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Gulf of Mexico oil spill

Large scale oil spills (eg Gulf of Mexico and the Braer, off Shetland), involve various organisations with specific roles in the clean up, remediation, evidence gathering and environmental issues.

SEPA's Director of Science and Strategy, Professor James Curran, said: "The shorelines around the Gulf of Mexico will suffer serious environmental consequences from the oil spill. There will be extensive work required to both contain this spill and complete the subsequent clean up.

The cost for which could be substantial. The following information describes the issues and preparations taken in Scotland to avoid similar disasters." 

Crude oils vary in appearance and composition dependant on origin, 75% of the mixture is hydrocarbons. Polycyclic aromatic hydrocarbons (PAH) are the most toxic and persistent form of hydrocarbon found in crude oil and can taint fish and shellfish.

Following an oil spill the lighter fraction evaporates and some of the components dissolve. Some oil is dispersed by wave action into small droplets and the remaining oil may mix with water to form an emulsion. Oil in water may be degraded quickly by marine bacteria, whereas oil deposited on the sea bed may persist for several years.

Tidal movement tends to transport the slick en-masse rather than disperse it. Wind has the dominant effect of the movement of a slick and can transport it large distances and against tidal movement: affecting whether an oil slick reaches shore. Prevailing winds will determine the distance it travels its consequences eg large scale seabird mortalities. Waves will tend to break up the slick into smaller oil patches.

At sea a slick can cause contamination of fish and shellfish, and these fish may become tainted and therefore unsellable. Wild fish stocks will generally avoid the affected area but may not reappear for some time.

The Braer oil spill off Shetland in 1993 caused considerable harm to the local environment, as the storm weather prevented timely clean up operations. In the case of the Braer, impacts on the local sea fishing industry were significant as an exclusion zone was set up (the final restriction was lifted in May 2000) in the waters off Shetland. These restrictions were placed on both fishing and harvesting of wild fish, farmed Atlantic salmon, shellfish and crustaceans.

The Braer report provides more extensive information.

The use of dispersants is regulated in Scottish shallow waters by Marine Scotland. In the open sea, the benefits of using dispersants would be to prevent the oil from subsequently drifting ashore; the risks of using dispersants on oil spills in the open sea are considered low. Dispersants are not used in all circumstances, as spills of marine diesel oil, for example, will eventually evaporate and dissipate without intervention. Therefore treatment of an oil spill will be determined by many factors: the type of oil; tidal conditions, wind and prevailing weather patterns.

The Braer oil spill of January 1993, shows the extent of recovery that can be required. Fishing restrictions were in place for various periods: for white fish these were lifted in April 1993; restrictions on harvesting farmed salmon were in place until December 1993; harvesting of most crustaceans and shellfish was restricted until 1994 and 1995 respectively. While a full recovery of the industry was not until May 2000 when harvesting of mussels and lobsters could resume.

Subsequent monitoring after the Braer incident has shown that the impact of the oil spill on the environment and ecology of South Shetland was largely minimal in the longer term, due to natural phenomena. Adverse impacts did occur, but these were both localised and limited in nature due to the resilience of ecosystems and populations of species

Could a similar incident happen in Scotland?

The situation in the Gulf of Mexico is very different to that in Scotland, in that the oil platform Deepwater Horizon in the Gulf of Mexico was drilling for oil in a water depth of about 1,500m, compared to the typical depths of less than 100m in the North Sea.

Who is responsible for oil spills in Scottish waters?

Various organisations have responsibilities if an oil spill occurs:

• the Maritime and Coastguard Agency (MCA) takes the lead in pollution from shipping at sea
• ports, harbours, oil facilities and offshore installations have statutory responsibilities for clean-up operations in their jurisdictions
• In Scotland SEPA takes the lead as the environmental regulator in responding to pollution from land based sources.
• local authorities (or the Department of the Environment in Northern Ireland) have accepted the non-statutory responsibility for shoreline clean-up

What would happen if there was an oil spill in Scottish waters?

Any incident should be reported to HM Coastguard. The Coastguard then instigates the National Contingency Plan, including clean-up operation, for which the MCA has produced a national Marine Pollution Clean-up Manual. The purpose of this manual is to give technical guidance to personnel from different organisations on oil spill response operations, in particular the UK maritime local authorities and other public bodies who would be involved in responding to oil pollution. This includes guidance on considering response options in oil spill contingency plans and more specific guidance on the technical aspects of shoreline protection and shoreline clean-up.

What is the Scottish Government's role in the event of an oil spill?

Within the National Contingency Plan (NCP) the Scottish Government has overall responsibility for the protection of the marine environment and the living resources that it supports in waters adjacent to Scotland. The Scottish Government manages this responsibility through the provision of advice on fisheries, environmental and natural heritage matters from Marine Scotland Science, SEPA and SNH respectively. The Marine Planning Branch of Marine Scotland has lead responsibility within the Scottish Government for co-ordinating briefing to the Scottish Ministers and the Press Office of the Scottish Government Media and Communications Group.

The Scottish Government and its agencies would also be involved in any Shoreline Response Centre and Environment Group set up under the terms of the NCP to deal with the incident. In addition, the Scottish Government is responsible as licensing authority for approving the use of chemical dispersants in shallow coastal waters.

What is SEPA’s role in an oil spill?

SEPA is responsible for the protection of the environment in Scotland. In the case of an oil spill, SEPA would support the Maritime and Coastguard Agency, Marine Scotland, SNH and other agencies in providing the necessary regulatory or scientific expertise and advice, as required, in line with the National Contingency Plan and the procedures outlined above.

SEPA would advise on the impacts of oil spills on the shore, particularly when these affect licensed sites such as marine caged fish farms. SEPA would contribute to local plans by advising on protecting vulnerable estuaries, identifying priority sites for protection, and on plans to apply dispersant or deploy booms.

Who else has responsibilities in the event of an oil spill in Scottish waters?

Oil and gas activities within the UK are regulated by the Department for Energy and Climate Change (DECC). Scottish Natural Heritage (SNH) or the Joint Nature Conservation Council (JNCC) provide advice to DECC enabling them to consider nature conservation issues to minimise environmental effects on marine mammals, birds, fish and seabed habitats.

When was the last serious oil spill in Scottish waters?

The last serious oil spill in Scottish waters occurred on 5 January 1993 when the oil tanker MV Braer, with a payload of about 85,000 tonnes of crude oil, ran aground at Garths Ness on the southern tip of the Shetland Isles, just a few kilometres north-west of Sumburgh Head.

Can those responsible for an oil spill be prosecuted?

The organisation responsible for taking the lead role in a pollution incident will normally be the one responsible for passing the papers to the Procurator Fiscal for consideration of prosecution. For offences offshore, the Department for Transport will take the lead, for ships in harbours it will be the port authority or MCA if the harbour authority declines to act.

How do we find out what natural resources may be at risk in Scotland?

National oil spill coastal sensitivity maps for the whole of the coastline of the UK that identified what was potentially at threat in each area have been overtaken by MAGIC (Multi-Agency Geographic Information for the Countryside). This has widened its geographic scope to include information for Scotland, Wales and marine areas as part of the Coastal and Marine Resource Atlas. This resource atlas is a tool for Maritime Contingency Planning and Response. It was commissioned in recognition of the need to update the 1990 Government and Industry sponsored coastal sensitivity maps produced by the Nature Conservancy Council. The Atlas contains environmental and other resource datasets covering the Great Britain coastline and marine areas of the UK Continental Shelf. The Atlas is designed as a web based tool to access a wide range of information on coastal and marine resources.

Can the effects of oil spills in marine waters be predicted?

The MCA has an Oil/Chemical spill modelling system which uses basic oceanographic information to work out spill movement. In more complex cases the MCA can call on the modelling group at the Centre for Fisheries and Aquaculture Science (CEFAS) to conduct more detailed modelling. CEFAS has a UK wide 8km grid linked to a spill model. They have higher resolution models throughout much of England and Wales, but not Scotland. There are many other models of Scotland’s coast that could be used to model spills (Scottish Water, Consultancies, Academia), although these are not set up for this purpose.