Harbour Porpoise

Wednesday, 24 November 2010 22:56

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At around 1.2 metres long, the harbour porpoise is much smaller than its dolphin relatives and much, much smaller than the minkes and other great whales that swim in Scottish waters. Harbour porpoises are widespread around Scotland, and you might see them from a boat, harbour, beach or clifftop almost anywhere from Shetland to the Borders.

What to look for
In addition to being small in overall size, the harbour porpoise has a small, triangular, fairly upright dorsal fin (a dolphin’s dorsal curves backwards). It doesn’t break the surface for long, so you have to keep looking at a patch of water where you think you’ve seen some action to catch glimpses of the same animal - or others in its group - surfacing again. Harbour porpoises can use quite shallow water. So scanning the nearby sea from a harbour wall, or watching from the deck of a ferry as you draw near the land, can be ways to glimpse a porpoise.

Interesting facts
Harbour porpoise need to watch their backs in case a larger relation is out to get them. Bottlenose dolphins in the Moray Firth sometimes catch and kill them. In many parts of Europe, porpoise numbers have slumped because of drownings in fishing nets, but the population around many parts of Scotland still seems to be fairly strong.

When and where to see
Go on any accredited wildlife-watching boat tour around Scotland and you’ll have a good chance of seeing harbour porpoise.

Taxonomy	Taxon	English term
Phylum	Chordata	Sea squirts, fish, reptiles, birds and mammals
Class	Mammalia	Seals, walrus, dolphin and whales
Authority	(Linnaeus, 1758)
Recent synonyms	None
Recorded Distribution in Britain and Ireland	The harbour porpoise has been recorded around all coasts of Britain and Ireland.
Habitat information	It can be found in cool temperate and subpolar waters. Usually found in near shore waters, but occasionally over deeper waters.
Description	Phocoena phocoena is a small cetacean with a blunt short beaked head. It exhibits counter-shading with the animal being generally dark grey on the back and white on the belly. A short, wide-based, triangular dorsal fin, with small bumps on the leading edge is situated midway along the back. The flippers are dark, small and rounded at the tips. The straight mouth line is dark and slopes upwards towards the eye.
Identifying features	Body dark grey on back to white below. Dorsal fin short, triangular, wide based, upright and set near middle of back. Prominent median notch in flukes. Upper jaw not extending much or at all past lower jaw. Teeth blunt with expanded crowns, laterally compressed, small with 22 to 28 pairs of teeth in upper jaw and 21 to 25 in lower. Maximum size to about 2 m.
Additional information	Phocoenids appear to live in smaller groups and have a simpler social structure than most delphinids. Most harbour porpoise are found in small groups consisting of less than 8 individuals but occasionally form large, loose groups of 50 to several hundred for feeding and migration. The harbour porpoise is listed on Appendix II of CITES and Appendix II of the Bern Convention and Annexes II and IV of the EC Habitats Directive. It is also on Appendix 2 of the Bonn Convention (Anon, 1999z). All species of cetaceans are given protection under the Wildlife and Countryside Act 1981 and the Wildlife (Northern Ireland) Order 1985 (Anon, 1999z). All cetacean species are listed on Annex IV (Animal and Plant Species of Community Interest in Need of Strict Protection) of the EC Habitats Directive (Anon, 1999x). All whales are listed on Annex A of EU Council Regulation 338/97 and therefore treated by the EU as if they are on CITES Appendix I thus prohibiting their commercial trade (Anon, 1999x). Whaling is illegal in UK waters (Fisheries Act 1981), but neighbouring countries maintain the right to hunt (Anon, 1999x). An 'Agreement on the Conservation of Small Cetaceans in the Baltic and North Seas' (ASCOBANS), formulated in 1992, has now been signed by seven European countries, including the UK. Under the Agreement, provision is made for protection of specific areas, monitoring, research, information exchange, pollution control and heightening public awareness. Although aimed primarily at dolphins and porpoises, ASCOBANS includes all toothed whales except the sperm whale (Anon, 1999x).

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Comment Link Tuesday, 15 March 2011 15:55 posted by Felsfrasery
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