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Toxic pesticide again in use on salmon farms

UK - Salmon farmers are again using a toxic pesticide years after it was thought to have been phased out. The chemical, teflubenzuron, known commercially as Calicide, and is given to salmon to kill sea lice parasites.

Concerns about the polluting effects of the substance, 90 per cent of which is excreted by the salmon into the sea, have been raised by shellfish farmers.

A 1999 report by the Scottish Environment Protection Agency (Sepa) found teflubenzuron to be "potentially highly toxic to any species which undergo moulting within their life cycle. This will therefore include some commercially important marine animals such as lobster, crab, shrimp and some zooplankton species." Safety reports commissioned by the manufacturer, Nutreco, revealed Calicide can still be found in sediment on the sea bed nearly two years after use.

Sepa grants licences for Calicide, but sets strict limits on concentration levels, rendering adoption by salmon farms largely impractical. The chemical disappeared from use in 2005-2006, yet Sepa has now revealed its re-emergence at three different sites this year, as salmon farmers try to tackle resistance of sea lice to two other treatments.

At a meeting of fishing industry heads and government officials, a regional development officer announced the reintroduction of Calicide in the Western Isles due to the diminishing effectiveness of SLICE and Exis treatments.

The recently released minutes of the Tripartite Working Group state: "Certain producers had started to source and use Calicide as an alternative. Sepa were asked to review their discharge licences to allow the use of greater quantities."

David Oakes, a Western Isles scallop farmer, said: "I was told by Sepa years ago that Calicide wasn't being used. It's a chitin inhibitor, and most shellfish have chitin as part of their make-up, so it cannot be good for us. It's been shown that it's detrimental to the environment so it's a big concern."

Source: SundayHerald