Use of a Commercial Dredge to Estimate a Hardshell Clam Population by Stratified Random Sampling

With stratified random sampling, use of a commercial dredge provided a valid estimate of the population of the hardshell clam Mercenaria mercenaria in Narragansett Bay, Rhode Island. Because of the nonrandom distribution pattern of M. mercenaria, treatment of the data with normal statistics would indicate a mean of 1.64 bu per dredge tow with a variance of 1.80. Stratified sampling, due to its inherent weighting feature, provided a similar estimate of 1.36 bu per tow with a variance of 0.033.