and the Mid-Atlantic TRT addresses waters from the Connecticut/New York border through the North Carolina/South Carolina border. The teams submitted draft take reduction plans to NMFS and we finalized the plans in 1998.

The Harbor Porpoise Take Reduction Plan (HBTRP) requires commercial fishermen to use pingers in gillnets in designated times and areas. There are also times and areas where gillnet fishing activities are prohibited. The HPTRT continues to meet to monitor the progress of the take reduction plans in achieving the MMPA long-term goal of reducing harbor porpoise bycatch to a zero mortality and serious injury rate.

In July 2009, NMFS proposed to amend the regulations implementing the HPTRP [pdf] (74 FR 36058) to address the increased incidental mortality and serious injury of the Gulf of Maine/Bay of Fundy stock of harbor porpoises in gillnet fisheries throughout the stock's U.S. range.

Regulatory Overview
This species is protected under the Marine Mammal Protection Act of 1972 as amended. NMFS has classified the following U.S. stocks of harbor porpoises as "strategic" stocks: Bering Sea, Gulf of Alaska and Southeast Alaska. Harbor porpoises are considered Vulnerable on the IUCN Red List This link is an external site..

Last updated: March 1, 2015

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