The phrase “dead zone” sounds like something straight out of a Halloween horror movie, but it’s a reality all too familiar to the Louisiana fishermen and shrimpers who fish the waters of the northern Gulf of Mexico.
About five miles off the coast of Louisiana and stretching an estimated 6,700 to 8,500 square miles from Texas to the Mississippi River, the northern Gulf dead zone is an oxygen-depleted area that cannot support marine life.
For Louisiana fishermen, the dead zone amounts to about 235,000 tons or 470 million pounds of seafood lost every year, said Paul Greenberg, author of Four Fish: The Future of the Last Wild Food.
Greenberg was a moderator for a panel discussion about the dead zone at the recent Chef’s Collaborative National Summit in New Orleans, which gathered food safety experts, scientists and chefs interested in sustainable, local foodways.
The Gulf dead zone, technically known as a hypoxic (low-oxygen) zone, has been caused by a confluence of environmental factors, but panelists agreed that nutrient-rich fertilizer entering the Mississippi river from the Midwest’s farm belt is a major concern. When those nutrients (specifically nitrogen and phosphorus) flood into the Gulf, it creates the perfect environment for a massive algae bloom, depleting the oxygen that marine species depend on to live.
Panelist Lance Nacio, a Louisiana shrimper, has seen firsthand the effects of the dead zone on the shrimp he catches. “In September and October, shrimp go dormant to survive the dead zone,” said Nacio.
Despite the dark tone of the discussion, Greenberg offered a positive note, citing the reversal of what was once the largest dead zone in the Black Sea. When fertilizers became too expensive for farmers to use after the collapse of the Soviet Union, the size of the dead zone decreased dramatically. “This is a very solvable problem,” Greenberg said of the northern Gulf dead zone.
Cynthia Sarthou, executive director of the Gulf Restoration Network, offered several solutions, including reductions in nitrogen and phosphorus loads in run-off and tying subsidies in the Farm Bill to nutrient reduction plans by farms.
Both Nacio and Paul Hartfield, U.S. Fish and Wildlife endangered species biologist, discussed the value of removing river cut-offs and levees that both increase the speed of the Mississippi river and funnel the water directly into the Gulf.
Nacio said removing the “straight jacket” on the Mississippi would spread the nutrient-rich run-off into surrounding agricultural flood zones and Louisiana’s marshlands – essentially “feeding” these areas and potentially aiding in wetland restoration.
But the flush of fresh river water would also destroy oyster beds seeded in the brackish waters along Louisiana’s coastline, Hartfield noted.
There are feasible solutions to reducing the northern Gulf dead zone, and the panelists agreed it is a complex environmental problem that is – literally – growing.