It has been ten days since the last update so apologies for that. The numbers of smolts caught in the Avon traps increased greatly last week with the water temperatures increasing in the lovely sunny weather. This weekend it has turned a lot colder with snow falling down to below 500′.
The total catch in the Avon traps to date is 2647 salmon and 166 trout. The trout numbers this year are similar to 2014 but on this day last year we had caught 4543 salmon. We are expecting a lower smolt run this year due to the impact of the big August spate but with the exception of last week the winter of 2014/2015 and the spring of 2015 have been more normal compared to the exceptionally mild conditions pertaining last year. So the catch is lower so far but the peak of the run is likely to be later this year.
The catches in the Tommore Burn trap have been steady at a low level over the last two weeks although the 13 salmon smolts caught today was the best daily catch since the 9th April. The burn has been low so we may well see another burst of fish if the level rises again. In total we have caught 296 salmon and 32 trout in the Tommore traps. The vast majority of the salmon have been fin clipped but there is a proportion which have intact fins and may be wild smolts produced in the accessible part of the burn above the trap.
Salmon smolt catch at the Avon traps related to 9am river height in cm! Smolt number are the black bars, river height the blue line. (ingore the fact it says trout on the y-axis, that is an error)
Tommore salmon catch related to burn height (cm)
Avon salmon smolt catch related to river temperature. Temperature is a realy important factor for smolt migration. This week the numbers of salmon smolts captured increased on the back of a rise in temperature despite the river height falling.
Tommore Burn trap salmon catch related to burn temperature. In the Tommore Burn the water level appears to be a more important migration cue. Not surprising considering the small size of the burn. This may also explain why the migration appears to have been a lot earlier in the burn than in the river; the fish may take advantage of the higher early spring water levels.
We have undertaken a number of recapture trials in the Avon. I don’t have the results at hand but the recapture rate appears to be similar to those obtained in 2014. We also monitor the Avon traps for fin clipped fish and yesterday there were 6. Again I don’t have all the figures available but that was the highest daily catch of fin clipped fish. The recent catches in the Tommore Burn have been low so these fin clipped fish may have been earlier migrants that were waiting in the Avon until ready to move further downstream. Alternatively they may have been fish that left the Tommore Burn as autumn parr. Without applying a further mark to the Tommore fish we won’t be able to establish that.
On this date last year we had caught 146 salmon parr in the Avon traps. These are generally smaller fish in the 60-85mm range which will not smolt this year. Steve and I mentioned that we had caught comparatively few so far this spring; probably in the order of 30-40. Not sure what the implications are of that, if anything.
The forecast is for the colder weather to remain this week so we are expecting steady catches in the Avon traps.
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