FISHERY BULLETIN: VOL. 77. NO. 4 



swimming at the head of a group. Yet directed 

 movement does occur in cetacean schools. Killer 

 whales arrive off sea lion and sea elephant 

 rookeries at the proper time to catch pups (Norris 

 and Prescott 1961), and pilot whales arrive at 

 specific feeding grounds when squid come to 

 spawn or when capelin arrive in large schools 

 (Sergeant and Fisher 1957). Such patterns pre- 

 sumably have a learned component, and similar 

 patterns of dolphins opportunistically using 

 human activities to locate and capture food must 

 be largely or wholly learned. For instance, 

 bottlenose dolphins follow trawlers in the Gulf of 

 Mexico (Leatherwood 1975) and in the Gulf of 

 California (Norris and Prescott 1961) and obtain 

 fish and other food items stirred up by the trawl or 

 cast over the side during sorting of the catch. 



Tavolga and Essapian (1957) described adult 

 male bottlenose dolphins harassing newborn 

 calves and their mothers, and dominance by adult 

 females is also discussed. We have noted strong 

 aggressive behavior in captive male spinner dol- 

 phins at Sea Life Park oceanarium in Hawaii. In 

 the wild dolphin school, similar actions probably 

 serve to order the structure of the school. Females 

 and newborn young may be herded to their normal 

 position in the interior of the school. We expect 

 that such aggression combined with experience 

 may serve to regulate the direction of school 

 movement from various locations in a school. For 

 instance, adult male killer whales usually occupy 

 a position in travelling schools far out on the wings 

 of the moving group, and from this position direc- 

 tional signals may be communicated to the school 

 as a whole (Norris and Dohl in press). 



The tendency of spinner dolphins to rest over 

 shallow sandy areas is most probably a protective 

 adaption allowing the quiescent school to place a 

 protective bottom close beneath it and a shore 

 nearby on one flank. The chances of attack from 

 those directions by large deepwater sharks are 

 correspondingly reduced. With much individual 

 behavioral flexibility suppressed in resting 

 schools, collective wariness rises, we presume 

 through sensory integration by the school. Thus, 

 the use by spinner dolphins of alert daytime- 

 feeding spotted dolphin schools in the open eastern 

 tropical Pacific Ocean, we feel, may account for the 

 otherwise unusual daytime association between 

 these two species. 



We regard this study as preliminary, allowing 

 glimpses into the life of one wild dolphin species 

 and focusing our attention on important problem 



areas such as acoustic signalling, school structure, 

 energetics, and social relationships. 



ACKNOWLEDGMENTS 



The assistance we have been given in this study 

 has been great. We thank our vessel captains, Dan 

 Camacho, Frank Cunningham, Georges Gilbert, 

 Roger Gray, George Hanawahini, and Vern Han- 

 son, and also our observers, Larry Hobbs and 

 David Bryant. 



We thank also William Arbeit, George Barlow, 

 Marlee Breese, Gregory Bateson, Paul Breese, 

 Robert Eisner, William Evans, Sheri Gish, Sharon 

 Gwinn, Ted Hobson, Ingrid Kang, William 

 McFarland, Fred Munz, Karen Pryor, Scott 

 Rutherford, William Schevill, Robert Shallen- 

 berger, Edward Shallenberger, and William Wat- 

 kins for other field assistance. 



The discussions we have had with George Bar- 

 low, Gregory Bateson, William Perrin, William 

 Rogers, and Karen Pryor have helped a good deal 

 to clarify our ideas of what these often elusive and 

 hard-to-see animals were doing. 



Sherwood Greenwell went far out of his way 

 helping with our observation posts on his land. 

 Bob Haws and Don Brandy, especially, helped 

 with the flying. Tap Pryor assisted us many times 

 with ships and support. The MOC grew from the 

 hands and mind of Jimmy Okudara. 



Richard Young and John Walter of the Univer- 

 sity of Hawaii identified the cephalopod and 

 shrimp remains in stomach contents. 



Nothing could have been accomplished without 

 patient programmatic support, most of which 

 came from the Biological Branch of the Office of 

 Naval Research, through the continuing interest 

 of Deane Holt, Helen Hayes, Charles Woodhouse, 

 and Ron Tipper. Other support (for the hukilau 

 work) came from the National Marine Fisheries 

 Service and from the Oceanic Institute. 



Finally, our thanks to Bob Leslie, native of 

 Kealakekua Bay, and some of his fishermen as- 

 sociates, such as "Only LeRoy," we learned much 

 about our animals and the place where they lived. 



LITERATURE CITED 



Caldwell, M. C, and D. K. Caldwell 



1967. Dolphin community life. Los Ang. Cty. Mus., 

 Q. 5(4>:12-15. 



DoHL. T. P., K. S. Norris. and I. Kang. 



1974. A porpoise hybrid: Tursiops x Steno. J. Mammal. 

 55:217-221. 



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