Snail darter

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Snail darter
Percina tanasi.jpg
Status ESA DL.svg
Delisted (ESA) [2] [3] [4] [5]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Percidae
Genus: Percina
Species:
P. tanasi
Binomial name
Percina tanasi
Etnier, 1976

The snail darter (Percina tanasi) is a small species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is found in East Tennessee freshwater in the United States and in small portions of northern Alabama and Georgia. [5] First recorded in 1973, the snail darter was listed as endangered under the U.S. Endangered Species Act of 1973 by 1975. The species was at the center of a major environmental law controversy that involved a lawsuit seeking to halt the completion of Tellico Dam, which posed a risk of extinction for the snail darter by blocking its migratory route. The case was eventually appealed to the U.S. Supreme Court, which ruled on it in its 1978 decision Tennessee Valley Authority v. Hill .

Contents

In 1978, the U.S. Fish and Wildlife Service, Tennessee Valley Authority (TVA), and Tennessee Wildlife Resources Agency launched a recovery plan to preserve the snail darter by transferring the species to other river systems. [6] Its native range was originally in the lower parts of the Little Tennessee River, the Sequatchie River, and in Chickamauga Creek, but was later eliminated from the Little Tennessee River by the completion of Tellico Dam. [7] The species was then transplanted into the Hiwassee River in southeastern Tennessee.

The species inhabits large creeks or deeper portions of rivers and reservoirs with gravel and sand shoals substrate. The snail darter spawns between February and mid-April with the female producing 600 eggs which drift downstream. Juveniles occupy slack water habitats and migrate upstream to the breeding ground. The lifespan of the snail darter ranges between 2 and 4 years. The snail darter adult length ranges between 55 and 90 mm (2.2 and 3.5 in). [8] The species’ diet consists mostly of snails and insects (caddisflies, midges, and blackflies). Snail darters have camouflage dorsal patterns and burrow in the substrate to conserve energy and hide from predators. They are largely preyed upon by banded sculpin (Cottus carolinae). [9] The specific name tanasi derives from capital of the Cherokee Nation located on the Little Tennessee River where the species was first recorded. [10] The species was relisted as threatened in 1984 after being successfully transplanted into other river systems. [6] In 2022, it was delisted by the U.S. Fish and Wildlife Service due to recovery. [2] [5]

Geographic distribution

The original range of the snail darter was thought to be strictly in the lower portion of the Little Tennessee River with a few individuals dispersing into the headwaters of Watts Bar Lake below Fort Loudon Dam. Prior to the completion of the Tellico Dam in 1979, TVA biologists made several efforts to relocate the remaining individuals of the species into other river systems. In 1975 the species was successfully transplanted to the Hiwassee River, where the population has risen to about 2,500 individuals. Another transplant attempt was made to the Nolichucky River in 1975, but was later stopped by the discovery of another federally protected species, the sharphead darter (Etheostoma acuticeps). Other unsuccessful transplant locations included lower parts of the Holston River, French Broad River, and middle Elk River. With the completion of the Tellico Dam, the snail darter was extirpated from the Little Tennessee River. In 1980, additional populations of snail darters were discovered in South Chickamauga Creek in Chattanooga, the lower portion of Big Sewee Creek in Meigs County, the lower Sequatchie River in Marion County, Little River in Blount County, and the lower portion of Paint Rock River in Madison County, Alabama. [6] These discoveries indicated the snail darter's possible range as being from the lower reaches of major tributaries of the Tennessee River from the northward bend in Alabama upstream; the snail darter was reclassified from endangered to threatened in July 1984. [7]

Additional populations were identified prior to the species' 2022 delisting, including in the Flint River, although the snail darter has not been found there since 2012, in the Elk River and in Bear Creek, all tributaries of the Tennessee River. TVA surveys have located the snail darter in Chickamauga Lake, Nickajack Lake, Guntersville Lake, Wheeler Lake, the Pickwick Reservoir and part of the Fort Loudoun Lake, as well as a finding of juveniles in Watts Barr Reservoir. [5] Reproduction is believed to be occurring in Chickamauga Lake, Nickajack Lake and Wheeler Lake. [5] : 60302–60303 

Snail darter, Percina tanasi Snail darter FWS 1.jpg
Snail darter, Percina tanasi

Ecology

The snail darters are found in gravel shoals free of silt and aquatic plants, with moderate to strong currents, and moderate depths. [11] The substrate generally consists of dark micaceous sand, with little to no silt, and 25 to 50 percent of the area scattered with gravel. Agricultural development has also affected the water clarity, and silt run-off causes problem for reproduction and migration. In 1976, the winter temperature ranged from 41° to 54 °F, and summer temperature averaged near 64 °F in the Little Tennessee River. These temperature fluctuations are due to impoundments, resulting in colder water when the dam is discharging and warming water when flow is diminished. Current velocities ranged from a moderate 0.25 m/s to nearly 0.7 m/s. [9] The snail darter actively feeds in spring and winter with a diet consisting of 60% small gastropods (5mm or less in diameter) and other prey such as caddisflies, midges, and blackflies. Snails are the preferred food source until late spring when they outgrow the gape size of the fish, resulting in a diet change to insect larvae. [12] The most effective predator on adult snail darters is Cottus carolinae while Salmo trutta, Morone chrysops, Sizostedion canadense, and other darters would prey on eggs and juveniles. The snail darters’ dorsal patterns and coloration allow the fish to camouflage with the substrate to avoid detection from predators. Burrowing behavior also is a defense mechanism and can help conserve energy for the current. [9]

Life history

The snail darter spawning occurs in early February through April when water temperatures range from 12°-13 °C. The female produces over 600 eggs and has multiple mates over the course of two weeks. The snail darter does not display territorial behavior during the breeding, unlike other species of darters. The eggs are deposited on the shallowest portion of gravel shoals and hatch after 15–20 days. Silt run-off can deprive eggs of oxygen, leading to higher mortality. When eggs hatch, the larvae drift downstream to deeper, calmer water and feed on zooplankton. The larvae are phototaxic (attracted to light) which may have implications regarding diurnal movements in the water column or depth maintenance. [6] After 3 to 4 months of age, the juveniles migrate upstream during spring, and remain at the breeding shoal areas. The snail darter reaches sexual maturity at one year. The snail darter life span is 2 to 4 years, depending on predation and access to the breeding ground. More research on the snail darter life history is needed. [8]

Current management

The snail darter was a federally protected species under the Endangered Species Act of 1973 between 1975 and 2022 as a result of habitat destruction from the completion of the Tellico Dam. Another factor in the decline of snail darters is siltation, which degrades spawning habitat and food availability. Other influences include agricultural development, environmental contamination and pollution, and channel modification, which affect water clarity, reproduction success, and migration patterns. [13] A recovery plan was made and completed on May 5, 1983. The recovery efforts focused on finding and transplanting individuals to suitable habitat areas in the Tennessee River, continuing research to locate already-existing populations, and maintaining current populations of snail darters. Programs are in progress to educate the public and to work with state officials and local citizens to broaden protection efforts. However, more recent research on snail darters is still needed to better manage and protect the species and its habitat. The U.S. Fish and Wildlife Service, TVA, Tennessee Wildlife Resource Agency, and other law enforcement agencies are utilizing legislation and regulations to protect the snail darter during the recovery effort. [14] It is recommended that at least five separate viable populations should be maintained, the species should be kept on the Federal List of Endangered and Threatened Wildlife, and federal permits to collect the species should be required.

On October 5, 2022, the US Fish and Wildlife ruled that the species is no longer threatened. It was removed from the Federal List of Threatened and Endangered Wildlife on November 4, 2022. [5]

Taxonomy

The snail darter was first formally described in 1976 by the American ichthyologist David A. Etnier with the type locality given as the Little Tennessee River near mouth of Coytee Spring in Loudon County, Tennessee. [15] The specific name refers to the settlement of Tanasi in Monroe County, Tennessee which was the capital of the Cherokee Nation until 1725 And which is the origin of the name Tennessee. It is placed in the subgenus Imostoma and appears to be closely related to the stargazing darter (Percina uranidea). [16]

Related Research Articles

<span class="mw-page-title-main">Little Tennessee River</span> River in the United States of America

The Little Tennessee River is a 135-mile (217 km) tributary of the Tennessee River that flows through the Blue Ridge Mountains from Georgia, into North Carolina, and then into Tennessee, in the southeastern United States. It drains portions of three national forests— Chattahoochee, Nantahala, and Cherokee— and provides the southwestern boundary of the Great Smoky Mountains National Park.

<span class="mw-page-title-main">Tellico Dam</span> Dam in Tennessee, United States

Tellico Dam is a concrete gravity and earthen embankment dam on the Little Tennessee River that was built by the Tennessee Valley Authority (TVA) in Loudon County, Tennessee. Planning for a dam structure on the Little Tennessee was reported as early as 1936 but was deferred for development until 1942. Completed in 1979, the dam created the Tellico Reservoir and is the last dam to be built by the Tennessee Valley Authority.

<span class="mw-page-title-main">Tellico Village, Tennessee</span> Census-designated place in Tennessee, United States

Tellico Village is an unincorporated planned community, and census-designated place on the western shore of Tellico Reservoir in Loudon County, Tennessee, United States, about 30 miles (48 km) southwest of Knoxville. Its population was 5,791 as of the 2010 census and and 7,311 at the 2020 census. Tellico Village is the second largest area by population in Loudon County behind Lenoir City.

Tennessee Valley Authority v. Hiram Hill et al., or TVA v. Hill, 437 U.S. 153 (1978), was a United States Supreme Court case and the Court's first interpretation of the Endangered Species Act of 1973. After the discovery of the snail darter fish in the Little Tennessee River in August 1973, a lawsuit was filed alleging that the Tennessee Valley Authority (TVA)'s Tellico Dam construction was in violation of the Endangered Species Act. Plaintiffs argued dam construction would destroy critical habitat and endanger the population of snail darters. It was decided by a 6-3 vote, in which the U.S. Supreme Court ruled in favor of Hill, et al. and granted an injunction stating that there would be conflict between Tellico Dam operation and the explicit provisions of Section 7 of the Endangered Species Act.

<span class="mw-page-title-main">Snail darter controversy</span> Environmental controversy in Tennessee, United States

The snail darter controversy related to the discovery in 1973 of an endangered species during the construction of the Tellico Dam on the Little Tennessee River; the dam project had been authorized and begun before passage of protective environmental legislation. On August 12, 1973, University of Tennessee biologist and professor David Etnier discovered the snail darter in the Little Tennessee River while doing research related to a lawsuit under the National Environmental Policy Act (NEPA). The lawsuit said that the Tellico Reservoir, to be created by Tellico Dam, would alter the habitat of the river to the point of killing off the endangered snail darter.

<span class="mw-page-title-main">Amber darter</span> Species of fish

The amber darter is a small, endangered species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is native to the Conasauga River and Etowah River in Georgia and Tennessee in the United States. It typically inhabits riffle areas over gravel and sand bottoms, hiding in aquatic vegetation when present. It feeds on small invertebrates and probably breeds between late fall and early spring. It is an uncommon fish with a small range and the International Union for Conservation of Nature has classified its conservation status as being "endangered".

<span class="mw-page-title-main">Tangerine darter</span> Species of fish

The tangerine darter or river slick is a small species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is found in the eastern United States. It grows to a length of 4.3 to 7.1 inches, males being bright orange-red while females are yellow. It is insectivorous, picking insect larvae off aquatic plants and the riverbed, and sometimes rolling small stones over to expose prey. It breeds in late spring and early summer, typically in shallow sandy or gravelly riffles. Pollution and habitat degradation may be a problem in parts of its range; however, it is a fairly common fish with a wide range and the International Union for Conservation of Nature has classified its conservation status as being of "least concern".

<span class="mw-page-title-main">Common logperch</span> Species of fish

The common logperch, sometimes simply known as the logperch, is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. Like other logperches, it has the typical vertical barring along the flank and a subterminal mouth.

<span class="mw-page-title-main">Trispot darter</span> Species of fish

The trispot darter is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is endemic to northern Georgia and southern Tennessee in the United States, where it occurs in the Conasauga River and its tributaries and historically in the Alabama River system. It requires two interconnecting habitats; outside the breeding season it occupies the peripheral zones of the main river, with slow-moving water and silt gravel substrates with vegetation cover; during the breeding season it moves to warmer water with a clay-bottomed substrate with much vegetation. The population of this fish is declining due to loss of suitable habitat because of stream impoundment and land development. The International Union for Conservation of Nature has assessed its conservation status as being "vulnerable".

<span class="mw-page-title-main">Boulder darter</span> Species of fish

The boulder darter is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is endemic to Alabama and Tennessee in the United States, where it occurs in the Elk River system and Shoal Creek. It is found in small rivers and fast-flowing streams, at least 2 ft (0.6 m) deep, with boulders or a rocky base. It feeds on aquatic insect larvae but little is known of its natural history. The population trend of this fish is unknown but it is affected by a rise in siltation and the impoundment of water within its range by the building of dams. The International Union for Conservation of Nature has assessed its conservation status as being "vulnerable".

The Conasauga logperch is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is endemic to the United States. It is one of 184 species of darters in North America. It has been listed as endangered throughout its range with critical habitat under the U.S. Endangered Species Act since August 5, 1985.

<i>Dromus dromas</i> Species of bivalve

Dromus dromas, the dromedary pearlymussel or dromedary naiad, is a rare species of freshwater mussel in the family Unionidae. This aquatic bivalve mollusk is native to the Cumberland and Tennessee River systems in the United States, where it has experienced a large population decline. It is a federally listed endangered species of the United States.

<span class="mw-page-title-main">Dusky darter</span> Species of fish

The dusky darter is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is found in, but not confined to, both large and small rivers, and shallow creeks, in the eastern, southern, and southeastern United States, particularly the Mississippi River drainage system.

The Citico darter is a threatened species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is native to Tennessee. This species was formerly subsumed within Etheostoma percnurum. The E. percnurum group now consists of four distinct species: E. percnurum, E. marmorpinnum, E. lemniscatum, and E. sitikuense.

<span class="mw-page-title-main">Gilt darter</span> Species of fish

The gilt darter is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It can be found in a number of states in the Mississippi River drainage of the United States although it has been extirpated from some river systems in which it was at one time present, mostly due to siltation and pollution problems. Males are more colorful than females and can grow to a length of about 9 cm (3.5 in). It is a benthic fish that feeds primarily on small aquatic insect larvae. Males form territories during the breeding season in late spring and early summer. Spawning typically takes place at the upper ends of riffles with sandy and gravelly bottoms interspersed with larger cobbles. Some organisations are endeavouring to conserve populations of the gilt darter and re-introduce it to states where the fish has been extirpated but suitable habitat still exists.

<span class="mw-page-title-main">Mobile logperch</span> Species of fish

The Mobile logperch is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is found in the Mobile River basin in Mississippi, Alabama, Tennessee, and Georgia in the southeastern United States. It inhabits clear shallow water and is often associated with Podostemum (riverweed). It grows to about 18 cm (7 in) and is distinguishable from other darters by the distinctive shape of its head and by its pale-yellow base color, with narrow bars on back and sides. It feeds on small invertebrates and breeds between February and May. Lake fish move into small streams to spawn. It is a common fish with a wide range and the International Union for Conservation of Nature has classified its conservation status as being of "least concern".

The olive darter is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is native to Tennessee, Kentucky, North Carolina, and Georgia, in the United States. It is found in the headwaters of Tennessee River system and the middle reaches of the Cumberland River system, its ideal habitat being clear, cold water over rocky substrates. It grows to a length of about 5 in (13 cm) and is an insectivore, feeding mainly on insect larvae on the riverbed. The fish matures at age two and lives till about age four. Up to 1500 eggs are spawned which fall to the riverbed and get lodged among gravel. The olive darter is classified as a "vulnerable species", being affected by habitat destruction and siltation, often resulting from damming and impoundment of the rivers or the creation of weirs. It is also affected by the change in the forest riparian habitat resulting from the killing of trees by the hemlock woolly adelgid.

The saddleback darter is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is native to the eastern United States. This darter species is widespread, occurring from the Escambia River drainage west to the Mississippi River basin and as far north as the Wabash River historically. Some populations have been reported in the Tennessee River drainage. The saddleback darter is aptly named as it has 5 saddle-like patterns on its dorsum, with the first occurring near the first dorsal fin and the fifth near the caudal penduncle. Adults can attain a maximum size of about 3 inches or 7.8 centimeters. The saddleback darter typically occurs over sand and gravel runs of creeks and small to medium-sized rivers and is sometimes found in very shallow water. This darter's diet consists of invertebrates such as caddisfly larvae, beetles, mayflies, and stoneflies. The saddleback darter deposits eggs over sand and gravel shoals during the spring. This species has an average lifespan between 2 and 3 years.

The sickle darter is a recently identified freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is closely related to a well-known darter, Percina macrocephala. Discovered in 2007 in the upper Tennessee River drainage, the sickle darter is around 90.5 mm (3.56 in) in length and is a slender bodied, freshwater and benthopelagic fish that most likely feeds on small crayfish and mayflies, since it shares a large mouth and long snout with its sister species. The known distribution of the sickle darter is the upper drainage of the Tennessee River of Tennessee, North Carolina and Virginia. It is distinguished from all other Percina darters except its sister species P. macrocephala by a dark suborbital bar and a black bar subtending a medial black spot on the base of the caudal fin. It stays in mostly rocky, sandy, or silty substrates in clear creeks or small rivers in the Appalachian Mountains. The sickle darter spawns in late winter in gravel shoals. It also has large scales which make it different from macrocephala. It is known to be extirpated from most of its home habitat mainly because of agricultural practices that cause siltation and turbidity which causes most populations of the sickle darter to be widely scattered. But where it is found, it can be observed with regularity. Taking all this into consideration, the sickle darter does not have a formal conservation status under any federal or state law although its closely related species is considered a species of concern by the TWRA. Future management plans should include finding more locations of the sickle darter and decreasing further habitat destruction in known distributions by stating it as a fish of concern by state law.

<span class="mw-page-title-main">Halloween darter</span> Species of fish

The Halloween darter is a small freshwater fish native to North America. It is found in Georgia and Alabama in the drainage basin of the Apalachicola River, specifically in the Flint River system and the Chattahoochee River system. It prefers shallow, fast-flowing areas with gravel bottoms in small and medium-sized rivers. It was first described in 2008, having not previously been distinguished from the Blackbanded darter (P. nigrofasciata), formerly thought to occur in the same watershed. Blackbanded darter has since been split again with Westfall's darter now recognised from the Apalachicola drainage. The species is somewhat variable, being generally blackish dorsally, with some individuals having indistinct saddle-like barring. Males have orange and dark lateral striping while females have dark stripes and a yellowish-green belly. At a maximum standard length of 101 mm (4 in), males are slightly larger than females, and both sexes develop distinctive orange barring on the edge of the first dorsal fin during the breeding season.

References

  1. ↑ NatureServe (2013). "Percina tanasi". IUCN Red List of Threatened Species . 2013: e.T16595A19033649. doi: 10.2305/IUCN.UK.2013-1.RLTS.T16595A19033649.en . Retrieved 20 November 2021.
  2. 1 2 "Snail darter (Percina tanasi)". Environmental Conservation Online System. U.S. Fish & Wildlife Service. Retrieved 2 June 2023.
  3. ↑ 40 FR 47505
  4. ↑ 49 FR 27510
  5. 1 2 3 4 5 6 U.S Fish and Wildlife Service Species Assessment Team; Tennessee Ecological Services Field Office (5 October 2022). "Endangered and Threatened Wildlife and Plants; Removing the Snail Darter From the List of Endangered and Threatened Wildlife". Federal Register. 87 (192): 60298–60313. 87 FR 60298
  6. 1 2 3 4 Etnier, DA & Starnes, WC. 1993. The fishes of Tennessee. Knoxville, TN: University of Tennessee Press.
  7. 1 2 Ashton, MJ & Layzer, JB. 2008. Distribution of the Threatened Snail Darter (Percina Tanasi) in the Upper Tennessee River Drainage. Journal of The Tennessee Academy of Science 83:52-56.
  8. 1 2 Page, LM. 1983. Handbook of Darters. Neptune City, NJ: TFH Publications.
  9. 1 2 3 Starnes, WC. 1977. The ecology and life history of endangered snail darter, Percina (Imostoma) tanasi (Etnier). Knoxville, Tennessee: PhD dissertation, University of Tennessee. 144 pp.
  10. ↑ Kuehne, RA & Barbour, RW.1983. The American Darters. Lexington, KY: University Press of Kentucky.
  11. ↑ Ashton, MJ & Layzer, JB. 2010. Summer microhabitat use by adult and young-of-year snail darters (Percina tanasi) in two rivers. Ecology of Freshwater Fish 19:609-617.
  12. ↑ Haag, WR & Warren ML. 2006. Seasonal Feeding Specialization on Snails by River Darters (Percina Shumardi) with a Review of Snail Feeding by Other Darter Species. The American Society of Ichthyologists and Herpetologists 4:604-614.
  13. ↑ "Snail Darter". Environmental Conservation Online System. U.S. Fish & Wildlife Service. Archived from the original on 17 October 2011.
  14. ↑ Biggins, RG, Eager, RB & Hurst, H. 1983. Snail darter recovery plan. US Fish and Wildlife Service, Asheville, North Carolina.
  15. ↑ Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Percina ta as I ". Catalog of Fishes . California Academy of Sciences . Retrieved 5 November 2020.
  16. ↑ Etnier, D. A. (1976). "Percina (Imostoma) tanasi, a new percid fish from the Little Tennessee River, Tennessee". Proceedings of the Biological Society of Washington. 88 (44): 469–488.
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