Don Fishery Management Plan - RAFTS

4.2.5 Impact of Known ObstructionsSurvey PurposeThe remains of a number of weirs and abstraction points from now defunctmanufacturing industries are still present on the lower Don, but have been breached andare not thought to greatly delay fish migration. Four man-made obstructions on thecatchment have been highlighted which shall be evaluated for the impact they have onfish migration and the potential for improving access. They are:Loch dam on the Allt Veannaich (NJ 21851 08190)Weir on the Leochel Burn (NJ 55218 15890)Mill weir on the Esset Burn (NJ 57463 17950) andWeir on the Elrick Burn (NJ 89456 15440).Figure 4.2.2 Location of Known Obstructions to Fish Migration40Obstructions to MigrationN3020EssetBurnInverurieElrick BurnAlfordStrathdon10NeweMeoirVeannaichLeochelBurnAberdeenIncludes material based on spatial digital data from the Centre for Ecology and Hydrology. Copyrigh t CEH.8 Includes material based on Ordnance Survey 1:50,000 maps with the permission of the controller of H er Majesty’s Stationery Office. Crown copyright.00310 20 30 40 50 60 70 80 90Survey MethodThe habitat survey of the Don catchment will quantify the amount and quality of potentialfish habitat upstream of these obstructions and will identify any other potential obstaclesto fish migration on the river.Timed electric fishing of a large number of sites both up- and downstream of theobstacles will determine whether they are impassable to migratory fish or whether thereare certain flow conditions under which access is possible. Thirty timed sites above andbelow the obstructions would be preferable, but the length of the tributaries involvedindicates that this is unlikely to be achieved below the obstructions, in which case asmany sites as is practical should be fished below and at least the same number upstreamof the obstruction.26