Distribution of Pink Shrimp Larvae and Postlarvae 



C. P. Idyll, F. F. Koczy, Albert C. Jones, 



M. O. Rinkel, and D. Dimitriou 



University of Miami, Institute of Marine Science 



(Contract No. 14-17-002-29) 



Investigation of the relative abundance and distribution of larvae 

 and postlarvae of the pink shrimp (Penaeus duorarum ) in Florida Bay and the 

 adjacent Gulf of Mexico has been carried on by the Institute of Marine Science 

 of the University of Miami. Research has been divided into three phases: 

 (1) identification of the larval stages; (2) hydrography of Florida Bay and the 

 adjacent Gulf of Mexico; and (3) geographical and seasonal distribution of the 

 larvae. 



The first phase of the program, involving the collection, identifica- 

 tion, rearing, and description of pink shrimp larvae and postlarvae, has been 

 completed. 



Investigation of the current system in Florida Bay and on the Dry 

 Tortugas fishing grounds (second phase) has not shown the presence of an on- 

 shore current which could of itself transport shrimp larvae from offshore 

 spawning grounds to inshore nursery areas. The main water movements in 

 this region are due to tidal currents with a superimposed wind-driven com- 

 ponent. The influence of the tidal currents decreases with increased depth 

 and distance from shore until the wind-driven component becomes the major 

 factor in the water movement near the western limits of the spawning grounds. 



High salinity values on the bottom at the time of tidal change together 

 with theoretical considerations required a study of the bottom currents. Using 

 a nnodification of the Carruther's bottom current meter and a newly developed 

 Niskin "gimball" bottom current meter, measurements of bottom currents 

 were determined within 1 foot to 6 inches of the bottom. Velocity data from 

 these bottom current readings indicate that a continuous easterly current is 

 not present in the area, and that the current is, as expected, of low^ velocity 

 (well under 5 cm. /sec. ). 



The third phase of the program, seasonal and geographical distri- 

 bution of pink shrimp larvae and postlarvae, has continued. From July I960 

 to April 1961, 11 sampling cruises were made. A total of 758 plankton sam- 

 ples was collected. Of these, 550 have been examined. Examination of the 

 740 samples collected over the period July 1959 to June I960 was also com- 

 pleted. In addition, 95 plankton samples were taken this year from Florida 

 Keys highway bridges, from Everglades National Park, and from the Tor- 

 tugas fishing grounds with the Beyer plankton sled. 



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