It’s only midmorning, but shrimper Thomas Olander is already calling it quits for the day in a small bayou in St. Mary Parish, on the central Louisiana coast.
There aren’t enough shrimp out there — especially the highly sought-after jumbo shrimp that fetch the highest prices at the market.
“It's just not worth it,” Olander said, of his morning burning fuel, supplies and time.
A bad day on the water typically isn’t something to fret about. Some days are good, some days are bad, Olander said, and in the end it all evens out. But over the past few years, the bad days are outnumbering the good ones.
As the agricultural runoff from the Midwest contributes to a massive dead zone in the Gulf of Mexico, a sensitive habitat and livelihoods are threatened.
“We're not catching no large shrimp,” said Olander, who largely blames worsening environmental conditions. “There’s no explaining this here other than it’s something's wrong with our water.”
Olander grabs his phone to elaborate. He pulls up a picture of the Gulf water his cousin Douglas, also a fisherman, took from the deck of his boat earlier this summer.
“That’s that green slime,” he said, pointing. “That's that algae bloom right there.”
He flicks through a few more. The water resembles neon-tinged split-pea soup.
“And that's what causes the dead zone,” Olander said.
The dead zone is an area in the Gulf of Mexico where the oxygen is so low, sea creatures cannot survive. It forms every summer and measures in the thousands of square miles. The largest on record was in 2017: 8,776 square miles, bigger than some states.
How the Gulf's dead zone works
In 2019, the dead zone was measured at 6,952 square miles, though scientists say it might have been much bigger had it not been for the churning tides of Hurricane Barry, which made landfall just before researchers embarked on a weeklong cruise to measure it.
The dead zone is fueled by runoff pollution, primarily nutrients like nitrogen and phosphorus, which largely originates in the Midwest and travels to the Gulf via the Mississippi River.
The runoff comes from several sources, including manure and urban stormwater drainage, but the biggest contributor is agriculture — specifically, the fertilizers farmers spray onto their crops to help them grow. No matter the source of nutrient-laden runoff, it all travels down the Mississippi River and eventually empties into the Gulf of Mexico.
Once in the Gulf, the high levels of nitrogen and phosphorus cause massive algal blooms. When that algae dies, the water loses oxygen. So if you’re a shrimp and you call that water home, you either die or quickly evacuate.
“I like to think of that as the burning-building effect,” said Martin Smith, environmental economist at Duke University.
A few years ago, Smith published a study looking at how the dead zone affects the price of shrimp in the Gulf.
“When you're inside a building that's on fire, you run outside,” Smith said. “And when you get outside into the fresh air, you don't keep running — you take a breath and you stop.”
The stress of fleeing can stunt the growth of shrimp. Ultimately, Smith said, the dead zone causes the average price of shrimp to drop. Which means shrimpers like Olander make less money.
Issues upstream in the watershed
But the problem of nutrient pollution isn’t limited to the Gulf of Mexico, said Nancy Rabalais, a researcher at the Louisiana Universities Marine Consortium and Louisiana State University.
“It's also the watershed,” she said.
For more than 30 years, Rabalais has led the scientific team that measures the dead zone in the Gulf of Mexico. Rabalais points out that the same nutrient pollution that fuels the dead zone can cause harmful algal blooms closer to the source.
“The Midwest has many lakes and reservoirs that have very similar problems,” she said. “And it's toxic … you'll get sick.”
MORE: Missouri Farmers Try To Reduce Runoff But Cleaning Gulf Dead Zone May Take Decades
Rabalais thinks it behooves everyone, from the Midwest to the Gulf Coast, to work together to reduce nutrient pollution.
For his part, shrimper Thomas Olander doesn’t blame any particular Midwesterners, and certainly not the farmers. He sees himself as a farmer of the sea and identifies with the difficult economics farmers often face. But he does think the federal and state governments should do more to help shrink the dead zone — and fast.
Several states in the Mississippi River watershed have been working with the federal government on the issue. Twelve, including Missouri, have created plans to reduce or better manage the amount of nutrients they flush into the Mississippi River.
Whether that’s enough to start shrinking the dead zone is unclear. But Olander wants to see a healthier Gulf soon.
“Doing nothing but studying [the dead zone] all the time is not doing anything,” he said. “We know there's a problem already ... let's start getting solutions done.”
Editor's note: This story is part of a collaboration between St. Louis Public Radio and New Orleans Public Radio on agricultural runoff that affects water quality in the Missouri watershed and the Gulf of Mexico.
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