Gear Effects on Marine Habitats: Harvesting Northern Quahogs in a Shallow Sandy Bed at Two Levels of Intensity with a Short Rake

Abstract

We studied the effects on invertebrate infauna and grain size of harvesting northern quahogs Mercenaria mercenaria with a short rake. The substrate was a mixture of medium-coarse sand (phi values, 0.847–1.159) that was covered by 0.5 m of water at low tide. Two experimental areas (I + II) in Raritan Bay, New Jersey, were subdivided into six 5.5-m × 5.5-m plots. We raked alternate plots, the unraked plots serving as controls. In area I, we raked the treatment plots once (in June 2000) and then sampled all plots for effects on invertebrates and grain size. The number of invertebrates in the five taxa we counted and the mean grain size did not differ significantly (P > 0.05) between treatment and control. In area II, we raked the treatment plots three times, one month apart (in July, August, and September 2000) and then sampled all plots. The results for invertebrates and grain size were similar to those for area I. This study suggests that short raking once or repeatedly during a harvesting season in a shallow sandy substrate does not measurably alter numbers of invertebrates or sediment grain size.