Iowa Darter

Etheostoma exile (Girard, 1859)

Etheostoma exile (Iowa Darter)
NY Watershed Biosurvey (image provided by NYS DEC)

Class
Actinopterygii (Ray-finned Fishes)
Family
Percidae (perches and darters)
State Protection
Not Listed
Not listed or protected by New York State.
Federal Protection
Not Listed
State Conservation Status Rank
S2
Imperiled in New York - Very vulnerable to disappearing from New York due to rarity or other factors; typically 6 to 20 populations or locations in New York, very few individuals, very restricted range, few remaining acres (or miles of stream), and/or steep declines.
Global Conservation Status Rank
G5
Secure globally - Common in the world; widespread and abundant (but may be rare in some parts of its range).

Summary

Did you know?

Iowa Darter occur farther west and north than any other darter in the United States (Page and Burr 1991).

State Ranking Justification

Historically occurring in about 36 waters, Iowa Darters are currently found in about 17 waters scattered throughout eight of the nine known watersheds. It has not been detected in the Allegheny watershed since 1948 (NYS DEC 2023). Historical populations in Oneida Lake and nearby streams and creeks in Oswego County, and Black Lake in St Lawrence County have not been recorded since the 1930s (Carlson 2005, Cohen 2006; New York Natural Heritage Program 2008). Carlson et al. (2016) noted decreased captures in Erie-Niagara and Ontario watersheds. Fish are captured infrequently or are known from few site in about half of the known watersheds (Carlson et al. 2016).

Short-term Trends

Little is known about the current status of Iowa Darters in New York (Carlson et al. 2016). Recent surveys (1993-2021) yielded very few fish, typically less than 10 per site, with few sites with higher counts (NYS DEC 2023). Thorough sampling and resurveys of historical sites are needed (Carlson 2005; Cohen 2006).

Long-term Trends

Once present in over 36 waters, the Iowa Darter has not been detected from the Allegheny watershed since 1948 (Carlson et al. 2016, Carlson 2005, Cohen 2006). In addition, historical populations in Oneida Lake and nearby streams and creeks in Oswego County, and Black Lake in St Lawrence County have not been recorded since the 1930s (Carlson 2005; Cohen 2006; New York Natural Heritage Program 2008). Carlson et al. (2016) noted decreased captures in Erie-Niagara and Ontario watersheds.

Conservation and Management

Threats

Any activity which might lead to water contamination, siltation, warming of waterways, or the alteration of natural hydrology could directly and indirectly impact aquatic habitats and Iowa Darter populations. Such threats might include roadway and agricultural runoff, industrial pollution, dams, bridge construction and maintenance, logging activities, and development near aquatic habitats (NYS DEC 2005). In addition, siltation decreases the amount of sunlight that reaches aquatic plants (EPA 2005) and lowers the quality of habitats needed for a variety of aquatic species (NYS DEC 2005). Point source pollution, such as effluents from municipal and industrial facilities, contribute to the degradation and pollution of aquatic habitats (EPA 2022, NYS DEC 2005, Mahar and Landry 2013, Strayer et al. 2004).
Altering natural waterflow can degrade habitat and restrict species movement. Dams directly restrict or impede species movement, alter the flow of water, change the water temperature, and contribute to sedimentation (NYS DEC 2005, Zaidel et al. 2021).
While modern day agricultural and silvicultural practices are an important aspect of the New York State economy, it is important to consider the effects on ecosystems and species. As these practices move closer to rivers and other waterbodies, the natural buffers are often removed. Riparian buffers maintain stream temperature and slow or prevent runoff of sediments from upland soil disturbances. Furthermore, they slow or reduce runoff from farm fields and pastures, such as contaminants from pesticides, fertilizers, manure, and sludge, into waterways (EPA 2005, NYS DEC 2005, Souza et al. 2020). Excessive fertilizer use can lead to algal blooms that can be deadly to aquatic life and overgrazing of livestock in fields could introduce pathogens, oxygen-demanding organics and solids, and invasive species to aquatic ecosystems (EPA 2005).
Approximately 10% of introduced, non-native species could have an impact on the health of ecosystems (McCormick et al. 2009). Invasive plants tend to outcompete native plants and can change natural processes (NYS DEC 2005). There is an increased risk of runoff and erosion when these plants are along streams and rivers. Aquatic invasive plants and animals can alter the water chemistry, change the nutrient regime, or decrease the dissolved oxygen levels. Introduced fish can alter trophic relationships resulting in a change in native fish populations and decreased water quality (McCormick et al. 2009).
Climate change is another threat that is likely to have lasting effects on aquatic systems. Irregular weather patterns can cause extreme drought, flooding, and temperature fluctuations. Heat waves are expected to be more intense (Frankson et al. 2022). The Northeast Region of the United States is expected to experience an increase in precipitation, more frequent storms, and higher than normal temperatures (EPA 2016, EPA 2022). Precipitation is expected to increase 10% to 15% in southern New York and 15 to 20% in northern New York by 2050 (Frankson et al. 2022). Extreme flooding can cause widespread erosion and runoff with added risk of contamination if flooding occurs at remediation sites, industrial sites, or wastewater treatment facilities (EPA 2016, EPA 2022). Temperature increases can significantly alter ecosystems. As water temperatures rise, the amount of dissolved oxygen decreases and evaporation increases, potentially lowering lake and stream levels (EPA 2022). Any combination of these events could change species distributions (EPA 2022) and those that cannot adapt or migrate may be extirpated from some areas (NYS DEC 2005).

Conservation Strategies and Management Practices

Protect water quality and reduce contamination and hydrological alteration (such as agricultural or road runoff, shoreline development, and damming) (NYS DEC 2005). Protect stream quality by maintaining both a shoreline buffer that includes herbaceous and/or woody vegetation along the shoreline, and a significant forested buffer. These buffers reduce sediment and contaminant runoff (EPA 2005, NYS DEC 2005, Souza et al. 2020), provide shade, regulate temperature, and provide organic matter to animals (Hughes and Vadas 2021). Riparian zones with herbaceous and woody vegetation have high “indicator scores” for macroinvertebrates and fishes (Hughes and Vadas 2021).
Remove barriers to maintain or restore natural flow to waterways. Where removal is not possible, research alternatives that allow flow above and below a barrier.
In general, avoid stream crossings. If crossings are unavoidable, use Best Management Practices (BMP) to minimize disturbance to streams. Time periods of disturbance when water flow is low or normal and install stream-crossing structures at a right angle to the stream (Watershed Agricultural Council Forestry Program 2018). Temporary methods to reduce runoff include water bars, gravel, geotextile fabric, rubber belt deflectors, open top culverts, strawbales, silt fencing, control blankets, and straw wattles (Watershed Agricultural Council Forestry Program 2018). Restore the disturbed area with native species as soon as possible. Areas that have been logged may also need ruts to be smoothed to reduce surface runoff (Watershed Agricultural Council Forestry Program 2018). Hughes and Vadas (2021) suggest that Best Management Practices may need to be applied to entire stream lengths and catchments to fully restore an aquatic ecosystem. If this is not possible, restore or manage a larger area around the directly disturbed area.
In general, tailor agricultural management plans to local conditions (e.g., soils, slope, land use). Often these plans aim to reduce pollution and increase farm productivity, but incentives could also be used to encourage sustainable farming practices. Proper management typically reduces runoff by 20-90% (EPA 2005). Consider using Integrated Pest Management (IPM) as an alternative to pesticide use. If pesticides and fertilizers are used, they should only be applied when needed, in the proper amount, and timed appropriately. In addition, rotate livestock to avoid overgrazing and to allow for vegetation regrowth. If needed, provide alternative water sources and shade to keep animals out of sensitive areas (EPA 2005).
Invasive species management can be time consuming and costly. Reduce the likelihood of non-native species being introduced into waterways. Boat-washing stations at boat launches can reduce transport of invasive plants and animals to new waterbodies. Educate anglers about the risk of releasing unused baitfish. If vulnerable species are present, consider a baitfish ban. Mechanical removal of some invasive plants may be needed in some rivers and streams. The use of pesticides to remove invasives can have a negative effect on ecosystems (McCormick et al. 2009) and should be a last resort to control invasive species.
Climate change is a global challenge. However, there are local actions that can help mitigate extreme weather events. Industrial and municipal infrastructure should be improved or replaced to be more resilient to flooding events (EPA 2016, NYS Comptroller 2023). Some suggested actions include installing or improving pumps to remove floodwater from facilities and installing protective structures, such as floodwalls. Ensure that existing bridges, dams, levees, seawalls, retaining walls, and wind barriers are prepared for extreme weather (NYS Comptroller 2023). Decrease runoff and erosion severity by installing large culverts, planting vegetation along riverbanks, and protecting and restoring wetlands (EPA 2016, NYS Comptroller 2023).

Research Needs

Little is known about the ecological requirements of Iowa Darter (Carlson 2005; Cohen 2006). More information is needed regarding life history, behavior, habitat, and ecological requirements. Further define habitat requirements for restoration and habitat protection (Carlson 2005; Cohen 2006). More sampling is needed to determine the current status of Iowa Darters in New York (Carlson 2005; Cohen 2006).

Habitat

Habitat

Iowa Darter inhabit slow, clear waters of lakes, ponds, and streams with ample submerged vegetation and substrates consisting of sand, peat, or organic material (Lee et al. 1980; Smith 1985). They are usually found among rocks or under shelter along the bottom. Spawning areas consist of shallower waters with ample vegetation, roots, and plant debris for egg laying (Copes 1976).

Associated Ecological Communities

  • Deepwater river
    The aquatic community of very large, very deep, quiet, base level sections of streams with a very low gradient. In places the water is deep enough so that light cannot reach the river bottom.
  • Great Lakes aquatic bed (guide)
    The aquatic community of the protected shoals of the Great Lakes or Lake Champlain. They occur in quiet bays that are protected from extreme wave action by islands, shoals, or barrier bars, and typically support large areas of "weeds" or aquatic macrophytes.
  • Marsh headwater stream (guide)
    The aquatic community of a small, marshy perennial brook with a very low gradient, slow flow rate, and cool to warm water that flows through a marsh, fen, or swamp where a stream system originates. These streams usually have clearly distinguished meanders (i.e., high sinuosity) and are in unconfined landscapes.
  • Unconfined river (guide)
    The aquatic community of large, quiet, base level sections of streams with a very low gradient.

Associated Species

  • Blackchin Shiner (Notropis heterodon) (guide)

Range

New York State Distribution

In New York, Iowa Darter can be found in lakes, rivers, and low gradient streams (Carlson et al. 2016) in Clinton, Erie, Franklin, Jefferson, Monroe, Orleans, Oswego, Seneca, and St Lawrence counties (Smith 1985, New York Natural Heritage Program 2023). They are confirmed from the following watersheds: Allegheny, Champlain, Erie-Niagara, Genesee, Ontario, Oswegatchie, Oswego, Raquette, and St Lawrence . However, Iowa Darter has not been found in the Allegheny watershed for decades (Carlson et al. 2016). In 2021, the species was found at one location in the Mohawk Watershed (NYS DEC 2023).

Global Distribution

The range of the Iowa Darter extends from the St. Lawrence watershed in New York west along the Great Lakes basin in northwest Pennsylvania, northern Ohio, Indiana, and Illinois, Michigan, Wisconsin, Minnesota, Iowa, Nebraska, North and South Dakota, southwestern Wyoming, and northeastern Montana. In Canada, Iowa Darters can be found from southern Quebec west to northern Alberta (Page and Burr 1991).

Best Places to See

  • East Branch Twelve Mile Creek (Niagara County)
  • Squeak Brook (St. Lawrence County)
  • St. Lawrence River (St. Lawrence County)
  • Niagara River (Niagara County)
  • Lakeview Pond (Jefferson County)

Identification Comments

Identifying Characteristics

The Iowa Darter is a slender fish, with a body that tapers anteriorly and posteriorly. It is mainly olive-brown in color, becoming yellow or white moving ventrally down the body. The lateral line is pale. There is a series of 9 to 12 vertical bars on the side of the body and there are the same number of dark, "vaguely saddle-shaped" blotches in the middorsal area. The snout is blunt with a longitudinal stripe on the side. The mouth is low and horizontal. There is a teardrop shaped spot below the eye. The dorsal fin is spiny and arched with blue spots near the base and dark spots throughout. The caudal fin is square with dark spots. The pectoral fins have some flecking and the pelvic and anal fins are translucent with little to no flecking. During breeding season, the males change color. The vertical bars on the body turn bluish-green and the spaces between the bars becomes red in color, gradually turning orange at the belly. The spiny dorsal fin acquires a pattern of alternating blue and red horizontal stripes. Juveniles resemble adult females (Smith 1985; Page and Burr 1991).

Characters Most Useful for Identification

The bright blue and red color pattern on males during breeding season is useful in distinguishing Iowa Darter from other darters (Page and Burr 1991).

Best Life Stage for Proper Identification

Adults, especially breeding males exhibit the characters useful for identification.

Behavior

Iowa Darter do not typically school except during the breeding season. They become mature at one year old. Males establish territories. Females can mate with several males and deposit eggs on roots, sand, or gravel (Copes 1976).

Diet

Young Iowa Darters feed mainly on tiny crustaceans. Adults feed on amphipods, midge larvae, and other insect larvae and aquatic organisms (Copes 1976; Smith 1985).

Best Time to See

This species is present year-round, with spawning occurring in the spring and lasting through summer (Smith 1985).

  • Active
  • Reproducing

The time of year you would expect to find Iowa Darter active and reproducing in New York.

Similar Species

  • Swamp Darter (Etheostoma fusiforme) (guide)
    During the breeding season, male Swamp Darter do not become brightly colored, but they develop breeding tubercles on the anal rays and the undersides of the pectoral fins. Breeding male Iowa Darters are brightly colored and do not develop tubercles. In New York, Iowa Darters are found mainly in the Lake Ontario and St Lawrence watersheds, whereas Swamp Darters are confined to eastern Long Island.

Iowa Darter Images

Taxonomy

Iowa Darter
Etheostoma exile (Girard, 1859)

  • Kingdom Animalia
    • Phylum Craniata
      • Class Actinopterygii (Ray-finned Fishes)
        • Order Perciformes (Perch-like Fishes)
          • Family Percidae (perches and darters)

Additional Resources

References

Carlson, Douglas M. 2005. Species Accounts for the rare fishes of New York. New York State Department of Environmental Conservation, Division of Fish, Wildlife and Marine Resources. Bureau of Fisheries, Endangered Fish Project. 75pp.

Carlson, Douglas M., Robert A. Daniels, and Jeremy J. Wright. 2016. Atlas of Inland Fishes of New York. New York State Museum Record 7. The New York State Education Department and Department of Environmental Conservation. Albany, New York.

Cohen, M. K. 2006. Species group report for Iowa darter. Pages 46-49 of Appendix A3, Species group reports for freshwater fish in: New York State comprehensive wildlife conservation strategy. New York State Department of Environmental Conservation. Albany, NY.

Copes, F. A. 1976. The Iowa darter, Etheostoma exile. American Currents. November/December issue. Available: http://www.nanfa.org/articles/aciowadarter.shtml (accessed 29 October 2008).

Environmental Protection Agency (EPA). 2005. Protecting water quality from agricultural runoff. https://www.epa.gov/sites/default/files/2015-09/documents/ag_runoff_fact_sheet.pdf.

Environmental Protection Agency (EPA). 2016. Adapting to climate change northeast. https://www.epa.gov/sites/default/files/2016-07/documents/northeast_fact_sheet.pdf.

Environmental Protection Agency (EPA). 2022. Region 2 climate adaptation implementation plan. https://www.epa.gov/system/files/documents/2022-10/bh508-R02%20Climate%20Adaptation%20Implementation%20Plan%209.19.2022%20HQ%20OP%20Copy.pdf

Frankson, R., Kunkel, K.E., Champion, S.M., Stewart, B.C., Sweet, W, DeGaetano, A.T., & Spaccio, J. (2022). New York State Climate Summary 2022. National Oceanic and Atmospheric Administration National Centers for Environmental Information. https://statesummaries.ncics.org/chapter/ny/

Hughes, Robert M., and Robert L. Vadas Jr. 2021. Agricultural Effects on Streams and Rivers: A Western USA Focus. Water 13, no. 14: 1901. https://doi.org/10.3390/w13141901

Lee, D. S., C. R. Gilbert, C. H. Hocutt, R. E. Jenkins, D. E. McAllister, and J. R. Stauffer, Jr. 1980. Atlas of North American freshwater fishes. North Carolina State Museum of Natural History, Raleigh, North Carolina. i-x + 854 pp.

Mahar, Amy and Jenny Landry. 2013. New York State Department of Environmental Conservation species status assessment for Lasmigona subviridis (Green Floater).

McCormick, Frank H., Glen C. Contreras, and Sherri L. Johnson. 2009. "Effects of nonindigenous invasive species on water quality and quantity." A dynamic invasive species research vision: opportunities and priorities 29 (2009): 111-120.

New York Natural Heritage Program. 2008. Biotics Database. Albany, NY.

New York Natural Heritage Program. 2024. New York Natural Heritage Program Databases. Albany, NY.

New York State Comptroller. 2023. New York's local governments adapting to climate change: challenges, solutions, and costs. https://www.osc.state.ny.us/files/local-government/publications/pdf/climate-change-2023.pdf

New York State Department of Environmental Conservation. 2005. A strategy for conserving New York's fish and wildlife resources. Final submission draft.

New York State Department of Environmental Conservation. 2023. NYS DEC Rare fishes shapefile 1850 to 2022 (updated August 9. 2023).

Page, L. M., and B. M. Burr. 1991. A field guide to freshwater fishes: North America north of Mexico. Houghton Mifflin Company, Boston, Massachusetts. 432 pp.

Smith, C.L. 1985. The Inland Fishes of New York State. New York State Department of Environmental Conservation. Albany, NY. 522pp.

Souza, Francine N., Rodolfo Mariano, Tassio Moreia, and Sofia Campiolo. 2020. Influence of the landscape in different scales on the EPT community (Ephemeroptera, Plecoptera and Trichoptera) in the Atlantic Forest region. Environmental monitoring and assessment 129: 391-391.

Strayer, David L., J.A. Dowling, W.R. Haag, T.L. King, J.B. Layzer, T.J. Newton and S.J. Nichols. 2004. Changing perspectives on Pearly Mussels, North America's most Imperiled Animals. BioScience 54:429-439.

Watershed Agricultural Council Forestry Program. 2018. New York State forestry voluntary best management practices for water quality. http://nysbmpguidelines.com/. Accessed on June 20, 2023.

Zaidel, Peter A., A. H. Roy, K. M. Houle, B. Lambert, B. H. Letcher, K. H. Nislow, C. Smith. 2021. Impacts of small dams on stream temperature. Ecological indicators 120:6-11.

Links

About This Guide

This guide was authored by: Shaw, Hollie Y.

Information for this guide was last updated on: September 27, 2023

Please cite this page as:
New York Natural Heritage Program. 2024. Online Conservation Guide for Etheostoma exile. Available from: https://guides.nynhp.org/iowa-darter/. Accessed May 26, 2024.