The river is getting so low now that the smolt trap is barely turning, although we are still catching fish. I timed the speed of revolution yesterday and it was taking 31 seconds to do one revolution whereas at the start of the project it was taking only 9 seconds. The speed of revolution is determined by the current speed which, at that site is a function of the river height. If the river drops any further the trap may stop revolving completely! However we intend to remove the trap at the end of this week anyway.
Here are graphs showing the daily catch of salmon and sea trout smolts since we started operating the trap in March.
Salmon smolt numbers are dropping but the sea trout smolt catch has remained relatively steady. In the last few days we have seen quite a few salmon smolts with fungus on wounds such as bird damage. If we had seen some proper rain in the last month most of these smolts would have been away to sea by now, avoiding some of the stresses and be in the environment they are adapted to.
I mentioned in an earlier post that we were recording evidence of predator damage. This morning we had two fish with unusual but similar wounds. The salmon smolt pictured below had very clear teeth marks on its belly, with score marks on its flank. The cause, well we are not sure but it looks very like the bite marks you see on Australian surfers when there is a Great White about! I’m not suggesting that there are sharks in the River Ayr but the marks could be the work of a trout or other predatory fish.