|Scientific Name:||Pteronotropis hubbsi|
|Species Authority:||(Bailey & Robison, 1978)|
Notropis hubbsi Bailey & Robison, 1978
|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 probably does not exceed 2.000 km2, and the population likely is declining due to continued habitat degradation. The species does not fully meet the criteria for Vulnerable: extent of occurrence exceeds 20,000 km2 (may be roughly 35,000 km2), the species occurs in more than 10 locations, distribution is not severely fragmented, and the rate of decline likely is less than 30 percent over 10 years or three generations.
|Range Description:||Spotty distribution includes lowlands of the Red, Atchafalaya and Ouachita river systems of southern Arkansas, extreme southeastern Oklahoma (Crooked Creek/Forked Lake, McCurtain County; Taylor and Norris 1992), extreme northeastern Texas, and Louisiana, and (formerly) a disjunct population (three sites) in extreme southern Illinois. With the exception of the latter population, all known sites are west of the Mississippi River. Most stations are in southern Arkansas and northern Louisiana. The Illinois population is considered extirpated, as none have been found since 1974 (Ranvestal and Burr 2002). The apparent disjunction in the range between Illinois and the nearest Arkansas population, some 440 km by air, may be an artefact of the fact that the species was not described until 1954. By that time much of the bottomland swamp and oxbow habitat of this species between Arkansas and Illinois had been ditched, dredged, or filled and converted to farmland.|
|Range Map:||Click here to open the map viewer and explore range.|
There are at least 32 known collection sites, but these may represent fewer distinct occurrences. The species is known from only three river drainages (formerly four, counting the Illinois population). However, each drainage may have several discrete occurrences. The species is probably under-sampled because of difficult access to habitat. No systematic range-wide search has been conducted.
TEXAS: Only two populations, in Caddo Lake and Big Cypress Bayou, are known from the state (Ranvestal and Burr 2002), but the population is estimated to number in the thousands (Price 1992). ARKANSAS: The Bluehead Shiner occurs primarily in tributaries of Ouachita River and in the Little River of southwestern Arkansas. The species is known to occur in at least 18 collection stations in nine counties, and could probably be found at more locations. It is not known how many separate occurrences these 18+ stations represent.
ILLINOIS: The species is known from just one location in the state, and has not been seen since 1974, despite extensive searches using a variety of sampling methods (Burr and Warren 1986). It has therefore been considered extirpated, but Burr and Warren believed that it may yet be present in inaccessible areas in Wolf lake.
LOUISIANA: Ten sites are known for the species, all from west of the Mississippi, these represent only two small population centres (Ranvestal and Burr 2002).
OKLAHOMA: Bluehead Shiners are known from two locations (Ranvestal and Burr 2002), both in McCurtain County within the Little River National Wildlife Refuge. One is from Forked Lake, which has been verified yearly from 1983 to present. The other was discovered in 1990 in a small slough (Vaughn 1992).
Little is known regarding abundance. Populations show high levels of geographic and temporal variability (Ranvestal and Burr 2002). Also, conventional sampling methods (i.e., seining, electrofishing, minnow traps) are often ineffective in the densely vegetated habitat preferred by this species (Burr and Warren 1986) which may result in unrealistic population estimates (Ranvestal and Burr 2002).
No data and no comments on abundance are available for most sites. The single Texas population has been estimated at thousands of fish (Price 1992, Taylor 1992). At other sites, several hundred fish have been captured during a single visit.
One population (Illinois) is thought to have been extirpated in recent years, but other populations have apparently remained viable. The population in the Ouachita River drainage in northeastern Louisiana apparently expanded dramatically between 1983 and 1991, then declined following regional flooding (Douglas 1992). This suggests that the species may be sensitive to changing hydrology. Continuing lowland stream degradation in the Ouachita River system in Arkansas (Robison and Buchanan 1988) suggested declining populations in the 1980s. Elsewhere, data on trends are lacking.
Trend over the past 10 years or three generations is uncertain, but distribution and abundance probably are slowly declining.
|Habitat and Ecology:||Habitat includes quiet backwater areas and pools of small to medium-sized, sluggish streams and oxbow lakes, with mud or mud-sand bottoms. Water typically is tannin stained, and a heavy growth of vegetation often is present. Typical plant associates are Proserpinaca palustris L., Polygonum hydropiperoides Michx, and Nelumbo pentapetala Walt., though no particular species is especially indicative of the fish (Bailey and Robison 1978). In Illinois, this species occurred in the vegetated margins of one lake, over mud, decaying plants and submerged logs in tea-coloured water, and in a few springs characterized by luxuriant growth of submerged aquatic plants (Burr and Warren 1986). Schools seek cover in vegetation when disturbed (Bailey and Robison 1978). Fletcher and Burr (1992) discovered the species spawning among bald cypress roots in a side bay off a bayou in Louisiana, in nests apparently built by warmouth sunfish. Distribution of larvae collected in the wild suggested that they may also spawn among other woody plant roots, and may not always use warmouth nests.|
Threats include draining, filling, farming, or flooding of backwater swamp habitat. For example, gravel removed from the stream bed degraded the type locality in Arkansas, and Robison and Buchanan (1988) mentioned continued degradation of lowland streams of the Ouachita river system. Alteration of stream courses and erection of barriers to dispersal and migration are also general threats. Lowland swamp habitat continues to disappear in southern Illinois, southeastern Missouri, western Kentucky and Tennessee, and northeastern Arkansas (Fletcher and Burr 1992). The species has been captured in flowing water in the Ouachita River, as well as in bayous, suggesting that it may tolerate a range of environmental conditions. However the low genetic diversity of this species (Warren et al. 1991) suggested that it may lack some resiliency to habitat change, and the short life span of adults, along with limited distribution, makes populations vulnerable to catastrophic destruction. Warren et al. (2000) and Jelks et al. (2008) rated this species as vulnerable, based on habitat loss/degradation.
Because of their rarity in the wild and beautiful breeding colours, Bluehead Shiners are highly coveted in the aquarium trade; over-collecting from the wild, coupled with short lifespan, disjunct distribution, and already frail status, leave populations highly vulnerable to decline (Ranvestal and Burr 2002).
Taylor (1992) commented that the species is probably fairly resistant to disturbance. Specimens were successfully transferred to aquaria and ponds for laboratory studies by Fletcher and Burr.
|Conservation Actions:||This rare fish has a limited range and is known from only 32 stations range-wide. These few known populations should be protected and monitored frequently, but with as little destructive sampling as possible. Thorough searches of potential habitat are needed, but effective methods of sampling in the heavily vegetated areas favoured by the species need to be developed first. More information on seasonal movements is needed to determine year-round habitat needs.|
|Citation:||NatureServe 2014. Pteronotropis hubbsi. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 07 July 2015.|
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