USE OF DYNAMITE TO RECOVER TAGGED SALMON 1 



by 



Richard W. Tyler 



ABSTRACT 



Experiments were conducted in July 1959, on the Kvichak River at 

 Igiugig, Alaska, to determine the effect on adult salmon of an underwater 

 explosion of dynamite and to determine whether dynamite could be used 

 to recover tagged salmon from large rivers. 



The experiments show that dynamite is an effective means of killing 

 salmon and that the direction and lethal range of the blast can be controlled 

 by varying the charge strength and water depth, and by the use of de - 

 flectors. 



Techniques for the use of dynamite in tag recovery work were de- 

 vised and put into use at the Kvichak counting sites where they proved 

 successful in the recovery of four tags. 



Experiments involving the underwater 

 detonation of dynamite were conducted for 

 two purposes: To determine the effective- 

 ness of an underwater explosion in killing 

 or immobilizing adult salmon, and to de- 

 termine if dynamite could be effectively 

 used to recover tagged salmon from large 

 Bristol Bay rivers. 



Since 1956 the Fisheries Research 

 Institute, under contract with the United 

 States (Bureau of Commercial Fisheries), 

 has conducted salmon tagging experiments 

 each year in the offshore waters of the 

 North Pacific and Bering Seas. These 

 studies represent a part of the research 

 program being carried out under the aus- 

 pices of the International North Pacific 



1 Contribution No. 75, College of Fisheries, University of 

 Washington. 



Fisheries Commission of which Canada, 

 Japan, and the United States are member 

 nations. The purpose of this research is 

 to determine the distribution of salmon at 

 sea with respect to continent of origin. 

 Many of these salmon are bound for the 

 rivers of Bristol Bay, Alaska as evidenced 

 by tag returns from the Bristol Bay gill - 

 net fishery and from records of tagged 

 salmon observations at counting stations 

 along Bristol Bay rivers. In addition to 

 these experiments, the U. S. Bureau of 

 Commercial Fisheries has conducted 

 several salmon tagging experiments in 

 Bristol Bay estuaries since 1955. 



With the adoption of towers in 1957 

 as a means of counting the escapement 

 of adult salmon into Bristol Bay rivers, 

 much difficulty has been experienced in 

 recovering tagged salmon from this 



