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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Shield Darter

Taxonomy: available through www.itis.gov

Identification: Generally similar to other species of Percina on the Atlantic slope (e.g., P. gymnocephala, P. nevisense, P. notogramma); Shield Darters can be separated from other similar species of Percina by the combination of black crescents on the first dorsal fin, a black bar on the chin, generally unscaled cheeks, and 6-7 horizontally rectangular or square black blotches along the side (sometimes connected by a narrow black stripe; summarized from Page and Burr 2011).

Size: to 9 cm SL

Native Range: Atlantic slope drainages: Susquehanna River south to James River (Page and Burr 2011).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Native range data for this species provided in part by NatureServe

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Means of Introduction: Shield Darters are thought to have entered Roundout Creek via the Delaware and Hudson Canal (Beebe and Savidge 1988; Mills et al. 1997).

Status: Established in Roundout Creek and Hudson River watersheds, New York (Beebe and Savidge 1988; Mills et al. 1997).

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

References: (click for full references)

Beebe, C.A., and I.R. Savidge. 1988. Historical perspective on fish species composition and distribution in the Hudson River estuary. American Fisheries Society Monograph 4:25-36.

Mills, E.L., D.L. Strayer, M.D. Scheuerell, and J.T. Carlton. 1996. Exotic species in the Hudson River basin: A history of invasions and introductions. Estuaries 19(4):814-823.

Mills, E.L., M.D. Scheuerell, J.T. Carlton, and D.L. Strayer. 1997. Biological invasions in the Hudson River basin. New York State Museum Circular 57:1-51.

Page, L.M., and B.M. Burr. 2011. Field guide to freshwater fishes of North America north of Mexico. Peterson Field Guides series. Houghton Mifflin Harcourt, Boston, MA.

Other Resources:
Fishes of New York - Cornell University/New York Department of Natural Resources

Author: Neilson, M.E.

Peer Review Date: 10/17/2012

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.