Attempts to characterize the population dynamics of the softshell clam Mya arenaria are complicated by a lack of nonlethal genotyping techniques and reliable tagging methods. A straightforward and nonlethal technique for clam genotyping is presented here, as well as a new method for the long-term tagging of clams. Hemolymph extracted from M. arenaria was used directly in a polymerase chain reaction to amplify successfully a DNA fragment suitable for sequencing. Tested M. arenaria showed 100% (n = 10) survival after a period of 4 wk. In a separate experiment, passive integrated transponder (PIT) tags were inserted between the mantle and shells of 72 clams that were monitored for tag retention and mortality. Among all PIT-tagged clams, there was 100% survival and 92% tag retention. These methods provide a mechanism by which softshell clams can be genotyped and individually monitored during field experiments.