AN ANALYSIS OF GRAVEL, PENS, CRAB TRAPS AND CURRENT BAFFLES AS PROTECTION FOR JUVENILE HARD CLAMS (Mercenaria mercenaria)1

The major hindrances to field grow-out of juvenile hard clams (Mercenaria mercenaria) are wash by currents and predation. Previous data suggested that the effects of wind-driven and tidal currents could be ameliorated by baffles and to some extent by pens and gravel. In our experiments predation protection was provided by gravel, pens and crab traps. Analysis of variance (ANOVA) was performed on quantitative samples of juvenile hard clams (2 mm seed) taken quarterly from field plots established in October 1975. All possible combinations of gravel, current baffles, pens and crab traps were examined. The results are interpreted as showing the varying seasonal effects of current action (storms) and predation on these newly planted and growing seed. The protection afforded by the combination of gravel and baffles was statistically superior to any of the individual or combined effects of the four variables for the first 11 months. The method has the advantages of being simple and promises to be adaptable to infaunal species in wide variety of habitats with a minimum of modification.