Friday, November 8, 2019

Oysters, eelgrass and burrowing shrimp

Chris McGann

An expanse of eelgrass, one of the critical components of
the Willapa Bay ecosystem being studied. 
Washington Sea Grant, a program at the University of Washington's College of the Environment, hosted the first of four workshops in support of the Washington Coast Shellfish Aquaculture Study in South Bend last week.

The study is aimed at pulling together and advancing research to better understand the tidal ecosystems of Willapa Bay and Grays Harbor, with particular attention to interactions among shellfish aquaculture, eelgrass and burrowing ghost shrimp.

Burrowing Shrimp are a native species that become a problem
for oyster farmers when their populations grow to excess. 
The problem with burrowing shrimp

Willapa Bay is home to some of the most productive oyster farms in the country, but in recent years it has been plagued by a booming burrowing shrimp populations that are threatening thousands of acres of oyster beds.

Left unchecked, the burrowing shrimp populations can grow to such high densities that broad swathes of the tidelands are reduced to unstable muck devoid of other sea life. The quagmire created by the shrimp is devastating for bottom culture oyster growers, who have no available tools to prevent their crop of oysters from sinking into the soft mud and suffocating.

The soft mud created by a burrowing
 shrimp infestation in Willapa Bay. 
Research dating back several decades in Willapa Bay has illuminated many characteristics of burrowing shrimp including survival rates, growth patterns, biomass production and long-term population trends in shrimp-dominated areas. But scientists know much less about other elements of their life cycle including recruitment, population dynamics and the influence and interaction of other species, such as birds, eel grass and shellfish.

The study

The Washington Sea Grant study will compile existing information and coordinate new research about the bay’s ecosystem to advance a shared understanding among scientists, resource managers and shellfish farmers of how the ecosystems of Willapa Bay and Grays Harbor function.

With a better understanding of the biology of the shrimp, their interaction with native eel grass, and oyster farms, Sea Grant believes stakeholders will be able to make informed and effective choices to develop solutions.

Sea Grant’s stated goal is “to sustain shellfish aquaculture in the two bays by establishing a collaborative ecosystem-based management framework that will highlight potential solutions to the current challenges and support ongoing participation from tideland managers, owners and regulators.”

Discussion is critical to the success of the study.
The workshop established a working group representing entities that own, manage or regulate shellfish beds, public tidelands and other natural resources, including shellfish farmers, public agencies and tribes. WSDA’s Aquaculture Coordinator Laura Butler is a member of the working group. Washington Sea Grant believes the dialogue between all the entities is as essential to the success of the study as scientific and technical contributions.

Although the study is not a public decision-making process, the public was invited and several community members attended and listened to local, regional and global experts and the working group’s dialogue. The group collected public comments submitted on notecards at the event. The public input will be incorporated into future discussions.


Projects currently contributing to this study are funded by a $400,000 appropriation from the Washington State Legislature and a $1.2 million grant from NOAA’s National Sea Grant College Program.

Future Workshops

The study will include three more workshops scheduled over the next two years. These workshops will move the study forward and develop the tools needed for an ongoing ecosystem-based management collaboration among stakeholders.