FISHERY BULLETIN: VOL. 70, NO. 1 



investigating the distribution and biology of sev- 

 eral odontocete cetaceans off the southern Cali- 

 fornia coast. In order to delineate migration 

 routes and to keep track of local herds of the com- 

 mon dolphin, Delphinns delphis auctt., a tagging 

 program was initiated. During the same period, 

 a tagging program was also initiated for Tur- 

 siops tnoicatus on the west coast of Florida. 

 The special problems associated with tagging 

 odontocete cetaceans required the modification 

 of old and the development of new tagging tech- 

 niques. 



This paper discusses the relative merits of 

 the four marking methods used by our labora- 

 tory. In addition, it presents some preliminary 

 results of the program in order to substantiate 

 the utilitv of the various methods. 



METHODS AND RESULTS 



We have used modified dart-type vinyl spa- 

 ghetti tags (Floy Manufacturing Company) on 

 four species of Eastern Pacific delphinids in an 

 area from Point Conception, Calif., to Cabo San 

 Lucas, Baja California, Mexico, and throughout 

 the Gulf of California. Our original spaghetti 

 tags were 5 mm in diameter by 17 cm long. In 

 order to increase visibility and flow character- 

 istics of the tag, we increased the length to 30 cm 

 (Figure 1). Using the modified tag, w^e have 



marked 240 D. delphis, 10 Lagenorhynchm 

 obliquidens, 8 Tursiops pilli auctt., and 13 Stenel- 

 la gmffmani to date (July 1971). The animals 

 were all tagged at the anterior insertion of the 

 dorsal fin while they were surfing on the bow 

 pressure wave. Several dolphins were observed 

 to continue riding the bow pressure wave after 

 being tagged, so the tagging process apparently 

 did not affect their normal behavior. 



A T. gilli auctt., tagged on 27 October 1970, 

 off Magdalena Bay, Baja California, was recov- 

 ered by an American tuna boat off Manzainillo, 

 Mexico, on 22 January 1971. The animal had 

 covered at least 816 km between the time of tag- 

 ging and the time of capture, a period of just 

 less than 3 months. 



Three D. delphis bearing spaghetti tags have 

 been observed swimming in the vicinity of the 

 Coronado Islands near San Diego, Calif., and 

 at least one spaghetti-tagged D. delphis has been 

 sighted off Magdalena Bay, Baja California. 

 Each of these animals was known to have been 

 carrying the tag for from 2 weeks to several 

 months. 



Circular plastic "button" tags (10 cm diam) 

 (Figure 2) were through-bolted to the dorsal 

 fins of 46 D. delphis and 6 L. obliquidens between 

 1967 and 1970. These tags are similar to those 

 employed by Norris and Pryor (1970) in Hawaii, 

 but are larger to make them more easily spotted. 

 Button tags were attached to animals captured 

 off the southern California coast, or near Cedros 



' V 



1 'J 



r 



■■™ffTraeAi.«i»««u»«i! 



Figure 1. — The dart-type spaghetti tag in place on the tagging apparatus. 



62 



