Invaders Lurking in Texas Waters Pose Risks

The armored catfish may just look ugly, but these invasive fish can also cause a lot of damage. Photo courtesy of Joshua Buzzard via Flickr.

By Abbey Adkison
For Reporting Texas

Piranha in Pearland, prehistoric-looking armored catfish in the Guadalupe River, and zebra mussels in Lake Texhoma: They’re unnatural, and they’re bad for Texas waterways.

The Texas Parks and Wildlife Department has launched marketing campaigns to enlist recreational boaters to help rid the state of these and other unwanted “invasive” species, any non-native plant or animal that can pose an economic or health threat.

The department doesn’t cite a statewide economic toll, but it estimates that invasive species costs the country about $137 billion every year.

“Texas has a fairly long list of invasive species,” said Luci Cook-Hildreth, an aquatic biologist for the parks department. Like the armored catfish, they pose multiple risks, she said. “We’d rather they’d all not be here.”

Cook-Hildreth said that the armored catfish, or Hypostomus plecostomus (plecos, for short), have been documented in Texas since the 1960s. They burrow into riverbanks, muddying the waters and weakening the banks. When large colonies establish themselves, as they have in the San Marcos River, the cloudy water makes it difficult for other fish and plants to survive.

There are economic costs, too. “There are issues with depositing massive amounts of silt in places where it wasn’t before,” Cook-Hildreth said.  “Economically, that’s a problem, certainly with folks who are rice farmers. It can be a problem for real estate around the area where catfish are digging into the banks because sometimes banks actually collapse and people lose land.”

A newer problem is the zebra mussel, which has been in the state since 2009. Though tiny, they can attach themselves to almost any surface, allowing them to sink buoys, destroy boating equipment and block intake valves to power plants.

“Zebra mussels are a pretty big, scary deal because the economic impact is huge,” said Cook-Hildreth. The parks department has launched a campaign for recreational lake users urging them to clean and dry their boats and fishing equipment to prevent the larvae from spreading to other bodies of water. Zebra mussels and fast-growing plants like giant salvinia can take over lakes and ruin boats.

Experts say that pets released from aquariums are the most significant cause of invasive species in non-native ecosystems. Parks department personnel are guessing that’s how the piranha ended up in a Pearland Lake near Houston.

Gary Coffman, owner of aquarium store Austin Aquadome, said many types of exotic species like piranhas can’t be sold legally in Texas because they could survive the mild winters and reproduce.

“I can almost guarantee you would not be able to get one,” he said of piranhas. “The problem with it is that other states, Northern states, there’s no problem with them cause they’re not going to winter over.”

Although prohibited species are difficult to purchase in stores, private individuals have easier access. Buying over the Internet and “swaps” within aquarium-related societies create a market regardless of the consequences and some buyers may not know that what they are purchasing is illegal.

Coffman said that although most common aquarium fish wouldn’t survive in the wild, people often don’t realize the implications of releasing their pets. “That’s probably the most common thing that occurs to people, is just to flush it,” he said.  “We try to dissuade from those kind of things and from releasing it into the wild.” A poster in his store reminds patrons that releasing any kind of exotic species in Texas is illegal, with up to $500 in fines and possible jail time.

Wildlife experts say the armored catfish likely escaped from the San Antonio Zoo in the 1960s.  “Catfish are amazingly hardy,” said Cook-Hildreth. “They can actually live outside of the water for a certain period of time. Any fish that can do something like that, it’s usually a good characteristic for invasive species. They’re pretty hard to kill.”

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