Nature and Wildlife - Habitats and Species

Marine Mammals

Cetaceans off the Merseyside and Lancashire Coast in 2004

Steve White, Lancashire Wildlife Trust

2004 saw unprecedented numbers of cetaceans in inshore waters in Lancashire and Merseyside. The overwhelming majority were Harbour Porpoises, the first report of which were two adults close offshore from Crosby Marine Park on 1 April. There were regular sightings of at least one in the same area until at least 2 May, and on 18 April one was tracked into the Mersey as far as Runcorn. Another was seen from the Mersey Ferry on 14 May and the following day at least six, and probably more than twelve, were seen from Liverpool Pier Head. Two were near Eastham Lock on the Cheshire side of the inner Mersey on 16 May. One was off Marshside on 20 April and a pod of ten was wandering between the mouth of the Ribble and Blackpool South Pier on 4 May. Further north, one was seen off Jenny Brown's Point on 16 May and two off Heysham on 2 July.

Harbour Porpoises are always the commonest cetaceans in Lancashire's shallow inshore waters but such numbers have never been recorded before. It seems likely that considerably more were present than these records suggest, particularly since little seawatching takes place - at least off the Sefton coast - during April and May.

The first explanation for their presence so close to shore was that they had been attracted by an unusually plentiful fish supply. But this optimism was soon shattered when corpses began to wash up on the beaches. Five were found on the Sefton coast in the first week of May and a further 18 had been found there by late December, mostly before mid-July. At least another five corpses were found on the Cheshire side of the Mersey Narrows and North Wirral Shore and one at Blackpool during May. The reasons for this large-scale mortality are unknown but there was no evidence that it was a result of 'by-catch' by fishing vessels. Unconfirmed reports of a couple of post-mortems suggested the animals were underweight and in poor condition and carrying heavy parasite loads. Another theory is that at least some deaths might have been caused by Bottle-nosed Dolphins and it is possible that an abundance of fish in onshore waters may have brought the two species into conflict - but there is no evidence for either supposition.

Good numbers of Bottle-nosed Dolphins were seen - but only on one day. Twelve were seen off Jenny Brown's Point on 16 May and perhaps two of these off Heysham the same day. Remarkably, a Bottle-nosed Whale was also off Jenny Brown's on 16 May.

The only other species recorded was a 15m Sei Whale, weighing 36 tonnes, brought into the Liverpool docks, stuck on the bow of a container ship on 20 July. It is thought, however, that the fatal collision occurred off western Ireland.