Texas By Nature: Texas State Fish Under Threat

May 27, 2009

Release from: Oak Hill Gazette (Austin, Texas)

When Texas State legislators were establishing a state fish in 1989, they sought a species as iconic as the pecan tree and bluebonnet, Texas' official tree and wildflower, respectively. After much consideration, they settled on the Guadalupe bass (Micropterus treculii), a smallish species that at one point was found in nearly all free-flowing rivers and creeks in the Edwards Plateau.

Like all "black bass" — smallmouth, large, and spotted — the Guadalupe bass is actually a member of the sunfish family. Green with black markings, the Guadalupe is the smallest of the black bass — adults top out around 3.5 pounds — and makes its home in fast-moving streams of the Guadalupe, Colorado, Brazos, San Antonio and Nueces river watersheds.

Unfortunately, these denizens of fast-moving waters face a bleak future as a result of increasing hybridization with non-native smallmouth bass.

A recent study conducted by researchers from Texas State University and the Texas Parks and Wildlife Department found that more than half the bass in the Blanco River were hybrids — the teams collected no pure Guadalupe bass at all. These findings mirrored other comprehensive studies undertaken by TPWD and partners in the upper Guadalupe basin.

"The Guadalupe bass is an important element in many of our freshwater conservation initiatives," said Laura Huffman, Texas state director for The Nature Conservancy. "The decline of true Guadalupe bass in Texas is a prime example of the toll that invasive and non-native species take on our state."

Guadalupe bass spawning generally starts in May and lasts into June. However, a secondary spawn is sometimes observed in August or September. The male fish construct gravel nests in shallow waters where lured females may lay as many as 9,000 eggs before the males chase them away to stand guard. Native to the northern and eastern Edwards Plateau, the species has all but disappeared from many parts of its historic range, the Brazos River basin and large sections of the Colorado and upper Guadalupe drainages. Pure Guadalupe bass introduced into the Nueces River have thrived, and TPWD and partners are reintroducing large, pure populations into the fish's historic range within the upper Guadalupe.

The Conservancy's freshwater work on the Blanco, Guadalupe, Pedernales, Nueces and Sabinal rivers all benefit this iconic Texas species.

To learn more about the species the Conservancy works to protect in Texas, visit nature.org/texas.