Brown shrimp, continued 



Table 5.06. Relative abundance of brown shrimp in 

 31 Gulf of Mexico estuaries (from Volume I). 



Relative abundance: 



O Highly abundant 



® Abundant 



O Common 



V Rare 



blank Not present 



Life stage: 



A - Adults 



S - Spawning 



J - Juveniles 



L - Larvae/postlarvae 



E - Eggs 



has compiled a comprehensive review of the toxic 

 responses of penaeid shrimp. 



Ecological : The brown shrimp is consumed by many 

 finfish species and by large crustaceans. Large juve- 

 nile stocks of these and other penaeid shrimp appear 

 to be important in supporting large populations of 

 certain juvenile fish species (Heftier 1 989). The loss of 

 marsh habitat and reduction in freshwater inflow into 

 the bays have come under scrutiny as major factors 

 influencing shrimp production (Kutkuhn 1966, Minello 

 and Zimmerman 1 983, Minello and Zimmerman 1 984). 



Range 



Overall : The brown shrimp extends farther north than 

 any of the other western Atlantic species of Penaeus 

 (Fischer 1 978). It is distributed from Martha's Vinyard, 

 Massachusetts, around the tip of Florida and through- 

 out the Gulf of Mexico to the northwestern Yucatan 

 Peninsula. 



Within Study Area : In U.S. waters of the Gulf of Mexico, 

 the brown shrimp is distributed throughout bays, estu- 

 aries and coastal waters (Table 5.06). For the pur- 

 poses of Table 5.06, all larval and postlarval stages of 

 brown shrimp are considered together as "larvae" (L). 

 However, the brown shrimp is uncommon in Florida 

 Bay and is conspicuously absent along the western 

 Florida coast from the Sanibel grounds to Apalachicola 

 Bay. Its maximum density occurs along the coasts of 

 Texas, Louisiana, and Mississippi (Allen et al. 1980, 

 Williams 1984, NOAA 1985). 



Life Mode 



This species is found in neritic to estuarine habitats and 

 is pelagic to demersal, depending on life stage. Eggs 

 are denser than seawater and are demersal (Kutkuhn 

 1966). Larval stages are planktonic, their position in 

 the water column is dependent on time of day, water 

 temperature and clarity (Temple and Fischer 1965, 

 1967, Kutkuhn, et al. 1969). Nauplii are demersal, 

 becoming pelagic as they develop through the 

 protozoeae and mysis stages (Lassuy 1983). 

 Postlarvae spawned in the fall may burrow into the 

 sediments to escape cooler temperatures and over- 

 winter (St. Amant et al. 1966, Aldrich et al. 1968). 

 Postlarvae move into estuaries and transform into 

 juveniles (Cook and Lindner 1970). Adults generally 

 inhabit offshore waters ranging from 14 to 110 m in 

 depth (Renfro and Brusher 1982). The brown shrimp 

 is most abundant from March to December with opti- 

 mum catches occurring from March to September 

 (Copeland and Bechtel 1974). This species typically 

 seems to have an annual life cycle; however, captive 

 individuals have survived for over two years (Perez- 

 Farfante 1969, Zein-Eldin pers. comm.). 



56 



