The Biological Bulletin, Vol 195, Issue 2 168-173, Copyright © 1998 by Marine Biological Laboratory

RESEARCH NOTE

Migratory Behavior of Ovigerous Blue Crabs Callinectes sapidus: Evidence for Selective Tidal-Stream Transport

R. A. Tankersley, M. G. Wieber, M. A. Sigala and K. A. Kachurak
Department of Biological Sciences, 1000 Hilltop Circle, University of Maryland Baltimore County, Baltimore, Maryland 21250

In the late summer and early fall, newly inseminated female blue crabs (Callinectes sapidus) leave low-salinity areas of estuaries and migrate seaward to spawn near the entrance. We tested the hypothesis that migration of female C. sapidus to spawning grounds is facilitated by selective tidal-stream transport (STST). We monitored the swimming direction of adult crabs from a stationary platform located about 1 km inside the entrance to the Newport River Estuary (Beaufort, North Carolina). Swimming activity near the surface occurred primarily at night and most crabs avoided swimming against tidal currents. Eighty-one percent of the crabs observed moving down-estuary toward the inlet during ebb tide were ovigerous females. Of the 36 gravid females captured traveling in ebb currents, 97% possessed dark egg masses containing late-stage embryos. Conversely, nearly all (98%) adult crabs observed traveling in flood currents lacked egg masses, and all the females captured while migrating up-estuary exhibited signs of recent spawning. These observations indicate that ovigerous blue crabs use ebb-tide transport to migrate seaward to spawn and flood-tide transport to reenter the estuary shortly after larval release.