PORT ARTHUR —
When Kim Tran pulled a pair of foot-long shrimp out of her husband’s net last shrimp season, it was not a lucky catch, but an indication of a major risk to the ecosystem of the Gulf of Mexico.
The massive shrimp was identified by Texas Sea Grant Extension as the highly carnivorous Asian tiger shrimp, whose Gulf Coast population has exploded over the last year, threatening the native stock of smaller white and brown shrimp.
“The shrimpers are worried,” said Tran, who also volunteers as a translator for the non-English speaking Vietnamese fishermen in Port Arthur. “The growing of the population of the tiger shrimp means the lowering of the population of the white shrimp. The shrimpers are very worried.”
Although Asian tiger shrimp have appeared in the Gulf of Mexico since about 2006, biologists have seen a significant jump in the population over the past shrimp season, which began in September of 2011, according to Terrie Looney, extension agent for the Texas Sea Grant Extension in Jefferson County.
The adult tiger shrimp can grow to 18 inches long and is identifiable by its distinct black and white stripes.
Until scientists can gather more information, little is known about the recent population surge, where it came from and what potential effects it could have on the ecosystem.
“We are trying to get the DNA samples to do some tests and find out where they came from,” said Looney. “We don’t know quite how they got here.”
One theory proposed by scientists is that the shrimp escaped during an accidental release from an aqua culture facility or shrimp farm on a river that feeds into the gulf.
Another popular theory is that the shrimp were sucked into the ballast of a ship somewhere in the Pacific Ocean and deposited into the Gulf of Mexico after navigating the globe.
The ballast of large ships, like oil tankers, can take on hundreds of thousands of gallons water at a time and store them underneath the hull to control buoyancy.
“They are required to dump the ballast periodically,” said Looney. “But it is on the honor system so we don’t really know.”
Scientists have not been able to prove that the shrimp are reproducing in the wild of the Texas coast because the juveniles look so much like the native shrimp.
Texas Sea Grant is asking fishermen to collect tiger shrimp, especially juveniles, freeze them in a sealable bag and record the date time, location and water depth.
“If we find little ones either we have a consistent source or they are reproducing,” added Looney. “We want to learn by looking for juveniles and then we can tell, if they are breeding, where.”
The shrimp compete with native shrimp populations for food, eat their eggs and are prone to diseases, which can potentially reduce the population of native shrimp.
Accord to Looney, 80 percent of the creatures in the Gulf of Mexico feed on the shrimp.
“The natural system gets out of balance,” said Looney.
The only white lining is that the tiger shrimp taste good, according to fishermen, and fetch high prices in fish markets.
“We joke about selling these things for twice what we sell our regular shrimp but the truth is these could cause major damage to our ecosystem,” said father Sinclair Oubre, Port Chaplain at the International Seafarer Center in Port Arthur.
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