THORNE: DIGITAL DATA-PROCESSING SYSTEM 



the integrated voltages from the DDAPS in 

 1971. The theoretical variance of the relation- 

 ship should be considerably less according to 

 the model of Moose and Ehrenberg (1971). The 

 greater part of the observed variability is un- 

 doubtedly associated with the catching process. 

 Further development and understanding of 

 methods of target strength measurement are 

 needed so that this variability may be reduced 

 and absolute densities can be directly estimated. 



ACKNOWLEDGMENTS 



The digital data acquisition and processing 

 system (DDAPS) was developed under the Uni- 

 versity of Washington Sea Grant Marine Acous- 

 tics Program in cooperation with the North- 

 west Fisheries Center, NMFS, Seattle. Both 

 Sea Grant and NMFS are agencies of the Na- 

 tional Oceanic and Atmospheric Administra- 

 tion, U.S. Department of Commerce. 



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