IV-86 



Movement to the estuary probably takes from three to five weeks and, 

 despite the large numbers of oostlarvae entering the estuary, onlv 

 an estimated five out of every hundred eggs produce shrimp that 

 survive to this stage. 



By the time the estuary is entered, the oostlarvae have developed 

 from planktonic to benthic feeders and have developed a wide 

 tolerance to varying salinity and temperature conditions. From 

 about two to nine months the juvenile shrimp grow rapidly from 

 perhaps one-half inch in length to commercial size before returning 

 to the sea and completing the life cycle. 



The life cycle of the three primary commercial species are similar 

 but the species differ in their penetration of the estuary and their 

 utilization of the estuarine environment after the adult stage is 

 attained. The brown shrimp spawns in waters 150 to 230 feet in depth 

 and remains a relatively short time in the estuarv. The white 

 shrimp rarely is found in waters deeper than 100 feet and p ssesses 

 a greater affinity for fresh water than do the others. 



The estuary fulfills two primary functions: (1) provision of 

 adequate nourishment during a period of rapid physical growth and 

 (2) protection from predators. A large proportion of the shrimp's 

 diet appears to consist of small, invertebrate animals, such as worms, 

 mollusk larvae, and small crustaceans, as well as fish larvae and 

 nematodes. 



