AN encouraging increase in the number of young salmon has been noticed in tributaries of the River Tone, according to surveys by the Environment Agency.

It is believed to be largely due to increased flows during the salmon migration period, allowing adult fish to swim past barriers and access spawning grounds upstream.

Juvenile (parr) salmon parr have been found as high up the Tone catchment as Waterrow for the first time in 20 years, as well as in many feeder streams and tributaries, including Halse Water, Hillfarrance Brook and the Three Bridges Stream.

Matthew Pang, of the EA, said: “This is living proof that adult salmon have not only been able to migrate up the River Tone but also access many of the tributaries within the catchment and utilise habitats that were inaccessible to them in the past.

“‘One of the limiting factors affecting salmon populations is access to suitable habitat. Allowing salmon to use the full range of habitats they need during their lifecycle will help maintain and increase the number of salmon in the Tone and other rivers.”

The news of salmon returning to the tributaries has been welcomed by local councillor and conservationist Gwilym Wren, who lives near the Hillfarrance Brook.

He said: "This is very encouraging news and testament to the excellent work that has been done in the catchment.

"There have already been sightings of otter, lamprey and bullhead in the stream.

"The presence of these key species is a sign of a healthy watercourse rich in biodiversity."

Weirs and man-made structures can have a significant impact on migratory fish.

The increase in numbers of young salmon shows how important it is to remove barriers so that adult salmon can reach their spawning grounds.

The Environment Agency has recently repaired two fish passes on the Tone at French and Firepool weirs in time for this year’s salmon run and will be looking for opportunities to improve fish passage elsewhere in the catchment.

The Agency has also been looking at surrounding land management issues to try and help improve the water quality and reduce the amount of sediment entering the river.

Lowland rivers are vulnerable to pollution and run-off from surrounding farmland.

If the Tone’s salmon population is to thrive, streams such as the Hillfarrance Brook need to be carefully managed and protected.

"One of the biggest threats to spawning beds is silt. It clogs the riverbed with fine particles of soil and starves developing salmon eggs of oxygen. So it is important farmers and landowners take all necessary steps to prevent excessive amounts of silt entering watercourses like the Hillfarrance Brook,’ said Mr Wren.