bottery circuit- 

 firing position - 



closed circuit (safe) 



14 gage leading wire — 



EB cap with 20 gage 

 4 ft. leg wire and charge—^. 



Calculation of Required Voltage 



14 gage lead wire ■ 2 52 ohms per lOOOf t 

 EB caps, w/4ft leg wires ■ 1.53 ohms/cap 

 minimum current per cap = 3 amps 

 100ft. I4gage lead wire = 0.25 ohms 

 3 EB caps = 4.59 ohms 



circuit resistance =4.84 ohms 



volts ■ ohms x amps 



= 484(0.3)3 = 4.36 



«0N* 



I OFF \ 



Figure 6. --Dynamite circuit used at the Kvichak River counting 

 towers and calculation of required voltage. 



to assume a normal pattern shortly after 

 recovery activity ceased, and particularly 

 so during heavy migration. 



The counts for three days during 

 which recovery attempts were made are 

 shown in table 1. The hourly counts were 

 of 10 minutes duration each and were 

 made on or near the hour from tower No. 1 

 and about 15 minutes after the hour from 

 tower No. 2. Of the five recovery attempts 

 made on these days little or no effect on 

 subsequent counts can be seen. 



The 1959 Kvichak tag recovery effort 

 emphasized the importance of positively 

 identifying a tag from counting towers. 

 The Kvichak recovery effort was Intended 

 to be limited to high seas tags from the 

 1958 and 1959 high seas tagging experi- 

 ments. These tags consisted of j-inch, 

 white Petersen disc tags; 3/4-inch, red 

 and white Petersen disc tags; and white 

 spaghetti tags. During the Kvichak run 



four recovery attempts were made on 

 tag-bearing salmon. In each of these 

 attempts the observer was reasonably 

 certain that the tag he saw was a high 

 seas tag; however, when the fish were 

 retrieved, three were found to be local 

 Kvichak tags and one was a Fish and 

 Wildlife Service Nushagak Bay tag. In 

 two of these recoveries a yellow disc 

 was mistaken for a white disc. In addi- 

 tion, two recoveries were made of salmon 

 bearing predator scars which were mis- 

 taken for white disc tags. 



The full-time observation periods 

 were generally limited to times of good 

 visibility when It was believed that a tag 

 could be positively Identified. Under Ideal 

 conditions of calm water surface, mini- 

 mum surface glare, and clear water this 

 probably was true but under average con- 

 ditions it was difficult to distinguish a 

 1-inch disc tag from a 5/8-inch disc tag 

 or a yellow tag from a white one. 



CONCLUSION 



An underwater explosion of dynamite 

 was found to be a very effective means 

 of killing adult red salmon. Negligible 

 external damage to the fish occurred 

 from the explosions, but there was ex- 

 tensive internal damage caused which 

 apparently was due to the difference in 

 density between the air bladder and sur- 

 rounding organs and tissues. 



In tests using f-stick charges of 

 40 -percent ammonium gelatin dynamite 

 a direct relationship was found to exist 

 between water depth and the effective 

 killing range of the pressure wave. This 

 range was increased by approximately 

 15 percent at the 4- and 6-foot depths 

 by doubling the charge strength. It was 

 also found that a solid object in the path 

 of the pressure wave reduced the lethal 

 range in that direction. 



Dynamite can be effectively used in 

 the recovery of tagged adult red salmon 

 from large rivers. By the use of multiple, 

 j-stick dynamite charges the migration 

 path can be completely covered. Detonation 

 of the charges can be accomplished from 

 the counting towers by the tower watch- 

 man. 



