I haven’t touched the top beat of the river channel (upstream of the weir), other than to pollard a couple of the willow trees which had snapped and windblown as a result of being allowed to get too large. However, whilst out on the tractor and topper in the weir pool paddock last week, I downed tools and had a quick wander along the bank. For the most part, the channel is deeply incised, similar in width, straight and trapezoidal, although there is evidence of some deeper pools and reasonable gravels through the length. Very little in-channel cover is present, with the exception of alongside the weir, where a Willow tree has collapsed into the channel. Interestingly, there is little macrophyte growth – probably because it was heavily overshaded, but I’ve reduced a few of the trees along the lengths, both to allow to some sunlight in and encourage some in-channel macrophyte growth, and also allow some fishing to take place.
I was wandering along the channel when a slight movement fairly tight to the bank I was walking on caught my eye (there is little marginal habitat due to the steep and incised banks). Four Barbel between 4lb and 12lb were tightly packed together on one of the shallow (2ft deep) gravel areas, in the only spot of sunlight coming through the trees onto the gravel – caused by me reducing a tree a few days previously. They seemed incongruous there, as there was no cover for some distance up and downstream, and the rest of the channel was in the shade. Tightly packed they were, with the two smaller fish at times resting on top of the two larger fish. I believe three of these were the same fish I had seen spawning a few days previously. The two best photos are below, and apologies for the quality but unusually I didn’t have my DSLR to hand, so they are taken on my phone camera. If you click on them, they should enlarge!
With this in mind, I am currently working on a plan and drawings to add some woody debris cover into the top channel. Hopefully this will provide both mature and juvenile fish with some much needed flow and hydro-morphological variation and cover to lie up under. I shall also (consent permitting) create some pool and riffle areas with the excavator, both to break up some of the concreted gravel, but also not only provide some features to fish to, and change the substrate and bed level around. I shall keep you up to date on the plans, which will probably take place in the autumn before the winter flows come.
I believe in the last century that the bed level of this particular channel was increased in height, chiefly to back the water level up and divert the flow through a (now disused and infilled) decorative canal on the neighbouring estate, which may be the reason why there is still a good gravel substrate in the channel, when much of the gravel which originally would have been present in the other beats has been dredged out.