Field Performance and QPX Disease Progress in Cultured and Wild-Type Strains ofMercenaria mercenariain New York Waters

Abstract

ABSTRACT A field experiment was conducted to compare the performance of different hard clam (Mercenaria mercenaria) strains in local clamming waters of New York state. Experimental clams included a Mercenaria mercenaria notata seed obtained from a Florida broodstock, and 2 New York seed strains obtained from local hatcheries, including a cultured M. mercenaria notata strain and a first-generation “wild-type” strain. Quahog parasite unknown (QPX) was acquired by the Florida clams in less than 2 mo of a July deployment of grow-out cages. Prior field studies comparing susceptibility of northern and southern hard clam strains observed QPX acquisition after clams had overwintered in the field, raising the question that higher susceptibility observed in southern seed clams could be a result of poor adaptation to winter water temperatures. Our results show that the southern strain acquired QPX after the clams had only been exposed to the warmest period of water temperatures for this field site (22.3°C on average...