MIGRATIONS AND GEOGRAPHIC DISTRIBUTION OF PINK SHRIMP, 

 PENAEUS DUORARUM, OF THE TORTUGAS AND SANIBEL GROUNDS, 

 FLORIDA ' 



By T. J. Costello and Donald M. Allen, Fishery Biologists {Research) 

 Bureau of Commercial Fisheries Biological Field Station, Miami, Fla. 



ABSTRACT 



Pink shrimp, Penaeus duorarum, frequent the estua- 

 rine waters of south Florida as juveniles. As adults, 

 they support valuable fisheries on the offshore Tortugas 

 and Sanibel trawling grounds in the Gulf of Mexico. 

 To study the Tortugas and Sanibel shrimp stocks as 

 biological units, 15 mark-recovery experiments in which 

 biological stains were the marking agents were made. 

 These experiments (1) indicated timing and direction 

 of shrimp migrations; (2) delineated estuarine nursery 

 grounds; and (3) outlined geographic ranges of Tortugas 

 and Sanibel shrimp stocks. 



Prior to migrating offshore, the length of time spent 

 by juvenile pink shrimp in the nursery areas varies from 

 about 2 to at least 6 months. In migrating from nursery 

 areas, some shrimp travel at least 150 miles (nautical) 

 before recovery on the offshore grounds. Although 

 migration routes are broad, shrimp emanating from 

 particular sections of the nursery grounds demonstrate 

 distinct distributional patterns on the offshore grounds. 



The nursery grounds of the Tortugas shrimp stocks 

 include Florida Bay and estuaries extending at least 

 as far north as Indian Key on the southwest coast of 

 Florida. The nursery grounds of the Sanibel shrimp 

 stocks are confined to the southwest coast of Florida 

 and include estuaries extending at least from Indian 

 Key north to Pine Island Sound. 



The geographic ranges of the Tortugas and Sanibel 

 pink shrimp stocks overlap in the nursery areas near 

 Indian Key and in the offshore water between the two 

 trawling grounds. Apparently, Tortugas shrimp do 

 not migrate to the Sanibel grounds and migration from 

 the Sanibel to the Tortugas grounds is minimal. 

 The geographic distributions depicted may constitute 

 minimums for two reasons: First, the absence of fishing 

 effort in certain contiguous areas prevented observations 

 which could extend the known distribution. Second, 

 larval and postlarval pink shrimp may migrate to or 

 from areas beyond the ranges frequented by Tortugas 

 and Sanibel shrimp as juveniles and adults. 



The migrations and geographic distribution of 

 pink shrimp, Penaeus duorarum, supporting com- 

 mercial shrimp fisheries on the Tortugas and 

 Sanibel grounds, have not been described pre- 

 viously. These two fisheries, located in the Gulf 

 of Mexico off the southwest coast of Florida, 

 provide a total shrimp catch of about 18 million 

 pounds (heads on) annually. Knowledge of pink 

 shrimp movement and distribution both on and off 

 the grounds will contribute to a more thorough 



1 Contribution No. 193. Bureau of Commercial Fisheries Biological 

 Laboratory, Galveston, Tex. 



Note.— Approved for publication Sept. 29, 1964. 



FISHERY BULLETIN: VOLUME 65, NO. 2 

 774-711 O— 66 11 



understanding of this animal's biology and serve 

 as a basis for management of this resource. 



The catch on the Tortugas and Sanibel grounds 

 consists primarily of maturing and adult pink 

 shrimp. This species has a life history similar to 

 other members of the genus Pevaeus. As adults, 

 the female pink shrimp extrude eggs in offshore 

 waters. After hatching, the young shrimp pass 

 through larval and into postlarval stages as they 

 move toward the coast. Coastal shallows and 

 estuaries, utilized as nursery grounds, furnish an 

 ecological environment considered necessary for 

 these shrimp during the early stages of their 

 development. The shrimp gradually move off- 



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