Increasing shellfish-borne illnesses from Vibrio parahaemolyticus (Vp ) in the Northeast US during the past 10 years has triggered intensive management practices based on a limited understanding of risks. Current gear-based production requires extensive pre-harvest handl ing that, during warm months , can increase Vp levels in oysters and potentially increase the risk of illness. Field-testing of Vp control measures for pre-harvest practices was conducted in Maine, New Hampshire and Massachusetts where aquaculture practices, regulations, environmental conditions, and Vp populations all vary. O ysters were t emperature-abuse in Little Bay NH, Spinney Creek ME, and Plymouth Harbor and Katama Bay MA. The abundances of total (tlh) , potentially pathogenic (tdh & trh) , and tdh allele-variants using assays developed to identify regionally important pathogenic strains, were measured in bottom and surface cultured oysters exposed to air for 3-48 hours from sub-ti dal and inter-tidal locations. Temperature abused, un-exposed and re-submerged exposed oysters were sampled after 1-10 days. Total Vp concentrations significantly increased in abused oysters and remained higher than in unexposed oysters for up to 8 days, depending on treatments . Both tdh and trh were elevated in abused oysters compared to control oysters but these pathogenic markers returned to environmental levels quicker than total Vp . The prevalence of specific tdh alleles as proxy for Vp strain types 36 and 631 (tdh3 ) varied and provided further resolution of this specific pathogenic population . The study provides scientifically sound findings for each state to use in managing pre-harvest practices to reduce Vp -related public health risks.