Braer oil spill

The Event: Grounding of the oil tanker Braer at the Shetland Islands, resulting in the spilling of its cargo of crude oil into the sea

Date: January 5, 1993

The oil spilled when the Braer ran aground killed or sickened thousands of shellfish and led to severe economic setbacks for the local fishing industry.

When the oil tanker Braer ran aground at the southern tip of the Shetland Islands, located about 210 kilometers (130 miles) north of the Scottish mainland, more than one million barrels of crude oil were spilled into the Atlantic Ocean. Under the severe wind and wave conditions that prevailed around the Shetland Islands at the time, the spilled oil thoroughly mixed into the turbulent seawater and rapidly dispersed. Ten days after the spill, the concentrations in the vicinity of the wreck had fallen from several hundred parts per million (ppm) to 4 ppm, still about two thousand times the normal level.

Being less dense than water, most of the oil floated. The lightest, most volatile hydrocarbons started to evaporate, decreasing the volume of the spill but polluting the air. Subsequently, a slow decomposition process occurred, caused by sunlight and bacterial action. After several months, the oil mass was reduced by approximately 80 percent.

Shortly after the Braeroil spill, all fishing activities were prohibited in the surrounding areas. For most shellfish species, this ban remained in effect for more than two years, until the spring of 1995, when they were judged to be free of any significant levels of oil contamination. Shortly after fishing resumed, however, the catches of lobsters and queen scallops were found to be very poor, and the proportion of young lobsters and scallops was abnormally low.

Supported by the Shetland Fishermen’s Association, the North Atlantic Fisheries College carried out a number of laboratory trials in 1996 and 1997 to determine what effects crude oil may have on lobsters and scallops and to investigate whether the Braeroil spill could have had adverse effects on these stocks. During the experiments, researchers used Norwegian Gullfaks crude oil, the same type as the Braer’s cargo, to simulate the spill conditions. Results of the study showed that in the short term, adult scallops and lobsters could survive exposure to relatively high concentrations of oil, but lobster eggs and larvae suffered high mortality rates. Although the oil did not kill the adult lobsters, it did cause major behavioral abnormalities, including significant reductions in feeding, movement, responsiveness to stimuli, and aggression.

In May, 1997, the Scottish Office Fisheries Department released a document indicating that the Braer oil spill polluted a much wider area than previously thought. The report showed that levels of oil in prawns and mussels from a 1,036-square-kilometer (400-square-mile) zone of excluded fishing were still rising in 1996, and there were indications that the tides had spread the oil underwater all around the Shetland Islands’ 1,450-kilometer (900-mile) coastline. Fishermen reported that their fishing grounds were ruined, with nothing replacing what was being caught. Into the late 1990’s, considerable work was still being undertaken to rectify the damage done by the Braer oil spill, particularly by the large quantities of oil that had become incorporated into subtidal sediments.

Bibliography

Burger, Joanna. Oil Spills. New Brunswick, N.J.: Rutgers University Press, 1997.

Clark, R. B. Marine Pollution. 5th ed. New York: Oxford University Press, 2001.

National Research Council. Oil in the Sea III: Inputs, Fates, and Effects. Washington, D.C.: National Academies Press, 2003.