Threatened fishes of the world: Micropterus treculii (Vaillant and Bocourt 1874) (Centrarchidae)

Abstract

Common name: Guadalupe bass. Conservation status: Considered threatened (Edwards 1980; Hubbs et al. 1991) and of conservation concern (Johnson 1987; USDI 1989). Identification: Medium-sized centrarchid (maximum TL=463 mm) with an elongated body. Ten to 12 dark, lateral bands 1/2 to 2/3 of body depth in height over yellowish brown to greenish olive background (Hubbs and Bailey 1942). D 9–11 (ten), 11–13 (12), A 3–4 (three), 9–11 (ten), P 14–16 (15–16). Photograph of 81 mm (TL) individual by Chad Thomas. Distribution: Endemic to the Brazos, Colorado, Guadalupe, and San Antonio river drainages of the Edwards Plateau and introduced in the Nueces drainage (Hubbs et al. 1991). Abundance: Historically up to 7% of fish assemblages (Edwards 1980). Habitat and ecology: Found in small to moderate size streams and rivers, except headwaters (Guillory 1978). Associated with runs and riffle tailraces (Boyer et al. 1977). Diet primarily of Ephemeroptera, Megaloptera, crayfish, and fish (Edwards 1980; Farquhar 1995). Reproduction: Spawns from March to August, but primarily April through June (Edwards 1980). Nest guarders, depositing eggs in siltfree cobble and gravel depressions (Boyer et al. 1977). Fecundity, on average, 4,200 eggs (Edwards 1980). Males mature by age 1 and females mature at age 2 (Edwards 1980). Threats: Introgressive hybridization with Micropterus dolomieu is the greatest threat to Micropterus treculii (Edwards 1979; Whitmore 1983; Morizot et al. 1991; Littrell et al. 2007). It has been extirpated from the Blanco River (Littrell et al. 2007) despite restorative stocking efforts. Reduced stream flow also threatens M. treculii (Edwards 1980; Bowles and Arsuffi 1993). Conservation action: Texas Parks and Wildlife Department established a stocking program in the Guadalupe drainage to decrease hybridization and no longer stocks M. dolomieu within the range of M. treculii. Data on the status of introgressed M. treculii populations is needed to effectively allocate restoration efforts.