Impact Reports

Burrowing Shrimp and Invasive Eelgrass

2016

PARTNERSHIPS

Within the past decade, a new aquatic weed, non-native Japanese eelgrass, has invaded the tidal flats, causing total crop losses in numerous commercial clam farms. Shellfish production in Washington is a $60 million a year industry. Several major pests plague this industry, resulting in major crop loss.

Shellfish production in Washington is a $60 million industry annually. Several major pests plague this industry, resulting in major crop loss. One of the most important pests is subterranean burrowing shrimp. These shrimp bioturbate (stir up) the sediment, causing the oysters to sink and die. For 60 years the industry had been using the insecticide Sevin to control this pest, but due to lawsuits, its use was phased out in 2013. Without alternative controls for shrimp, tens of millions of dollars in annual crop revenue will be lost and the industry will quickly lose its economic viability in southwestern Washington.

Within the past decade, a new aquatic weed, non-native Japanese eelgrass, has invaded the tidal flats, causing total crop losses in numerous commercial clam farms. This weed now dominates the upper tidal flats of several Washington estuaries and many clam farms have ceased operation due to its impact on production. Japanese eelgrass, not only threatens the economic viability of the shellfish industry, but has also resulted in significant changes in estuarine ecology. State and federal regulatory agencies have been resistant to management of eelgrass until more studies are conducted on the ecological impacts of this invasive species, and the potential non-target impacts of its management. For the shellfish growers to maintain their $10 million clam industry, the negative impacts of invasive eelgrass have to be proven, the species be considered invasive by regulatory agencies, management options developed and implemented, and the non-target impacts of its control be documented.

Burrowing shrimp: Over the past decade, we led a collaborative research effort to develop and test alternative mechanical, biological, and chemical control of burrowing shrimp. One chemical, imidacloprid, was the only viable solution. Next, we led a project to obtain a registration for imidacloprid to control burrowing shrimp in Willapa Bay. Funding and collaboration among stakeholders, industry, three universities, and state and federal agencies were obtained in order to proceed with the registration and permitting process. Extensive research on ecological impact and fate of imidacloprid was done. An Integrated Pest Management (IPM) approach was developed to achieve maximum efficacy with minimal impact. Outreach was provided in newsletters, presentations in workshops, numerous grower meetings and field days, conferences and professional meetings, project reports, and by holding numerous collaborative meetings and tours with regulatory agencies. » More …