WOLCOTT, T.G.; WOLCOTT, D.L.; HINES, A.H.; MEDICI, D.A.; NC State Univ., Raleigh and Smithsonian Environmental Research Center, Edgewater MD: Migration of adult female blue crabs from mating areas to the maternity suite: when, where, and who cares?

Adult female blue crabs (Callinectes sapidus) migrate from upper estuaries, where mating occurs, to high-salinity spawning grounds before producing a series of broods. When females migrate, and what routes they take, provide an essential basis for management decisions aimed at protecting broodstock, and for estimating population reproductive output. In the tidally-forced Chesapeake Bay and in North Carolina?s shallow, wind-forced estuarine system, we are investigating the assumptions that females mating in spring/early summer migrate promptly to spawning grounds and that they begin producing broods that summer. In the upper Chesapeake Bay, trawling for migrating females on ebb tides, ultrasonic tracking and conventional mark-recapture experiments all indicate that migration begins in October, after the protected ?migration corridor? is again opened to crab potting. In NC?s Pamlico Sound, mark-recapture experiments likewise are showing that mated females remain in the upper sub-estuaries for the remainder of the summer. Many commercial crabbers are convinced that after mating, females remain up-estuary to ?fatten up?, adding to their somatic and gonadal tissue. Only when water temperatures begin to decline, and brood production has already ceased in spawning areas, do they migrate seaward in a fairly synchronous burst. They begin production of broods the next spring after overwintering in the bottom mud. This suggests that winter mortality must be calculated into estimates of larval output by the blue crab broodstock. It also seems probable that fishery closures in the Chesapeake migration corridors will need to be adjusted based on appropriate temporal and spatial data about migration.