|Scientific Name:||Etheostoma maculatum|
|Species Authority:||Kirtland, 1840|
|Red List Category & Criteria:||Vulnerable B2ab(iii) 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 area of occupancy is unknown but perhaps less than 2000 sq km, population size is unknown but relatively small, number of locations is 19, distribution is severely fragmented, and habitat quantity and quality (and probably the species' distribution and abundance) are subject to continuing declines.
|Range Description:||This darter has a spotty distribution in the Ohio River basin from northwestern Pennsylvania (upper Allegheny River and French Creek) and western New York through Ohio (Big Darby and Deer Creeks, Scioto basin) to north-central Indiana (upper Wabash River, East Fork White River, and Blue River) and south to West Virginia (middle section of the Elk River system) and Kentucky (Trautman 1981, Osier 2005, Simon 2005, Page and Burr 2011). The species is now absent from much of former range (Kuehne 1983).
Extent of occurrence is roughly 200,000 square kilometers, but the species is absent from the vast majority of this area.
|Range Map:||Click here to open the map viewer and explore range.|
Mayasich et al. (2004) reviewed current status and determined that this species occurs (based on post-1970 records) in two waters (USGS Hydrologic Units) of the Allegheny River drainage, eight waters of the Green River drainage, a single water of the Kanawha River drainage (10 sites along the Elk River; Osier 2005), six waters of the Ohio River drainage, and two waters of the Wabash River drainage. The number of occurrences and locations is larger than the number of hydrologic units.
This species is extremely localized and uncommon (Page and Burr 2011). It was moderately common in the 1970s in French Creek, New York (Smith 1985).
The species is now scarce and highly localized in Ohio. Trautman (1981) commented that the size of spotted darter populations in Ohio varied considerably. Bowers et al. (1992) also presented data indicating that Spotted Darter populations fluctuate considerably within short time periods. Jay Stauffer, (Pennsylvania State University, pers. comm.) commented that in New York, only a few Spotted Darter individuals have been observed in recent years, and the species has gone from no official listing in that state to "threatened" status. Kuehne and Barbour (1983) noted that the darter currently known as Etheostoma maculatum was absent from much of its historical range.
Trend over the past 10 years or three generations is uncertain, but distribution and abundance probably are declining.
|Habitat and Ecology:||Habitat includes large rubble and boulder areas, adjacent to or in swift deep riffles, in small to medium, clear rivers (Lee et al. 1980, Page and Burr 2011). Adults apparently spend the winter in areas somewhat deeper and with slower current (Kuehne and Barbour 1983). In the Elk River, West Virginia, Spotted Darters were observed primarily in glide habitats near large rocks and in moderate current velocities (Osier and Welsh 2007). Eggs are laid on undersides of stones in quiet water areas near heads of riffles in water 15–60 cm deep (Page 1983).|
Threats include siltation, damming of flowing waters, changes in water quality, and introduction of non-native predator species (Simon 2005).
Because they are so limited, populations in New York (Paul McKewon, New York Department of Environment & Conservation), West Virginia (Cincotta 1987), and Pennsylvania are probably most affected by agricultural, forestry, urbanization, and other land uses that result in silt deposition. In New York, Bowers et al. (1992) noted that stream channel alterations and increased turbidity and siltation due to poor agricultural and silvicultural practices could have significant adverse effects.
In West Virginia, stream sedimentation resulting from recent coal mining operations may be the biggest threat (Dan Cincotta pers. comm.). This is primarily because of the need for low sulphur coal, which is available in this area, and new mining technologies ("mountain-topping"). Within the Elk River watershed in West Virginia, sedimentation results from many sources, including logging, coal mining, and oil and gas extraction and may degrade Spotted Darter habitat (Osier and Welsh 2007).
Much basic information required for appropriate management activities for Spotted Darter populations is unknown. Some details of life history are lacking, as well as population and metapopulation dynamics, including movement patterns. This information is necessary for proper management. Because population fluctuations may be extreme, and extant populations are so fragmented, regular monitoring of all populations is needed. Captive propagation techniques, developed for related species (Rakes et al. 1999) may be used for this potential need.
Some extant Spotted Darter populations are extremely vulnerable because of small size and extent. If events occur which result in further fragmentation (habitat barriers - even if temporary), recolonization may be unlikely because of small source populations and disjunct nature of all extant populations. Recovery may be aided by reintroduction or augmentation, and should be considered a reasonable management activity. If water and habitat quality has improved in other areas where the species is currently believed to have been extirpated, consideration should be given to reintroducing the species. Captive propagation might be necessary to obtain enough individuals for these efforts.
Actions are needed to control sediment runoff from mining, row crop agriculture, forestry, and degradation of riparian zones and aquatic habitat by livestock. Restoring riparian vegetation, fencing livestock from streams and providing alternate water sources are recommended. In some areas, modifying dam releases and removal of small barriers, such as mill dams, might be considered. If habitat and water quality is improved, or barriers removed, reintroductions should be considered. Natural processes should be allowed to proceed so that the streambed and stream banks become stabilized.
Bowers et al. (1992) indicated considerable annual variation in population size and density may occur. Therefore, critical populations should be monitored annually.
Bowers et al. (1992) made specific recommendations for monitoring a Spotted Darter population in New York. Their sampling methods included setting a seine downstream of a riffle, and disturbing the substrate so that fishes beneath the rocks would be swept into the seine (kick-seining). All fishes collected in a single kick-seine attempt were identified and released, and the process was repeated until no new species were encountered. They then compared the number of Spotted Darters observed per unit area at the various survey sites. In streams clear enough, direct observation with snorkel (also keeping track of the number of individuals observed per unit effort) may also be an appropriate survey technique, and is less invasive (Heacock 1995, Greenburg 1991, Jay Stauffer pers. comm. and P. W. Shute pers. obs.).
The most immediate research need is to determine the actual current abundance of Spotted Darters throughout their range, movement/dispersal patterns, and metapopulation dynamics. This information will be necessary before we can determine the watershed area appropriate for sustaining viable Spotted Darter populations. The population studied by Bowers et al. (1992) fluctuated considerably, but these data were from near the northern limit of Spotted Darter's range, and may not be comparable to other populations. However, if these fluctuations are natural, they may help explain the current disjunct range of the species. Also, population fluctuations like those reported by Bowers et al. may indicate a need for frequent, regular monitoring, especially of very small, restricted populations.
Also, a more complete understanding of life history (more details on seasonal habitat preferences and larval or juvenile habitat requirements, documenting for example) will help ensure management activities are appropriate to protect habitats and other factors necessary to complete all life history stages. Although some life history information is available (Raney and Lachner 1939), more details are needed, especially to document similarities in ecology among populations range-wide. This information might be important when attempting to restore and/or manage Spotted Darter populations. For example, a related species, the Boulder Darter (Etheostoma wapiti) is believed to have larvae that drift with the current for several days or weeks after hatching (Rakes et al. 1999). The current disjunct Spotted Darter distribution pattern might be somewhat explained if larvae of this species also drift after hatching, and clean habitats suitable for adult Spotted Darters downstream of spawning sites are lacking. This behaviour would also require a broader, riverine ecosystem perspective for proper long-term management of Spotted Darter populations.
In the event reintroduction or population augmentation is believed to be necessary or beneficial, techniques should be developed to propagate Spotted Darters in captivity. Natural source populations appropriate for reintroduction into particular watersheds may not be large enough to remove individuals to be successful for these type projects.
|Citation:||NatureServe 2013. Etheostoma maculatum. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 25 April 2014.|
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