Grass-eating carp raising concerns on Lake Austin

AUSTIN – An effort to control the pesky, non-native hydrilla weed in Lake Austin has apparently worked almost too well.

For a little more than a decade, Texas Parks & Wildlife has worked with the City of Austin and Friends of Lake Austin in a team effort to come up with a plan to control hydrilla, a stringy weed that can wreak havoc on boats and pose a danger to swimmers.

Over the past decade close to 30,000 sterile, grass-eating Asian carp have been introduced in to Lake Austin because their favorite food is hydrilla.

That hydrilla is gone and experts say the carp are now eating anything and everything, including all of the native grasses like milfoil, the reeds, even leaves off of trees hovering over the water.

“We had to do a little more because of the aggressiveness of the hydrilla and we ended up having maybe a little bit too much for the vegetation to recover,” said Marcus DeJesus, a marine biologist with Texas Parks & Wildlife.

There are also reports that some of the carp are now turning into meat eaters and consuming some of the smaller native fish.

“Now we have no vegetation in the lake which is not what we want and there’s a lot of fish out there consuming anything they can,” said DeJesus.

While DeJesus says the carp aren’t reproducing they are expected to have a lifespan between 5 and 10 years and can get up to 50 pounds.

“We know we have the tools to change it and turn it back around. This is not a monster that’s going to stay here forever,” he said.

One fishing guide told KVUE the non-native carp can eat half of their body weight in food a day.

Fishing guide James Roberts showed KVUE an area of Lake Austin where reed plants used to jet out of the water. Roberts is not only concerned about the disappearance of the grass which means the disappearance of fish nurseries, he’s also concerned about the water clarity and water safety.

Roberts says grasses are natural buffers for wakes and waves made by boats and other watercraft, but with little to no grass in Lake Austin there’s a question about the impact to safety as the weather turns nice and the lake gets more crowded.

“Back when there was grass it acted as a buffer. It would slow these wakes down. Even the reeds would do the same thing, The waves would hit the reeds and dissipate. Now, on these bulkheads the waves just hit and bounce back and forth,” said Roberts.

When it comes to solutions, Texas Parks & Wildlife is now working with local angling groups who are planning to come out and plant more vegetation.

There is also talk about possibly holding a carp fishing tournament to encourage people to fish out the non-native species, but no plans have been formulated.

Source: KVUE