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Harvested, Not Poached

By Rachel Wallach

As a boy, Dave Love raised oysters with his family in the marshes of Virginia. As a grad student in North Carolina, he studied shellfish and water quality. And as project director for the Public Health and Sustainable Aquaculture Project at the Johns Hopkins Center for a Livable Future (CLF), he chose oysters to star in some of his latest research.

Love, PhD, MSPH, is a systems guy. Public health, diet, food production and the environment are pieces of a single puzzle, he says, linked in constant interplay. With pressures like population growth, climate change and resource depletion, Love and his CLF colleagues work to better understand the food system and how to achieve balance.

Oysters, a “perfect aquaculture species,” have simple needs and deliver large benefits—when properly treated.

Convinced that aquaculture—growing seafood in controlled conditions—is a powerful strategy to restore that equilibrium if sustainable methods are used, he sought a research project that could help make his case. Because oysters’ needs are simple and their benefits large—they eat what floats by and clean the water while doing so—they are the “perfect aquaculture species,” says Love.

In Maryland’s Chesapeake Bay, polluted waters are off-limits for oystering. So when Love heard that people were still occasionally getting sick from eating oysters, he wondered if the shellfish were being illegally harvested in contaminated areas. The resulting paper, just published in the Journal of Shellfish Research, sheds light on poaching patterns that highlight the need for more intensive enforcement and reveal challenges within Maryland’s wild-caught oyster industry—challenges that oyster aquaculture could solve, say Love and five co-authors.

Digging through citations issued by the state dating back to 1959, the authors found that poaching does have the potential to make people sick; about 6 percent of the tickets were for harvesting oysters out of season (contamination is more likely in warmer months) or from contaminated areas, or storing them inappropriately.

But poaching poses a greater danger to the Bay’s oyster population itself: 75 percent of citations were for harvesting too-small oysters. When oysters are harvested below market size, the population can’t rebound, Love says. Oysters are essential for a healthy Bay for two reasons: they filter the water when they eat, and they build reefs that other organisms use.

The state of Maryland has already initiated a two-pronged approach to restore the oyster population. Oyster bars in areas off-limits for harvest allow oysters to flourish, says Kennedy Paynter, a co-author and research associate professor at the University of Maryland. The bars are often intentionally located near sewage outfalls so that these oysters—not meant for consumption—can benefit from the accompanying nutrients; but any oysters poached there may be contaminated.

Without stronger enforcement, the potential for an outbreak of disease is significant.

The state is also using loan incentives to drive the shift to sustainable aquaculture. Love’s team hopes their paper will encourage such efforts to balance the interests of watermen, resource managers and public health by switching from a wild-harvest approach (which leaves openings for poachers) to a farm-raised approach, where individuals tend their own sites.

“We wanted to say to the General Assembly, ‘Here’s some evidence that shows you guys are headed in the right direction in strengthening laws for harvesting from the Bay,’” says Love.