We would like to thank Meridian Salmon Ltd for their help in carrying out these experiments. We are particularly grateful for the help from Area Manager Iain Webster and Site Managers Kenny Robertson and Alistair Geddes. Warren Harvey was very helpful in monitoring the equipment, filling in many data sheets and providing support at the test site. In Orkney we would like to thank Fiona Winthorpe and her staff for help in the field. Stephanie King, Livio Favaro, Emma Whittington, Pete Buchanan, and Caya Sievers helped with data collection and analysis.