Baffle, NoGravel 



Figure l. — Diagram of one site of the experimental design indicating the presence of each plot and the net for protection of juvenile 

 Mercenaria mercenaria . Included in one site with a net would be a crab trap (not illustrated). The net was pushed into the substrate. 



Table l. — ANOVA table for survival of hard clam, Mercenaria mercenaria, juveniles 

 with tests of pens, baffles, gravel, and traps and their interactions. Identical SS in the 

 July data were caused by clams being absent in all sites with no baffle and no gravel. 



*"P<0.001, "P<0.01, •P<0.05. 



clams sampled vs. 31 clams sampled in penned 

 areas with traps), and, in part, to predation at the 

 no pen no trap site, 23 clams sampled vs. 15 clams 

 at the no pen plus trap site. These data indicate 

 that trapping is essential in penned areas, but that 



when pens are absent crab trapping is of no 

 benefit. 



Within 2 wk following the July sampling, in- 

 spection of the sites revealed that clams 1.5-4.0 cm 

 high had been crushed. These shell fragments 



539 



