|Scientific Name:||Micropterus treculii|
|Species Authority:||(Vaillant & Bocourt, 1874)|
Dioplites nuecensis subspecies treculii Vaillant & Bocourt, 1874
Micropterus treculi (Valliant & Bocourt, 1874)
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Reviewer(s):||Smith, K. & Darwall, W.R.T.|
|Facilitator/Compiler(s):||Hammerson, G.A. & Ormes, M.|
This species is listed as Near Threatened because its area of occupancy is unknown but may be less than 2,000 sq km and the species faces ongoing threats and probably a slow decline as a result of interactions with the non-native smallmouth bass and possibly reduced stream flows, whereas extent of occurrence is more than 20,000 sq km, number of locations exceeds 10, distribution is not severely fragmented, and population size probably exceeds 10,000. Continuing decline caused by ongoing threats from non-native species and reduced streams flows could reduce the population such that it qualifies for Vulnerable in the foreseeable future.
|Range Description:||This bass is endemic to streams of the northern and eastern Edwards Plateau, including portions of the Brazos, Colorado, Guadalupe, and San Antonio basins; it is also found outside of the Edwards Plateau streams in decreased abundance primarily in the lower Colorado River; two introduced populations have been established in the Nueces River system (Hubbs et al. 2008).|
|Range Map:||Click here to open the map viewer and explore range.|
This species is represented by at least several distinct occurrences (subpopulations), and probably more than 10 locations (as defined by IUCN). The Texas Natural History Collections (1997) mapped 69 collection sites and two introduced populations.
Total adult population size is unknown but presumably exceeds 10,000. This bass is regarded as common (Page and Burr 1991, 2011). Stocking of large numbers of pure M. treculi was underway in Texas in the 1990s (G. Garrett pers. comm. 1997).
Trend over the past 10 years or three generations is uncertain but probably relatively stable or slowly declining. Three generations span roughly 10 years. Littrell et al. (2007) reported an apparent decline in the frequency of pure Micropterus treculii in the Blanco River over the preceding 10 years; no pure M. treculii specimens were collected from the Blanco River during the study. Extirpation from the Blanco River occurred despite restorative stocking efforts (Bonner and Bean 2008).
|Habitat and Ecology:||Habitat includes gravel riffles, runs, and flowing pools of creeks and small to medium rivers (Page and Burr 2011), and is established in a few reservoirs (Tomelleri and Eberle 1990). This bass prefers lentic habitats. It is abundant in downstream sections of small streams, in shallow swift waters, often in riffles or at the head of pools, and is absent from extreme headwaters. It prefers fast currents along the lower ends of riffles and runs (Tomelleri and Eberle 1990). It is moderately tolerant of high turbidity and variable temperatures. Eggs are laid in nests made on the bottom by males in relatively slow moving pool areas close to a source of current in water greater than 1 m in depth (Edwards 1997).|
Spawning sites are similar to those of the introduced smallmouth bass (M. dolomieu); this has resulted in mass introgressive hybridization, especially throughout the Guadalupe River basin (Edwards 1997). Interspecific hybridization and introgression pose serious threats to the genetic integrity of M. treculii (Whitmore 1983, Littrell et al. 2007).
Reduced stream flow also threatens M. treculii (Edwards 1980, Bowles and Arsuffi 1993).
|Conservation Actions:||Conservation needs include maintaining intact healthy habitats and restoration of degraded habitats.|
|Citation:||NatureServe 2014. Micropterus treculii. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 04 September 2015.|
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