Winter 2005

Marine Mammals in the Irish Sea

A variety of marine mammals are present in the Irish Sea, though on the whole they go unnoticed. The most commonly encountered species is the grey seal which are common on the sand banks around Hilbre Island during the summer months. The seals do not breed in the Dee, but use the area to haul out, feed and moult, over 500 have been recorded on the sand banks. The common seal has also been recorded in the area but is a far less frequent visitor.

The grey seals can sometimes be seen patrolling the waters along the Sefton Coast, especially around Formby Point and beyond the designated bathing area at Ainsdale. Normally you only get to see the seal’s head bobbing above water intently watching you. They are probably as curious about us as we are about them.

Unfortunately you can occasionally find them stranded on our coastline, these are normally young or sick seals. If they do not return to the sea on their own they are taken by the RSPCA to a rehabilitation centre.

Numerous cetacean species (porpoises, whales and dolphins) have been recorded in the eastern Irish sea. The most commonly encountered species are harbour porpoise, bottle-nosed dolphins and minke and long-finned pilot whales, which are either resident throughout the year or are seasonal visitors. However, the only species to have been seen alive from the Sefton Coast is harbour porpoise and, with the exception of 2004 when they were seen regularly at the mouth of the Mersey and further up the coast, such sightings are rare. Recent live sightings in the Mersey have almost always been of harbour porpoises but have included bottlenosed dolphin and minke and long-finned pilot whales. The dolphins and pilot whales made their way back out to sea under their own steam but the minke whale became stranded on sandbanks at Widnes and was saved due to the actions of Mersey Inshore Rescue Service.

Unfortunately, you are far more likely to encounter a dead animal washed up on the beaches or on the sandbanks of the Mersey Estuary. The vast majority of such casualties are harbour porpoises but in the past 40 years killer, fin and sei whales have also been found – they may, of course, have died some considerable distance from our shores.

Live harbour porpoises have been spotted in the River Mersey much more frequently in recent years, presumably following shoals of fish entering the river on incoming tides, such as herring and sprat. The return of the fish and cetaceans is due to the cleanliness of the river after a massive clean up effort over recent years. The most you will normally see of the cetaceans is their top fin as they break the surface to breathe. Only if you are really lucky will you see them jumping. Please report any sightings to the Sefton Coast Rangers or the Lancashire Wildlife Trust.

For more information about seals in the Dee visit

Sea Mammal research unit

Lancashire Wildlife Trust
0151 920 3769