DISEASE TREATMENT IN HARD CLAMS, Mercenaria mercenaria1

ABSTRACT Diseases have been considered to be major factors in the failure of laboratory and commercial bivalve culture. Much of the work on disease has concentrated on the larval stages, but little information exists for the period from settlement to the age of about nine months. We noticed substantial mortalities of 2–10 mm shell height Mercenaria mercenaria which had been held all winter in the grow‐out facility of our laboratory. In subsequent years we developed several methods for treating the clams to decrease the mortalities. Although presumptive tests indicated the presence of Vibrio bacteria we did not confirm the etiological agent and did not establish direct evidence that bacterial pathogens caused the observed mortalities. The most effective treatment tested for general purpose commercial usage was a two‐hour bath of bleach at either 9 or 18 ppm.