Can cold water be used to remove lice?
Many Norwegian Atlantic salmon farms are using warm water thermal delousing to control salmon lice in farms. However, treatments can lead to poor welfare outcomes for fish. Kathy Overton alongside researchers from the University of Melbourne and Institute of Marine Research tested if reverse thermal delousing by rapidly reducing water temperatures to very low treatment temperatures could reduce salmon lice without any negative side effects for fish. To do this, they tested the effects of transferring salmon from 15°C to cold water at different temperatures and durations. They found that treatments of −1°C water for 10 min and 1°C for 240 min treatments reduced mobile lice loads, but created more skin and eye damage than controls. While cold water treatment reduce mobile lice numbers, the cold shock reaction in salmon (illustrated in the video below) was identified as a major hurdle in industry-scale application.
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