Movement and Microhabitat Associations of Guadalupe Bass in Two Texas Rivers

Abstract

The Guadalupe bass Micropterus treculii is endemic to Texas and is threatened by introgression with introduced smallmouth bass M. dolomieu as well as habitat degradation. This study described and quantified the movements and habitat associations of Guadalupe bass to assess the factors that may influence current populations. Radio-tagged adult Guadalupe bass were tracked in the Pedernales River (n ¼ 12) and South Llano River (n ¼ 12) from January through August 2008. Available microhabitats were measured and modeled in terms of depth, velocity, substrate, and cover for about 1.5 km in the Pedernales River and 1.2 km in the South Llano River. Rates of movement were greatest during the reproductive season, ranging from less than 1 to 9 m/d. Instream cover (such as undercut banks and woody debris) was preferred during daylight hours throughout the study period, although the distances from cover increased from January to August. Habitat shifts from cover to open water occurred at night and from woody structures to boulders and ledges during a large flood pulse. The habitats most suitable for adult Guadalupe bass had a depth of 1.0 m and a current velocity of 0.05 m/s, and habitat selection was strongest for eddy mesohabitats with smaller substrates. By July, the Guadalupe bass in the South Llano River were associated with runs with greater current velocities, whereas those in the Pedernales River were associated with pools with greater depths, largely owing to the low flows and reduced habitat availability in the Pedernales River. Environmental factors, including the availability and suitability of instream cover, are probably the strongest influences on the distribution and abundance of Guadalupe bass.

Seasonal habitat use of alligator gar in a river–floodplain ecosystem at multiple spatial scales

“…Selection for shallow depths and low to intermediate velocities, especially in response to higher flow, is known in several riverine fish species, including black basses (shoal bass, Stormer & Maceina ; Guadalupe Bass, Perkin et al. ), common carp (Butler & Wahl ), muskellunge (Brenden et al. ) and other lepisosteids (Helfman et al.…”

The Early Life History of the Guadalupe Bass: Lessons for Culturing a Threatened Species

“…Some aspects of GB early life history (spawning season and location, fecundity, some nest and egg characteristics, and behavior) have been partially described by Hurst et al (1975), Boyer et al (1977), Edwards (1980), and Carmichael and Williamson (1986). Other published observations on GB have primarily focused on water quality tolerance (Edwards 1978(Edwards , 1980Tomasso and Carmichael 1986;Sullivan et al 2013;Matthews et al 2017), introgression with SMB (Edwards 1979(Edwards , 1980Whitmore and Butler 1982;Whitmore 1983;Garrett 1988Garrett , 1991Morizot et al 1991;Littrell et al 2007;Bean et al 2013;Bean and Grabowski 2015;Fleming et al 2015), habitat (Hubbs 1957;Edwards 1978Edwards , 1980Farquhar 1995;Perkin et al 2010;Bean and Grabowski 2015), phylogeny (Johnson et al 2001;Bagley et al 2011), and reproductive behavior (Lutz-Carrillo et al 2015). Studies of the GB diet are limited to observations of predominantly juvenile and adult fish (Edwards 1980;Day 1981;Carmichael and Williamson 1986;Farquhar 1995).…”

“…The species is threatened due to habitat degradation (Edwards ; Perkin et al. ), reduced stream flows (Bowles and Arsuffi ), and hybridization with introduced Smallmouth Bass M. dolomieu (SMB; Edwards ; Whitmore ; Littrell et al. ).…”

“…), habitat (Hubbs ; Edwards , ; Farquhar ; Perkin et al. ; Bean and Grabowski ), phylogeny (Johnson et al. ; Bagley et al.…”

“…The Guadalupe Bass Micropterus treculii (GB) is endemic to streams draining the Edwards Plateau in central Texas (Hubbs 1957;Edwards 1980). The species is threatened due to habitat degradation (Edwards 1978;Perkin et al 2010), reduced stream flows (Bowles and Arsuffi 1993), and hybridization with introduced Smallmouth Bass M. dolomieu (SMB;Edwards 1979;Whitmore 1983;Littrell et al 2007). Restoration efforts have included stocking hatchery-reared GB fingerlings into select rivers (Fleming et al 2015;Garrett et al 2015).…”