THE annual counting and tagging of juvenile wild Atlantic salmon on the River Frome has yielded the lowest number of fish in more than 20 years of monitoring - hugely concerning scientists running the project.

It follows the recording of the lowest ever number of adults returning from sea to spawn last year – further confirming the continued steep decline of salmon in Dorset's rivers.

A report published by the Environment Agency and Cefas shows that salmon numbers across England and Wales were the lowest since records began in 1997.

Numbers of wild Atlantic salmon in rivers have crashed by some 80 per cent over the past 40 years.

Salmon leaping in the water during electro-fishingSalmon leaping in the water during electro-fishing (Image: GWCT) Rivers which had tens of thousands of salmon in the 1980s now only have a few hundred in them. They are now classified as endangered in the UK and on the IUCN Red list along with other threatened species like elephants, pandas and polar bears.

In a bid to try to identify what is causing this and what can be done to reverse it, the Game & Wildlife Conservation Trust’s (GWCT) Fish Research team spend four weeks in late summer in the river catching, weighing, measuring and micro-chipping the juvenile salmon, known as parr, that have hatched in the spring.

Based near Wareham, they head out every morning to a different section of the River Frome, trying to cover as much of the juvenile salmon habitat within the 35-mile-long river as possible.

The aim every year is to tag 10,000 salmon parr, but this year the team did not even manage to catch half of that – only 3,813 salmon were caught and tagged.

GWCT researchers electro fishing for salmon in the River Frome near Dorchester GWCT researchers electro fishing for salmon in the River Frome near Dorchester (Image: GWCT)

GWCT fisheries senior research assistant Will Beaumont led the project, which took place between August 22 and September 20, and forms part of a 'Core Salmon Rivers' research programme in partnership with the Atlantic Salmon Trust and the Missing Salmon Alliance

He said: “We have failed to hit 10,000 parr in the past on several occasions, but usually it’s not this far off. This year has been the worst we’ve ever had.”

“Why that is, is hard to say. Water levels are high, which made it hard to fish some sections, and the rain and floods during the winter are likely to have affected egg survival. We will be going through our data to try to identify the cause, but we don’t know yet.

“But the fact remains that salmon is such a fast-declining fish, that finding so few parr this year is concerning. We have seen this downward trend for years, but this is a record low.”

To try to identify what is causing the continuing decline in wild Atlantic salmon, the GWCT’s Fish Research Centre has been studying the health and lifecycle of this iconic species since 1973 and therefore have data going back more than 50 years, making the Frome monitoring programme one of the longest running and most comprehensive of its kind in Europe.

Since 2005, they have caught and tagged salmon parr every autumn and are using this data to try to find solutions to help fish populations recover.