In just a matter of months, small juveniles that started out less than 1/4-inch wide 

 grow into large juveniles and small adults like this one. 



Martin Posey sweeps a net along an oyster habitat 

 near Sneads Ferry as he checks for crabs. 



more compelling because of the growing 

 interest in crabbing and some signs that 

 crabbing may be declining. Blue crabs 

 are the most important commercial 

 fishery species in the Southeast with a 

 market value of $124 million per year 

 along the Atlantic and Gulf coasts. More 

 people are joining the industry in North 

 Carolina and Florida, but the harvests 

 aren't growing. 



"We need to know what the critical 

 habitats are in order to manage them, protect 



them and enhance them," Posey says. 



What makes Posey's research even 

 more useful is his choice of a region that 

 hasn't been studied much for its crab 

 habitats. 



In a joint study with Florida 

 researchers, Posey is trying to figure out 

 what kinds of habitats juvenile blue crabs 

 prefer along the North Carolina and 

 Florida coasts and to see whether those 

 habitats are interchangeable. In the past, 

 more attention has been given to the mid- 



Atlantic and northern Gulf coasts. 



The general theory has been that the 

 vulnerable young crabs, which face the 

 gravest danger from the claws of bigger 

 blue crabs, would rather live in tangled 

 masses of sea grass. But, Posey says, that 

 theory doesn't explain how blue crabs 

 have flourished along the southeastern 

 coast of the United States, where sea grass 

 doesn't grow from southern North 

 Carolina to northern Florida. 



To test the crabs' preferences, Posey 

 and his colleagues are trying a number of 

 approaches. In one, they compare the 

 number of crabs they find monthly at 

 three types of sites — sea grass beds, sand 

 flats and oyster beds. They set up the 

 North Carolina test areas at Masonboro 

 Island, Swan Point and Middle Marsh and 

 established two other sites in Florida. 



In July, when Posey and research 

 associate Troy Alphin pushed sweep nets 

 through the shallow water at Swan Point, 

 they found more juveniles in the sand flats 

 burrowing under the mud along the edge 

 of the water. The results vary month by 

 month, though. 



The researchers also will look at the 

 kinds of habitats juvenile blue crabs 

 choose in laboratory experiments, and 

 they will study the effects of predators by 

 tethering the crabs in different types of 

 habitats. 



Posey's research is expected to yield 

 crucial information about the early part of 

 the blue crab's life. That information 

 could help state regulators know which 

 kinds of habitat to protect, Posey says. 

 And protecting habitat would be a positive 

 action to promote the well-being of crabs 

 rather than a negative step such as 

 enacting rules and restrictions. 



With the study less than half finished, 

 there's no telling how their hypotheses 

 may be confirmed or challenged. For 

 example, scientists may end up looking at 

 fresh and brackish areas of estuaries in an 

 entirely different light as blue crab nurseries. 



"It's an area that's not been consid- 

 ered important for blue crabs," Posey 

 says. "If that's true, there's a whole new 

 habitat that we never thought of before 

 that's critical." □ 



COASTWATCH 23 



