2019 Electrofishing Surveys Complete

Friday 11th October, 2019

Despite being hampered by high water levels in September, the Foundation’s monitoring team completed their 2019 juvenile salmon and trout surveys earlier this week.

For those unfamiliar with electrofishing, it involves temporarily stunning fish, identifying and counting them before returning them to the river unharmed after a short recovery period. The Foundation undertakes what are called 5-minute riffle surveys while Natural Resources Wales (NRW) and Environment Agency (EA) carry out fewer but more detailed quantitative surveys.

Salmon parr found in the Honddu, a Monnow tributary, in September 2019

Without ever being a definitive method of assessing fish stocks, the annual surveys give us an idea of where and how successfully salmon and trout are spawning in our river systems. They provide us with information on areas such as to what extent a new fish pass construction has worked.

We are still waiting for NRW’s and EA’s results but in the meantime, the highlights from the Foundation’s surveys this year include…

River Usk

This year’s results show that the lower and middle Usk tributaries had poor salmon recruitment again. The majority of the fry were found in upper tributaries and the main stem, where salmon fry and parr numbers were the best for a number of years. Thankfully, trout numbers remain strong throughout the Usk system.

River Wye

Elan: An increase in salmon fry and parr numbers from last year, both in sections where new gravel has been introduced and below (see here for details). Salmon were also found further upstream than before in the section opposite Elan Village and salmon fry were found in 4 and trout fry at 6 of the 7 monitoring sites within the section that was previously denuded of gravel. In 2016 only 9 salmon fry where caught in the whole Elan survey. This year we caught 165, a marked improvement!

Newly introduced gravel in the Elan. The river is producing considerably more juvenile salmon and trout since the gravel introductions started in 2016Irfon: Good numbers of salmon fry (32) and parr (7) above the Gwesyn junction in Abergwesyn, even though an acid event was recorded in high water in March. We are relieved that there seems to have been no adverse effect on fish numbers from an acid spike that we recorded in the Irfon in March.

Elsewhere in the Irfon catchment both salmon and trout numbers were good to excellent, with especially impressive numbers in the Garth Dulas where 103 juvenile salmon were caught in 5 mins at 1 site.

Monnow: Encouragingly, salmon were found from above Monmouth all the way up the main stem sites to Oldcastle on the Monnow. Salmon fry and parr were also found on the Honddu a mile upstream of Pandy. This is the best distribution of salmon we have recorded in the Monnow and the first time salmon have reached the Welsh part of this catchment. The Monnow’s trout results were not particularly strong although sites on the Honddu, Olchon and Dore returned decent numbers.

Lugg & Arrow: There still appear to be problems with salmon being unable to penetrate the upper catchments in any number. Trout populations seem to be strong and stable in this catchment.

Lower Wye: Salmon fry and parr were recorded at 3 sites between Hereford and Kerne Bridge. This is an area from which they were absent in ‘00s, almost certainly due to excessive soil loss in Herefordshire. Their presence is testament to the work local farmers have been doing to look after their soils since then.

The full results from this year will be posted on our website soon.

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