HEWITT ET AL.: DEVELOPMENT AND USE OF SONAR MAPPING 



Continuing development of acoustic stock as- 

 sessment techniques rests on the comparison of 

 measurements and the best available theoretical 

 models for target strength and fish school bio- 

 mass. Improved instrumentation, particularly 

 data logging and processing equipment will make 

 the comparison more timely and useful. The 

 existing system will be used seasonally over the 

 entire California Current survey area (about 

 200,000 nautical miles^) in 1975. It is intended 

 that the data base thus furnished will allow a 

 balanced approach to such biological problems as 

 migration and patchiness of fish schools in the 

 context of better theory and instrumentation. 



ACKNOWLEDGMENTS 



We express our gratitude to the Marine Re- 

 search Committee of California for their support 

 and encouragement. The charter boat experiment 

 could not have been conducted without the assis- 

 tance of Peter Fletcher, Chairman of the Califor- 

 nia Fish and Game Commission, and Ray Arnett, 

 Director of the California Department of Fish and 

 Game. We extend our thanks to John Zankich 

 and his able crew aboard the FV Southern Ex- 

 plorer and to Peter Lipanovich and crew on the 

 FV Rigel for their exemplary effort. Robert Vent, 

 Isaac (Ed) Davies, and William Batzler of the 

 Naval Undersea Center provided equipment and 

 advice on a problem of common interest, i.e., the 

 acoustic characteristics of fish schools. Kenneth 

 Mais and his colleagues with the California De- 

 partment of Fish and Game Sea Survey were a 

 valuable source of experience. John Graves, a 

 graduate student at the University of California, 

 San Diego, and Gayle Turner, a NCAA Junior 

 Fellow, assisted in the field work. We are in- 

 debted to D. V. Holliday for his considerable assis- 

 tance in editing the manuscript. 



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297 



