A shrimp boat heading back to the coastal Louisiana port of Venice on May 5, 2010.

(Mira Oberman/AFP/Getty Images)

At a Glance

A team of researchers from Duke University find a link between coastal low-oxygen levels and the price of jumbo shrimp.Coastal hypoxia, caused by nitorgen and phosphorus-laden runoffs from the land, is a global problem.The study may help policymakers value the economic impact of reducing nutrient pollution in our oceans.

Brief spikes in the price of jumbo shrimp are likely the consequence of a low-oxygen dead zone that develops off Louisiana's coastline each year, a new study says.

Published Monday in the , the study's authorsexamined the link between the formation of the dead zone and price hikes. They found that while the price for jumbo shrimp increases, the cost for smaller shrimp generally falls.

Unfortunately for Gulf commercial fishers, the benefits of the price hike are quickly countered by an influx of jumbo shrimp imports from foreign producers and farm-raised shrimp.

The authors wanted to find a quantifiable measure of the economic impact of coastal hypoxia on the shrimp industry on the Gulf Coast, which they believe could have global ramifications, as well.

"Coastal hypoxia is a growing problem worldwide, but economic consequences for fisheries are largely unknown," the authors note in the study's abstract. "We provide evidence that hypoxia causes economic effects on a major fishery that was once the most valuable fishery in America."

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Researchers tracked the price of shrimp by size groups between 1990 and 2010. In this graph, the size groups are to the right, with the dark blue line at the tip indicating one to 15 shrimp per pound, which is the large shrimp category.

(Proceedings of the National Academy of Sciences)

The findings of the study also provide a better understanding of the broader effects of low-oxygen levels in the Gulf, helping economists and policymakers "quantify the real-world market value of reducing nutrient pollution flowing into our oceans," said Martin Smith, a professor of environmental economics at the Duke University Nicholas School of the Environment, in.

"Many studies have documented the ecological impacts of hypoxia, but establishing a clear causal link to economic losses in affected fisheries has been elusive," said Smith. "Our study does this by showing how seasonal hypoxia off the Louisiana and Mississippi coasts drives monthly fluctuations in market prices in the Gulf brown shrimp fishery, a major fishery that was once the most valuable in America."

Coastal hypoxia is characterized by low or depleted oxygen levels in water, which threatens marine ecosystems worldwide, by slowing the growth of fish and shellfish. In extreme cases, the hypoxia can trigger widespread local die-offs.

"It’s caused when nitrogen and phosphorus-laden runoff from inland watersheds spurs the growth of oxygen-consuming algae in offshore waters," notes Smith in the news release.

The researchers monitored monthly trends in the price of Gulf brown shrimp from 1990 to 2010 and found a "recurring pattern of spikes in the price of large shrimp relative to small ones during months when hypoxic dead zones occurred — typically late spring and summer."

A fleet of shrimp trawlers in Bayou La Batre, Alabama.

(U.S. Coast Guard)

“Because fishermen are catching more small shrimp and fewer large ones during these months, the price of small shrimp goes down and the price of large ones goes up, creating a short-term disturbance in the market that we can track,” Smith said.

Previously, researchers measured the effects of hypoxia byexamining the quantity of shrimp caught at different locations along the coast. But, as the authors note, shrimpers are smart and travel elsewhere outside the hypoxic areas to find the shrimp, which brings in a human factor.

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This and the global impacts of imports and farm-raised shrimp complicates matters for scientists trying to "quantify any regional economic impacts of the dead zone," Smith notes.

“In science, we typically try to compare a treated group or area to some kind of control. When fishermen respond to hypoxia by moving around, they undermine our ability to use non-hypoxic areas as controls,” Smith said.

“Looking at prices rather than quantities allows us to see the economic signal more clearly, without interference from these human and natural feedbacks that can compound or obscure the effects of hypoxia on a fishery,” he said.

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