At the start of June we ventured out of Ayrshire to work with Lomond Fisheries Trust to install baffles in two culverts on the Fruin system that were preventing migratory fish access to the upper habitats. This is work that is being supported by the Wild Fisheries Fund, a grant maker that has and continues to support Ayrshire projects. We were involved here at the request of Lomond Fisheries Trust as we have considerable experience and knowledge of retrofitting baffles into culverts and bridge aprons that prevent or hinder migratory fish.
A few days after completion, we returned to retighten everything with an impact driver and remove any left over materials. This job is done barring a few alterations that may be necessary once we see culverts in a spate.
Beth (Lomond Fisheries Trust) and Stuart begin the process by placing timbers into the culvert to ‘gather’ and direct water down the left hand side of the culvert.
Three of us were building two fish passes on burns for Loch Lomond Fisheries Trust in Glen Fruin so it was long days and heavy work. The other two continued with invasive weeds control locally while Jenifer looked after the office and all enquiries etc. It is unusual for us to be outwith Ayrshire but we all enjoyed the change of scenery and working in a new environment although for Carolyn it was a return to her old stomping grounds!
Carolyn drills another length of timber into place – these stainless rods are secured in place with a chemical resin anchor system.
These structures require a certain amount of trial and error to achieve the desired outcome – often we return to fine tune these installations after seeing how they behave in a spate when you would expect fish to be running. These are installed in low flows and sometimes require tweaks to get them operating optimally.
Fortunately there had been a bit of rain and this helped us see the way the water flowed as we built these structures and enabled us to tune them so they hopefully work in much larger flows when salmon and trout may be expected to run towards the back end of the year. In reality, they will offer better opportunity for fish to pass across a wide range of flows. If we need to go back to make adjustments we will but I’m pretty certain these two fish passes will work well.
Working in the first culvert with limited head room was a challenge and I think Carolyn came off best in that one with Struan and myself rather hunched for 2 days. The other was much taller but access was more difficult down a steep bank. These fish passes were built using Larch sleepers bolted to the culvert inverts. Ballevoulin culvert had a granite cobble bed while Auchengaich Burn culvert was made from reinforced concrete. All timbers were fixed using a specialist resin anchor system and stainless steel studs and fixings.
Trial and error!
We felt an alteration was necessary at the downstream end of the fish pass near the end of the day so quickly cut and rearranged a few sleepers to create a better entrance point. We may still alter this further to create a better attraction point.
I’m keen to see both burn in spate so Beth from Lomond FT with either let us know when they are running full or send us some pictures.
Water quality was tremendous and both burns have excellent spawning habitat although both would probably benefit from a few more trees. I wish everywhere in Ayrshire was like this but sadly very few burns come close.
