UNDERSTANDING THE ECOLOGY OF SHELLFISH AND THEIR PATHOGENS TO IMPROVE SHELLFISH MANAGEMENT AND PRODUCTION

<b>Project Methods</b><br> Because this is an umbrella project, the methods provided below are brief. Detailed protocols are provided in funded or anticipated external grants that pertain to selected aspects of one or more objectives.Objective 1. Data on oyster disease and oyster pathogens in New Jersey dates back to 1950 or earlier, but continuous data have only been collected since 1989. Data will continue to be collected from the NJ seedbeds in collaboration with the New Jersey Shellfisheries Council and NJDEP. As funding permits, additional data will be collected from other areas in Delaware Bay as well as other parts of New Jersey. To further assist the management of the oyster industry, we will monitor transplant operations to determine the time period before a bed receiving transplants returns to a pre-transplant state. Surprisingly, this has not been done systematically in the past despite heavy reliance on transplanting oysters as a management tool. Growth, mortality and dermo will also be monitored. Monitoring protocols and recommendations to management will be made annually at the stock assessment workshop usually held in February each year.Objective 2. Recently, farmers and state and federal regulators have become increasingly concerned about vibriosis, a human illness that can be associated with consumption of raw and undercooked seafood. Vibrio bacteria, the etiological agent of vibriosis are naturally occurring and among the most abundant bacteria in the marine environment (Thompson et al. 2006). Although only a small fraction of environmental strains cause illness in humans, their widespread distribution in marine and estuarine environments raises concerns for seafood safety. Therefore, developing effective grow-out, harvesting and handling methods that minimize levels of harmful Vibrios in oysters is of paramount importance to the industry. Specific concern about Vibrio parahaemolyticus (Vp) is increasing as a result of unexplained and unexpected outbreaks during the past decade. Vibrio parahaemolyticus is one of ten Vibrio species implicated in human foodborne disease, and is the leading cause of gastroenteritis worldwide associated with the consumption of seafood. Results from a recent FDA risk analysis study indicated that the most important risk factor is the level of V. parahaemolyticus in oysters at the time of harvest. To address this problem we will quantify total and pathogenic Vp (Vibrio parahaemolyticus), and total Vv (Vibro vulnificus), in oysters grown in subtidal and intertidal grow-out conditions over the course of the Vibrio high-risk season (May-September) in oyster farms located across the salinity gradient of the Chesapeake and Delaware Bay regions. Additionally, for intertidal grow-out systems, we will evaluate the time required for levels of pathogenic and total Vibrios to return to levels found in subtidal grow-out systems following resubmergence.Objective 3. The HSRL pathology lab routinely conducts health assessments for various labs and aquaculture operations. This work has led to the discovery and description of novel parasites such as the protozoan Minchinia mercenariae in hard clams (Ford et al. 2009). A recent masters student was able to document an unusually high occurrence of a ciliate parasite in oysters from Great Bay, NH and will soon be publishing that work. Follow up studies are planned for molecular characterization. Continued surveillance work will provide similar opportunities. In the course of conducting health evaluations for shellfish seed being transferred within and among water bodies across multiple jurisdictions it has become apparent that there is a lack of uniformity and appreciation for the biology and ecology that control host-pathogen interactions such that policies based on political boundaries make much of the regulatory framework ineffective and inefficient. To resolve this, funding from USDA APHIS VS was obtained for a preliminary visioning workshop that was then leveraged to obtain funding from NOAA Sea Grant to begin developing a shellfish health management system. We have already convened a workshop of more than 50 stakeholders representing industry, resource managers, extension agents and academia that proposed the creation of a shellfish advisory panel (Bushek and Carnegie 2014). We will assemble that panel and task them with developing working groups and subcommittees to address developing a hatchery certification protocol, developing a database management system, articulating a zoning strategy and developing a shellfish health surveillance program. Key assays will also be evaluated and standardized, including novel molecular assays, for diagnostic suitability in surveillance of shellfish health and interstate transfer or transfer among water bodies or zones.Objective 4. The Delaware Bay Oyster Restoration program of the mid 2000s was highly successful producing potential economic returns reportedly as high as 75:1 from some specific efforts (Ashton-Alcox 2010). Averaged across the entire Delaware Bay, the program was able to sustain the oyster population and the oyster fishery through a record period of consecutive recruitment failures. Recovery was well on its way until floods in 2011 killed about 35% or the oysters in the upper portion of the Bay equivalent to about 25% of the total abundance in the fishery (Munroe et al. 2013). Along the shores of the Delaware Bay, sea level rise and storms have been rapidly eroding beach and marsh shorelines. Funds are being sought to restore oyster, marsh and beach habitats and innovative technologies such as spat-on-shell and living shorelines are being developed and evaluated to address these issues. A portion of this work is determining the habitat value of the restored areas for benthic and nektonic fauna.