SURVEYS to establish the reasons behind a salmon crisis on the Tweed has identified the central Borders as killing grounds for young fish.

And the Tweed Foundation, who are carrying out the studies, have also recorded almost record numbers of predatory birds residing on the river.

The world-famous river Tweed has gone from an all-time high 23,000 salmon catches in 2010 to an all-time low of 5,510 last year.

Hundreds of jobs which rely on the £24 million generated each year from angling are under threat with the rapid decline.

In April scientists released 60 transmitter-tagged salmon smolts into the Gala Water in a bid to find why there has been such a collapse in fish numbers.

The pilot project is aimed at estimating survival rates, identifying areas of high losses and establishing strategies to reduce the number of casualties.

The tracking study also complements previously conducted dietary analysis of goosanders and cormorants taken from the river.

While the study sample was low - up to two million smolts every year head for the North Sea - the findings have given experts at the Tweed Foundation plenty food for thought.

Of the 45 fish who made it into the Tweed only 16 reached the sea.

Almost all of smolt deaths that were recorded on the famous river happened between Galashiels and Sprouston.

A spokesman for the Tweed Foundation stated: "Before entering the main river, 45 smolts were detected at the first receiver located in the Gala Water at the smolt trap.

"Six smolts disappeared between this receiver and the first main river receiver at Galafoot.

"For the 23 smolts that didn't make it from Galafoot to Berwick, 21 were lost between Galafoot and Sprouston.

"Losses between receivers in this area were similar - seven between Galafoot and Upper Mertoun, six between Upper Mertoun and Makerstoun and eight between Makerstoun and Sprouston.

"There were only two losses between Sprouston and Berwick."

The tracking study took place just a month after researchers found the second-highest number of goosanders on the Tweed between Ettrickmouth and Berwick.

Ahead of male birds leaving for their annual migration to northern Scandinavia, a head count of 250 goosanders was recorded.

The study also found 44 cormorants on the river during the April count.

Although it has been established that some of the smolts were killed by goosanders due to final locations of the transmitters and an otter is likely behind some of the deaths on the Gala Water, limited technology has prevented identification of the type of predator responsible for the majority of the losses.

But a more extensive study will be carried out next year.

The spokesman added: "As the 2019 tracking work is a trial study with a relatively small sample size, caution must be taken in extrapolating the results to the wider population of salmon smolts and assigning losses to particular predators.

"Based on the findings of the 2019 trial smolt study, we will be repeating the tracking surveys in 2020 and 2021 with larger, more representative samples.

"One possibility is to use the study to track a larger sample of fish in 2020 and then compare those results with a similar-sized sample in 2021 using a different bird management strategy for goosanders and cormorants to see whether smolt survival can be improved."