Large-Scale Movements of Postcopulatory Female Blue Crabs \u3ci\u3eCallinectes sapidus\u3c/i\u3e in Tidal and Nontidal Estuaries of North Caroline

For migratory species, understanding the timing, direction, and mechanism of migration is critical for successful fisheries management. We investigated migratory movements of postcopulatory female blue crabs Callinectes sapidus in three estuaries with different tidal regimes in North Carolina using a mark–recapture study. All crabs tagged were within about 2 weeks of the terminal molt to maturity (mating generally takes place immediately after the molt). In general, distances traveled (mean ± SE = 6.8 ± 0.6 km) and net movement rates (0.5 ± 0.05 km/d) were quite low compared to those in previous studies of mature (but not necessarily recently molted) female crabs, suggesting that rapid seaward migration does not take place until several weeks after mating, presumably upon production of a clutch of eggs. Although most crabs moved short distances (85% moved \u3c 15 km), movement was generally oriented seaward, indicating that some down‐estuary movement occurs prior to oviposition, especially in crabs mating in low‐salinity estuaries that would be unsuitable for embryonic and larval development. Crabs moving seaward in the weeks between molting/mating and first oviposition were likely walking rather than swimming and taking advantage of seaward currents, as indicated by the low movement rates and similarities among the three areas