Evaluation of low and high frequency sound for enhancing fish screening facilities to protect outmigrating salmonids
high frequency, sound, pumps, irrigation, irrigation canal, canal, screens, mesh, fish screen, rainbow trout, trout, chinook, salmon, low frequencies, startle response, juvenile, salmonids, hatchery
U.S. Department of Energy, Bonneville Power Administration
Fish screening facilities are used to prevent fish from being entrained in pumps ortrapped in irrigation canals. Screens have diminished utility when they are needed to protect fishthat are less than 40 mm long. Small mesh screens are easily clogged and tolerances for sealingthe sides and bottoms of screen civil works are difficult to construct and maintain. If fish screenscould be enhanced with a behavioural barrier component, screen mesh and seals may not needto be so small. We subjected 30-70 mm rainbow trout (Oncorhynchus mykiss) and Chinooksalmon (O. tshawytscha) fry to low frequency (7-14 Hz) and higher frequency (150, 180, and 200Hz) sound fields to assess the possibility of using underwater sound as a behavioural barrier forenhancing fish screening facilities. Both species responded to infrasound by an initial startleresponse followed by a flight path away from the source and to deeper water. Theseobservations indicate that juvenile salmonids, as small as 30 mm long, have infrasound detectioncapability when the particle motion exceeds 10-2 m/s 2 at a frequency of 7-10 Hz. Additionally, itmay be possible to predict the direction of response for juvenile salmonids. We observed astartle response in wild Chinook salmon when exposed to high-intensity (162 dB //ìPa), 150-Hzpure tone sound. No observable effects were noted on hatchery Chinook salmon or rainbow troutfry when exposed to 150, 180, or 200 Hz high-intensity sound.