11/02/2012 04:15 pm ET Updated Jan 23, 2014

Invasive Gulf Tiger Shrimp Could Creep Into Local Markets

This article was originally published in The Louisiana Weekly in the Oct. 29, 2012 edition.

Trawlers in Louisiana's Gulf are catching Asian tiger shrimp this fall but in numbers that are too small to enter marketing channels. Local vendors and restaurateurs say they're not interested in these black-striped creatures -- an invasive species that makes native, white and brown shrimp look dainty. One day, Gulf tigers could be on your plate, however. U.S. East and West coasts chefs embraced tiger shrimp from Indonesia, Thailand and Vietnam a while ago.

Out in the Gulf, Lafitte, La. shrimper Ronald Dufrene -- on his boat for 20 days straight this month -- has found Asian tigers in his catch. "This is the time of year we see them," he said last week. "Last night, I caught my first tiger in deep water." The others he found were in shallow water.

Dufrene cooks them for dinner on his boat. "They're mild, firm and tasty, and I'm going to try making them the way I do lobster," he said. They grow as long as 14 inches and can weigh a pound. A big one is bulky enough to make a couple of shrimp po-boys.

Tiger shrimp were first spotted in Gulf waters 24 years ago but they haven't reached the New Orleans market yet. Across the Mississippi River on the city's West Bank, Harold Toups, owner of Captain Boz's Seafood at the Shrimp Lot in Westwego, said last week, "I've never seen any Gulf tigers here in the lot. I don't want any of them, and I don't plan to get any of them." He also stays away from imported tigers and other foreign shrimp. The 27 stalls at Westwego's Shrimp Lot sell local white and brown shrimp, he said.

At Pascal's Manale Restaurant, home to barbequed shrimp in New Orleans, chef Mark DeFelice said, "We don't fool with tigers from Asia or the Gulf. We only serve white Louisiana shrimp." He's been there 25 years, and said, "That's what works for us. I doubt we'll ever serve tiger shrimp."

At Breaux Mart, which owns five supermarkets in Greater New Orleans, meat and seafood manager Brad Horton, said, "All the shrimp we sell is Louisiana fresh or frozen. We don't sell imported or domestic tiger shrimp." But he said Breaux Mart does sell imported crawfish tails from China -- packaged by Bernard's, a Louisiana brand.

Unless you're a friend or relative of a shrimper, you probably haven't tasted Gulf tiger shrimp. But you may have eaten imported tiger shrimp, possibly without knowing it. National hotel chains, including those operating in New Orleans, buy them, said Chris Berg, sales specialist at New Orleans Fish House, locally-owned seafood wholesalers. Imported tigers are served up as as shrimp cocktail at banquets and on cruise ships. "Hotels buy them peeled and cooked from Asia, and all the hotel kitchens do is blanch them," Berg said. "Hotels save on labor that way. The workers in Asia are paid maybe $2.00 a day and machines in Asia do some of the work."

Toups said less-expensive, seafood chain restaurants use imported tigers and other foreign shrimp, and national supermarket chains sell them.

How exactly did tiger shrimp, or prawns as they're called in other countries, get to Louisiana's coast? "Ballast water in ships may have brought them here," shrimper Dufrene said.

Jerald Horst, a retired Louisiana State University fisheries professor, said two theories prevail. "One is they got away from scientists and experimenters in experimental shrimp farming operations," he said last week. "The other is that they were swept up from Latin America." Established wild populations of tiger shrimp exist from Guyana to Colombia in South America and off the Dominican Republic in the Caribbean.

Horst said, "The possibility of them traveling from South America is tenuous, however, since we don't see South American species of shrimp and crabs up here" in the Gulf. He said, "I suspect what's gone on is the inadvertent or purposeful release of tiger shrimp from parties unknown," within U.S. or nearby waters. "The biology of these creatures suggests they're not going to cross the open ocean," he said. "Yet all of a sudden, these shrimp popped up here."

Wild tiger shrimp were first reported in the U.S. in 1988 after 2,000 of them escaped from a Bluffton, South Carolina facility. Later that year, several hundred were caught by shrimpers in South Carolina, Georgia and Florida. Sightings subsided for awhile, but in a 2005 hurricane, tigers escaped from a fish farm in the Dominican Republic. In August 2007, one was caught in Vermilion Bay, Louisiana, and then others were reported in Florida, South Carolina and North Carolina.

Last year, shrimpers found them in fairly significant numbers, with 591 sightings reported along the U.S. southeast and southern coasts to the National Oceanographic and Atmospheric Administration and the U.S. Geological Survey. In Louisiana last year, 125 tiger shrimp sightings or catches were reported to the state Dept. of Wildlife and Fisheries, including a few in Lake Pontchartrain. In South Carolina, sightings last year were twice Louisiana's number.

Horst said the Gulf tiger shrimp population could expand from current levels. Gulf tigers eat native shrimp and crabs and have a plentiful food source. Female tigers produce more eggs than native white and brown shrimp. "A cold winter here could knock back the numbers of tigers, which are a tropical species, but they'd probably start building up again," he said. "We've been warned about disease from tiger shrimp but it hasn't shown up in the Gulf yet."

In a June report about the southern U.S. sightings, USGS said, "The black tiger shrimp ... is a more aggressive predator on soft-bodied invertebrate, benthic organisms than native shrimp, and feeds primarily on small crabs, shrimp, bivalves and gastropods." In addition to consuming native shrimp, non-native tigers may have an advantage over them in competing for food resources, USGS said.

"If black tiger shrimp were to become endemic to the Gulf and reach commercially viable numbers, New Orleans chefs would probably serve them," Horst said. "They'll puff up and say tigers are among the fresh, local products that they're using. And they would use them based on the merits of their taste and size, too."

Celebrity chefs in California, Seattle and New York City serve imported tiger shrimp, sometimes in Creole sauces. Japanese restaurants serve them, and cooking programs on American TV have shown ways to prepare them.

But out of loyalty to native shrimp, local industry members don't like tigers much, and they particularly dislike tiger shrimp imports. "Imports from Asia and other places are killing us," Toups said. Last week, Louisiana white shrimp at the Westwego Shrimp Lot were priced at $1.50 to $4.00 a pound, depending on the grade.

"Prices have been higher than this, and I blame current levels on shrimp coming in from other countries," Toups said. Local demand took a hit from the 2010 BP spill but "customers aren't talking about that now," he also said.

USGS, NOAA and the South Carolina Dept. of Natural Resources, together with independent scientists, are researching how tiger shrimp reached the U.S. Gulf and the Atlantic. A year ago, they began gathering tiger specimens and started archiving tissue. In Louisiana, fishermen are encouraged to ice or refrigerate any tiger shrimp they catch, record the location and contact the state Dept. of Wildlife and Fisheries at 225-765-2949.