Juvenile growth in the estuary is rapid, requiring only 3 to 4 months to 

 maturity. As water temperatures cool in the fall and shrimp reach lengths of 

 3 to 4 inches, they emigrate from nursery areas, using tidal currents and sa- 

 linity gradients to move to overwintering and spawning grounds. Some of the 

 younger, smaller shrimp may overwinter in deeper portions of bays until spring 

 and then move offshore. 



Major pink shrimp fishing grounds are along the southwest coast from Fort 

 Myers to Tortugas and from Apalachicola Bay to Panama City. White and brown 

 shrimp are most abundant near Apalachicola Bay and Jacksonville. Rock shrimp 

 are most abundant near Apalachicola Bay and from Cape Canaveral to Georgia. 

 They become sexually mature (3.5-4.0 inches TL) near the time they arrive at 

 their overwintering grounds. They are 6 to 8 months old and of legal size (47 

 whole shrimp per pound or 70 tails per pound). Growth slows as they move 

 deeper offshore. Maximum age is about 2 years; but few live longer than 12 to 

 14 months. 



Shrimp larvae feed on algae and zooplankton. Post larvae, juveniles, and 

 adults are oninivores, feeding largely on detritus and microorganisms. 



Blue Crabs 



The blue crab ( Callinectes sapidus ) supports a major fishery in Northwest 

 Florida. In 1970-80, annual landings ranged from 1.2 to over 2.3 million lb. 

 The average price per pound dockside was 22 cents and the 1980 landings of 1.9 

 million lb had a dockside value of $401,685. Northwest Florida contributes 

 about 10% of the total Florida blue crab catch. The monthly landings of blue 

 crabs along the west coast of Florida in 1965, 1970, and 1975 are given in 

 Table FSH-36 in the Data Appendix. 



Blue crabs mate and spawn year-round except in northern areas of Florida 

 when water temperatures drop below 60°F. Subsequent to mating in brackish 

 waters (8-18 ppt salinity), females migrate to nearshore high salinity waters 

 ( 25 ppt) near mouths of estuaries to spawn. Alongshore migration on the west 

 coast towards Apalachicola Bay by some females suggests that the bay area may 

 be a primary spawning area. Females spawn at least twice, producing from 

 700,000 to 2,000,000 eggs per "sponge." Spawning peaks in April-June. 



Blue crab larvae go through zoea stages lasting 31 to 49 days and one 

 megalopa stage lasting 6 to 20 days. Zoea are planktonic until molting into 

 the megalopa stage, which utilizes tidal currents to drift into estuarine 

 waters where they molt into the first crab stage (2-3 mm carapace width [CW]). 



Small crabs ( 40 mm CW) live in a variety of shallow water habitats in 

 the estuary (e.g. grass beds, muck bottoms) and gradually move to deeper water 

 as they increase in size. Adult size ( 120 mm) is achieved after 18 to 20 

 molts in 12 to 14 months. 



The size range of adults usually is 120 to 140 mm CW, most of which are 

 commercial size. After reaching adult size, crabs are known to live at least 

 one more year, and a few may live 3 to 4 years. Primarily a shallow water 

 species (up to 35 m deep), adult blue crabs live in a variety of habitats 

 ranging from gulf waters with 34 ppt salinity to inland freshwater rivers up 

 to 120 miles from the coast. Annual commercial landings in Florida in 1968-78 

 averaged 17 million lb. 



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