adult fish was different from that of untreated 

 tags. 



Procedure: Four groups of 50 adult fish (mean 

 length 122 mm) were selected and tagged using 

 the scalpel-forceps method. One group was 

 tagged with clean dry tags, another with tags 

 treated with Liquamycin (oxytetracycline hy- 

 drochloride, a broad base antibiotic), and two 

 groups with Roccal (a germicide and disinfec- 

 tant) at concentrations of 1:1,000 and 1:10,000. 



Results: The loss of tags treated with Li- 

 quamycin was 40% , that of tags treated with 

 Roccal was 22-26% , and that of untreated tags 

 was 22% (Table 1). 



Discussion: The higher shedding rate of 

 treated tags may have resulted because incision 

 healing was slowed by the antibiotics. Bayliff 

 and Klima (1962) mention that antibiotics can 

 slow the rate of healing, although they found 

 no increased shedding of antibiotic-treated tags 

 in their study. Since untreated clean dry tags 

 had the lowest rate of tag loss and were more 

 easily handled, they were selected for future 

 experiments. 



Table 1. — Experiment 1; effects of an antibiotic and 

 a disinfectant on the mortality and shedding in groups 

 of 50 adult fish. 



Table 2. --Experiment 2; effects of tagging location 

 and direction of insertion on the mortality and 

 shedding in groups of 50 adult fish. 



Tag treatment 



Dead 



Shed 



Total 



loss 





1 



dumber 



Number 



Percent 



Liquamycin 



4 



16 



20 



40 



1:1,000 Roccal 



2 



9 



11 



22 



1:10,000 Roccal 



1 



12 



13 



26 



Untreated 



7 



4 



11 



22 



Control 











(not tagged) 



1 



— 



1 



2 



Experiment 2 



Objective: To determine whether injecting 

 the tags posteriorly, rather than anteriorly, 

 into the adult fish by the scapel-forceps method 

 would reduce tag loss. 



Procedure: Two groups of 50 fish (mean 

 length 150 mm) were selected. In Group 1 the 

 tag was inserted into the fish anteriorly as in 

 Experiment 1. In Group 2 the tag was inserted 



Tagging 

 method 



Dead Shed 



Total 



loss 



Anterior 

 Posterior 



Number 



2 1 

 7 



Number 

 3 

 7 



Percent 

 6 



14 



posteriorly through an incision 15 mm above 

 the pectoral fin tip. 



Results: Insertion of tags anteriorly resulted 

 in less tag loss (Table 2). 



Discussion: Since Bayliff and Klima (1962) 

 also had similar results, we decided to insert 

 tags anteriorly. 



Experiment 3 



Objective: To determine which method of in- 

 serting the tags — scalpel-forceps, tagging gun, 

 or gun-forceps — causes the least tag loss in 

 adult fish. 



Procedure: Fish in groups of 50 (mean length 

 131 mm) were tagged using three methods: (1) 

 scalpel and forceps, (2) a long-barreled tagging 

 gun, and (3) tagging gun and forceps. In method 

 3 the tag was pushed deeper into the body 

 cavity with forceps because the tag, when in- 

 serted with the long-barreled tagging gun, did 

 not appear to penetrate deeply enough to pre- 

 vent shedding. 



Results: The mortality from all methods was 

 low, but shedding of tags inserted with the gun 

 was high (Table 3). 



Discussion: Since the tagging-gun method 

 was much faster and is not as dangerous to the 

 taggers as the other two methods which involve 

 an open scalpel blade and since most of the 

 tags were probably shed because of poor tag 

 penetration with the long-barreled gun, we de- 

 cided to conduct all further tests with recently 

 purchased short-barreled guns. Short-barreled 

 guns, which had about one-half of the tag pro- 

 truding from the barrel, injected tags farther 

 into the body cavity of fish than did long- 

 barreled guns, which had only about one-eighth 

 of the tag protruding from the barrel. 



