The purpose of fussing over the porpoise

Another Life:Dubliners can regularly spot them from the Dart, between Killiney and Dalkey, which must be a great way to start the day. Howth Head and Dún Laoghaire Pier give great chances, too.

So it may have seemed a bit odd for some city viewers, watching RTÉ news the other night, to see harbour porpoises being counted in the beautiful wild waters around the Blaskets, off Kerry, for purposes of conservation.

But Ireland's smallest and commonest cetaceans, like so much of our wildlife, need a few guaranteed safe places to live, and the Blaskets, along with Roaringwater Bay in Co Cork, have been made Special Areas of Conservation for the animal. If the experts of the Irish Whale and Dolphin Group (IWDG) are heeded, Dublin Bay and Galway Bay will soon follow suit, thus doing even more for the porpoise under the EU Habitats Directive.

Since Phocoena phocoena is so common in Irish waters, especially in the south, why the fuss? It used to be common off the English Channel beaches where I swam as a boy; it's a rarity there now, as it is in the Baltic Sea, where once it was abundant. And while the latest EU survey reports favourably on the porpoise population in the waters around Ireland and Britain - a stable 328,000 is the current estimate - many threats persist.

Bycatch in trawls or entanglement in bottom-gill-nets has accounted for thousands of porpoise and dolphin deaths. Between 1987 and 2001, the Danish fishing fleet alone was killing about 5,600 porpoises each year in the North Sea. Casualties in the Celtic Sea were also substantial. There has been serious investment in research on "pinger" alarms on the nets to scare the cetaceans away, and progressive EU legislation on their use.

But pinging still has its problems. Used on static nets, whether porpoises are around or not, continuous pinging (a sound based on wide-band signals) is a loud and polluting under-sea noise and - as important - animals get used to it. A more intelligent generation of pingers interacts with porpoises, switching on in response to their own sonar clicks.

Fixed to trawls, however, the present interactive pingers get confused by trawl and engine noise and Bord Iascaigh Mhara is involved in developing a unit that can discriminate between background noise and the echolocation sounds of cetaceans. The obliging bottlenosed dolphins of the Shannon are helping to test the work in progress.

Along with their smaller size (less than two metres), the lack of a beak is what chiefly marks out the shape of a porpoise. But unless found dead ashore, as many are in winter, the porpoise is slow to show much of itself in the sea. For those who haven't seen porpoises swimming, there's a shaky video minute of a small group off the Old Head of Kinsale at youtube.com/ watch?v=B_JfnPmAwho. They give the characteristic curving glimpse of back and fin, like the black rim of a turning wheel, that makes some people wonder if porpoises spend their lives turning somersaults.

The Blaskets survey, funded by the National Parks and Wildlife Service, is being led by the IWDG's coordinator, Dr Simon Berrow, and Joanne O'Brien, from the Galway-Mayo Institute of Technology, who is doing a PhD on small cetaceans in Galway Bay and north Connemara. Along with visual patrols from the flying bridge of the MV Blasket Princess, based in Dunquin, submerged hydrophones with computers, called T-Pods, will log the porpoises' clicks and offer up their data once a month. In the meantime, a watcher from nearby Slea Head saw a remarkable gathering of about 70 porpoises on the last day of August.

Porpoises get their share in the IWDG's Guide to the Identification of Whales and Dolphins of Ireland, which has sold a remarkable 4,000 copies and is now in an even more impressive second edition. A collaboration between naturalist Jim Wilson and Simon Berrow, it packs as much information and as many splendid photographs and illustrations into a pocket-sized book as one might find in a production of twice the size and price. A lengthy review in the journal, Aquatic Mammals, endorses its profiles of the 24 whale and dolphin species recorded around Ireland, and the value of photographs "which show what these animals really look like at sea". Now that whale- and dolphin-watching expeditions are a becoming a regular attraction off counties Cork and Kerry, the guide lists the rules in a code of conduct adopted by the Department of the Marine. Among them are injunctions to keep at least 100 metres distant from whales, not to pursue them or dolphins or spend more than 30 minutes in their company.

Times have certainly changed around the Blaskets since the 19th-century islanders drove a school of porpoises ashore for slaughter.

"It was a tough job getting the porpoises home and salting them," recalled Tomás O'Crohan in The Islandman. "But the people didn't spare their trouble, for in those days you could hardly get anybody to exchange a porpoise for a pig."

Guide to the Identification of Whales and Dolphins of Ireland costs €15 (inc p&p), from the Irish Whale and Dolphin Group, Merchants Quay, Kilrush, Co Clare. See also www.iwdg.ie

Eye On Nature

Since the end of August the shoreline along the Co Sligo coast and up to Co Donegal has been littered with hundreds of Janthina pallida. I also found a great many large fresh Velella with Janthina adherent to their underside.

John-Mark Dick, Skreen, Co Sligo

Generally found in more southern regions of the European waters, the mauve sea snail, Janthina pallida, is lighter in colour than its cousin, the violet sea snail, Janthina janthina. It is unusual for it to reach our shores but a number of strandings were reported from Cornwall coasts last December and January. It is also a rare sight to find Janthina actually feeding on the by-wind-sailor (Velella velella).

On August 26th, at the mouth of Killary Fjord, Co Mayo, we saw a sun fish, Mola mola, first just under the water surface and then its characteristic small triangular dorsal fin twitching above the water. Owen McCarthy saw one between Keem Bay and Achill Head.

David Cabot, Carrigskeewaun, Co Mayo