Redd Surveying with drone technology
With Salmon spawning taking place throughout the catchment in November, Tweed Foundation staff took advantage of low water conditions in the second week of November to survey sections of the Upper Tweed and Whiteadder.
Counting Redds (where gravel is turned over by Hen fish to lay their eggs) is not a precise method of assessing the abundance of adult fish, but it does give us a chance to understand where and when spawning is taking place, helping us to interpret results from our juvenile monitoring. The traditional method of counting Redds involves walking along a stretch of river, noting their location. However, this is limited to quite narrow watercourses with clear, low water.
Using a recently acquired drone to look directly down into the water, we were able to survey sections of river up to 20 m wide and in some areas of the Upper Tweed, we were able to record the numbers of spawning fish as well. Walking alongside the drone, we were able to cover around 5 km of watercourse in a single day. Some drone footage of spawning fish can be found on The Tweed Foundation Facebook page.