An alternative to thresholding during echo-integration data collection

Determination of threshold to reduce the amount of noise included in echo-integration data has always been a relatively arbitrary operation. Values selected in the field often are too low and allow noise integration or are too high and bias against low fish-density situations. This paper describes an alternative method for reduction of non-reverberatory (ambient) acoustical noise and electrical interference encountered during echo-integration data collection. Automatic or manual implementation may be easily accomplished.