The English Channel hosts thousands of wintering guillemots and razorbills and it's also the world's busiest shipping lane.
These seabirds are the major casualty in marine pollution incidents. Between January 29 and February 6, 2013, more than 500 birds, mainly guillemots, were killed or rendered helpless by a pollution event off the south coast involving a man-made substance called polyisobutene (PIB).
Although the source has not yet been identified, it is possible this may have resulted from a legal shipping activity.
PIB is used in anything from engine oil to chewing gum and cling-film. In sea water, it becomes glue-like and floats near the surface, where it comes into contact with seabirds seeking food, in some cases sticking their wings to their bodies.
Marc Smith, Dorset Wildlife Trust, witnessed the latest tragedy: "It was heart-breaking seeing the birds washing up along the shore. Some were so covered in this horrible substance they were literally stuck to the beach – still alive but unable to move.
"Exhausted, freezing and emaciated – they were the lucky ones. For every bird we rescued we knew many more had perished at sea. Dead birds littered the beach."
More than 300 live casualties were taken for treatment and at least 200 dead birds were recorded. The species involved, their poor body condition, the timing and widespread distribution of birds washed ashore and the weather at the time all suggest the pollutant was released somewhere offshore in the Channel, possibly south of Cornwall, some days before the birds were found.
PIB is believed to have been responsible for thousands of seabird deaths in the Irish and North Seas in at least four incidents since 1994. Such numbers are just the tip of the iceberg, as many more seabirds are affected out to sea than ever wash ashore.
It is still legal though, with conditions, to discharge PIB and several other noxious chemicals into the sea when washing out cargo tanks.
Under the international MARPOL Convention, which regulates polluting discharges at sea, PIB is classified under "substances presenting a hazard to either marine resources or human health and therefore justifying a limitation on the quality and quantity of discharge into the marine environment."
This means that between 75 and 350 litres of PIB (depending on the age of the ship) can be legally discharged each time a ship washes its tanks. However, these regulations ignore the potentially serious impacts on marine wildlife from releasing these chemical substances.
The RSPB believes this must change.
No-one knows how much PIB is released into our seas and the RSPB fears more seabirds will suffer and die until the regulations are changed. The RSPB's five point action plan calls for:
Urgent review of the hazard classification of PIB and other legally dischargeable substances under MARPOL, in relation to their impacts on the marine environment (including seabirds).
Testing of such substances for their effects in more realistic marine conditions, including how they change consistency and degrade, their toxicity if ingested and effects when mixed with other substances.
Formal monitoring and a central database for recording pollution incidents involving chemical substances.
Further scientific research on the effects of noxious substances on marine ecosystems, in addition to visible species such as seabirds and marine mammals.
Strict enforcement and prosecution of illegal discharges of any polluting substance.