The footpath guide 'Paths around Kelso Morebattle and Yetholm' (Scottish Borders Council 2011) informs that this was a salmon trap. Presumably the fish swam into cages to be lifted out from above. Nowadays this stretch of river is prized fishing territory, but it is equally enjoyable for the impecunious pedestrian.
Uploaded to Geograph by Jim Barton on 30 April 2013
Photo © Jim Barton, 30 April 2013. Licensed for reuse under this Creative Commons licence