SOUTH PADRE ISLAND An exotic, large species of shrimp is being found once again in the Gulf of Mexico and posing a potential threat to the $700 million Gulf shrimping industry, according to Tony Reisinger, a Texas AgriLife Extension Service agent for coastal and marine resources in South Texas.

"They're known as black tiger shrimp because of their bright yellow stripes," Reisinger said. "They are the biggest saltwater shrimp in the world. They are predatory, aggressive and could carry diseases that can harm native species of shrimp."

Female shrimp are slightly larger than males and can grow to an average of about a foot in length and can weigh almost one pound, he said. They are native to the Indo-Pacific region of the world.

"Black tiger shrimp eat the same type of food as our three, much smaller native species, but as they grow they can also eat the native species, which are the brown, white and pink shrimp. And they prey on small oysters, threatening that industry as well," Reisinger said.

The fear is that black tiger shrimp will out-compete and possibly displace native species, Reisinger said. So far, there have been 200 official reports of black tiger shrimp in the Gulf. The southernmost find was at Aransas Bay in the Corpus Christi area, some 115 miles north of the jetties at South Padre Island.

"There are lots of unanswered questions about black tiger shrimp," he said. "We know there was an accidental release of black tigers from a research facility in South Carolina in 1988. Some were caught as far away as St. Augustine, Fla. But most were thought to have been caught by local fishermen, because in 1991 they suddenly disappeared. Then in 2006 they started showing up again. These could have come from a shrimp farm in the Caribbean that was breached by a hurricane a few years ago, but we just don't know."

Genetic studies are currently being conducted by the Texas Parks and Wildlife Department. Other organizations, including Texas A&M's Texas Sea Grant are also looking into the issue.

"The fear is that these cannibalistic shrimp have already established breeding populations in the Gulf," Reisinger said. "That could have serious implications for the entire Gulf shrimping industry, including the fleet of shrimpers here in deep South Texas."

The shrimp fleet in Brownsville and Port Isabel consists of 135 vessels that ply the Gulf waters in Texas, Louisiana and as far away as Florida.

"In 2010, shrimpers here produced a $52 million catch, with an economic impact of three times that much," he said. "Throughout the Gulf of Mexico, shrimping is a $700 million a year industry."

Where they came from, where they're going and what they will do in the meantime is anybody's guess, but it's important to study what they're up to and why, Reisinger said.

"If we can figure out where they are coming from, if we find out for example that a foreign country is raising them in unsecured areas,, the United States could apply trading pressure to stop the practice. But who knows? At this point, there are just too many questions and stories."

Another unanswered question is why there are no sightings of young black tiger shrimp.

"It could be because the young blend in with the native species and just can't be distinguished," he said. "There just needs to be more studies done."

Reisinger has met with the Brownsville-Port Isabel Shrimp Producers Association to discuss their concerns and share what he knows.

"We talked about the species facts, their history and we're asking shrimpers to save and freeze any black tiger shrimp they catch, note the location and date they were caught and turn them over to Texas Parks and Wildlife."

Reisinger said he has three frozen samples, with more coming in from Brownsville shrimpers currently off the coast of Louisiana.

"Black tiger shrimp are beautiful creatures, some say they are good to eat, others don't," he said. "They can survive in all sorts of environmental conditions and in very deep waters. But they are so aggressive and pose so many potential dangers to our way of life in the Gulf of Mexico, it'sprudent that we investigate and learn as much as we can about this new invasive species in order to protect our resources."