IRVINE ET AL: AN EVALUATION OF TAGGING CETACEANS 



Spaghetti Tags 



Spaghetti tags (Floy Tag and Manufacturing, 

 Inc., Seattle, Wash., Model FH 69A) were tested 

 on some dolphins captured from April through 

 June 1976. The attachment technique was 

 similar to that described by Evans et al. (1972), 

 except that the tags were applied to animals in a 

 stretcher. 



Natural Marks 



Some dolphins had disfigured or uniquely 

 shaped dorsal fins. A photo catalog of these 

 recognizable untagged animals was compiled as 

 a reference for field identification. 



RESULTS 



Nine hundred ten tagged dolphins were 

 sighted; 781 were identifiable, and 129 others 

 were not. When field identification was uncer- 

 tain, photographs of combinations and locations 

 of tags or tag remnants were often examined to 

 verify individual identities. A compilation of 

 tagging and sighting results is presented in 

 Table 1. 



Radio Tags 



Ten dolphins were radio tagged and tracked 

 for up to 22 d (Table 2). Eight of these were later 

 recaptured and examined. In five instances, the 

 saddle was lost, apparently because the bolt 

 ripped through the fin (for example, see Figure 

 IB). Fin damage was apparent 3 to 6 wk after 



tagging by which time saddles no longer fit 

 snugly over the leading edge of the fin. When 

 loosened, the saddles titled backwards creating 

 an obvious drag; this shifting caused the bolts to 

 migrate dorsoposteriorly. When RT-8 was re- 

 captured after wearing a transmitter for 22 d, 

 the two bolt holes had not healed nor appeared 

 infected. The forward bolt had migrated dor- 

 soposteriorly about 1.5 cm (Fig. ID), and the 

 saddle was fouled with algal growth and mono- 

 filament line. When RT-9 was recaptured after 

 46 d, the saddle and rear bolt were missing, but 

 the front bolt was still present but bent, with part 

 of the dissolving nut attached. The partially 

 healed wounds appeared discolored and necrotic, 

 but showed no obvious signs of infection. Only 

 RT-6 showed no fin damage from the radio tag, 

 but the tag (with malfunctioning transmitter) 

 was removed <8 h after attachment. 



Two dolphins, RT-9 and RT-10, developed 

 aberrant swimming behavior after 10 and 17 d, 

 respectively. Both animals were observed to 

 respire without bringing the dorsal fin to the 

 surface in a typical cetacean rolling motion, 

 although each could move rapidly under water. 

 Evaluation of the problem was impossible 

 because RT-9 evaded recapture attempts during 

 this period, and RT-10 was not sighted during 

 capture operations. 



One animal, RT-7, died 17 d after tagging, 

 apparently of causes unrelated to the radio tag. 

 Necropsy results implicated pulmonary damage 

 from parasitism as a cause of death. It could not 

 be determined if the capture-tagging process 

 contributed to the cause of death. Tissue 

 autolysis precluded histopathological examina- 

 tion, and no parasites were found. 



Table 2.— Radio tagging results. 



'inconsistent signals during the last 6 h 

 direction finder malfunction after 6 d 

 inconsistent signals during the last 3 d 



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