Environmental Statement - Maersk Oil

Balloch Field Development Environmental Statement
Section 6 Accidental Spills
the egg and juvenile stages that are the most vulnerable to spilt hydrocarbons. An oil spill could
potentially result in the tainting of fish and a reduction of its commercial value.
Therefore, in the unlikely event of a very large spill occurring from the proposed operations, it is
recognised that there is some potential for a moderate impact on certain fish species, though the
scale of this will be dependent upon the size and duration of the spill.
6.6.4. SEABIRDS
The effects of oil on birds have been widely studied and include both immediate chronic impacts
which can cause mortality and longer‐term, sub‐lethal impacts that could affect individuals and
populations over many years (e.g. Camphuysen et al., 2005; Perez et al., 2009). To assist in
determining the likely impact on birds from a release of oil, the JNCC has produced an Offshore
Vulnerability Index (OVI) from which it is possible to indicate the sensitivities of birds at different
times of the year (Section 3.6.4). The OVI of seabirds within each offshore licence block in the vicinity
of the Balloch development is shown in Table 3‐12 as well as Figure 3‐13, Figure 3‐14 and Figure 3‐15.
The JNCC has ranked the blocks on a four point scale using the OVI criteria as detailed in Section 3.6.4.
Seabird vulnerability for the entire year is classified as moderate and there is a degree of monthly
variability in the sensitivity of seabirds to surface pollution. Generally, seabird vulnerability decreases
after the winter period when large numbers leave offshore waters to return to their coastal colonies
for the breeding season. Species commonly found in and around the Balloch area include fulmars,
gannets, shags, herring gulls, kittiwake, arctic terns, guillemot, razorbills, black guillemots and puffins.
Other species which are present but recorded in lower numbers include cormorant, arctic and great
skuas, black headed gulls, common gulls and greater and lesser black‐backed gulls (Stone et al., 1995).
Seabirds are vulnerable to surface oil that can coat feathers, thereby reducing buoyancy, or be
ingested through preening, causing illness and other sub‐lethal effects. Seabirds that encounter oil
slicks either offshore or deposited on the coastline would be expected to have a reduced rate of
survival. A long term blowout with a large surface slick under calm weather conditions could have a
significant impact upon seabirds (moderate/severe impact). The degree of any impact is dependent
upon the season and the extent of offshore areas and coastline impacted. Seabirds that are oiled in
the coastal area could be caught and rehabilitated. The likelihood of successful treatment is
dependent upon a number of factors including the degree of oiling and local wildlife response
capabilities.
6.6.5. MARINE MAMMALS
Marine mammals are generally less vulnerable than seabirds to fouling by oil (Geraci, 1990).
However, they are at risk from hydrocarbons and other chemicals that may evaporate from the
surface of an oil slick at sea within the first few days of a spill (Gubbay and Earll, 2000; SMRU, 2001).
The fur of young seal pups may become contaminated by oil, lowering their resistance to cold. The
loss of insulation properties is not considered a significant risk for adult seals and cetaceans that have
relatively little fur. Where oil does come into contact with the skin there is the potential for it to
cause irritation to the eyes or burns to mucous membranes. Ingestion of oil by marine mammals can
damage the digestive system or affect the functioning of liver and kidneys. If inhaled, hydrocarbons
can impact the respiratory system. Section 3.6.5 summarises the marine mammals associated with
the area of the development. The main marine mammals occurring in the area are cetaceans,
although there is a slight risk expected to these only in a tier 3 spill. Marine mammals most at risk
from a prolonged blowout are seals, especially those present in coastal regions where oil could beach.
Oil that beaches at known seal colonies, especially during periods of haul‐out, breeding or pupping,
would be expected to increase the magnitude of any impacts.
6.6.6. SOCIO‐ECONOMIC IMPACTS
In the event of a major release, there would probably be an exclusion of commercial fishing from the
area until it could be determined that oil levels had diminished and the absence of taint had been
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