60 



Abstract — The variability in the 

 supply of pink shrimp (Farfante- 

 penaeus duorarum) postlarvae and 

 the transport mechanisms of plank- 

 tonic stages were investigated with 

 field data and simulations of trans- 

 port. Postlarvae entering the nursery 

 grounds of Florida Bay were collected 

 for three consecutive years at chan- 

 nels that connect the Bay with the 

 Gulf of Mexico, and in channels of 

 the Middle Florida Keys that connect 

 the southeastern margin of the Bay 

 with the Atlantic Ocean. The influ.x of 

 postlarvae in the Middle Florida Keys 

 was low in magnitude and varied sea- 

 sonally and among years. In contrast, 

 the greater postlarval influx occurred 

 at the northwestern border of the Bay, 

 where there was a strong seasonal 

 pattern with peaks in influx from 

 July through September each year. 

 Planktonic stages need to travel up to 

 150 km eastward between spawning 

 grounds (northeast of Dry Tortugast 

 and nursery grounds (western Florida 

 Bay) in about 30 days, the estimated 

 time of planktonic development for 

 this species. A Lagrangian trajectory 

 model was developed to estimate the 

 drift of planktonic stages across the 

 SW Florida shelf. The model simu- 

 lated the maximal distance traveled 

 by planktonic stages under various 

 assumptions of behavior. Simulation 

 results indicated that larvae traveling 

 with the instantaneous current and 

 exhibiting a diel behavior travel up 

 to 65 km and 75% of the larvae travel 

 only 30 km. However, the eastward 

 distance traveled increased substan- 

 tially when a larval response to tides 

 was added to the behavioral variable 

 (distance increased to 200 km and 

 85% of larvae traveled 150 km). The 

 question is, when during larval devel- 

 opment, and where on the shallow SW 

 Florida shelf, does the tidal response 

 become incorporated into the behavior 

 of pink shrimp. 



Variability in supply and cross-shelf transport 

 of pink shrimp iFarfantepenaeus duorarum) 

 postlarvae into western Florida Bay 



Maria M. Criales' 



John D. Wang^ 



Joan A. Browder^ 



Michael B. Robblee'* 



Thomas L. Jackson^ 



Clinton Hittle" 



' Rosenstiel School of Marine and Atmospheric Science, MBF 

 University ol Miami 

 4600 Rickenbacker Causeway 

 Miami, Florida 33149 

 E-mail address (for M M Cnales) mcrialesa'Tsmas miami edu 



^ Rosenstiel School of Marine and Atmospheric Science, AMP 

 University of Miami 

 4600 Rickenbacker Causeway 

 Miami, Florida 33149 



3 NOAA Fisheries, Southeast Fisheries Science Center 

 75 Virginia Beach Drive 

 Miami, Florida 33149 



■* United States Geological Survey 

 Center for Water and Restoration Studies 

 3110 SW9'^ Avenue 

 Ft Lauderdale, Florida 33315 



Manuscript submitted 16 September 2003 

 to the Scientific Editor's Office. 



Manuscript approved for publication 

 30 June 2005 by the Scientific Editor. 



Fish. Bull. 104:60-74 (2006). 



Patterns of recruitment of coastal spe- 

 cies are highly variable, mainly because 

 of the complex interaction of biotic anii 

 abiotic factors across the different life 

 history stages. These factors include 

 but are not limited to reproductive 

 dynamics, larval dispersal and behav- 

 ior, physiological tolerances, and the 

 hydrometeorological regime in which 

 their life stages develop (e.g., Shanks, 

 1995; Cowen, 2002). The commercially 

 valuable tropical penaeid shrimps that 

 use different habitats during their life 

 cycle (offshore spawning grounds and 

 estuarine nursery habitats) have to 

 cope with a large suite of physical 

 processes and stimuli (Rothlisberg 

 et al., 1995, 1996). The pink shrimp 

 iFarfantepenaeus duorarum) of Dry 

 Tortugas is one of the most economi- 

 cally and ecologically important spe- 

 cies in southwest Florida. The pink 

 shrimp supports an important year- 

 round fishery of about 4000 metric 

 tons in an area of 10,000 km- between 

 Dry Tortugas and Key West (Iversen 

 et al., 1960; Klima et al., 1986). The 



Tortugas fishery is directly depen- 

 dent on young shrimp that migrate 

 from inshore nursery areas onto the 

 offshore fishing grounds (Sheridan, 

 1996; Browder et al., 2002). Recruit- 

 ment shows no relationship to spawn- 

 ing size; therefore harvest fluctuations 

 are apparently due to environmental 

 conditions rather than fishing opera- 

 tions (Nance and Patella, 1989). To 

 effectively manage this species, it is 

 necessary to have accurate informa- 

 tion on the processes linking nursery 

 and spawning ground populations. 



Pink shrimp population dynamics 

 are affected by physical processes and 

 environmental conditions occurring 

 in the southwestern (SW) Florida 

 Shelf of the Gulf of Mexico, the At- 

 lantic coastal zone, and the Florida 

 Bay. Early research on gonad develop- 

 ment (Cummings, 1961), distribution 

 of larval stages (Jones et al., 1970), 

 and analysis of length frequency 

 distributions of fishery stock data 

 (Iversen et al., 1960; Roberts, 1986) 

 indicated that the center of spawn- 



