Whale sharks at risk from plastic pollution in the remote British island of St. Helena

The whale shark is the largest fish on the planet and inhabit the island of St. Helena’s waters from November to June as they migrate across the South Atlantic. Wildlife groups and environmentalists are concerned that the amount of plastic collecting there could prove deadly for whale sharks, which are already enlisted as endangered by the International Union for the Conservation of Nature because they often become tangled in fishing nets or collide with boats.

The tiny volcanic island of St. Helena, which lies 4,000 miles from England in the South Atlantic, is Britain’s second-oldest overseas territory, and was where Napoleon was imprisoned before he died in 1821. Despite its isolated location, the island is now awash with plastic garbage that washes in from South America and beyond, even though its nearest neighbour is thousands of miles away.

Whale sharks are particularly at risk from garbage pollution in the ocean because their main diet is plankton, which they need to suck up in huge gulps. As well as problems with microplastics, large pieces of garbage can pierce stomach linings, and plastic bags are mistaken for jellyfish that block intestinal tracts digestive systems.

David Barnes, of the British Antarctic Survey, said, “There has been an absolutely dramatic change in St Helena. In 2003, there was one plastic item per every three metres. By 2007, that had changed by three times the amount and now we’re finding hundreds of plastic items per metre in some places so that’s a 1000-fold increase – there are unbelievable levels of change and it’s happened in our lifetime. The animals that eat plankton and smaller algae are not discriminating between microplastics and their food. They can process the natural food but the microplastics stay in their stomach and build up until they have a stomach full of plastic which, in some circumstances, can weigh more than the actual organism and then they will die.”

Research into plastic levels on St Helena were recently published in Current Biology. It is estimated that eight million tonnes of plastic are dumped in the world’s oceans each year and the Ellen Macarthur Foundation has estimated there will be more plastic than fish in the ocean by 2050, an 83 percent of the world’s tap water is now contaminated. There is growing evidence that plastic is entering the marine food chain, with fish, turtles, sea birds, and cetaceans from around the world all testing positive for plastic contamination.

The World Wildlife Fund is calling for people to avoid using single-use plastics and straws. Lyndsey Dodds, Head of UK Marine Policy, WWF UK said, “We need to go further and faster - plastic is choking our oceans and leading to the demise of some of our much-loved marine animals. Many of us are doing our bit, but it’s time producers were made to face up to their responsibilities too. We need a ban on all unnecessary single-use plastic items by 2025, and other laws that respect the amazing natural systems upon which we all depend, weaning ourselves away from our throwaway culture.”