were incapable of coordinated swimming 

 activity during this period. Their motions 

 were similar in every case and easily 

 detectable, thus making it possible without 

 internal examination to determine when an 

 explosion had had a lethal effect. These 

 reactions may be described as follows: 

 For the first few minutes the fish were 

 very listless, either belly up orwith tend- 

 ency to roll onto side, breathing action 

 very faint or undetectable, spasmodic 

 flaring of opercula and gills. Later, there 

 were observed continued spasms of the 

 gill muscles, and periodic spurts of vio- 

 lent, uncoordinated lateral muscle con- 

 tractions. Within ten minutes all fish had 

 died. 



Fish killed in tag recovery attempts 

 were sometimes within a foot or two of 

 the charge upon detonation. Internal dam- 

 age to these fish was similar but slightly 

 more extensive than in those killed on the 

 periphery of the blast. These fish were 

 either killed instantly or died shortly after 

 the blast. 



DESCRIPTION AND RESULTS 

 OF VARIABLES TESTED 



Effect of water depth on lethal range 



Experiments using a charge strength 

 of one -half stick were conducted to find 

 the lethal range at varying water depths. 

 The depths tested were 2, 3, 4, 5, and 

 6 feet. During testing at each of these 

 depths the charge was placed directly on 

 the bottom and the caged salmon were 

 held within several inches of the bottom. 

 The usual procedure was to place a fish 

 at a desired distance from the charge and 

 then detonate the charge. The fish was 

 subsequently observed for a period of at 

 least 15 minutes for signs of abnormal 

 behavior. If none were visible the distance 

 was decreased by a foot. This process 

 containued until abnormal behavior of 

 the fish was observed indicating damage 

 had occurred. Occasionally, fish appeared 

 to be listless but these were capable of 

 coordinated swimming motion for at least 

 15 minutes after the blast, and for the 

 purposes of tag recovery, were considered 

 to have escaped the effects of the blast. 

 In each case where a fish showed abnormal 

 behavior it was held in a live box for 

 further observation. 



The results of these experiments are 

 shown in figure 2. The killing range in 

 shallow water is short, being about 3 feet 

 in 2 feet of water. The range increases 

 rapidly in greater water depths to about 

 16 feet in 6 feet of water. The curve 

 suggests a maximum range for a j-stick 

 charge of about 18 feet. 



Figure 2. 



12 3 4 5 



DEPTH OF WATER IN FEET 



-Lethal range of one -half stick of dynamite in water 

 of various depths. 



The varying reflective qualities of 

 bottom materials may greatly influence 

 the lethal range of a given charge. Fine 

 silt and mud sediment will more effec- 

 tively absorb a portion of the pressure 

 wave than will a hard-packed bottom 

 material (Fox, 1950). Bottom materials 

 over which the Kvichak experiments were 

 conducted had good reflective qualities 

 and may have increased the values ob- 

 tained for the lethal ranges. 



Effect of varying charge strength on the 

 lethal range 



Early in the testing it became obvious 

 that small charges would be adequate for 

 tag recovery purposes and for this reason 



