Ken Wiegardt stands on the oyster beds of Willapa Bay, Washington, watching sediment pile up where his family's shellfish used to thrive. A fifth-generation oyster farmer, Wiegardt has seen his nursery ground decimated by creatures barely larger than his hand—burrowing shrimp that dig through the seafloor like relentless engineers, turning productive farmland into what one researcher a century ago called a marine "Swiss cheese." By last month, the damage forced him to lay off three oyster shuckers who had worked with him for years.
For at least a hundred years, these small native shrimp have been a headache for Washington's shellfish farmers. A 1929 University of Washington researcher named Belle Stevens documented the struggle, noting that oyster growers had tried various defenses but found "no really adequate and at the same time practical method" of stopping them. By dragging sediment to the surface—a single four-inch shrimp can move a handful each day—they bury clams and oysters under layers of displaced mud. The problem worsened dramatically after 2018, when the Department of Ecology instructed farmers to stop using pesticides, which while effective, poisoned salmon, crabs, and other creatures in the ecosystem.
Now, University of Washington researchers have developed a solution that borrows from the construction industry rather than chemistry. The method uses a custom-built floating platform equipped with six concrete vibrators to compact sediment in targeted 50-square-foot regions. The vibration consolidates the mud, trapping shrimp in their burrows and starving them of oxygen. Within days, they die.
Led by UW biology professor Jennifer Ruesink, the team tested this approach at four sites around Willapa Bay. The results matched pesticide effectiveness, reducing live shrimp populations by between 72 and 98 percent. The study, published May 12 in the Journal of Shellfish Research, represents the first non-chemical proof-of-principle for controlling these destructive creatures at scale.
The breakthrough came from an unexpected collaboration. After a mechanical "crushing" experiment using a tracked vehicle failed, Ruesink's co-author Alan Trimble suggested a radical shift in thinking. "You're thinking like a dirt farmer and you need to start thinking like a concrete engineer instead," Trimble told her. The insight proved illuminating: concrete vibrators work by removing air bubbles from wet slurry, a process identical to what happens in a mudflat. Rather than crushing, the solution was consolidation.
The impact for farmers like Wiegardt is tangible. Jolly Roger Oysters has lost 75 percent of its nursery ground, and the farm's carrying capacity has plummeted from 265,000 bushels of market-ready oysters to just 75,000. The new vibration method offers hope without sacrificing the ecosystem balance that Ruesink emphasizes is critical. Burrowing shrimp remain essential food for gray whales and sturgeon, and the species' larval phase connects entire ocean populations. Shrimp that settle in the estuary can live up to ten years, making their presence both necessary and manageable when controlled strategically.
For family-owned shellfish operations across Washington, this non-chemical solution arrives at a crucial moment—offering a way to reclaim productive farmland while keeping the larger estuary intact. The vibration method represents more than technical innovation; it signals a path forward where farming practices and marine ecosystems can coexist.