Phocoena phocoena

• Order: Cetacea
  
• Suborder: Odontoceti
  
• Family: Phocoenidae
  
• Genus: Phocoena
  
• Species: phocoena

Distribution and Habitat
Harbour porpoises are found in the temperate waters of the northern hemisphere in a nearly circumpolar distribution. They generally inhabit coastal waters with a depth of less than 150 meters, and their common name is derived from their regular appearance in bays and harbours. Many populations of harbour porpoises are migratory.

Natural History
Harbour porpoises are one of the world's smallest cetaceans, growing to an average length of 1.55 m and a mass of 55 kilograms. Female porpoises are usually larger than males. It is believed that porpoises can live as long as 20 years. Harbour porpoises become sexually mature between 3 and 5 years of age. After that time, female porpoises usually produce one calf every year. Porpoises feed on herring (Clupea harengus), capelin (Mallotus villosus) and gadoid fishes such as pollack (Pollachius virens) and hake (Merluccius bilinearis). Porpoises also eat squid. Recently weaned porpoises eat euphausiid shrimp. Harbour porpoises are deep divers, capable of reaching depths in excess of 200 meters.

Status and Protection
Many harbour porpoise populations around the world have been depleted through bycatch in fisheries. This has led some countries to afford them special status. In Atlantic Canada, harbour porpoises are listed as threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Northwest Atlantic harbour porpoises are currently designated as a strategic stock under the U.S. Marine Mammal Protection Act (MMPA) because current levels of killing exceed the estimated Potential Biological Removal (PBR) level for the population. Harbour porpoises are listed in the IUCN Red List of Threatened Species as vulnerable throughout their range.

Threats to the Species
Porpoise populations throughout their range continue to be threatened by incidental mortality in many fisheries. In North America alone, bottom set gill nets catch hundreds of porpoises yearly. Chemical and noise pollution may also threaten this species.