Catching Fish in the "Dead Zone"

Where Science and Business Intermingle

Scott Avanzino and Bobby Adisano show off a wahoo they caught while fishing in the Gulf of Mexico south of Venice.

JOHN N. FELSHER

Returning to Cocodrie on a blistering day in August, our fish coolers overflowed with more than 17 species, including 11 tuna caught in the Gulf of Mexico after just three hours of actual fishing time.

“Just another day in the heart of the dead zone,” quips Capt. Tommy Pellegrin of Custom Charters. “Every year, they put out a news release about the Gulf of Mexico dead zone. I’ve been running charters in the Gulf for decades. In all that time, I’ve never returned home without catching fish. When I’m fishing offshore, I probably come back with an average of 300 to 400 pounds of fish. Sometimes, we catch more than 1,000 pounds.”

Each summer, the Louisiana Universities Marine Consortium (LUMCON) releases its annual “dead zone update” outlining the area of hypoxia, or low oxygen, in the Gulf of Mexico. According to LUMCON, the hypoxic area stretches all along the Louisiana coastline and covers 5,000 to 9,000 square miles. Nutrients, primarily phosphorus and nitrates, flow into the Mississippi River and down to the Gulf of Mexico. In the Gulf, those nutrients feed a phytoplankton bloom. These microscopic plants comprise the basic building block for an entire ecosystem. Uneaten phytoplankton sinks to the seabed and decomposes. The decomposition process consumes oxygen, creating hypoxic areas.

“Phosphorus and nitrogen is good for the coastal system because it supports the food web that supports the fisheries,” explains Dr. Nancy N. Rabalais, executive director for Cocodrie-based LUMCON. “However, there’s been an increase in the amount of phosphorus and nitrogen since the 1960s because of human activities up the watershed. There’s not enough money to do more studies, and our research has already been cut back by the National Oceanic and Atmospheric Administration.”

During the summer, sunshine heats water near the surface while deeper water remains colder. Therefore, the Gulf stratifies into a warmer, oxygenated layer and a cooler layer with little or no oxygen. The same temperature stratification happens in many large freshwater lakes like Toledo Bend and occurs at major river deltas throughout the world.

Stratification begins in the spring as waters warm and peaks in September. The hypoxic area fluctuates frequently. A strong storm could mix the layers. The thickness of the hypoxic layer also varies widely. In some places, it might take up half the water column. In other places, only the bottom few feet remains hypoxic.

“The hypoxic zone usually occurs in the coastal waters from about 12 feet deep out to about 90 feet deep,” Rabalais says. “The hypoxic zone is not really present in the winter because we have too many cold fronts. That mixes up the layers and brings oxygen to the bottom. Most bays and estuaries are fairly well mixed.”

Despite annual dire warnings about hypoxia, Louisiana still offers some of the best saltwater fishing anywhere in the United States. In 2011, commercial fishermen landed 1.8 billion pounds of shellfish and finfish like red snapper in the Gulf. Louisiana alone accounted for 1.3 billion pounds, according to the National Marine Fisheries Service.

“We catch a lot of snapper,” said Capt. Daryl Carpenter with Reel Screamers Guide Service in Grand Isle, ((225) 937-6288, realscreamers.com.) “We catch a lot of the bigger snapper higher



The deckhand gaffs a red snapper caught during a fishing trip to the Gulf of Mexico.

“Uneaten phytoplankton sinks to the seabed and decomposes. The decomposition process consumes oxygen, creating hypoxic areas.”

in the water column. I think the hypoxic zone can become a serious problem, but it’s localized. Fish are able to move into areas with better water quality. Sometimes, we have to move a little farther to find the fish.”

Louisiana produces about 34 percent of the seafood landed in the 48 contiguous states and more than 76 percent of the seafood caught in the Gulf of Mexico. The Louisiana commercial seafood industry contributes about $2.4 billion to the state economy each year, according to Ewell Smith, executive director for the Louisiana Seafood Promotion and Marketing Board. Add recreational fishing into the equation, and the economic impact rises to more than $3 billion a year.

“Louisiana has always been a strong seafood producer because of the Mississippi River,” Smith says. “About 80 to 85 percent of the seafood produced in the Gulf spends at least part of their lifecycle in the vast delta estuaries created by the river. It’s this system that drives the fertility of our fisheries.”

Louisiana leads the nation in shrimp production with about 90 to 100 million pounds landed per year for a total value of more than $132 million, Smith says. That’s about 29 percent of the national harvest and 42 percent of the Gulf total. The Sportsman’s Paradise also leads the list in crawfish, alligator and oyster production. Louisiana oystermen bring in about 250 million pounds of oysters in the shell or about 61 percent of the national harvest. The state comes in second in finfish production behind Alaska and a close second in blue crab production behind Maryland with 43.7 million pounds valued at $36.2 million.

“The commercial seafood industry directly creates about 30,000 jobs in Louisiana and thousands of secondary jobs,” Smith says. “The other element is tourism. Food is a big part of our culture. People come to South Louisiana to eat seafood and to fish. Whenever there’s a negative news story about fishing in the Gulf, that impacts tourism.”

Much of the South Louisiana economy depends upon seafood production and recreational fishing. In 2012, recreational anglers spent 23 million days fishing in the Gulf of Mexico and spent $806 million in Louisiana alone. If sportsmen see a news report about the dead zone, they may go elsewhere to fish. That hurts the Louisiana economy.

“When people hear ‘dead zone,’ they think the entire area from top to bottom is lifeless,” Pellegrin sums it up. “That hurts my business and the business of every other charter boat captain and all the marinas along the coast. There’s no way we can quantify the economic loss to this state when people decide to go elsewhere to fish because they heard about the dead zone. Some of my clients want to go see the dead zone. I say, ‘You’ve been in the middle of it all day. That’s where we caught this 900 pounds of fish!”


Sea birds flock to a shrimp boat preparing to anchor after a night of trawling in the Gulf of Mexico south of Cocodrie.


 

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