To improve our understanding of in-river salmon smolt survival, 2020 was the second year of a four year smolt tracking study carried out on Tweed. With the last recorded movements of tagged smolts in early June, 338,000 recorded tag detections have now been processed and analysed. The summary online report can be found at https://arcg.is/191v4v0 .
The main river results for 2020 were very similar to 2019, with an overall loss of 57.4% in 2020 compared to 59% in 2019 and again most losses were in the Middle Tweed between Galafoot and Kelso. Work in 2021 and 2022 will focus on whether these losses are representative of the natural population.
With a larger sample size in 2020 (240 vs 60 in 2019), a surprising result was the high losses of smolts detected in the lower Gala Water, with around 30% of tagged fish disappearing in this area. There is no obvious reason for these results, particularly as recorded numbers of fish eating birds are very low in this section of river.
Commenting on the report, James Hunt, The Tweed Foundation Biologist says :-
“The Tweed smolt tracking project continues to provide new insights into the movement patterns of our smolts and where losses are taking place. With the baseline of data that we are collecting, we now have the potential to investigate why these losses are taking place and whether changes in river management, particularly in relation to the bird licence for fish eating birds, can lead to measureable improvements in smolts survival.”