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U.S. FISH AND WILDLIFE SERVICE
SPECIES ASSESSMENT AND LISTING PRIORITY ASSIGNMENT FORM - Spotted Darter
Below are the Pages 1 - 4 of the Status Assessment. Download the entire 37-page Spotted Darter Candidate Status Assessment (PDF; 344KB)
SCIENTIFIC NAME: Etheostoma maculatum Kirtland
COMMON NAME: spotted darter
LEAD REGION: Region 3
INFORMATION CURRENT AS OF: July 25, 2011
We determined that threats to spotted darter are not of sufficient imminence, intensity, or magnitude that would cause substantial losses of population distribution or viability. Therefore, it was not elevated to Candidate status.
ANIMAL/PLANT GROUP AND FAMILY: Fishes, Percidae
HISTORICAL STATES/TERRITORIES/COUNTRIES OF OCCURRENCE: New York, Pennsylvania, Ohio, Indiana, Kentucky, West Virginia
CURRENT STATES/COUNTIES/TERRITORIES/COUNTRIES OF OCCURRENCE: New York, Pennsylvania, Ohio, Indiana, Kentucky, West Virginia
LAND OWNERSHIP: Spotted darters are found in perennial streams. Ownership of the bottoms of streams varies; however, perennial streams are typically regulated as state and/or federal jurisdictional waters. Land use decisions throughout entire watersheds can affect fish populations within individual streams. Land ownership within each watershed occupied by spotted darters is variable and comprised of a mix of private, federal, state and other publicly owned land. There is no comprehensive database describing land ownership within the range of the spotted darter. However, the U.S. Forest Service maintains a database of ownership of forested land by county. Some available information for land ownership within the range of the spotted darter follows.
New York: No federally owned land occurs in the only county in the range of the spotted darter (Chautauqua County) (United States Forest Service 2008). Approximately 4.3 percent of the forested land in Chautauqua County is state-owned (U.S. Forest Service 2008).
Pennsylvania: Approximately 15.1 percent of forested areas in counties within the range of the spotted darter are in federal ownership (Forest Service land) and 6.3 percent is in state ownership (U.S. Forest Service 2008). Ownership of land adjacent to French Creek in Pennsylvania is almost exclusively private (Mayasich et al. 2004, p. 17).
Ohio: Approximately 0.7 percent of forested land in counties in the current range of the spotted darter is federally owned (agency owner unspecified) and 7.9 percent is state-owned (U.S. Forest Service 2008). In the Big Darby Creek watershed, an area targeted for conservation, the three main land-owning conservation entities (Franklin County Metroparks, The Nature Conservancy (TNC), Ohio Department of Natural Resources (ODNR)) own approximately 4,047 ha (10,000 ac) of land (approximately 2.8 percent of the watershed) (Sasson 2008, pers. comm.).
Indiana: Approximately 7,821 hectares (ha) (19,325 acres (ac)) (4.1 percent) of the 190,202-ha (470,000-ac) Blue River watershed are in conservation ownership, including the Harrison/Crawford State Forest Complex along the lower section of the Blue River (Hauswald 2008, pers. comm.). Several federal and state properties are located in the East Fork White River watershed, including the Hoosier National Forest and Martin State Forest (Mayasich et al. 2003, p. 17).
Kentucky: With the exception of Mammoth Cave National Park, ownership of riparian areas adjacent to the Green and Barren rivers in the range of the spotted darter is almost entirely private (Mayasich et al. 2004, p. 17). Approximately 2.0 percent of forested areas in counties within the range of the spotted darter is federally owned (Department of Defense: 1.3 percent; Unspecified: 0.7 percent) (U.S. Forest Service 2008). The state owns no forested land (U.S. Forest Service 2008).
West Virginia: Approximately 1 percent of forested land in counties within the range of the spotted darter is in unspecified federal ownership and 3.1 percent is state-owned (U.S. Forest Service 2008). West Virginia streambeds are owned by the state (Mayasich et al. 2004, p. 17).
LEAD REGION CONTACT: Laura Ragan, 612-713-5157, firstname.lastname@example.org
LEAD FIELD OFFICE CONTACT: Jeromy Applegate, 614-416-8993 ext. 21, email@example.com
The spotted darter is a member of the Perch family (Percidae), a group characterized by the presence of a dorsal fin separated into two parts, one spiny and the other soft (Kuehne and Barbour 1983, p. 1). Darters are smaller and more slender than other percids. Most darters, including those in the genus Etheostoma, have a vestigial swim bladder, which decreases buoyancy, allowing them to remain near the bottom with little effort (Evans and Page 2003, p.64).
Etheostoma is the largest and most diverse of the darter genera (Kuehne and Barbour 1983, p. 66). Species of Etheostoma differ from Percina spp. in possessing scales on the midline of their belly that are similar in shape and size to the scales on their flanks (Stauffer et al. 1995, p. 294). Species of the darter genera Crystallaria and Ammocrypta have more elongate bodies than Etheostoma spp. and have a naked midline on their belly (Bailey et al. 1954, p.140).
Distinguishing morphological characteristics of the spotted darter include: laterally compressed body, subequal jaws, sharp snout, short pectoral fins, an absent/weak suborbital bar, and a rounded posterior edge of the caudal fin (Zorach and Raney 1967, p. 300). They often exceed 60 millimeters (mm) (2.36 inches (in)) standard length (Kuehne and Barbour 1983, p. 116). The opercle and belly are scaled, the cheek is slightly scaled to unscaled, and the nape and breast are unscaled (Page 1983, p. 100). Lateral line counts are usually 56 to 65 scales, and vertebrae number 37 to 39 (Kuehne and Barbour 1983, p. 117). Spotted darters are sexually dimorphic. Males have black-edged red spots on the body and a bluish-green breast that intensifies in color at spawning time. Females have dark spots on the body that are larger and more diffuse than the males (Keuhne and Barbour 1983, p. 116).
Spotted darters superficially resemble bluebreast darters (E. camurum), but the two can be distinguished by the latter having a black margin on its soft dorsal, caudal, and anal fins (Stauffer et al. 1995, p. 304). Small spotted darters can resemble Tippecanoe darters (E. tippecanoe), but Tippecanoe darters have an incomplete lateral line (Stauffer et al. 1995, p. 304).
The spotted darter was described as Etheostoma maculata by Kirtland (1841, pp. 276-277). Jordan and Eigenmann (1885, p. 71) emended the species epithet to maculatum to conform to the neuter gender of Etheostoma. The spotted darter was subsequently listed under the genera Etheostoma, Nothonotus, and Poecilichthys by various workers through the early 1950s. Bailey et al. (1954, pp. 139-141), and Bailey and Gosline (1955, pp. 6, 10) reduced the number of darter genera to three (Ammocrypta, Etheostoma, and Percina), placing the spotted darter in the subgenus Nothonotus. Three subspecies were subsequently recognized by Zorach and Raney (1967, p. 297): the spotted darter (Etheostoma maculatum maculatum) Kirtland in the Ohio River system including the Wabash and Green river systems, bloodfin darter (E. m. sanguifluum ) (Cope) in the upper Cumberland River system below Cumberland Falls, and wounded darter (E. m. vulneratum) (Cope) in the upper Tennessee River system. These subspecies have since been elevated to distinct species within the genus Etheostoma, subgenus Nothonotus: E. maculatum (spotted darter), E. sanguifluum (bloodfin darter) and E. vulneratum (wounded darter) by Etnier and Williams (1989, p. 987).
Preliminary results from genetics research suggest that all known populations of E. maculatum are appropriately described as a common species (Keck and Near 2008, pers. comm.; Porter 2008, pers. comm.). However, ongoing morphological assessments of the Elk River population may reveal characteristics that distinguish it as distinct from other E. maculatum populations (Welsh 2008, pers. comm.). Until and unless a morphological and genetics analysis of broader scope is completed and can demonstrate distinct differences, we will consider all populations of E. maculatum as a single species, and a valid taxon for consideration as a candidate.
Darters typically exploit riffle habitat in streams, in part because shallow riffles contain few predators capable of eating darters (Kuehne and Barbour 1983, p. 1). Substrate heterogeneity in riffles creates “velocity shelters,” areas of low velocity used by darters (Harding et al. 1998, p. 995). Interstices of coarse riffle substrate also trap organic debris, which is processed by bacteria and fungi, creating an energy source for aquatic invertebrates, the preferred food type of most darters (Kuehne and Barbour 1983, p. 1). Darters are typically more selective feeders than other benthic stream fishes (Hansen et al. 1986, p. 68).
Spotted darters are habitat specialists that take advantage of their extremely laterally compressed body to live under and among large, heterogeneous, unembedded substrates in riffles and glides (Raney and Lachner 1939, pp. 157-159; Burr and Warren 1986, p. 306; Bowers et al. 1992, p. 19; Osier and Welsh 2007, p. 457; Kessler and Thorp 1993, p. 1090; Kessler et al. 1995, p. 368). They are associated with deeper water and larger rocks than similar species (Raney and Lachner 1939, p. 158; Kessler and Thorp 1993, pp. 1087-1089; Osier and Welsh 2007, p. 456). They typically do not tolerate silt or embedded substrates (Kessler and Thorp 1993, p. 1090; Osier and Welsh 2007, p. 457). In the Blue River, Indiana and the lower Allegheny River and upper Ohio River in Pennsylvania, spotted darters are found in the tailwaters of some dams, where higher velocities help maintain these conditions (Baker et al. 1985, pg. 605; Fisher 2008, pers. comm.; Spears 2008, pers. comm.). Slight winter movement into deeper areas within and adjacent to riffles has been observed (Raney and Lachner 1939, p. 158; Albin 2008, pers. comm.).
Spotted darters typically spawn in May and June (Raney and Lachner 1939, p. 160; Weddle and Kessler 2008, p. 21; Ruble et al. 2008, Appendix 2). Raney and Lachner (1939, p. 159) found that spawning sites were spaced at least 120 centimeters (cm) (47.24 in) apart in the head of a riffle in water 15-60 cm (5.9-23.62 in) deep. Up to 350 adhesive pale yellow 2 mm (0.079 in) diameter eggs were deposited in tight wedge-shaped masses on the undersides of 90-275 cm (35.43-108.27 in) diameter flat rocks (Raney and Lachner 1939, p. 161). Weddle and Kessler (2008, p. 22) found that egg clump dimensions averaged 20 mm (0.79 in) long by 13 mm (0.51 in) wide and were deposited under rocks averaging 24.7 cm (9.72 in) long and 18.2 cm (7.17 in) wide. Observations of up to five distinct egg size classes in females indicate that spotted darters spawn multiple times in a single season (Raney and Lachner 1939, p. 162; Weddle and Kessler 2008, p. 24). Male spotted darters guard the eggs while remaining mostly under or adjacent to the nest rock (Raney and Lachner 1939, p. 162). First spawning activity is reported to occur at two years for both males and females; males spawn through year four and females through year five (Raney and Lachner 1939, p. 164).
The species’ extremely pointed snout makes them well-adapted for picking macroinvertebrate prey from underneath rocks (Kessler et al. 1995, p. 368). Macroinvertebrates, especially larval insects, comprise a large portion of their diet. Larval midges (Diptera, family Chironomidae), stoneflies (Plecoptera), caddisflies (Trichoptera), mayflies (Ephemeroptera), and beetles (Coleoptera), as well as adult water mites (Hydracarina) are important food items (Raney and Lachner 193, p. 162; Hansen 1983, Appendix B; Kessler 1994, p. 29). Spotted darter eggs have been found in the stomachs of spotted darter adults (Raney and Lachner 1939, p. 162).
The spotted darter historically occurred in the Ohio River drainage in New York, Pennsylvania, Ohio, Indiana, Kentucky and West Virginia (Table 1). In addition to the historical streams of record in Table 1, spotted darters probably occurred in other streams in the Ohio River basin with suitable habitat. Raney and Lachner (1939, p. 158) speculated that its presence had likely been overlooked by many collectors who had not thoroughly worked deeper riffles. In addition, small benthic fishes are difficult to collect in deeper water (Ohio Environmental Protection Agency (OEPA) 1988, p. 4-10). Troutman (1981, p. 670) noted that there may be considerable variation in the numbers of spotted darters in individual populations from one year to another, although he did not discuss a cause for this phenomenon. These factors may help explain why spotted darters went undetected in the Elk, Blue, East Fork White, lower Allegheny, and Ohio Rivers until after 1975. Considering that many larger parent streams in the Ohio River Basin were extensively impounded and polluted beginning in the 1800’s, degrading or eliminating spotted darter habitat (Ortmann 1909, pp. 90-110; U.S. Army Corps of Engineers (USACE) 1981; Trautman 1981, pp. 17-24), it is reasonable to believe that the species also inhabited some of these parent streams historically but were extirpated prior to detection.
Current Range/Distribution and Population Estimates/Status
Range-wide status assessments in the literature indicate that spotted darters are localized and uncommon (Kuehne and Barbour 1983, p. 117; Page 1983, p. 100; Page and Burr 1991, p. 305). Although there is no range-wide systematic sampling to monitor distribution and status, a number of river-wide surveys have been conducted in some basins in some years. Available information on distribution and status in each major system is presented below and summarized in Table 1 and Figure 1.
Above are the Pages 1 - 4 of the Status Assessment. Download the entire 37-page Spotted Darter Candidate Status Assessment (PDF; 344KB)