A report by the Whale and Dolphin Conservation Society (WDCS) for the International Whaling Commission (IWC) this month has found that plastic dumped in the oceans could pose a severe threat to whales.
The literature review done by Dr Mark Simmonds, Director of WDCS found hundreds of cases where cetaceans had been either sickened, disabled or killed by the millions of tonnes of plastic debris which are dumped each year in the seas.
Among the cases cited were two Sperm whales found stranded on the California coast with over 200 kg of fish nets and other synthetic debris in each of their stomachs which had resulted in one of their stomachs rupturing and the other starving due to a blockage in their digestive tract.
Seven male Sperm whales found stranded on the Adriatic coast of southern Italy were stuffed with half-digested squids' beaks, fishing hooks, ropes and plastic objects, while a dead Minke whale which washed up on the coast of Normandy was found to have nearly a tonne of plastic in its stomach including plastic shopping bags from two well-known British supermarkets.
Whilst most cetaceans die from ingestion or entanglement of fishing gear, Simmonds is calling for a review of the damage that plastic debris can also cause.
Toothed whales, sperm and beaked whales seem at the greatest risk from plastic. Simmonds added: "Cuvier's beaked whales in the northeast Atlantic seem to have particularly high incidences of ingestion and death from plastic bags.
"We don't yet know enough about marine debris to rank it against other threats, but as it continues to sadly grow in the oceans, it will surely play a greater and greater role."
Other scientists noted that in many parts of the world whale strandings are not even reported or recorded and the examination of gut contents is extremely rare.
Studies have shown that litter concentrates in ‘convergence zones’ which are formed by currents and wind and this is where whales feed on abundant prey. As yet, scientists do not know much about the potential risk to filter feeders which can eat huge amounts of food. A single Blue whale, for example, eats up to 3,600 kg/8,000 lb of krill each day during the feeding season and this means that there is a danger that toxins in plastic will break down over time.
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