Smolt traps update

I have not posted any recent updates from the smolt traps, mainly because catches have been low. However in the Dulnain over the last week catches improved with today’s catch of 91 salmon smolts/presmolts the best to date. River levels remain low, and cold; it was only 2.8oC at 0930 this morning and the gauge was reading 10cm; it doesn’t go much lower.

Salmon smolt/presmolt catch to date.  I forgot to take a note of the river levels and temperatures over the last week but the level was 10cm today, although it had risen a few centimetres, to about 13cm, during the few days prior.

The state of smoltification is advancing all the time with smolts now outnumbering presmolts by a margin.

Selection of salmon smolts photographed during processing today. Most of these would have been classed as smolts although their silver coating will become more pronounced as the spring progresses, and as they migrate downstream.

We have now completed three recapture trials with recapture rates of 20%/20%/22%, although there may be one or two more fish from the last marking still to arrive back at the trapping site. This tells us that during these conditions (low and cold) that we are catching about one in five of the smolts migrating downstream. We will continue to mark fish over the remainder of the smolt run, particularly if river heights and temperatures increase, as they must. Virtually all the fish from each marking have been recaptured the next day with only one or two stragglers.

The number of salmon smolts/presmolts caught so far is 592 with an additional 88 parr. The parr are generally less than 90mm and will not smolt until next year. at the earliest. It is good to see these little parr as fry counts in 2016 were lower than in previous years in the Dulnain, primarily due to the spates over the winter of 15/16.

The trout catches have been variable but todays catch was also the highest to date.

This graph shows the trout catch to date. The total of all trout, including parr, so far is 216. Most of the trout caught have been parr with a few smolts starting to appear. Note the temp today was 2.8oC, little wonder with the frosty night.

In the Tommore Burn there have been very few fish caught recently, the total number of fin clipped salmon smolts trapped so far is 45, much lower than in the last two years, but we could easily catch 200 in one night if conditions change. The level in the Tommore Burn is currently 10cm. That is the lowest level recorded since we started operating the trap in 2015, there is therefore little incentive for the smolts to move, although if levels remain low they will have to migrate. Flows are critical at smolt time and a nice wee spate in the near future would be very welcome.




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