SYRINGE 

 NEEDLE 



INJECTOR HEAD 

 (3cc SYRINGE 

 FITS INSIDE) 



HOSE CLAMP 



PLUNGER FOR SYRINGE 

 IS INSIDE THIS SECTION 



RUBBER BAND 



1" (2.5 cm) ALUMINUM TUBING 



T-Jl. 



I I 

 I I 



^ 



TAG 

 APPLICATOR 

 DART TAG 

 (INSIDE APPLICATOR) 



SPRING-LOADED 

 INSIDE 



FiCURE 1. — A tag and injection device for large pelagic fish. 



Results and Discussion 



On the night of 27-28 January 1986, the crew 

 and passengers of a 34 m long-range sportfishing 

 boat. Royal Polaris , tagged, injected, and released 

 36 yellowfin tuna, all estimated to be >45 kg. Six 

 of these fish were recaptured from 14 to 83 days 

 later, indicating that the tagged fish were active 

 and feeding. 



Differences in return rates between this 

 method and the padded deck method (Table 1 ) are 

 possibly due to such factors as differences in size 

 and age of the fish tagged, fishing effort in the 

 tagging area, or the amount of stress caused by 

 different fishing methods, rather than some char- 

 acteristic of the pole method. 



The otoliths from recaptured fish displayed the 

 yellow-green fluorescent mark when viewed 

 under ultraviolet light, but the marks appeared 

 much fainter than those on otoliths returned from 

 the program which used a padded deck. Since the 

 dosage each fish received was monitored by the 

 amount (if any) left in the syringe after applica- 

 tion, failure of the device to deliver the full 

 amount of OTC was ruled out. Similarly, the 

 needle size was nearly the same for both treat- 

 ments, and pore seepage is assumed equal. There 

 were, however, differences in the type of OTC 

 used. Liquamycin LA-200, used with the pole de- 

 vice, was found to contain a slow-release agent 

 (2-pyrrolidone) which extends the antibiotic ef- 

 fect over time. Evidently the agent also slows de- 



Table 1. — Comparison of tag return rates from the padded 

 deck method (unpubl. data, Inter-American Tropical Tuna 

 Commission, La Jolla, CA) and pole injection device method for 

 yellowfin 100 cm (20.5 kg) at release. 



Releases 



Returns 



Percent 



Padded deck 

 Pole device 



49 



36 



16 



6 



32.7 

 16.7 



position of the fluorophors such that their concen- 

 tration in the area of osteogenesis and hence the 

 brilliance of the mark is diminished. I recommend 

 that an OTC solution without slow-release agents 

 be used, e.g., Anchor Oxy-Tet 100, as in previous 

 experiments. 



Acknowledgments 



I appreciate the assistance of J. Allen and his 

 staff at the San Diego Wild Animal Park, and 

 T. Dunn for input into the design of the injection 

 equipment, and the crew and passengers of the 

 Royal Polaris, especially J. Heyn, W. Lang, 

 F. LoPreste, and C. Miller, for their assistance 

 and dedication to the project. 



Literature Cited 



Anonymous 



1982. Annual Report of the Inter-American Tropical 

 Tuna Commission, 1981. Inter-Am. Trop. Tuna Comm., 

 p. 27. 



Bayliff. W H . AND K N. Holland 



1986. Materials and methods for tagging tunas and bill- 

 fishes, recovering the tags, and handling the recapture 

 data. FAG Fish. Tech. Pap., 279; 36 p. 



Beamlsh. R J . AND G A McFarlane 



1983. The forgotten requirement for age validation in 

 fisheries biology. Trans. Am. Fish. Soc. 112:735-743. 



Campana. S E., and J D Neilson 



1982. Daily growth increments in otoliths of starry floun- 

 der (Platichthys stellatus ) and the influence of some envi- 

 ronmental variables in their production. Can. J. Fish. 

 Aquat. Sci. 39:937-942. 

 Foreman, T J 



In press. An assessment of age determination techniques 

 from hard parts of northern bluefin tuna iThunnus thyn- 

 niis L.) from the Pacific Ocean. Inter-Am. Trop. Tuna 

 Comm., Bull., vol. 19. 

 GODSIL, H C 



1938. The high seas tuna fishery of California. Calif. 

 Div. Fish Game, Fish. Bull. 51, p. 3-41. 

 Weber. D . and G J Ridgway. 



1967. Marking Pacific salmon with tetracycline antibi- 

 otics. J. Fish. Res. Board Can. 24:849-865. 



646 



