IMPORTANCE OF SAMPLING IN ASSESSING RIVER HEALTH
Importance of sampling in assessing river health. The Forth Rivers Trust (FRT) recently engaged in a fish sampling exercise of tributary burns of the River Devon in Clackmannanshire, Scotland, in a bid to assess populations of young trout and salmon.
One way of monitoring fish populations, especially juveniles, is electro-fishing – a specialist technique that temporarily stuns the fish, enabling them to be scooped-up into a net before being later released unharmed back into the river.
As such, I was delighted to have been invited by FRT to participate in an electro-fishing session on the Dollar Burn. Headed-up by Jo Girvan, the team consisted of Jack Wootton, who also works for the Trust, volunteer Bethany Robinson and Colin Smail of the Devon Angling Association.
The Dollar Burn, along with Alva, Menstrie and Tillicoultry burns are regularly monitored by the Trust to assess how fish populations are faring and also to detect any trends.
Jo slowly wades slowly upstream, sweeping an anode into the water ahead of her. Jack is right behind and he quickly lifts up into his net any fish affected by the electrical current, which are then gently placed into a pail of water. Fish that are missed, recover within seconds and dart back to the bottom of the burn.
After a carefully timed sampling period, we return to the bankside and examine the live-catch. Jo is pretty satisfied with the result, with 39 young trout and six small salmon caught. The good number of one-year-old trout is especially encouraging, as it indicates that the most recent spawning season was relatively successful.
We also caught an eel, which caused a bit of excitement, as their numbers have plummeted alarmingly in Europe over the last few decades. This eel will stay in this burn for a few more years yet before embarking upon an epic migration to the Sargasso Sea off America to spawn.
The Devon Angling Association works closely with the Trust to ensure that the main river and its tributaries remain in a good environmental condition. In many ways, anglers are the unsung heroes of the Devon, with the Association removing obstacles in the river that may impede fish migration, clearing bankside paths, managing invasive weeds such as Himalayan balsam, and participating in other initiatives to ensure people enjoy the river and that its diverse wildlife can prosper.
By Keith Broomfield