The drug that’s meant to save Salmon but is killing the creatures on the Ocean floor.
A disturbing recent report from Rob Edwards in the Sunday Herald.
A toxic drug fed to caged salmon in Scotland is due to be withdrawn from the market after scientists found that that it can leak into lochs and kill crabs, shrimps and lobsters.
Food pellets laced with a chemical called teflubenzuron have long been given to farmed salmon around the coast in order to control sea lice infestations. The lice eat salmon, killing them or stunting their growth, and can cause multi-million-pound losses for fish farmers. But salmon excrete the chemical, which then pollutes the seabed around fish farms at levels than can be lethal to marine wildlife. Shellfish are poisoned and prevented from making new shells to protect them as they grow.
Now the Scottish Environment Protection Agency (Sepa) says it has persuaded the company that markets the drug to withdraw it. Campaigners, however, warn that replacement drugs could do just as much harm, and are demanding a much broader legal ban.
The latest research on teflubenzuron was conducted by scientists from the Institute of Marine Research and the National Institute of Nutrition and Seafood Research in Bergen, Norway. They detected high concentrations in sediment around a salmon farm on a fjord north of the city. They estimated that it took 170 days for the teflubenzuron pollution to reduce by half, suggesting that it will persist in the marine environment for years. The drug was found in most of the wildlife they tested, including worms, crabs and fish. In a study published in the journal, Science of The Total Environment, the researchers concluded that the levels in king crabs, shrimp and two species of lobster were high enough to kill them as they naturally shed and replace their shells. Teflubenzuron is designed to prevent animals from making chitin, a tough cellulose material vital for renewing shells.
Teflubenzuron has been regularly used on salmon farms in Scottish sea lochs along the west coast and on islands for years. According to Sepa, environmental quality standards for the drug were breached once in 2011, six times in 2012 and six times in 2013.
Photo – © Richard Dorrell
