New Counter at Nethermills

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Ayrshire Rivers Trust have kindly supplied details of how things are going at the new Nethermills counter.

While they can’t publish real time counts of the fish entering the river, they can inform readers as to how things are going in terms of the counter’s performance and some details of the fish they have been observing going through the fish passes at Nethermills.

The counter is designed to record fish moving through the upper fish pass. This doesn’t include small trout below around 40cm but it may record some. Any trout and salmon over that sort of size should hopefully be recorded both by the counter and the 3 video cameras that operate 24 hours and 7 days a week.

A night time view of the cameras illuminated by infra red lights.

With any new counter, there has to be a period of tuning to ensure it operates under all circumstances and as designed. This can take time to get the accuracy to an acceptable level and the Ayr counter is proving to have a few teething difficulties so far with quite a number of fish incorrectly recorded or missed. While that may not be ideal, the designers Fishtek, are still working hard to resolve the issues ably assisted by Ayrshire Rivers Trust who will manage the cleaning and downloads regularly. They operate this counter for Marine Scotland Science who funded the device and installation. ART are funding the time for maintenance and downloads and to a large degree the analysis.

With some validation having been performed by biologists at ART, they say that the numbers of salmon going through is encouraging at times despite the lack of water this year.   On most days in June and July (that have been analysed, there were salmon moving upstream but on days when there was a slight lift in the water, the numbers increased. Hopefully these runs will continue late into the season but the last few years have been poorer towards the back end. Time will tell.

So far the most salmon recorded in a single day was 39 but not every day’s video has been scrutinised yet. It takes up to 7 hours to review one day’s videos depending on water clarity and viewing conditions. Bright sunshine can lead to surface glare and missed fish so the best conditions are on dull overcast days with flat lighting. There is one overhead camera and two underwater side viewing cameras. The most useful is the overhead camera as this allows the fish lengths to be estimated and ART have reported some very large fish indeed, some in excess of 90cm long moving through.

A decent sized June salmon in the fish pass (un retouched)


One of very few sea trout entering the river so far


An overhead shot with a salmon of around 60 – 63 cm moving through the counter and fish pass

While the side imaging cameras are perhaps less useful in terms of length, they do afford the opportunity to assess the condition, lice levels, damage, sex etc., but much depends on the water clarity and water levels, light and when the cameras were last cleaned. Currently ART staff visit and clean them every 6 days to ensure maximum opportunity to see the fish clearly but this may reduce once the counter becomes more accurate or sunshine levels reduce as it is weed growth and algae that cause most problems.

ART provided a few nice clear shots that show fish moving through. They will provide more information on how things are going as they can.

The count will not be available anytime soon as there’s still much to do to improve accuracy.  Eventually however, the count, average size, run timings etc will all become clear; what better management tool could there be?

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