|Scientific Name:||Notropis oxyrhynchus|
|Species Authority:||Hubbs & Bonham, 1951|
|Red List Category & Criteria:||Vulnerable B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v) ver 3.1|
|Reviewer/s:||Smith, K. & Darwall, W.R.T.|
|Facilitator/s:||Hammerson, G.A. & Ormes, M.|
This species is listed as Vulnerable because its extent of occurrence is less than 5,000 sq km, area of occupancy is less than 2,000 sq km (based on 1 km x 1 km grid cells), number of locations can be regarded as fewer than 10, and habitat quantity and quality (and species distribution and abundance) are subject to ongoing declines.
|Range Description:||The Sharpnose Shiner historically occurred throughout the Brazos River system, including the Double Mountain and Salt Forks of the Upper Brazos River drainage. Now it is very rare or possibly extirpated downstream of Possum Kingdom Reservoir (USFWS 2002). It has been documented in the South and North Forks of the Wichita River within the Red River Basin but has not been collected from the Wichita River drainage since the 1950s (Moss and Mayes 1993). An introduced population may exist in the Colorado River above Buchanan Reservoir (Hubbs et al. 1991); however, the validity of this population is still in question (e.g., Moss and Mayes 1993).|
|Range Map:||Click here to open the map viewer and explore range.|
This species is represented by a small number of distinct occurrences (subpopulations) and locations (as defined by IUCN). It is known from a few dozen sites, including 24 sites upstream of Possum Kingdom Reservoir (Moss and Mayes 1993). Recently it was recorded at 10 of 13 sites sampled in the upper Brazos basin (Ostrand 2000). Additional collection efforts have produced few specimens in the middle and lower Brazos River (see USFWS 2011). Some of the collection sites mentioned above are not distinct occurrences or locations but rather represent portions of larger occurrences or locations.
Total adult population size is unknown (USFWS 2011) but probably exceeds 10,000. Extensive sampling at thirteen sites within the Upper Brazos by Ostrand (2000) in 1997 and 1998 produced 2,791 Sharpnose Shiners at 10 sites (Garza, Kent, Fisher, Stonewall, and Knox counties), where they represented one of the seven dominant species. The population of Sharpnose Shiners upstream from Possum Kingdom Reservoir is estimated to represent 8% of the fish assemblage (Ostrand 2000).
Historically, Sharpnose Shiners throughout the Brazos River and several of its major tributaries within the watershed. Within the upper Brazos region (upstream from Possum Kingdom Reservoir), the Sharpnose Shiner is common and may have increased in abundance in recent years (Wilde and Durham 2007). Downstream from Possum Kingdom Reservoir, the Sharpnose Shiner population is in decline (Bonner and Runyon 2007), or may be completely extirpated, and the population within the Wichita River is completely extirpated, representing a reduction of approximately 69 percent of the historical range (USFWS 2011).
Trend during the past 10 years or three generations is uncertain but distribution and abundance likely have declined overall. Within the upper Brazos region, the Sharpnose Shiner may have increased in abundance in recent years (Wilde and Durham 2007), but declines have occurred elsewhere in the range USFWS 2011).
|Habitat and Ecology:||
Habitat includes sand and gravel runs of medium to large rivers; less often in sand- and mud-bottomed pools (Page and Burr 2011).
Sharpnose Shiners are obligate riverine fish that occur in fairly shallow water (38 to 82 cm in depth) in broad, open sandy channels with moderate current (Moss and Mayes 1993). Ostrand (2000) found abiotic factors associated with Sharpnose Shiner habitat to include specific conductance 0.20 m/s, and high turbidity (41 NTU).
USFWS (2011) summarized threats as follows:
The primary threat to the Sharpnose Shiner is habitat loss and modification due to current and future reservoir development. Reservoir development within the Brazos River Basin is largely responsible for the modification of habitat in the river that has rendered major portions unsuitable for the Sharpnose Shiner. The three major impoundments of the Brazos River proper have apparently extirpated the Sharpnose Shiner from the middle Brazos region and reduced it to relict populations within the lower portion of the river. Proposed reservoir development in the upper Brazos region is a significant threat to the extant populations. While only one reservoir is currently permitted (Post Reservoir) in the upper Brazos region, others are included in the Texas State Water Plan as a potential source to meet the demand for water through the year 2060.
Additional substantial threats to the Sharpnose Shiner are in-stream sand and gravel mining, industrial and municipal discharges, CAFOs, desalination, excessive sedimentation, and the spread of invasive saltcedar. The effect of saltcedar within the upper Brazos region threatens the existing Sharpnose Shiner habitat. Saltcedar encroachment in the upper Brazos and tributaries is probably an indirect result of impoundment of the river. Desalination is a potential future threat in the upper Brazos River Basin. In-stream sand and gravel mining, excessive sedimentation, and industrial and municipal discharges coupled with the effect of impoundments, reduce the likelihood of the Brazos River sustaining viable populations of the Sharpnose Shiner downstream of Possum Kingdom Reservoir. These threats combined with the substantial reduction in historic range due to anthropogenic factors justify the candidate status of the Sharpnose Shiner.
|Conservation Actions:||The impacts of algal blooms and mining of sand and gravel on fish populations in the Brazos River basin need to be determined (USFWS 2002).|
|Citation:||NatureServe 2013. Notropis oxyrhynchus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 07 December 2013.|
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