SIZE DISTRIBUTION OF PINK SHRIMP, Penaeus duorarum. 



AND FLEET CONCENTRATIONS 



ON THE TORTUGAS FISHING GROUNDS 



by 

 Edwin S. Iversen, Andrew E. Jones and C. P. Idyll' 



ABSTRACT 



A study of the pink shrimp, Penaeus duorarum, on the Tortugas fishing 

 grounds was undertaken during 1957 and 1958 to provide information on 

 the nature of the relation between the size of shrimp and the depth of 

 water where they occur, together with fleet concentrations and degree 

 of discarding of small pink shrimp. The average carapace length of both 

 male and female shrimp increased both with depth of water and with 

 northerly distance from the Florida Keys. Snnall pink shrimp were most 

 abundant from September 1957 through May 1958, appearing on the 

 eastern and southeastern portion of the grounds, where the highest try 

 net catches were made. The fleet concentrated there during December 

 to June but was more widely distributed during the summer. Apparently, 

 few small pink shrimp were discarded. 



INTRODUCTION 



THE FISHERY 



The pink shrimp, Penaeus duorarum, sup- 

 ports valuable commercial fisheries off 

 the south coast of Florida and the Cam- 

 peche area of the Gulf of Mexico. This 

 species is of recent economic importance, 

 having been caught in large quantities 

 only since 1950. Little is known of the 

 details of its life history and much has to 

 be learned before a rational conservation 

 plan can be devised for the fishery. The 

 present investigation has been one phase 

 of a research program on the pink shrimp 

 and its fishery on the Tortugas grounds 

 off the southern end of Florida. The work 

 was supported by a Saltonstall-Kennedy 



funds through the U. S. Bureau of Com- 

 mercial Fisheries, Contracts Nos. 14-17- 

 008-7 and 14-17-008-23. 



The Tortugas shrimping grounds (fig. l) 

 are roughly rectangular in shape, about 

 60 miles long (east and west) and 25 miles 

 wide (north and south). The eastern corner 

 of the grounds is located about 12 miles 

 north -northwest of Key West, and the 

 grounds extend past the Dry Tortugas 

 Islands. The depth of water on the fishing 

 grounds ranges in a gradual gradient from 

 about 9 fathoms on the east to about 25 

 fathoms on the west, with most fishing 

 taking place in depths from 11 to 19 

 fathoms. The bottom is mostly white sand 

 and mud. Some outcroppings of rock 

 occur, esi>ecially in shallow extension of 



>The authors are members of the Marine Laboratory, University of Miami, Coral Gables, Florida. 



1 



