4 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



course, conclusive evidence of their absence from 

 a region so poorly known ichthyologically as the 

 West Indies. Nevertheless, all of the evidence 

 points to a discontinuous distribution with no 

 regular contact between the population known 

 from Cape Cod to Costa Rica and the South 

 American population known from Trinidad and 

 the east coast of South America south of the 

 Amazon. 



In connection with possible future work with 

 the sandbar sharks, it should be noted that the 

 E. milherti from Trinidad were taken in eddies 

 of the very strong, westerly current flowing be- 

 tween Trinidad and Tobago; and t^ii^ recruit- 

 ment for this stock could take place in part by 

 tran.sport by tlie Equatorial Current of the grow- 

 ing young to Trinidad from shore waters of the 

 African coast. 



The stock of Eulam/a mllberti in the eastern 

 Atlantic is known from scattered records from 

 the Mediterranean and the west coast of North 

 Africa as summarized by Tortonese (1956). 

 These records cover a long period of time and 

 although critically reviewed by Tortonese and 

 unquestionably accurate, they give little basis for 

 an estimate of the abundance of the sandbar 

 shark in relation to the abundance of other large 

 species of the area. For our purposes hei-e, that 

 is, to estimate the relative importance and abun- 

 dance in comparison with other large sharks of 

 the area, reports by Cadenat (1950, 1957) on 

 E. milherti and other species from the coast of 

 Senegal are quite informative. Cadenat has been 

 able to make observations on fresh material from 

 a fishery taking relatively large numbers of the 

 larger species of shai'ks. His reports suggest that 

 the stock of E. miThei-ti off northwest Africa is 

 a strong one. 



The list of species of large sharks reported by 

 Cadenat is quite similar to lists of large sharks 

 from the southeastern coast of the United States. 

 The endemic species of both areas are the smaller 

 sharks. 



Precisely the same factors of prevailing wind 

 and surface currents that make the southern 

 crossing from the North African coast to Trini- 

 dad easier for man when it is from east to west 

 may be expected to ojierate for sharks. Simi- 

 larly, for a more northerly crossing, the one from 

 west to east is more easily followed. The postu- 



late that such contacts as exist between the stocks 

 of the western Atlantic and the stock of the 

 eastern Atlantic result from exchanges following 

 this general clockwise circulation is a reasonable 

 one. No actual evidence of regular contacts be- 

 tween the three stocks exists, however, and there 

 is substantial reason for the belief that move- 

 ments of individual sharks from one stock to an- 

 other are relatively infrequent occurrences. 



Knowledge of the distribution of large sharks 

 in oceanic situations at considerable distance 

 from land was extremely meager until very re- 

 cently when data from oceanographic vessels and 

 exploratory fishing vessels became available. The 

 niost comprehensive study covers sharks of the 

 Central Pacific (Strasburg, 1958) in which data 

 .showing patterns of distribution of some of the 

 larger species is given. Before the appearance of 

 that study and of a less comprehensive account 

 of Atlantic pelagic sharks (Backus et al., 1956), 

 questions of shark distribution seaward of the 

 continental shelves were unanswerable. 



Now, while it is known that neritic species of 

 large sharks are capable of moving over great 

 distances of open ocean, there is increasing evi- 

 dence that they rarely do. , \ 



ECOLOGICAL AND SYSTEMATIC RELA- 

 TIONSHIPS OF THE GENUS EULAMIA 



The genus EiiJ-amia may be divided into two 

 groups on the basis of the structure and arrange- 

 ment of the dermal denticles. The group to 

 which E. milherti belongs is characterized by 

 noninibricate denticles as contrasted with the 

 other group which has denticles with overlapping 

 edges or points. The milherti group includes 

 comparatively few species. Probably Eulamia 

 dussumieri. (Miiller and Henle) and E. japonicm 

 (Schlegel) of the western Pacific belong here. In 

 the Atlantic, the group is represented by a deep- 

 water species, Enlamia ultima Springer, which is 

 quite different from milberti, not only in its mor- 

 phology but in its habitat. Aside from E. altima, 

 the only Atlantic representative of the genus 

 Eulamia (or any carcharhinid genus) with 

 widely spaced, noninibricate denticles is Eulamia 

 milherti. the sandbar shark. 



E. milhfrt) lias the shoalest range and occupies 

 the most inshore habitat of any of the 5 or 6 

 species of Evlam/n of the Atlantic coast of Nortli 



