480 



Fishery Bulletin 93(3). 1995 



300 

 270 

 240 

 210 



> 180 



E 

 o 

 C 150 - 



| 



J 120 



90 - 



60 



30 







Penaeus duorarum 

 Sicyonia sp. 

 Solenocera sp 



LEG1 LEG2 LEG3 LEG4 



Figure 6 



Mean relative abundance (larvae/10 m 2 ) and standard 

 deviation of the pink shrimp, Penaeus duorarum, the 

 rock shrimp Sicyonia sp., and the humpback shrimp, 

 Solenocera sp., at the sampling stations of the Tortugas 

 transect during the four legs of the LH3 cruise, 29 May- 

 30 June 1991. (*) = significant differences in mean rela- 

 tive abundance between legs, within species (P<0.05). 



thermocline as a consequence of the Tortugas Gyre. 

 Criales and McGowan ( 1994) found Solenocera larvae 

 in high abundance (62% of the penaeoid larvae) at an 

 inshore station of Looe Reef transect during the pres- 

 ence of the Pourtales Gyre, whereas few larvae (only 

 15%) were captured in the absence of the gyre when 

 the Florida Current intruded close to the coast. 



The combination of the cyclonic gyre circulation 

 and inshore surface Ekman transport convergence 

 should result in a concentration of larvae in the in- 

 terior of the gyre and in an onshore transport in the 

 eastern portion. Onshore Ekman transport is ex- 

 pected to be relatively high in the Lower Keys and 

 Dry Tortugas where prevalent southeast winds fa- 

 vor onshore transport toward the east-west oriented 

 coast. The importance of Ekman transport on recruit- 

 ment has been shown in the Florida Keys for 

 Scyllarus larvae (Yeung and McGowan, 1991) and 

 for other decapod larvae particularly brachyuran 

 larvae in other regions (see Hobbs et al., 1992; 

 McConnaughey et al., 1994). 



Substantial gaps exist in our knowledge of the life 

 histories of penaeoid shrimps. For example, larval 

 development of Solenocera spp. has not been con- 

 ducted for any of the five western Atlantic species 

 (Perez-Farfante and Bullis, 1973), and larval devel- 

 opment of only one of the seven western Atlantic spe- 

 cies of Sicyonia spp. is known (Cook and Murphy, 



1965). As long as our knowledge of the life history 

 and larval development of these species remains lim- 

 ited, further conclusions regarding interactions of 

 recruitment processes with the physical environment 

 will remain uncertain. 



This research showed the effects of the Tortugas 

 Gyre circulation on dispersal and abundance of local 

 coastal (P. duorarum and Sicyonia sp.) and oceanic 

 (Solenocera sp.) shrimp species. The modal progres- 

 sion of P. duorarum zoeae to postlarvae within the 

 same 15-day period in which the gyre recirculated 

 in the Tortugas region indicates that P. duorarum 

 larvae, in addition to the advective process postulated 

 by Munro et al. ( 1968), may recirculate within the gyre 

 during their development. Retention of larvae by the 

 gyre circulation at the Dry Tortugas, combined with 

 wind driven transport on the southeast Florida shelf, 

 is a plausible recruitment pathway for pink shrimp 

 recruiting to the nursery grounds of Florida Bay. 



Acknowledgments 



The authors gratefully acknowledge M. F McGowan 

 for his assistance and design of the biological sam- 

 pling, W. Richards and A. Jones of the Southeast Fish- 

 eries Science Center of Miami for their continuous 

 support during the course of this research, C. Yeung 

 and C. Limouzy-Paris for their cooperation in the 

 preparation of the manuscript and figures, E. Will- 

 iams for analysis of oceanographic data, and the per- 

 sonnel of SEFC AR and crew of the RV Long Horn for 

 making samples and data available. This work forms 

 part of the Southeastern Florida and Caribbean Re- 

 cruitment project (SEFCAR), funded by the National 

 Oceanic and Atmospheric Administration through co- 

 operative agreement No. NA90RAH00075 with the 

 University of Miami. 



Literature cited 



Allen, D. A., J. H. Hudson, and T. J. Costello. 



1980. Postlarval shrimp (Penaeus) in the Florida Keys: spe- 

 cies, size, and seasonal abundance. Bull. Mar. Sri. 30:21-33. 

 Chuensri, C. 



1968. A morphometric and meristic study of postlarval 

 brown shrimp, Penaeus aztecus Ives, pink shrimp P. duorarum 

 Burkenroad, and white shrimp P. setiferus ( Linnaeus ). M.S. 

 thesis, Univ. Miami, Coral Gables, FL, 108 p. 

 Cook, H. L. 



1966. A generic key to the protozoean, mysis, and postlar- 

 val stages of the littoral penaeidae of the northwestern 

 Gulf of Mexico. Fish. Bull. 65:437-447. 

 Cook, H. L., and M. A. Murphy. 



1965. Early development stages of the rock shrimp, 

 Sicyonia brevirostris Stimpson, reared in the laboratory. 

 Tulane Stud. Zool. 12(4): 109-127. 



