NSWC/WOL/TR 76-161 



specialists, including biologists and chemists, should be involved, 

 and more attention should be given to the selection of the site 

 and the time of the year. 



It is not clear at the present time how reliable a particular 

 monitoring method would be. Consider for example, Shot 4 in the 

 1976 series. A rough estimate was made of 1000 fish killed within 

 a radius of 300 meters. The first trawl collected 26 fish, or 

 2.6% of the estimated total. 



It was estimated that the actual trawl width when under tow 

 is about 1.8 meters. The trawl was towed about 450 meters, 

 resulting in a sweep of 8100 square meters of surface. Using the 

 estimated fish-kill radius of 300 meters gives a circular surface 

 area of 283,000 square meters. The swept area was 2.9% of the 

 estimated kill area, which is consistent with the percentage of 

 fish collected. This is doubtless fortuitous, as the fish 

 distribution was patchy and the radius of fish kill was a rough 

 estimate. 



The most reliable count would be one based on the collection 

 of every floating fish. However, the question of the number of 

 dead fish on the bottom has not been answered. There is no simple 



fallen to the bottom decompose and rise to the surface. On a 

 practical basis, an accuracy better than + 50% should probably not 

 be expected. 



The accuracy of chemical analysis of a sample can be better 

 than + 1% in laboratory work and probably better than + 10% with 

 field procedures. However, the overall reliability depends 

 highly on the number of samples and the locations and times of 

 sampling. Because of the nature of the turbulent motions in the 

 environment and in the surface pools, an individual sample could 

 easily be taken in a spot where the concentration is considerably 

 above or below average. If an accuracy better than + 50% is 

 required, it is necessary to traverse an explosion pool with 

 probes and acquire continuous recordings of each traversal. 



In the case of relatively small-scale routine testing, such 

 as that done by the Naval Surface Weapons Center in the Potomac 

 River, Patuxent River, and Chesapeake Bay with a crew of four to 

 five men, a continuing monitoring program, including Procedures 

 such as II or III in Table 4.1 and an occasional chemical monitoring 

 with Procedure I in Table 4.2 seems to be the maximum practicable 

 effort. However, even this would require the addition of one man 

 to the field crew. A member of the regular experimental group 

 could operate the boat, and the additional man could be responsible 

 for the collection, sorting, weighing, and identification of fish 

 specimens and the collection of water samples. When the collection 



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