Preliminary investigations into the response of O+ twaite shad (alosa fallax) to ultrasound and its potential as an entrainment deterrent

Water is abstracted from riverine, estuarine and marine environments to supply potable water, power stations, hydroelectric facilities and industry. Such abstractions inevitably carry with them the risk of fish entrainment, defined as „the drawing in of fish of any life stage at a water intake‟ (Turnpenny & O‟Keeffe, 2005). It is possible, however, that entrainment losses can be reduced to an acceptable level with the use of appropriate fish screening technologies. Fish protection solutions for water intakes are manifold and include: alterations to intake design; management of the abstraction regime; modification of existing screens to make them “fish friendly”; provision of fish return systems; and the installation of physical screens or behavioural deterrents to prevent or minimise entrainment. There are however a range of site specific constraints which influence the suitability of each solution.