Eels are being considered as a natural control for a Scottish loch's plague of introduced crayfish.
Loch Ken in Dumfries and Galloway has seen its fish stocks severely depleted in recent years by an invading army of American signal crayfish (Pacifastacus leniusculus).
The crayfish were first reported in the Loch Ken area in 2004, but they are now reaching massive numbers with anglers reporting them as a nuisance.
A research scheme funded by the Scottish government carried out by Marine Scotland in 2009 trapped and killed over one million crayfish in five months, but despite this the crayfish continue to be a problem.
In response, the Galloway Fisheries Trust and Scottish Power, (which has hydro-electric schemes in the area) are coming together to help to draw up proposals to fight the damage these creatures cause. They hope that efforts to encourage an increase in European eel (Anguilla anguilla) populations within the Loch will increase pressure on the crayfish numbers, as eels are a major predator of their young. At the same time £700,000 of funding is being sought to carry on the trapping scheme for a further three years.
The American signal crayfish was first introduced to the UK in 1976 as part of an attempt to farm them commercially for food. They soon escaped and unfortunately were found to be carriers of 'crayfish plague' (Aphanomyces astaci), a species of water mould that they are largely resistant to, but to which the UK native crayfish, (Astacus astacus) has little defence against. As a result it has decimated populations, leading to the native crayfish being listed as a 'vulnerable'species on the IUCN 'Red List'.
The European eel is itself listed as 'critically endangered' on the same list.