GeoResources - Geography website

The Effects Of The Oil Spill

Oil came ashore along 200 kilometres of coastline, with the worst hit areas within the Milford Haven waterway and along the south Pembrokeshire coast. Estimates suggested that about 6% of the total oil spill came ashore, that about 40% of the oil – including many of the components that are toxic to marine life – evaporated rapidly after release, and about 52% of the oil dispersed in the seawater, due to natural mixing and the use of chemical dispersants sprayed onto the oil from aircraft. The remaining 2% of the oil was left floating on the sea surface and this was collected and taken away.

As a precautionary measure, a ban on all fishing and the collection of edible plants and seaweeds was imposed shortly after the spill for an area stretching from St David’s Head to Worm's Head on the Gower Peninsula. Fishing for salmon and sea trout was also banned in the rivers flowing into this area. Over the following year the ban was gradually lifted in stages until all remaining restrictions were removed on 12 September 1997.

In the weeks following the spill large numbers of dead or dying animals were washed ashore – mostly bivalve molluscs (such as cockles and razor shells) and sediment-dwelling animals of the lower shore. Large numbers of limpets were killed on heavily-oiled rocky shores near to the grounding site, with 90% mortality recorded in some areas. Topshells and periwinkles also died, though in lower numbers. In the area affected by oil, potentially vulnerable mammals included grey seals, porpoises, bottlenose dolphins, otters, and greater horseshoe bats hibernating in coastal caves. However, no impact of the oil spill on these sea mammals was recorded.

South-west Wales supports about half a million breeding seabirds, including internationally important populations of gannets, Manx shearwaters, razorbills, storm petrels and puffins. Around 7,000 oiled birds were washed ashore following the spill (though it is likely that the total number of birds killed was several times higher than this). Over 90% of the oiled birds were of three species – common scoter (see picture below right), guillemot and razorbill.

The oil spill affected the amenity value of this tourist area in several ways. Oil was visible on the beaches (see picture above left) and in the sea and its smell was unpleasant. There were public concerns about bathing water quality at the start of the tourist season. Parts of the coast path were closed for safety reasons during clean-up operations and climbers were advised against using two of the best areas in Pembrokeshire. An analysis of the impact on tourism throughout Pembrokeshire suggested a loss of about Ł2 million in 1996.