AUSTIN (KXAN) — A year after a study discovered underwater plant life at Lake Austin had disappeared, researchers are finding vegetation is still struggling to return to the waters.
“We’re seeing skinnier fish, smaller fish,” said John Ward an angler with Texas Tournament Zone. “Numbers are down. They’re a little harder to catch relative to the grass.”
KXAN Investigates went along with Texas Parks and Wildlife and City of Austin officials as they surveyed the lake this month, searching for plant life.
“We’re out here in peak season to see if we can find something. Hopefully we’ll find something,” said Marcos De Jesús, Texas Parks and Wildlife district supervisor
Last year, when De Jesús did a similar study, he found no underwater plant life at the lake. The discovery was a stark contrast to 2012 when invasive hydrilla spread across the reservoir. City researchers believe the drowning of a swimmer is linked to hydrilla, the plant contributed to flooding, and damaged Tom Miller dam. So, the state approved record amounts of sterile grass carp to help control the plant.
In February, KXAN Investigates found the number of grass carp the city put in the lake exploded in recent years. As the hydrilla grew, the city kept stocking sterile grass carp to eat it. According to stocking records, 6,000 carp entered Lake Austin in December 2011. In 2012, the city put in more than 17,000 more carp. Then, 9,000 more of the fish went into the lake in May 2013. In those 18 months, officials stocked the lake with more carp than in the entire previous seven years combined.
“What I believe is that we stocked as many carp we needed to stock to see a reduction in hydrilla,” said De Jesús said earlier in the year. “Unfortunately, because of the circumstances that are beyond our control, it turned out to be too many.”
But a new study completed this month found not much has changed under the surface of Lake Austin. A harsh winter, birds, and thousands of sterile grass carp were all reasons Texas Parks and Wildlife believed its last study on Lake Austin found no underwater vegetation. But plants still have not returned.
“After the control measures the lake has basically come down to nothing,” said De Jesús. “[It’s] something of concern, but, like I said we need to monitor our progress and try to make decisions based on science.”
De Jesús pointed out piles of sunken brush on the sonar screen during the recent lake study. A partnership placed the piles in the lake this summer to give fish — like bass — habitat.
The only other underwater plants KXAN Investigates saw on the trip, the city planted. The City of Austin has about 30 cages on Lake Austin to try to protect native plants and get them to grow.
“Once they get a chance to grow, the plants spread very quickly,” said Brent Bellinger, senior environmental scientist with the City of Austin.
De Jesús believes the sterile fish are living at least eight years right now. Even though it is not widely visible, hydrilla could also still come back as fish die off.
“We’re in a position now where we have to really focus on the future of the lake,” said Ward.
Ward notices a change in the bass. Bassmaster once listed Lake Austin as one of the top 10 bass fishing lakes in the country. This year, it didn’t make the top 100.
“We are going to use the results of this survey. We’ll get the workforce together and try to see what new options we have to try to help this lake get back to where it was,” said De Jesús.
De Jesús is striving to find balance.