Irvine from the air with the angling club water in the foreground
We had an interesting sort of morning looking at erosion on the lower Irvine with a view to suggesting solutions to Irvine Angling Club who are concerned about bank loss and instability on their stretch. It is a long term issue but we also identified that the river is shallowing due to silt deposits coming from upstream. A consequence of this is that the bed substrates are smothered by fine sediments and there’s virtually no cover anywhere for parr or fry in the stretch.
The left bank at the SWT reserve is eroding and would benefit from stabilisation however, we noted that two Sand Martin nest boxes on poles had be erected on this bank and a willow had been chopped down (presumably so it wasn’t in their flight path) so perhaps it will be a difficult job to convince SWT to either take action or allow others to do so. I’d be surprised if Sand Martins don’t use the natural eroding banks all over this area in preference to boxes but I suppose time will tell.
Planting or willow on a river bank shouldn’t prevent birds using burrows so long as bare earth cliffs are retained in suitable places
There are severe bank erosion problems and more trees and vegetative bank cover should help. This all takes time and effort to establish but given a chance, the habitat could be improved.
With the sun out, we put the drone in the air and could see that the river bed substrates are uniform and lacking in diversity. This is a problem for fish and leaves them vulnerable to predation from piscvorous birds as there’s a lack boulders and cobbles for them to hide amongst. This is partly due to the volume of silt coming downstream and depositing in the stretch. This has been going on for years and with banks eroding all along the river, will continue. Banks instability and erosion are a significant challenge for fishery management as generally speaking this is more often driven by agriculture or morphological alterations than natural movement.
Rock armour on the outside of the bend prevents the river moving but also constrains the river in high flows. This may be part of the reason that the inside of the bend is eroding which would normally be an area of deposition.
If we can and I’m sure we can, we will suggest a few things and assist the club by demonstrating techniques that they may find invaluable if put into practice at their problem areas. Of course some anglers will oppose trees on the riverbanks but it seems obvious that most would rather have fish and good habitat than few fish with little or no cover or lies? Getting anglers on board and supportive of an attempt to plant and restore banks will be essential.
There are areas where the bank side and marginal cover is excellent and this helps protect fish from predators but also holds the banks together
We will see what we can come up with and then talk to the club again. Hopefully in time the problems can be resolved but Rome wasn’t built in a day and the problems won’t disappear immediately.
A notorious poaching spot, the Pump House Pool. It would be good to see this obstacle removed but that’s not on the agenda at the moment nor likely to be, anytime soon.
It was good to be asked for advice and we are always pleased to help any clubs wishing to improve their beats.
