Weir Science: hi-tech counters detect Tweed’s second highest number of salmon on record

If you thought a fish counter is where you choose fish at Morrisons, think again. These infra-red scanners and cameras were first installed in some areas of Scotland’s Tweed District in the year 2000 and three hi-tech versions now monitor salmon levels. The good news is that two tributaries saw the second highest number of salmon on record in 2024, reveals the fly fishing permits and accommodation booking service FishPal.

EDINBURGH, Scotland, 2025-Mar-20 — /Travel PR News/ — While fly fishing on stretches of Scotland’s River Tweed and its tributaries sounds like a perfect getaway from the 21st century, modern technology is actually helping conservationists and anglers gain in-depth knowledge of the waters. Hi-tech fish counters have detected the second-highest number of salmon on record in 2024 in two of the three tributaries of the Tweed where they are installed.

The counters’ infra-red scanners record fish numbers and their cameras identify the species as they pass through narrow weirs in the three tributaries. The results are very encouraging for conservationists and anglers, reports the fly fishing permit and accommodation booking service FishPal.

Angling expert Will Draper, Head of FishPal, says: ‘The Tweed is the second-longest river in Scotland and takes great pride in the fact that it produces more salmon caught to the fly than any other river in Britain. Flowing into it are a number of tributaries, including the Whiteadder in Bottom Tweed and Gala Water and Ettrick in Middle Tweed. Narrow weirs (known as caulds around the Tweed) on these tributaries are perfect places to install fish counters. The wide stretches of the main Tweed are difficult to monitor but these weirs, originally built to divert water to local mills, are ideal places to site the equipment.

‘The great news is that Gala Water recorded its second-highest total on record in 2024 and so did the Whiteadder, while the Ettrick also saw an increase on the previous year. A total of 2,168 salmon were recorded by the counters on the Gala, well above the average of 1,363. Likewise, 890 were counted on the Whiteadder, significantly above the average of 628.

‘It’s also great news that the Ettrick saw numbers climbing again, as many of the Tweed’s spring stock spawn in the Ettrick system. The counters’ cameras are also useful for monitoring incidences of Saprolegnia, a kind of fungal infection sometimes found in salmon, as it can be seen in the images. While light infections may look unsightly, they can heal if conditions allow. Monitoring could prove vital for future control of this disease, which is actually caused by a cold water mould.

‘Each of these tributaries has its own unique history and characteristics that have influenced the fish populations that they contain. We can also use these numbers to build up a picture of the overall fish numbers in the area, as the catchment area upstream of the fish counters covers 15.4% of the Tweed District.

‘As we move further into March, spring salmon fishing is ramping up across Scotland and Ireland. Anglers can book permits and accommodation for the Tweed now, with rod permits available from just £35 a day on some beats. Multiple beats on the Tweed recorded good fishing last week. Birgham Dub was the standout performer, producing 10 salmon, while Lower Birgham, Hendersyde and Boleside all had multiple catches.​

‘With increasing activity and stable water levels, the Tweed continues to offer great early-season opportunities for those looking to land their first spring salmon of the year.​ FishPal’s free videos keep anglers up to date with what’s happening and conditions on our rivers and fisheries. The latest updates include coverage of this year’s River Tweed opening ceremony in February. This traditional event, led by Her Grace, The Duchess of Roxburghe, was a vibrant community celebration with pipers accompanying the customary blessing of the river with a dram of whisky!

‘For more information on booking permits and accommodation near all of Scotland’s great fishing rivers in 2025, see https://www.fishpal.com/Scotland/

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