Evaluation of Low-Frequency Sound Transducers for Guiding Salmon Smolts Away from a Navigation Lock
Behavioral Technologies for Fish Guidance: American Fisheries Society Symposium
American Fisheries Society
We evaluated the efficacy of a commercially manufactured, low-frequency (300-400Hz) sound transducer to guide yearling sockeye salmon Oncorhynchus nerka, coho salmon O. kisutch, and subyearling summer/fall chinook salmon O. tshawytscha smolts away from a lock and navigation channel. Tests were conducted during the spring of 1997 within the large lock chamber at the Hiram M. Chittenden Lucks, a navigation project in Seattle, Washington. Two low-frequency acoustic transducers (300/400 Hz) were deployed at the entrance to the large lock chamber and were operated over a 29 d period with four daily treatments (4 h periods, from 0530 to 2130) of sound on and sound off. A randomized block design (with day as the blocking factor) was used to determine treatment periods. Treatment and control periods within a day were randomly selected with two treatments (sound-on) and two control (sound-off) periods per day. Smolt density (average number of fish/m super(3)) in the lock chamber (downstream of the transducers) during treatment and control was estimated from acoustic data collected with a split-beam echo sounder, with species composition verified by purse seining. The sound treatment did not impact the density of salmonids measured within the lock chamber. Analysis of variance (ANOVA) showed no significant difference in the density of salmonids in the lock chamber between sound treatments or between days of the study. Similarly, no difference was detected between sound treatments at different times of day. The results from our evaluation suggest that low-frequency sound is not an effective means of guiding salmon smolts.