NSWC/WOL/TR 76-161 



Solomons to explore improved techniques for the monitoring of fish 

 kill and chemical pollution. This program was helpful in 

 demonstrating some of the practical aspects of this type of work 

 and in showing the time and manpower requirements for monitoring. 

 These tests will be discussed in Chapter III, following a discussion 

 of possible approaches in Chapter II. 



II. POSSIBLE MONITORING TECHNIQUES 



2 . 1 Biological 



The monitoring of the effects of explosions on marine life 

 should consist of two phases: (1) Pre-shot exploration of the test 

 area to estimate the fish population density and to determine if 

 other forms of marine life are present; and (2) Post-shot evaluation 

 of the area affected by the shot to determine the number killed 

 of each species. There are varying degrees of effort in both of 

 these, and the method employed should be consistent with the nature 

 and magnitude of the tests. 



Pre-Shot Exploration 



The simplest and most practical method to detect free- 

 swimming fish is to patrol the test area with a small boat 

 containing a commercial fish-finder of the type used by sport 

 fishermen. This should be done shortly before the explosion 

 because of the possible migration of fish into the area between 

 the time of monitoring and the time of the test. 



At the present time, commercial fishermen and marine 

 biologists are developing acoustic scanning methods that can be 

 used to study the behavior of fish and to estimate population 

 densities. However, these systems are complex and expensive 2 > 3 ' * 

 and would not be practical for use on routine explosion tests. 



Remote sensing of schools of fish from aircraft and 

 satellites is a method also under development at the present time, 

 but this, too, should be considered only if large-scale oceanic 

 tests are contemplated. 



Bottom dwelling marine life, such as oysters, clams, and crabs, 

 require trawling for detection. More sophisticated methods 



T. Cushing, D. , 1973: The Detection of Fish, 200 pp., Pergamon 

 Press 



3. Mathisen, 0. A., 1975: Three Decades of Hydroacoustic Fish 

 Stock Assessment, MTS Journal, Vol. 9 No. 6, pp. 31 - 34. 



4. Peterson, M. L. , Clay, C. S., and Brandt, S. B. , 1976: Acoustic 

 Estimates of Fish Density and Scattering Function, J. Acoust. 

 Soc. Am., Vol. 60, No. 3, pp. 618 - 622. 



