encountered in temperate waters than tropical, but nowhere abundant 

 (Bigelow and Schroeder, 1948; Lirabaugh, 1963; Lineaweaver and Backus, 

 1970). Remarkably little is known about this shark; for example, there 

 are still no reliable data on the number of young that may be found in a 

 single female. Much effort would have to be expended to gather information 

 on this species, but we feel that some attempt should be made to advance 

 our knowledge of this most-feared species. Tracking of single individuals 

 to which sonic tags have been affixed, for example, would be of great 

 interest. 



No excuse exists for the paucity of data on the tiger shark which is 

 one of the most abundant and widespread species of tropic seas. A broad- 

 based detailed study of this species could profitably be undertaken, 

 utilizing methods which would allow comparisons with life history data 

 gathered for other pelagic species. 



Because of their great abundance and the threat they pose to survivors 

 of air and sea disasters well off-shore (Suda, 1953; Strasburg, 1958; 

 Limbaugh, 1963; Nelson, 1969; Lineaweaver and Backus, 1970; Myrberg, et al, 

 1972), the oceanic white tip shark, Carcharhinus longimanus ( = C. maou) , 

 the silky shark, C. falciformis , and the blue shark, Prionace glauca , 

 should be investigated. For these three species, unpublished data are 

 available from tuna longline fishing, particularly from Japanese fishery 

 research vessels. 



Studies should also be carried out on at least one of the ubiquitous 

 near-shore species of Carcharhinus or Negaprion . Emphasis may well be 

 given to the proven dangerous species of Carcharhinus (Davies, 1964; 

 Johnson and Nelson, 1973) such as the bull shark, C. leucas , grey reef 

 shark, C. amblyrhynchos ( = C. menisorrah ) , or to the lemon shark, 

 Negaprion sp. (Springer, 1950; Banner, 1968). However, it should be noted 

 that studies of a smaller, less dangerous, but more feasibly investigated 

 species, such as the blacknose shark, C. acronotus , or the reef blacktip 

 shark, C^. melanopterus are not necessarily worthless from the practical 

 standpoint. Some of the basic biological information obtained for one 

 species of a genus may be extrapolated to other members of the genus. 

 Such comparative data are also needed to determine the roles that these 

 common species play in the ecosystem. 



d. Inter-Specific Relationships 



The most pertinent aspect of inter-specific relationships of sharks 

 involves their feeding habits. Although scattered data exist on food items 

 of sharks, much more work is needed on stomach content analyses, particu- 

 larly with regard to species of prey. The available data suggest that 

 most sharks are opportunistic feeders without clear preferences; this 

 view may have resulted simply from lack of information or poor identifica- 

 tion of prey. Limited studies have been carried out on natural predator- 

 prey relationships, i.e., preference, availability and abundance of prey, 

 habits of prey species, and their relationship to the shark's ability to 

 detect or capture them (see Banner, 1972). 



Interspecific shark predation is of particular importance. It is 

 known, for example, that the young of sandbar sharks, Carcharhinus 

 milberti , and "puppy" sharks, C_. porosus , are important food items for the 



