Sidescan Sonar
Klein 5410 (455 kHz) sidescan sonar towfish
Raw digital backscatter data from a Klein model 5410 sidescan sonar system were processed with QTC SIDEVIEW and CLAMS software. The resultant acoustic variables – three Q-values (Q1, Q2, Q3) representing the first three principal components of the data derived from image analysis of backscatter echoes, and a complexity metric measuring the variance of the Q-values in a geographic area – were used in multiple linear regression to model individual species abundance from bottom trawl survey data. Out of 35 taxa common in Bristol Bay, these acoustic variables were able to explain 9-54% of the variability in distribution of flathead sole, Pacific cod, walleye pollock, red king crab, basket star, and sponges. (Yeung and McConnaughey 2007). Combined with other environmental variables (e.g. temperature) collected during annual RACE bottom trawl surveys, our models explain a total of 67-86% of variability in the distribution and abundance of these species.
 
Distribution of Q1 values (the first principal component)
derived from sidescan backscatter parameters along survey trackline.
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