Publications

During the summer of 1992, a loss of 2- to 3-cm zebra mussels, Dreissena polymorpha, was recorded in the Hudson
River near Catskill, NY. We document this adult population crash and present field and laboratory data suggesting that predation by
blue crabs, Callinectes sapidus, was responsible. Dredge samples on July 8th indicated that the mean density of the largest zebra
mussel size class (length = 2 to 3 cm) in the Hamburg-Catskill-Germantownregion was 664 m-2 (range of 59 to 2,222 m-2, 14rucks
examined). In sharp contrast, extensive dredging on August II th did not recover a single mussel of that size class in that area. The
largest mussel collected on August 11th was only 0.7 em long, with over 100 rocks examined. An abundance of shell fragments and
detached, live mussels were considered evidence of predation, possibly by a large immigrant blue crab population present in the area.
Laboratory trials confirmed that these crabs can aggressively consume zebra mussels, particularly the size class that was virtually
eliminated in the Catskill area, and that their feeding does result in piles of shell fragments and removed, yet unconsumed mussels.
Further supportive evidence of the blue crab predation hypothesis was gained in the summers of 1993 and 1994, when blue crabs did
not migrate into the Catskill area and a massive decline in 2 to 3 cm mussels did not occur.