The Surrounding Sea - Gower - page 128

seas around Britain, but prompt action can save a turtle's life and the Marine Conservation Society web-
site provides guidance on this.
MARINE MAMMALS
Grey seals Halichoerus grypus frequently occur around the peninsula. On the Inner Head of the Worm up
to 20 animals at a time haul-out on the dropping tide and can easily be seen from the former coastguard
lookoutstation(Fig.68).TheyalsoappeartobreedontheWorm,althoughtherearenospecificrecordsof
this. Sometimes in the winter months one or two individuals can also be found on the shore near Sedgers
Bank in Port-Eynon Bay. In contrast common seals Phoca vitulina are very rare in the region.
FIG 68. Grey seal on the shore of Worms Head. (David Painter)
The harbour porpoise Phocoena phocoena is the most widespread and abundant cetacean in Welsh
waters. Investigations of tooth ultrastructure and genetic studies indicate that there are possible subpop-
ulations around the British Isles, one of which is based in the Irish Sea and around Wales. Porpoises are
common both inshore and offshore although certain coastal features such as headlands and islands regu-
larly attract high concentrations of animals. These habitats are characterised by strong tidal currents and
the animals appear to forage in the tide races that form in their vicinity. Because of this the time of their
appearance and location can be predicted to some extent by the tidal cycle. The two main areas of por-
poise sightings off Gower are in the vicinity of Worms Head and Burry Holms, where strong tidal races
occurontherisingtidebetweentheislandsandthepeninsula.BecauseofthelargetidalrangeintheBris-
tol Channel these races typically attain a velocity in the range of 2.8 to 5.5 kilometres per hour (1.5 to 3
knots) at the spring tides. Groups of up to 20 individual porpoises have been recorded at times, but they
most often occur in small groups of one to three animals.
Although the porpoise has been identified as a locally important species, surprisingly little is known
about this significant social predator and many basic questions, such as the size of the population around
Gower and breeding success, remain to be answered. Although they are frequently seen, they are shy and