grounds. Three tagging operations were carried out on 

 the cruise. 



a. Radiotags were attached to spotted dolphins, to 

 monitor herd movements, herd integrity, and re- 

 cruitment of associated yellowfin tuna to the herd. 

 The technique has been described by Evans (1971, 

 1974). Five dolphins were radiotagged and fol- 

 lowed. 



b. Fifteen spotted dolphins were measured, sexed, 

 and injected with lead acetate and tagged with 

 plastic deer ear tags placed in the dorsal fin. The 

 animals were pulled into a small skiff for exami- 

 nation and tagging. Technique of application was 

 described by Norris and Pryor (1970). The pur- 

 pose of the injection of lead acetate was to lay 

 down a time check in the hard tissues, so that 

 growth rates in teeth and bone could be calibrated 

 through examination of recaptured animals. The 

 technique was developed by Nishiwaki and Yagi 

 (1953). The tagged animals were also injected with 

 an antibiotic to combat sepsis. Results of this 

 experiment will be analyzed when tags are re- 

 turned (none returned with sufficient data to 

 date). 



c. One hundred and twenty dolphins were also tagged 

 with steel-dart spaghetti tags. 



5. In late 1972, NMFS chartered the seiner Inde- 

 pendence for a dolphin/tuna cruise. Sixty-one spotted 

 dolphins were injected with lead acetate and tagged 

 with plastic deer ear tags. Tagging was accomplished 

 through use of an aluminum chute supported by two 

 skiffs at the corkline of the seine (Fig. 3). In addition, 

 24 dolphins were tagged with steel-dart spaghetti 

 tags. 



6. Also in 1973, the seiner Trinidad was chartered by 

 NMFS for technological research on dolphin rescue 

 methods and equipment. During the cruise, 20 dol- 

 phins were tagged with steel-dart spaghetti tags. 



7. In late 1973, NMFS chartered the seiner John F. Ken- 

 nedy. The main purpose of the cruise was to conduct 

 research on dolphin-rescue methods, but some tagging 

 was also carried out. Twenty-two spotted dolphins in 

 a single herd were tagged with white deer ear tags, in- 

 serted in the dorsal fin. A 2-in diameter thin red 

 plastic disc was placed on the tag post on each side of 

 the fin to increase visibility of the tag in the water. 

 The objective was to tag dolphins in several herds, us- 

 ing a different color for each herd, and then to study 

 herd structure and integrity through observation of 

 tagged animals in the seine in subsequent hauls in the 

 same area. Rough weather, however, prevented 

 further use of the tagging chute (described above) 

 and completion of the scheduled tagging. In addi- 

 tion to the 22 dolphins tagged with ear tags, 59 spot- 

 ted dolphins were tagged with steel-dart spaghetti 

 tags. 



8. In late 1976, NMFS chartered the seiner Elizabeth C. 

 J. for a combined dolphin/tuna behavioral research 

 and gear research cruise sponsored by several govern- 

 mental and private organizations. Two types of tags 

 were used to mark dolphin schools so that they could 

 be followed and recaptured and the tagged dolphins 

 observed in the net. Radiotags were placed on seven 

 spotted dolphins and one spinner dolphin. The radio- 

 tags failed after only a few hours, but two were subse- 

 quently recovered (the recoveries are treated below 

 like other tag returns; the radio-transmitted data will 

 be presented elsewhere). In addition, 124 spotted dol- 

 phins and 8 spinner dolphins were tagged with steel- 

 dart spaghetti tags modified for greater underwater 

 visibility (see 3. Spaghetti tag with steel dart/braided 

 above) . 



ACCOUNT OF 

 RADIOTRACKING EXPERIMENT 



Transmitters were placed on one adult male (animal 

 A) and two adult females (animals B and C) captured in 

 a tuna seine on 21 November 1971. The object of the 

 experiment was to track the school and set the net on 

 what was assumed to be the same herd five times, at 24-h 

 intervals and at about 1000. The initial set was in the 

 afternoon, and the tagged animals were not released un- 

 til almost sunset. The chronology of events (Fig. 4) may 

 be summarized as follows: 



After the release of the tagged animals it became in- 

 creasingly obvious that the behavior of the male was 

 quite different from that of the females. At first all ani- 

 mals appeared to stay on the same relative heading. 

 After sunset the females began to move away from the 

 male and the decision was made to stay with the male. 

 After 6 h of tracking the females were separated from the 

 male by an estimated 12 n.mi. and their transmitted 

 signals were extremely weak. It was assumed the trans- 

 mitter on at least one of the two animals (B and C) had 

 failed. 



The vessel followed the male (A) until 1040 on 22 No- 

 vember when the first recapture set was made (set 2). 

 Net distance traveled between initial release and this re- 

 capture was 59 n.mi., in about 16 h. One of the females 

 (C) rejoined the male (A) at 0800 but separated from him 

 again at 0930 prior to the net set. An additional long- 

 range transmitter was placed on another male (D) during 

 set 2. Also, a long-life, short-range transmitter was 

 placed on another female (E). After release, A and D 

 stayed together and were rejoined by one of the females 

 from the first set (C). Female B was not seen again fol- 

 lowing her separation from A and C after initial release in 

 set 2. A, D, E, and C were followed until 1036 (set 3) on 23 

 November. Net distance traveled in 24 h was 28 n.mi. 

 During this period, the males (A and D) were separated 

 by some distance (3 n.mi.) from the school containing the 

 females (C and E). The set (3) was made on the portion 

 of the school containing the males A and D. They evaded 

 capture by passing between the boat and the net skiff be- 



