Synchronous emergence and mass migration in juvenile queen conch

An aggregation of juvenile queen conch Strombus gigas vath densities exceeding 250 ind. m-' was observed in the central Bahama Islands during April 1987. The newly documented wave-like aggregation comprised over 100 000 individuals of a single year class averaging 101 mm in total shell length. The aggregation moved an average of 4.8 m d-', en masse, in the direcbon of the ebb tidal currents. Observations between May and August 1987 showed that the mass migration was long-lived. We hypothesize the mass migration to be seasonally synchronous and to serve as a density-dependent or habitat-dependent dispersal mechanism for newly emerged l + year classes from centers of larval recruitment.