Restoring the Guadalupe Bass
The 'state' of Texas' state fish has improved from dire to hopeful.
By Dyanne Fry Cortez
When a Decatur Intermediate School third-grade class started a movement to name the Guadalupe bass the official Texas state fish in 1989, Texas Parks and Wildlife Department research biologist Gary Garrett agreed that this species might be the ideal candidate.
Cousin to largemouth and spotted basses, Micropterus treculii is the only black bass with a native range exclusive to Texas. The Guadalupe bass lives in the clear, running streams of the Edwards Plateau; it’s a fighting sport fish that river anglers love to catch.
Thirty years ago, scientists began to realize that the fish was in trouble, so Garrett thought the proposed state designation could bring needed attention to the Guadalupe bass. Surveys indicated numbers were declining; changes in the stream environment due to damming and decreased spring flow appeared to be at least part of the reason.
The Texas Parks and Wildlife Department unwittingly created another threat by stocking non-native smallmouth bass (Micropterus dolomieu) in the Guadalupe’s home range.
It seemed like a good idea at the time. Texas already had three native species of black bass, sharing overlapping ranges without getting much in one another’s way. A 1958 article in Texas Game and Fish described a plan to “put an additional good fighting fish in Texas waters,” starting that year with the South Llano River. In the 1970s, the department began stocking smallmouth in reservoirs along the Blanco, Guadalupe, Medina and San Gabriel rivers, and also in Cibolo and Onion creeks.
Some of those stockings created good smallmouth fisheries, but there was an unforeseen result. Introduced smallmouths began cross-breeding with their cousins, the native Guadalupe bass.
Closely related species that exist in the same area generally have habits that discourage cross-breeding. They spawn at different times or seek out different conditions. Smallmouth and Guadalupe bass never lived in the same streams, so they never evolved those inhibiting factors.
Alerted to the problem, biologists did extensive sampling across the Guadalupe’s range. Genetic testing techniques were limited at the time, but they used what they had to estimate the extent of hybridization. Results were alarming. In the Guadalupe River, 34 percent of fish sampled were some blend of smallmouth and Guadalupe bass. Hybrids made up 46 percent of samples in the San Gabriel River, 42 percent in Lake Travis and 6 percent in the Lampasas and Concho rivers.
In the Blanco, no pure Guadalupe bass remained. The state fish was in danger of being bred out of existence.
Beginning in 1988, TPWD’s Inland Fisheries Division undertook a comprehensive study of the life cycle, feeding habits, growth rates, preferred living conditions and threats to the well-being of the Guadalupe bass. Results of that research and recommendations for sustaining the species were included in “Guidelines for the Management of Guadalupe Bass,” published by the agency in November 1991.
Twenty-five years later, TPWD staff took stock of actions taken and lessons learned. In 2017, the department marked a major success — restoration of Guadalupe bass in the South Llano River after years of work — and produced a new 10-year plan for continuing to conserve this iconic fish and the rivers that support it.
Removal and repopulation, 1991–2016
After the 1991 assessment, the first measure was to quit stocking smallmouth bass in areas where Guadalupe bass populations needed to be protected or restored. TPWD hasn’t stocked smallmouth in Hill Country waters since 1990, but the department still maintains smallmouth fisheries in other parts of the state.
The next step was to stock large numbers of pure Guads in places where hybrids had taken hold, attempting to readjust the gene pool by sheer force of numbers. Biologists weren’t sure the technique would work, but over time, it did make a difference. Since 1992, the department has stocked more than 2.3 million Guadalupe bass fingerlings in the Guadalupe, Blanco, Llano and San Antonio riversheds.
Fortunately, the department had at least one purebred population to use as broodstock. In 1973, TPWD took 2,000 Guadalupe bass from the Guadalupe River and introduced them to the upper Nueces. Although out of their native range, those fish founded a self-sustaining population uncontaminated by smallmouth bass genes. In 1988, some of their descendants were used to establish a refuge population in the headwaters of the Sabinal River at Lost Maples State Natural Area.
Rearing Guads in a hatchery setting was tricky, since the species prefers to spawn in the dynamic environment of a running stream. A technician at TPWD’s Heart of the Hills Fisheries Science Center developed a special nesting box with a gravel bottom and a sunshade to simulate tree cover.
The first stream stocked with hatchery-reared Guadalupe bass was Johnson Creek, an upstream tributary of the Guadalupe River. Tens of thousands of fingerlings were stocked each year, but it was close to a decade before the hybrid population showed a significant decrease. In the mid-2000s, with support from the Guadalupe-Blanco River Authority and several fishing clubs, stockings moved downstream into the main river.
Scientists didn’t have much hope of restoring Guadalupe bass in the Blanco River until 2011, when severe drought reduced that stream to a series of disconnected pools. This gave TPWD a rare opportunity to round up the resident smallmouth and hybrid bass and remove them. When the river began to flow again in 2012, the department restocked it with pure Guadalupe bass. Most of the fish were deposited upstream of the Narrows, a gorge that contains five natural waterfalls. Biologists hoped this feature would serve as a barrier to keep unwanted fish in the lower river from recolonizing the cleared area. Results so far suggest they were right.
South Llano: Restoring the watershed
The 1991 guidelines noted that restocking wouldn’t be a complete solution to the plight of the Guadalupe bass. Ultimately, the state fish would not thrive in the absence of a healthy habitat. This line of thinking got a big boost in 2010. TPWD became part of the National Fish and Wildlife Foundation Southeast Native Bass Keystone Initiative, which sought to restore endemic black basses in several states. Working under this umbrella, TPWD collaborated with the newly formed Llano River Watershed Alliance and the Texas Tech University Llano River Field Station to launch a $1.4 million initiative on the South Llano River.
The initiative made it possible to address issues on a watershed scale with Guadalupe bass as a keystone species — in effect, a “poster child” for a whole ecosystem. It turns out that what’s good for fish is good for other life forms that live in river environments, including rare plants, salamanders and mussels.
Compared to some other streams in the fish’s home range, the South Llano was in good shape. Although smallmouth bass had been stocked there in the 1950s, the percentage of smallmouth/Guadalupe hybrids in the population was only 3 to 4 percent. Surrounding land was still primarily rural, and the river was comparatively pristine. Project participants aimed to demonstrate what could be accomplished with coordinated, proactive conservation measures.
Over the next five years, 793,000 pure Guadalupe bass were stocked in the river. Hybrids are now down to about 2 percent, and surveys aren’t finding any pure smallmouth bass.
Many low-water bridges on Hill Country streams tend to impede water flow and create barriers for fish and recreational river users. When a bridge on the South Llano needed to be replaced, TPWD and Texas Tech worked with the road builders on a fish- and paddler-friendly design. They’re hoping the Texas Department of Transportation will incorporate those considerations into standard practice.
Anything that happens in a watershed affects the health of the river, so the initiative addressed restoration of riverbanks and land management practices that prevent erosion and encourage water conservation. TPWD’s habitat conservation staff developed a restoration design manual and conducted a number of workshops for Hill Country landowners. In all, conservation partners helped restore 9,327 acres of aquifer recharge features, protected 50 springs and offered technical guidance that improved management of more than 123,000 acres of ranchland.
“One of our biggest accomplishments was getting wildlife conservation programs to include our priority rivers for grants,” says Tim Birdsong, habitat conservation chief for TPWD’s Inland Fisheries.
Looking ahead, 2018–2026
The success of the South Llano River project points the way to future restoration efforts in the historical range of the Guadalupe bass. The new conservation plan calls for building new partnerships and connecting with landowners and volunteer organizations in additional watersheds.
A primary objective is to restore Guadalupe bass populations to an extent that listing it as a species of concern is no longer warranted. Ten stretches of river are targeted for restoration, including the San Gabriel River, where work will start this spring. The goal for these areas is to reduce hybrids to less than 1 percent.
Eight stretches that already have good populations are tagged as priority areas for conservation. The goal is to keep smallmouth bass out of those areas, maintain or improve instream habitat and upland management practices, and control invasive plants that can damage rivers and riparian areas, especially arundo (giant cane) and elephant ear, known problems in the range of the Guadalupe bass.
The plan also calls for continued research. We’ve learned a lot about our state fish, but there is still a great deal that we don’t know. Biologists want to find out just what Guadalupe bass eat at different stages of life, what factors determine their growth and survival, and how much genetic variation exists between populations in different rivers.
The more we learn, the better our chances of ensuring that our state fish is still swimming in clear Hill Country streams for our great-grandchildren to enjoy.
The Llano River Watershed Alliance, Bass Pro Shops and the Texas Parks and Wildlife Department are sponsoring a prize giveaway to celebrate the return of our state fish to the South Llano River. Until Dec. 30, 2018. any angler who catches a tagged Guadalupe bass from the South Llano will receive a choice of prizes from an assortment of fly-fishing gear. See www.www.llanoriver.org/guadalupe-bass for details. |
