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AFSC/RACE/GAP/McConnaughey: Bristol Bay Reconnaissance Study-2002-Side scan sonar
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Environmental variables that are ecologically relevant and easily measured over large
areas are useful for modelling species distributions and habitats. Continuous acoustic,
sonar-backscatter data convey information about physical properties of the seabed,
and hence could be a valuable addition to that suite of variables. The potential utility
of acoustic backscatter was tested for improving habitat models of marine species
using data from a pilot sidescan-sonar survey conducted from 28 June to 3 July 2002
in the Bristol Bay region of the eastern Bering Sea (EBS). Raw digital backscatter
data were processed with QTC SIDEVIEW and CLAMS software to objectively segment bedform
based on statistical analysis of the echograms. Resultant acoustic variables - Q-values
(Q1, Q2, and Q3)-, representing the first three principal components of the data derived
from image analysis of backscatter echoes, and a complexity metric (compx) measuring
the variance of Q-values in a geographic area - were used in multiple linear regression
to model individual species abundance from bottom-trawl survey data.
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