Electronic system and data processing techniques for estimating fish abundance

Abstract

Among the techniques employed to estimate the stock size of pelagic fishes, acoustics has proven to be the most versatile and cost effective method. Furthermore, modern digital data processing equipment is paving the way for accurate onboard estimates of fish densities thus providing for optimum utilization of ship time and scientific personnel. Echo integration is a method of estimating fish densities acoustically, which, unlike echo counting, improves with increasing density. A Digital Data Acquisition and Processing System (DDAPS) has been developed at the University of Washington to implement the integration technique in real-time for two echo-sounders and 10 depth strata simultaneously. The system, which includes a small GP computer, contains other important features such as an automatic bottom following facility.