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Massive Electrofishing Census of Scottish Salmon

THE HERALD (SCOTLAND)

Young salmon to be electrocuted and counted in bid to monitor numbers
Helen McArdle
July 8, 2018

YOUNG salmon populations are to be mapped at more than 800 sites across Scotland in the first ever electro-fishing survey.

Biologists and volunteers will count the numbers of the fish at hundreds of randomly selected sites across 27 regions, amid efforts to tackle a slump in wild salmon stocks.

The data will be collected fro this month until September and will use electrofishing equipment so that the salmon can be counted without being harmed.

Although there has been controversy over the use of electrofishing to harvest razor clams, the technique commonly used by scientists and fisheries biologists to survey rivers and assess what fish are present.

It uses direct current electricity flowing between a submerged cathode and anode. This affects the movement of the fish so that they swim towards the anode where they can be caught.

When done properly, it stuns fish for around two minutes allowing them to be removed carefully with a net, examined and then returned alive to the river with no permanent injury.

The project - jointly funded by the Scottish Government, the Scottish Environmental Protection Agency (SEPA) and Scottish Natural Heritage (SNH) - is seeking to provide an accurate estimate of numbers of young salmon in Scottish rivers.

In March it emerged that the survival rate of wild salmon at sea has dropped to five per cent, compared to around 25 per cent 40 years ago.

Predators, poaching, salmon farming and pollution are believed to be among the factors putting pressure on stocks.

Environment Secretary Roseanna Cunningham said: “We are already assessing the populations of adult salmon but this new national survey is a significant milestone, which will help us estimate the numbers of young salmon in our rivers.

“The data gathered will also help SEPA classify electrofishing sites and SNH report on the condition of Atlantic salmon and freshwater pearl mussels in Special Areas of Conservation.

“This ground-breaking initiative is a great example of the partnership working that is essential if we are to safeguard the future of this iconic species.”

Iain Sime, SNH freshwater and wetlands group manager said: “It’s an exciting opportunity to report on the health of the ‘king of fish’ on a national scale for the first time, and to measure the health of Scotland’s rivers that are designated for the conservation of salmon. The monitoring will go a long way to helping us all ensure salmon continue to thrive in our rivers.”

The project is part of the £700,000 of funding announced for protecting wild salmon earlier this year. SEPA and Scottish Natural Heritage have contributed a combined £132,000 to the monitoring programme.

The Scottish Government has previously authorised a controlled trial into electro-fishing for razor clams. The shellfish are in high demand overseas, fuelling a lucrative black market trade. They can currently only be legally harvested by hand, by divers or by different types of dredges, but illegal fishing gangs have used electrofishing to boost catches.

The trial was launched in 2017 following a report by Marine Scotland which found that electrofishing had a lower environmental impact than methods like dredging and it had little short-term effect on other species.

However, envoronmental campaigners ClientEarth warned that there is uncertainty over the “medium to long-term impacts” on the seabed and the species.