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40-year report highlights disastrous effects of weather on fragile salmon populations

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Article written by 02 May 2013

The Game & Wildlife Conservation Trust (GWCT) has just released its latest report on salmon monitoring on the River Frome in Dorset. The report gives a fascinating insight on the rise and fall of salmon populations over 40 years and identifies that 2012 was one of the worst years on record for this species because of drought followed by extreme flooding throughout the year.

The Salmon & Trout Research Centre run by scientists from the GWCT uses technically advanced monitoring equipment to record the upstream and downstream movement of Atlantic salmon in the River Frome. It provides one of the most comprehensive, long-term records of salmon numbers in Europe.

2012 proved to be the most challenging year in the long history of this specialised research centre. River conditions severely disrupted the running of the various counting systems following extreme flooding, which interrupted both smolt and adult counting. In addition, unprecedented flooding led to a large number of big carp escaping from a nearby lake into the river, which resulted in difficulty in verifying some of the video records of fish swimming upstream.

Bill Beaumont, a biologist with GWCT and author of the report said, “In 40 years, this is only the third time that the calculation of only minimum estimates was possible and the first time when it was caused by adverse weather conditions. All the population estimates for juvenile salmon rely on the detection of PIT tags (Passive Integrated Transponder tags) which are used to individually mark juvenile salmon and because of the extreme conditions, it was only possible to run this detector for about half the year.”

However, despite the difficulties of recording this year, the GWCT’s technically advanced monitoring indicates that Atlantic salmon have suffered further declines because of the effects of a prolonged drought in 2011 and the spring of 2012. The new report highlights that the 2012 smolt run was estimated at fewer than 7,000 fish in comparison to runs that have reached around 13,000 fish in recent times.

This will undoubtedly have a major consequence for adult salmon returning to the River Frome and other rivers that have experienced similar conditions in the next few years.

To obtain a copy of the 2012 salmon research report produced by the Game & Wildlife Conservation Trust, please contact: Daniel O’Mahony on 01425 651060 or download a copy from the GWCT’s website: www.gwct.org.uk/salmonreport2012

Game and Wildlife Conservation Trust

The Game & Wildlife Conservation Trust is the leading UK charity conducting scientific research to enhance the British countryside for public benefit. Read more.

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