IRVINE ET AL: AN EVALUATION OF TAGGING CETACEANS 



FIGURE 1.— A. Single tube transmitter with spring antenna forward (on dolphin RT-2). B. Dorsal fin 8 mo after transmitter in A 

 was attached. C. Twin tube transmitter assembly with whip antenna aft. Dissolving nuts are top center and below the forward 

 portion of the tube. D. Dorsal fin from C 22 d after the transmitter's installation. Note discolored, apparently necrotic, area around 

 forward hole and apparent migration path of top bolt. 



bolt tags, double bolt tags were attached with 

 0.64 cm stainless steel bolts and nuts. 



Freeze Brands 



When first captured, all dolphins were freeze 

 branded with 5 cm high numerals on both sides 

 of the dorsal fin and on the body below the fin 

 (Figs. ID, 2C, D). Recaptured animals were 

 rebranded as necessary to improve visibility of 

 existing brands. Application times of 15 s with 

 irons cooled in a mixture of Dry Ice and alcohol 

 were used to brand the dolphins captured before 

 August 1975. Thereafter, liquid nitrogen was 

 used as the coolant. The application time 

 remained 15 s. When possible, the skin was 

 rubbed with an alcohol swab to lower the skin 



temperature by evaporative cooling prior to 

 branding. Before April 1976, the branding irons 

 were applied to the skin with a gentle rocking 

 motion to assure even contact. After that time the 

 irons were held firmly against the skin without 

 motion, and brand visibility was greatly 

 improved. In some cases, however, parts of the 

 brand did not show because of uneven contact 

 (Figs. ID, 2C, D). 



Roto Tags 



Numbered Roto tags (NASCO Inc., Ft. 

 Atkinson, Wis., Jumbo size) were attached to the 

 trailing edge of the dorsal fin of all dolphins 

 handled after January 1976. Red tags were 

 attached to females and yellow tags to males. The 



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