Non-native shrimp raising questions, eyebrows

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Non-native shrimp raising questions, eyebrows

By GRANT MARTIN
gmartin@islandpacket.com
Published Saturday, October 29, 2011   |  790 Words  |  

Many sea creatures -- from sharks to stingrays -- have made Tonya Desalve squirm during her decades of working at Benny Hudson Seafood on Hilton Head Island.

But nothing compares to the tiger shrimp in her freezer.

"This thing is scary," she said. "It's by far the ickiest thing I've ever seen."

At a third of a pound and more than a foot long -- Desalve says hers spans from thumb to thumb when she holds it with both hands -- a mature tiger shrimp makes its more common brown and white relatives look, well, shrimpy.

Similarly troubling is the rising rate at which the non-native tiger shrimp are being caught off the coast of South Carolina this fall.

According to data compiled by a federal task force, more than 70 have been reported caught off the state's coast this year. But that number is likely dwarfed by the number that have been caught and tossed back into the ocean.

"One of my friends says he's caught about 25 this year," said local shrimper Skip Toomer. "We're definitely seeing more and more of them around."

Tiger shrimp were first noticed in local waters in 2006. Their population has remained small and fairly constant until a sharp increase this year, according to the S.C. Department of Natural Resources.

Researchers and shrimpers agree that the local tiger shrimp population is increasing, but no one is sure how they got here.

There's no shortage of theories.

"We've heard that they may have come from the west coast of Africa or up through the Caribbean from Venezuela," said Al Stokes, manager of the Waddell Mariculture Center in Bluffton.

Others suggest they came in the wake of powerful tropical storms or as stowaways in the ballast tanks of ships traveling from their native southeast Asia.

"I think the most likely explanation is that they came from a farm owned by the Chinese in the Caribbean," Stokes said.

Tiger shrimp are farmed primarily in the Caribbean and South America, according to Stokes. They're among the most commonly farmed shrimp in the world. You may have even seen imported tiger shrimp on ice at your local market.

About 2,000 tiger shrimp farmed for research at Waddell escaped into local waters in 1988, but Stokes is quick to dismiss any connection to that event.

"They only live for a couple years," Stokes said. "Those shrimp disappeared for 18 years, and it's not likely that they're the ones returning now."

There's also debate on the tigers' impact on the local ecosystem.

"Right now, there's a fear of the unknown," said Craig Reaves, president of the S.C. Shrimper's Association. "There's concern because people just don't know what's going to happen."

Desalve said her shrimpers believe the non-natives are preying on the local white shrimp, citing party digested remnants of the smaller ones inside captive tigers as evidence.

Researcher David Knott says that's not plausible.

"The tigers are more omnivorous than the white and brown shrimp and eat things on the bottom of the ocean as well as a variety of vegetation," Knott said. "But one thing they're very unlikely to eat is another full-grown shrimp."

Knott said the tigers could carry a number of viruses that might affect brown and white shrimp, but cautioned that it's too early to tell their effect.

"There's no evidence of any competition with the native shrimp, but we're trying to learn as much as we can right now," Knott said.

To aid that effort, the state DNR posted signs near several local boat landings asking boaters and commercial fishermen to save and report any juvenile tiger shrimp they catch.

Knott said his agency hopes to analyze tissue samples from young tiger shrimp to learn whether the local population is reproducing.

While it may be too early to state definitively how the tiger shrimp arrived here, experts and shrimpers agree on one thing: They taste good.

"They're sweeter than white shrimp," said Reaves. "The texture's a little tougher, kind of like lobster meat."

Knott has yet to try one, but reported that a colleague had recently tried a soft-shell tiger shrimp.

The verdict?

"He said it tasted like chicken."

Follow reporter Grant Martin at Twitter.com/LowCoBiz.

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Jumbo shrimp! Giant crustaceans hit local waters, December 7, 2008