Giant Tiger Prawn Invades Gulf of Mexico

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Huge, hungry prawns from Asia have exploded across the U.S. Gulf Coast this year, potentially posing a serious threat to smaller native species.

The giant tiger prawn is more than just a jumbo shrimp. It’s a huge, hungry and highly invasive species that could pose a jumbo problem for the already embattled Gulf of Mexico ecosystem. And according to wildlife officials along the U.S. Gulf Coast, it had a very big year in 2011.

Formally named Penaeus monodon, the tiger prawn inhabits the Indian and Pacific oceans from Africa to Australia. It’s more predatory than many similar species, hiding during the day and hunting at night. It also has a ravenous appetite, helping some adults grow up to 14 inches and 23 ounces. Small groups have haunted the U.S. Gulf and Atlantic coasts since 2006, turning up in the Carolinas, Georgia, Florida and Alabama. Louisiana reports about 25 to 30 per year.

But according to Houma Today of Terrebonne Parish, La., there were nearly 100 reports of tiger prawns this fall in Louisiana alone, with one dock counting 100 individuals. Texas’ first-ever specimen was caught in June, the Houston Chronicle reports, followed soon after by four more. And the U.S. Geological Survey lists eight tiger prawns this year in Mississippi, 11 in Florida and 18 in Alabama — compared with zero, two and zero respectively in 2010. The USGS listed 42 such reports nationwide in 2009, and just 18 in ’08.
While no one is sure what kind of ecological impact tiger prawns could have in the Gulf, their appetite isn’t the only concern. The species is also a known carrier of at least 16 different viruses, including white spot, yellowhead and others that can kill shrimp. Experts say this array of dangers may threaten not only the Gulf’s native brown and white shrimp populations, but also some crabs and oysters.
“It has the potential to be real ugly,” Leslie Hartman, a biologist with the Texas Parks and Wildlife Department, tells the Houston Chronicle. “But we just do not know.” Fellow biologist Marty Bourgeois of Louisiana’s Department of Wildlife and Fisheries echoes that sentiment. “There’s a certain unknown about what ecological impacts that something non-indigenous like this can have on the local environment,” he tells Houma Today. “But it is somewhat alarming that these reports have suddenly ramped up.”
In addition to its vast native habitat, the tiger prawn is also one of the most widely cultivated species of shrimp or prawn on Earth, according to the U.N. Food and Agriculture Organization (see chart below). The top producers are mainly in Asia, but it’s farmed around the world. Scientists aren’t sure where the Gulf invaders came from, although a leading theory suggests they escaped from aquaculture facilities.
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