BLACKMOUTH SHINER
SCIENTIFIC NAME: Notropis melanostomus Bortone
CHARACTERISTICS: One of the smallest shiners in North America, reaching only 45 mm [1.8 in.] TL, with slender body, long and slender caudle peduncle, very large eye, distinct lateral stripe around snout and to base of caudal fin with a light stripe just above lateral stripe, basicaudal spot either absent or chevron-shaped, and mouth distinctly upturned (almost vertical) and bowed forward. Floor of mouth darkly pigmented. Fins falcate and pointed, anal fin long (typically 10-11 rays), caudal fin deeply forked, pored lateral-line scales typically 2-5, pharyngeal teeth 0,4-4-0 with the posterior three teeth on each arch serrated, long and numerous (15-18) gill rakers (Bortone 1989, Suttkus and Bailey 1990). Nuptial males with tubercles on dorsal surface of first six pectoral-fin rays, pelvic fins longer than females reaching beyond anal fin origin (Suttkus and Bailey 1990, O’Connell et al. 1998). Specimens from two populations (Alabama/Mississippi and Florida) show only slight morphological differences, but phylogenetic analyses of mitochondrial DNA reveal that these two populations are genetically divergent.
ADULT SIZE: In Alabama, all specimens collected (n = 41) were adults 29.7-38.2 mm (1.2-1.5 in.) SL with 1:1 sex ratio.
DISTRIBUTION. This species was first collected in 1939 in Pond Creek, tributary to Blackwater River, northwestern Florida, and was not collected again until 1976. A new population was discovered in adjacent Yellow River Drainage (Shoal River) in 1977 and in backwaters along the Blackwater River in the 1980s. Found in Black Creek, tributary to Pascagoula River, southeastern Mississippi in 1986 (Bortone 1989, Suttkus and Bailey 1990). In the 1990s, additional populations were discovered in Pascagoula River Drainage (O’Connell et al. 1998, Ross 2001). First collected in Alabama mid-April 2003 in backwater of Bay Minette Creek, Baldwin County, a tributary to lower end of Mobile-Tensaw Delta (Boschung and Mayden 2004). Specimens not collected at same site in early February 2004, but found in late March 2004. No other sites know for this species in Alabama, but no survey has been conducted for this species within the State.
HABITAT. Oxbow lakes and shallow backwaters (0.5-1 m [1.6-3.3 ft.]) of lowland medium-sized streams and rivers. Backwater areas typically connected to main stream in Florida, in Mississippi oxbows and floodplain pools only interconnected to stream during high water; Alabama site with connection to creek in February and April. Areas have clear, tannin-stained, acidic to moderately acidic (pH 5.4-6.8) water with no flow over soft mud and detritus or sand, and abundant submerged vegetation (pondweed, water-nymphs, and water-lilies). Occur in schools 0.2-0.5 m [0.7-1.6 ft.] below the surface in open areas adjacent to submerged vegetation, typically 1-5 m [1.6-16.4 ft.] offshore (Bortone 1989, 1993, Suttkus and Bailey 1990, O’Connell et al. 1998).
LIFE HISTORY AND ECOLOGY. In Florida and Mississippi, form tight irregularly-shaped schools at least 0.2 m (0.7 ft.) below the surface. These schools are almost always associated with submerged vegetation, and quite often beneath a school of brook silversides, Labidesthes sicculus, (Bortone 1993, O’Connell et al. 1998). Species is short-lived, less than two years, populations made up of few individuals over one year old. Minimum adult size 21 mm (0.8 in.) SL, adult sex ratio 1:1 (Suttkus and Bailey 1990, O’Connell et al. 1998). Spawning has not been observed, tuberculate males and gravid females collected from end of April to end of June in Florida. Males collected in Alabama in late March and mid-April with tubercles. Florida females with mature ova 0.75 mm in diameter (0.03 in.), fecundity 60-70 eggs, production of multiple clutches unknown (Bortone 1993). Ephemeral nature of isolated habitats in Mississippi may explain lower abundance (at most schools of hundreds of juveniles) relative to Florida populations (schools of thousands of individuals) and perhaps why most Mississippi sites exclusively either adults or juveniles (O’Connell et al. 1998). All Alabama specimens adults. In Florida, diet predominately plankton, mostly diatoms and desmids (phytoplankton) from August to February and cladocerans (zooplankton) from March to July (Bortone 1993). Additional life history research is needed to understand basic habitat requirements and reproductive strategies.
BASIS FOR STATUS CLASSIFICATION.
CONSERVATION AND MANAGEMENT RECOMMENDATION. A comprehensive survey of backwaters and oxbows in Bay Minette Creek is needed, as well as surveys in other creek and river systems in lower Mobile Basin possessing appropriate habitat. Surveys should also be expanded into oxbows and backwaters in Escatawpa and Perdido River systems in Alabama. Multiple excursions to a system are necessary during surveys due to the ephemeral nature of these habitats and the spotty occurrence of this species. Water quality and habitat monitoring and pollution abatement should be pursued for Bay Minette Creek. In addition to monitoring water quality, current laws regulating industrial discharge should be enforced, and best management practices should be encouraged and applied with regards to timber-harvest and construction activities. Additional life history research is needed to understand basic habitat requirements and reproductive strategies in all three populations. Further studies on the relationship of the Mobile Basin population to those in Florida and Mississippi are also warranted. Highly vulnerable due to short life span and ephemeral nature of habitat; many sites in Mississippi dry in mid-summer (O’Connell et al. 1998, Ross 2001). In Florida encroachment of urbanization is a concern for some populations (Bortone 1989, Suttkus and Bailey 1990). Alabama specimens have been collected in backwaters with connection to Bay Minette Creek, but stability of these areas unknown during low water conditions. Water quality is a concern; the town of Bay Minette is at the headwaters of Bay Minette Creek, and there are fish consumption advisories for this system.
REFERENCES CITED:
Bortone, S.A. 1989. Notropis melanostomus, a new species of cyprinid fish from the Blackwater-Yellow River drainage of northwest Florida. Copeia 1989(3):737-741.
. 1993. Life history, habitat assessment, and systematics of the Blackmouth Shiner (Notropis sp.), Blackwater River drainage. Florida Game and Fresh Water Fish Commission Nongame Wildlife Program Final Report, Tallahassee. 40 pp.
Boschung, H.T., Jr., and R.L. Mayden. 2004. Fishes of Alabama. Smithsonian Institution Press, Washington, DC. 736 pp.
O’Connell, M.T., S.T. Ross, J.A. Ewing III, and W.T. Slack. 1998. Distribution and habitat affinities of the blackmouth shiner (Notropis melanostomus) in Mississippi, including eight newly discovered localities in the upper Pascagoula River drainage. Southeastern Fishes Council Proceedings No. 36:1-6.
Ross, S.T. 2001. Inland fishes of Mississippi. University Press of Mississippi, Oxford. 624 pp.
Suttkus, R.D., and R.M. Bailey. 1990. Characters, relationships, distribution, and biology of Notropis melanostomus, a recently named cyprinid fish from southeastern United States. Occasional Papers of the Museum of Zoology, University of Michigan No. 722:1-15.
PREPARED BY: Bernard R. Kuhajda
