Orconectes sloanii 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Arthropoda Malacostraca Decapoda Cambaridae

Scientific Name: Orconectes sloanii (Bundy, 1876)
Common Name(s):
English Sloan's Crayfish

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2010
Date Assessed: 2010-06-01
Assessor(s): Schuster, G.A. & Taylor, C.A.
Reviewer(s): Collen, B. & Richman, N.
Contributor(s): Livingston, F., Livingston, F., Soulsby, A.-M., Batchelor, A., Dyer, E., Whitton, F., Milligan, H.T., Smith, J., Lutz, M.L., De Silva, R., McGuinness, S., Kasthala, G., Jopling, B., Sullivan, K. & Cryer, G.
Orconectes sloanii has been assessed as Least Concern. The extent of occurrence falls just above the threshold for Vulnerable. The presence of the aggressive invasive species Orconectes rusticus within this species range has been recorded as a threat, and certainly causes it to retract its range to smaller creeks in the presence of this invasive species.  However, a recent re-visitation of the 1991 sites surveyed by St. John (1991) revealed no further decline. Further research is recommended on similar sites to elicit the impact of O. rusticus across other areas of its range.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is found in southwestern Ohio and southern Indiana, USA (St. John 1988, St. John 1991, Thoma and Jezerinac 2000). In 1962 this species was found in 32 counties in Ohio and Indiana (Rhoades 1962). However, by 1988 a survey showed that this species had been extirpated from three of these 32 counties (St. John 1988). In the same survey, however, this species was found in five new counties in Indiana (St. John 1988). In a study in 1991 on the distribution of this species in Ohio, St. John (1991) found that the ratio of this species to O. rusticus had decreased in nine out of 15 sites and was now absent in one of the counties where it had previously been found. The present extent of occurrence (EOO) of this species has been estimated at just under 16,400 km², although a reduction in EOO of 4,349 km² from 1962 to 1991 has been recorded. This reduction in range is due to the range expansion of the invasive crayfish Orconectes rusticus (St. John 1988, St. John 1991, Thoma and Jezerinac 2000).
Countries occurrence:
United States (Indiana, Ohio)
Additional data:
Continuing decline in extent of occurrence (EOO):Yes
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species  is slowly being replaced by Orconectes rusticus as the more dominant crayfish species in certain parts of its range (St. John 1991, St. John 1988). In addition, a population reduction has been seen in certain areas of Ohio. Where O. rusticus is not present, this species is common to abundant in suitable habitat (S. Adams, G. Schuster and C. Taylor, pers. comm. 2009).
Current Population Trend:Unknown
Additional data:
Continuing decline of mature individuals:Yes
Extreme fluctuations:UnknownPopulation severely fragmented:Unknown

Habitat and Ecology [top]

Habitat and Ecology:This species inhabits the clear tributaries of streams and prefers clean, rocky-bottomed streams, preferring small to medium sized streams (Thoma and Jezerinac 2000). In the presence of O. rusticus it is found in small wooded riparian streams, and in the absence of O. rusticus it expands its range into fourth order streams up to 20 m across (R. Thoma pers. comm. 2009).
Continuing decline in area, extent and/or quality of habitat:Yes

Threats [top]

Major Threat(s): The range expansion of the invasive crayfish Orconectes rusticus is encroaching on the historic range of this species in certain areas, with O. rusticus slowly replacing this species as the more dominant species (St. John 1988; St. John 1991; Thoma and Jezerinac 2000). Increasing levels of pollution have been found to compound this threat as O. rusticus is the more resilient of the two species (Thoma and Jezerinac 2000).
St. John's (1991) sites were recently revisited and it was found that almost every one of the historic sites to be extant, with equivalent numbers (R. Thoma pers. comm. 2009).This species has been known, however, to coexist with O. rusticus in some parts of its range, especially outside of Ohio, effectively taking up a different niche form when it is in the presence of it (R. Thoma pers. comm. 2009).

Conservation Actions [top]

Conservation Actions: This species has been assigned a Global Heritage Status Rank of G3 by NatureServe (Taylor et al. 2007, NatureServe 2009) and assessed as 'vulnerable' by the American Fisheries Society (Taylor et al. 2007).

Citation: Schuster, G.A. & Taylor, C.A. 2010. Orconectes sloanii. The IUCN Red List of Threatened Species 2010: e.T15429A4583749. . Downloaded on 20 September 2018.
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