NATURAL HISTORY OF THE SANDBAR SHARK 



gether. liowever. has been to foster confusion in 

 the nomenclature. There apjiears to have been 

 a tacit assumption by some naturalists that sexual 

 dimori)hism accounted for differences in sandbar 

 sharks and bull sharks despite recognition of tlie 

 existence of both species. 



Superficially, the sandbar shark and the bull 

 shark i-esemble one another but, as will be shown 

 later, sandbar sharks can easily and positively be 

 separated from bull sharks on the basis of several 

 anatomical characteristics. Identification of 

 specimens from the Middle Atlantic States, par- 

 ticularly the Atlantic coast from Cape Cod to 

 Chesapeake Bay, presents an added difficulty be- 

 cause of the several very similar offshore species 

 which may be caught occasionally, but probably 

 rarely in inshore waters: Eulnmia obsciira (Le 

 Sueur), E. faJcifo-rmis (Miiller and Henle), E. 

 fo-ridana (Bigelow, Schroeder, and Springer), 

 and E. ultima Springer. Recent unpublished 

 records of the occurrence of E. inUherti young 

 and of the occurrence of Carcharhinus leucas 

 adults are rather numerous, and following publi- 

 cation of the first volume of Fishes of the West- 

 ern North Atlantic (Bigelow and Schroeder, 

 194S) there appears to be little confusion of the 

 two species. 



Belaboring the point tliat descriptive accounts 

 of carcharhinids must be detailed and selective to 

 have any meaning seems necessary to affect the 

 intrenched misconceptions about E. jnUherti that 

 can be derived from the literature. Fowler's 

 (lO-'iG) description of E. plumbeus (plumbeu-s = 

 mUherti), which was based on American Middle 

 States exam])les, although in a report on West 

 African marine fishes, is not unique in confusing 

 E. mUherti with another species,^ but it is de- 

 tailed enough to be especially vulnerable to criti- 

 cism. More elements of his description fit the 

 bull sliark, Carrharhhwis leucoK. than E. m/lberfi. 

 but additional confusion is inti-oduced by the 

 probability that juvenile and adult characteristics 

 of both species are mixed. There is no selection 

 of diagnostically useful characteristics for em- 

 phasis. The result is a plausible literary syn- 



3 Garman'8 illustration of CnrcJitirhinus phityoilon (1913. pi. 3. 

 flgs. 4 and fi) appears to bo very weli drawn from a sppcimen 

 of Eulnmia tnilberti. Bigelow and Scliroeder (1948) note tlmt 



Carman's illustration is mislabeled. Tbe acoompanyinR illustra- 

 tion of the teeth In Carman's plate .3. figure .5. appears to have 

 been drawn from the teeth of platyodon. CnrchnrliinUH iilalii- 



odon (Poey) Is a synonym of f. Irurnii (MUUer and Henle). 



thesis that is a hazard to one attempting to fit a 

 real shark to a position in zoological classification. 



POPULATIONS OF EULAMIA MILBERTI 



Sandbar sharks. Eulmnia milberti, occur in 

 portions of the temperate and tropical Atlantic, 

 the Caribbean, the Gulf of Mexico, and the Medi- 

 terranean. Our data in this study primarily cover 

 the population inhabiting the western North 

 Atlantic, the Gulf of Mexico, and the eastern 

 Caribbean. Later, the normal movements and 

 distribution of this population will be discussed. 

 We need fii-st to consider the relationships of the 

 various populations. In addition to the popula- 

 tion of the western North Atlantic two others 

 may be roughly defined. One occurs along the 

 coast of South America from Trinidad eastward 

 and southward. The other is found along the 

 west coast of Africa and is presumed to be con- 

 tinuous with the stock entering the Mediter- 

 ranean. 



The population occurring on the coast of South 

 America appears to be a minor one. The species 

 has been reported and figured by Ribiero (1923) 

 from the coast of Brazil. 



While engaged in commercial shark fishing in 

 April and May 1949, I made shipboard examina- 

 tions (Springer. 1949) of a series of sandbar 

 sharks from the north and east coasts of Trinidad 

 and identified them in error as E. phmbem. I 

 now believe that differences between the Trinidad 

 specimens and typical milberti from the Atlantic 

 coast of the United States are insufficient to war- 

 rant recognition of sejiarate species, and that the 

 conservative course, jiending accumulation of new 

 data, is to look upon the various Atlantic sandbar 

 sharks as representing a single species. At the 

 Trinidad locations, adult males and females as 

 well as young of all sizes from 4 feet upward 

 were taken on single setlines. Although com- 

 mercial shark fishing was carried on throughout 

 1949 from the coast of French Guiana westward 

 to the Gulf of Venezuela, sandbar sharks were 

 reported only from the north and east coasts of 

 Trinidad and chiefly from depth-s of 5 to 20 

 fathoms near Galera Point. 



Tliere are no records of sandbar sharks from 

 tlie West Indies north of Trinidad except from 

 the north coast of Cuba and from the western 

 inii't of the Bahama Banks. This is not, of 



