dangerous bull shark C. leucas . Thus, predation by the bull shark may be 



a natural control on the populations of other shark species. Conversely, 



the availability and abundance of the prey shark species may affect the 

 distribution and abundance of the predator. 



Information is also lacking on competition. In many localities quite 

 similar species with apparently identical food habits seem to occupy 

 the same habitat. A good example is the relationship between the silver- 

 tip and Galapagos sharks, which are often found together at offshore 

 islands (Limbaugh, 1963). 



3 . Behavior of Sharks 



a. Introduction 



Early investigations of shark behavior centered on the study of captive 

 animals with experiments demonstrating responsiveness under various 

 stimulus situations. While profitable research still continues along 

 these lines (e.g., Banner, 1967; Davies e_t a_l . , 1963; Gruber, 1967; 

 Hodgson and Mathewson, 1971; Graeber et_ al_. , 1973; Kleerekoper, 1967; 

 Kuchnow and Gilbert, 1967; Tester and Kato, 1966), technical developments 

 have recently permitted significant strides in studying these animals 

 under natural conditions (Banner, 1972; Hodgson, 1971; Myrberg et al . , 1969a, 

 1969b, 1972b) . Continued developments along these and other avenues will 

 aid dramatically in answering questions unresolved by previous research. 



b. Social Behavior 



Existing knowledge of social behavior in sharks is based largely on 

 fishery catch statistics and anectodal accounts. As discussed above, 

 recent technical developments and refinement of analysis, as used by 

 workers in various behavioral disciplines, will surely provide the 

 opportunity for obtaining a greater understanding of the social activities 

 carried out by these animals. Examples of such technical developments 

 include the use of underwater habitats, closed-circuit television, tele- 

 metry and photography (see Herrnkind, 1974) . Examples of the refinement 

 of analyses alluded to above include the use of information and communica- 

 tion theory; sequential, pattern interval, and time series analysis; the 

 ethogram; and various types of level-adequate motivation and situation 

 analyses (see Hinde, 1970; Marler and Hamilton, 1966; Myrberg, 1972a). 

 It is essential that innovative programs continue to incorporate quanti- 

 tative, as well as qualitative, information in their methodology. 



Various statements have appeared in the literature, regarding the 

 social organization and group structure of sharks (e.g., Springer, 1967); 

 yet, quantitative information exists presently for only two species: the 

 smooth dogfish, Mustelus canis , (Allee and Dickinson, 1954) and the bonnet- 

 head shark, Sphyrna tiburo , (Myrberg and Gruber, 1974). Virtually nothing 

 is known about shark behavior in the following broad areas: territoriality, 

 species recognition and interactions, reproductive behavior, agonistic 

 behavior and other sequentially related activities. Such knowledge is 

 critical in understanding, predicting and controlling any interaction 

 between sharks and man, including that of shark attack. For example, a 



