IRVINE ET AL: AN EVALUATION OF TAGGING CETACEANS 



et al. 6 in 1980 suggest that natural marks are 

 relatively permanent. 



DISCUSSION 



The most obvious shortcoming of tags attached 

 to the dorsal fin was the short longevity. Water 

 drag, tissue rejection, and attempts by dolphins 

 to shed tags may have contributed to tag loss and 

 fin damage. We had hoped that tissue would 

 grow tightly around the bolt sheaths and insulate 

 the wound from bolt-induced tissue irritation; 

 however, healing apparently never occurred 

 while bolts were in place. Since tag wounds did 

 not heal, different attachment methods or new 

 designs are needed. Transmitter packages on 

 two killer whales, Orcinus orca, were held for 6 

 mo by pins implanted diagonally to the plane of 

 the leading edge of the fin (Erickson 7 ), and may 

 offer an alternative method of attachment. The 

 relatively larger fin of a killer whale (vs. a 

 dolphin) may, however, have increased chances 

 of success. Carbon bolts attach human prosthetic 

 devices, 8 and are another attachment method 

 yet to be tested on marine mammals. 



Radio tags have proved useful to study the 

 ecology of small odontocetes (Evans 1971, 1974; 

 Evans et al. 1972; Gaskin et al. 1975; Wursig 

 1976), but the configuration used in this study is 

 not recommended for use on T. trwneatus. The fin 

 damage, premature transmitter loss, and 

 unusual swimming behavior which we ob- 

 served, may influence study results. These 

 factors have not been previously documented. 

 Radio tags caused no obvious behavioral effects 

 during captive tests on Delphinus delphis 

 (Martin et al. 1971). In field studies, however, the 

 radio tagged animals have been infrequently 

 sighted and never recaptured, so possible long- 

 term effects of the tags on the animals are 

 unknown. 



6 Wells, R. S.. M.D. Scott, A. B. Irvine, and P. T. Page. 1981. 

 Observations during 1980 of bottlenose dolphins, Tursiops 

 truncatus, marked during 1970-1976, on the west coast of 

 Florida. Report to National Marine Fisheries Service, Con- 

 tract No. N A80-GA-A-195, 21 p. Available Center for Coastal 

 Marine Studies. University of California, Santa Cruz, CA 

 95064. 



7 Erickson, A. W. 1977. Population studies of killer whales 

 {Orcinus orca) in the Pacific Northwest: a radio-marking and 

 tracking study of killer whales. Available National Techni- 

 cal Information Service, 5285 Port Royal Road, Springfield, 

 VA 22151 as PB-285615, 34 p. 



"Anonymous. 1977. The application of high purity carbon 

 technology for Rehabilitation Engineering Center at Rancho 

 Los Amigos Hospital. John F. Kennedy Space Center 

 (NASA) Report SED-77-100, 146 p. Kennedy Space Center. 

 Cape Kennedy, FL 32899. 



Freeze branding proved the most durable 

 marking method. The variability of marks on the 

 animals captured 5 yr after branding indicates 

 that tissue response to the branding process is 

 inconsistent. Freeze brands have remained 

 readable after several years in captivity, but 

 optimal coolants, application times, and pres- 

 sures have yet to be determined (Cornell et al. 9 ). 

 Our resighting, after almost 5 yr, is the longest 

 yet reported. Twenty-one of 26 of the dolphins 

 originally tagged in this study were observed 

 during 1980 and had freeze brands that were 

 either completely readable in photographs or 

 were legible enough to confirm identifications 

 indicated by other characteristics (Wells et al. 

 footnote 6). Maximum longevity of freeze brands 

 is still unknown, however. 



The comparatively high incidence of spaghetti 

 tag loss reported here is noteworthy because this 

 tagging method has been previously used with no 

 reports of rejection or abscess (Sergeant and 

 Brodie 1969; Evans et al. 1972; Perrin et al. 

 1979). Recent tests on captive dolphins have 

 shown, however, that tag loss may be related to 

 tissue rejection, attachment impact, or to the 

 angle of dart entry (Jennings 10 ). 



Recognition of natural marks provided useful 

 supplementary information in our study, and has 

 been used to study bottlenose dolphins in Texas 

 (Gruber 1981; Shane and Schmidly 11 ) and 

 Argentina (Wursig and Wursig 1977). Close 

 approach to the animals is usually required for 

 field recognition, however, and we felt that 

 photoidentification was necessary to verify most 

 of our sightings. 



This tagging study has demonstrated that 

 repeated sightings of tagged dolphins are 

 possible and can provide substantial amounts of 

 information about the behavioral ecology of 

 small cetaceans (Wells et al. 1980; Irvine et al. 

 1981). Selection of the tags to be used should, 

 however, involve consideration of tagging and 

 resighting effort, tag visibility and durability, 

 and potential harm to the tagged animal. Visual 



Cornell, L. H., E. D. Asper. K. Osborn, and M. J. White. 

 1979. Investigations on cryogenic marking procedures for 

 marine mammals. Available National Technical Informa- 

 tion Service, 5285 Port Royal Road. Springfield, VA 22151 as 

 PB-291570, 24 p. 



10 J. G. Jennings, Fishery Biologist, Southwest Fisheries 

 Center, National Marine Fisheries Service. NOAA, P.O. Box 

 271, La Jolla, CA 92038, pers. commun. October 1978. 



"Shane, S. H., and D. J. Schmidly. 1978. Population 

 biology of Atlantic bottlenose dolphin. Tursiops truncatus, in 

 Aransas Pass, Texas. Available National Technical Informa- 

 tion Service, 5285 Port Royal Road, Springfield, VA 22151 as 

 PB-283393, 130 p. 



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