With salmon catches continuing to drop year on year, the River Tweed Commission is looking at ways to solve the problem.
Salmon catches on the Tweed continued to fall in 2017 – following a national trend – with 7,003 caught, 15% down on the previous year, the commision revealed in its annual report on Monday.
While catches of salmon have been cyclical historically, governed by the changing currents and feeding patterns at sea, the commission is looking into the “phenomenon” of a rise in fish-eating birds along the catchment, in particular cormorants.
According to Andrew Douglas-Home’s Tweedbeats column, written last month, there are several large flocks of cormorants on the Tweed, ranging from 60 to 200 birds per flock and extending well above Kelso.
He adds: “They are not daily visitors, for they have established resident roosts here over the long autumn, winter and early spring months.”
The Tweed Foundation is tasked with monitoring numbers of piscivorous birds, and that information is used by the commission to support the application of a spring licence from Scottish Natural Heritage to scare the birds and also to remove a small number of birds to help protect the smolt run.
Based on the data collected, a further licence was granted in the autumn in order to expand the scaring regime, aimed at targeting those areas most vulnerable to predation on the river.
Commission clerk Fay Hieatt said: “The rise in cormorant numbers is a recent phenomenon. On the Tweed, the licence for cormorants this year was an increase on previous seasons.
“Many rivers are experiencing the same difficulty as the Tweed, with large numbers of cormorants now in river systems for many months at a time – only returning to the coast to breed – and a co-ordinated and concerted response with the support of Marine Scotland Science is the best approach to ensure that fishery boards around the country are able to tackle this issue.”
Scaring the birds can just shift the problem further up or downstream, she says.
Fay added: “To stay within the terms of the licence, scaring must be undertaken, and demonstrating that it has been – and whether or not it has been effective – assists in the licence granting the power to remove some birds from the system permanently.”
However, despite the low number of salmon catches, more are still caught on the Tweed than on any other UK river.
Catches of other fish, such as sea trout, were up on previous years, and there were reports of a good number of salmon moving upstream in the Tweed and its tributaries.
That led commission chairman Douglas Dobie to say in his report: “It is not unreasonable to be optimistic.
“Even a modest increase in adults returning to the river could significantly improve rod catches for both salmon and sea trout and see a welcome return of confidence in the river and the quality of the angling opportunities it can provide.”
However, a warning has been issued to anglers to keep the parasite gyrodactylus salaris at bay by cleaning and treating equipment that has been used outside Britain and Ireland in the preceding seven days before using it on the Tweed.
The report warns: “If this parasite gets into Tweed, it means the absolute end of our salmon.”