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Species of Concern

Status Assessment for the Indiana Crayfish
(Orconectes indianensis)

Taxonomy and Physical Description:

The Indiana crayfish, Orconectes indianensis was first described by Hay (1896). The species belongs to the Order Decapoda, Family Cambaridae, Genus Orconectes (Page 1985). Erichson introduced the name Cambarus in 1846, but Girard (1852) was the first to use it as a generic designation. Subsequently, all of the crayfishes belonging to the subfamily Cambarinae were assigned to the genus Cambarus. In 1942, Hobbs proposed a new classification of generic designation that subdivided the subfamily Cambarinae (Brown 1955, Pennak 1989). Now seven genera are recognized: Procambarus, Paracambarus, Cambarellus, Orconectes, Fallicambarus, Cambarus, and Troglocambarus (Pennak 1978). Hobb's classification system appears to be recognized by most researchers.

Reitz (1912) provided a detail physical description of the species. The body is stout and thickly covered with hairs. The rostrum is long and broad and lacking a medium keel. The acumen is one third to one half the length of rostrum and is long and triangular. The carapace is slightly depressed with a deep cervical grove and well-developed lateral spines. The surface of the carapace is finely punctate. The hepatic region is more or less spiny and granular. The areola is wide, width to length ratio of one to five or six. Post orbital ridges are grooved and end anteriorly in spines. The abdomen is equal in length or a little longer than the cephalothorax. The abdomen is narrower in the male than in the female. The chelipeds are proportionately longer and stouter in the male than in the female. The hand varies among individuals. The male sexual organs are slender and short extending to the third pereiopods. The tips cross and diverge slightly. The male sexual organs of the second form are articulate at the base with tips blunt and soft. The annulus ventralis of the female is small and rather flat.

Summary of the Life History:

Little is known about the ecology of the species. Pennak (1978) reported that decapods in general are active at dusk and dawn. Estivation occurs during the day except on cloudy days or in streams heavily shaded where crayfish may be active throughout the day. The maximum age for most crayfish species is three years (Boyd and Page 1978). In the study conducted by Page (1994), Indiana crayfish sampled in Indiana and Illinois were all age 1 or 2, confirming that 3 years is probably the maximum age. Page (1994) reported that the life history of O. indianensis is probably similar to the life history of O. kentuckiensis. Pennak (1978) stated that although crayfish species are omnivorous, they are seldom predaceous. Boyd and Page (1978), however, reported that O. kentuckiensis' diet consisted of 50 percent plant fragments and 51 percent arthropods. Contrary to Pennak, they believed that the partitioning of their diet was probably highly dependent on the availability of arthropods. Species identified in the stomach of O. kentuckiensis included amphipods, isopods, crayfishes, and immature caddisflies and midges. Boyd and Page's research (1978) documented fish as the primary predator of O. kentuckiensis. They also reported a 1:1 sex ratio and average fecundity of 109 ovarian eggs and 110 abdominal eggs produced by the female. Information gathered from the O. kentuckiensis study suggest that the number of eggs produced increases significantly with increasing carapace length. The number of eggs carried by female O. indianensis from 1972 to 1982 ranged from 120 to 178 with a mean egg diameter of 1.8 mm (Page 1985). Page (1994) found that the sex ratios varied markedly among samples. However, small sampling size could explain the variation documented.


The largest recorded O. indianensis sampled in Illinois or Indiana were a 35.0 mm carapace length female and a 33.4 mm carapace length form I male. The smallest form I male recorded was 17.7 mm carapace length (Page 1985). One-year old males averaged 15.2 mm (n=25) in carapace length and one-year old females average 13.4 mm in carapace length (n=22) (Page 1985). Boyd and Page (1978) reported that immature first year males underwent spring molt at approximately the same time as did the mature males. Prins (1968) documented this behavior with O. rusticus also (Boyd and Page 1978). Females of O. kentuckiensis, Procambus hayi, and O. propinquus did not demonstrate evidence of summer molt, i.e., growth occurred only during the spring (rearing) period (Payne 1922, Van Deventer 1937 cited in Boyd and Page 1978, Boyd and Page 1978).


There are two distinct types of male adults: form I and form II. Male forms are the result of a normal molt (i.e., shedding of exoskeleton). The males are characterized into these two groups based on the shaped of their pleopods. Form I males have corneous, hard, and distinctively sculptured pleopods; whereas the form II males' pleopods lack sculpture and are relatively soft (Pennak 1978). Only form I males are capable of copulation (Crocker et al. 1968, Pennak 1978, Page 1985). Form II males are found during periods between sexual activity seasons, and closely resemble the juvenile form (Crocker and Barr 1968). Form I males have been collected from March to November (Brown 1955; Page 1985, 1994). Form II males have been sampled in August and November (Brown 1955). Females carrying eggs (known as ovigerous) have been collected in March and April (Page 1985).


Very few researchers have studied the distributions of crayfishes in order to determine if crayfishes exhibit the phenomenon of home range (Bridgman unpubl. data, Henry 1951, Camaougis and Hichar 1959, Black 1963). Camaougis and Hichar (1959), studying O. virilis could not demonstrate evidence of territorialism. Henry (1951) documented migratory movement for Pacifastacus klamathensis. Downstream migration was observed in late spring and early summer, and upstream migration in the winter. Bridgman conducted a mark-release-recapture study of crayfishes in Louisiana, however, late sampling of strays invalidated the results. Black (1963) was the first to provide empirical evidence of the phenomenon of home range. He conducted a study to ascertain the home ranges of two stream-dwelling crayfishes, Procambarus penni and P. bivittatus. Of the 273 individuals marked, 48 recaptures were recorded. Only five (14%) of the recaptures had strayed from their marking area. Black concluded that crayfishes did exhibit the phenomenon of home range and that the home range was considerably less than 100 feet. No information is currently available on recruitment, growth, food habits, or mortality of O. indianensis.


Life cycle (see figure 1): In the spring (March through May) the sperm plug within the female breaks and her eggs are released. The eggs become fertilized and securely attached to the mother's pleopods (Pennak 1978). During this time, the female is said to be "in-berry" (Crocker et al. 1968, Pennak 1978). The incubation period, which is dependent on temperature, normally lasts for two to 20 weeks (Pennak 1978). Between April and June the eggs hatch and the young are in their first instar stage (Pennak 1978, Page 1985). The young go through three instar stages before leaving their mother. The time period for the first two instar stages is 2 to 7 days and 4 to 12 days respectively (Pennak 1978). Throughout the summer the young undergo 6 to 10 molts. Molting is a complex physiological process that is controlled by temperature, light, and hormonal interrelationships (Pennak 1978).


By September some of the young will be sexually mature and copulation will occur. The females carry the sperm until next spring. The form I males (sexually mature) will usually stay in form I throughout the winter and molt to form II the following spring. Shortly thereafter, the form II males will molt back again to form I. Following the first mating season, most species of crayfish have only two to four molts before death (Pennak 1978). The female will not molt, however, until the third instar young have left her. Young that have not reached sexual maturity by autumn will become sexually active the following spring; females usually are sexually mature after the first molt and males after the first or second molt (Pennak 1978). Copulation for the first time will occur and females will be "in-berry" for a very short interval.

Summary of Habitat Requirements:

Reitz (1912) described the habitat of O. indianensis as highly variable, ranging from deep holes to sluggish streams. Brown (1955) and Page (1985) identified suitable habitat as medium-sized streams containing riffles and rocky pools. More specifically, Page (1994) reported streams with forested banks, coarse substrates, slow to moderate current, and water less than 50 cm deep (note, most were found in water less than 30 cm deep) as preferred habitat. Vegetative cover was disregarded by both Brown (1955) and Page (1994) as a significant indicator of O. indianensis habitat. However, most streams inhabited by this species had forested streambanks for a minimum of a few meters from the edge of the water (Page 1985). Furthermore, stones and woody debris were identified as important for cover (Brown 1955 and Page 1985).

Summary of Historical and Current Distribution:

Orconectes indianensis is endemic to Indiana and Illinois. Rhoades (1962) characterized the historical and current range of O. indianensis in Indiana in relation to glaciation. Rhoades (1962) believed that the species was present throughout the entire Wabash River drainage and the dominant crayfish in the White River (eastern tributary of the Wabash River) prior to the Illinoian glacier. The ice filled the lower White River valley, dammed streams with terminal moraines; and as a consequence three marginal lakes were formed. During that time, these lakes served as the refugium for the O. indianensis. The effluents of these lakes carved the Patoka River valley. The terminal moraines constricted the distribution of O. indianensis to Patoka River and Illinoian sluiceways of the Patoka River (Little Pigeon River and Anderson Creek), and prevented re-establishment to the north. As a result, the species is presently confined to the Patoka River and its Illinioan drainages in Indiana. The historical accounts provided by Hay (1896), Eberly (1955), and Page (1985, 1994) are in accordance with Rhoades glacial theory. In addition, Page (pers. comm. 1994) believes that there is evidence demonstrating that O. indianensis occupies approximately the same range as it did historically. He noted that sites unoccupied by O. indianensis were occupied by species considered competitive with O. indianensis such as O. putnami. Therefore, O. indianensis could not have ranged beyond the existing range limits today.


Although previously documented by Reitz in 1912, Rhoades did not identify southeastern Illinois to be within the range of the species. Page (1985) reviewed the geological history and zoogeography of decapods in Illinois. He too believes that the distribution of O. indianensis was significantly influenced by glacial history. According to Page, very little, if any, post-glacial dispersal by O. indianensis has occurred, and consequently the species is confined to the Shawnee Hills physiographic region in Illinois.


Current and historical range:

Type locality: Patoka, Gibson County, Indiana (Hay 1896). Reitz (1912) reported that O. indianensis was documented from Kentucky. However, Rhoades has not, nor any other author to date, acknowledged the presence of O. indianensis in Kentucky.


Indiana Range: Page (1994) reported that O. indianensis is presently confined to the Patoka and Black River systems (Wabash River drainage) and the Pigeon Creek and Anderson River systems (Ohio River drainage).


Historical county distribution: Orange, Pike, and Warrick (Rhoades 1962); Gibson and Dubois (Hay 1896, Eberly 1955, Rhoades 1962, Page 1994); Spencer and Vanderburg (Rhoades 1962, Page 1994); and Perry and Posey (Page 1994).

Current county distribution: Crawford, Orange, Pike, Perry, Posey, Spencer, Vanderburgh, and Warrick (Page 1994).


Extirpated from Gibson and Dubois Counties.


Illinois Range:

O. indianensis is confined to the Saline River system, Honey and Rock Creeks (Ohio River system), and Brushy Slough (Wabash River system) in southeastern Illinois. Page (1985) hypothesized that Reitz's (1912) Wayne County record was probably a misidentification of, at that time, the undescribed O. stannardi species. He also suggested that Reitz's White County record could have been a misidentification of O. propinquus.


Historical county distribution: Gallatin, Johnson, Pope, Saline, and Williamson (Reitz 1912, Brown 1955, Page 1985, 1994); White (Reitz 1912, Brown 1955, Page 1994); Hardin (Brown 1955, Page 1994); and Wayne (Reitz 1912 and Brown 1955).


Current county distribution: Gallatin, Hardin, Johnson, Pope, Saline, White, and Williamson (Page 1994).


Populations Status and Trend Analysis:


The 1993 survey by Page (1994) was the first systematic status survey completed for O. indianensis in Indiana. The species was collected at all historical sites except at the Patoka River and the Little Pigeon Creek localities. Rhoades (1962) provides the only historical narrative account of O. indianensis in Indiana,


"I have collected the species in the Patoka River eastward to Orange County. Furthermore, I made collections of this species in Little Pigeon River and Anderson Creek as early as June 1943, and have taken it again in 1949, 1954, 1956, and 1959. It seems well established."


Based on the following, Page (1994, pers. comm. 1994) believes the species is stable in Indiana. First, the Indiana population appears to be as widespread as it was historically. Second, the Indiana populations are widely distributed, and hence, extirpation from one catastrophic event is highly unlikely. Yet, the proximity of the populations does not preclude recruitment.



In contrast to Indiana, the distribution of the O. indianensis in Illinois has been tracked since the early 1900's. Reitz (1912) conducted a statewide ecological assessment of all crayfishes in Illinois. Through her statewide work, she was able delineate the range of O. indianensis in Illinois. Brown (1955) further elucidated the Illinois distribution with his biological study of crayfishes in central and southeastern Illinois. Specimens collected during this study expanded the known distribution to Hardin County. Page (1985), as part of a statewide survey of crayfishes in Illinois, surveyed the historical and current localities of O. indianensis from 1972 through 1982. He concluded that the distribution of the species had been significantly reduced.


In the 1993 survey (Page 1994), O. indianensis was located at all but 3 of the sites sampled in 1972 and 1982. The species was not documented at Rock Creek (Hardin County), Rock Branch Battle Ford Creek (Saline County), and Brushy Slough (White County). The habitat in Rock Creek and Brushy Slough appears suitable, and additional sampling may show the species to be extant. Rock Branch Battle Ford Creek was polluted with oil at the time of sampling. According to Page (1994), O. indianensis is fairly common within a limited portion of the Saline River system in Gallatin, Hardin, Johnson, Pope, Saline, and Williamson Counties, and common in Honey and Rock creeks of the Ohio River drainage in Hardin County.


Page (1994) stated that although the Illinois population does not appear to be declining presently, the reduction of the species historical range and the threats to the mainstay of the population necessitates State protection.


O. indianensis is believed to be widely distributed throughout its known historical range in Indiana and Illinois. The species was collected at all but 6 of the historical sites in Indiana and Illinois. At 2 of the 6 sites, habitat appears suitable and the species may be extant. Further sampling is necessary to verify the status of each site.


Population estimates do not exist for any of the known populations. Population trend data is not available for Indiana. Trend status for Illinois was arrived at by comparing the number of specimens collected in previous surveys to the 1993 survey.








31 7 10 - 3*


12 12 9 3 3*


43 19 19 3 6


* Indiana: two historical sites were not surveyed in 1993, and they are presumed extirpated. Illinois: two of the sites may still be extant (see text).


Summary of Threats:

Very little information is available on site-specific threats. In Indiana, the type locality has been destroyed by stream channelization. Rhoades (1962) stated that the Patoka was the bastion for O. indianensis. Today however, the Patoka River watershed is threatened by coal mining, stream channel clearing, and poor water quality. Eight of the 11 sites sampled by Page (1994) within the Patoka River watershed fail to provide evidence of O. indianensis. Two of the 8 sites were badly polluted. Another existing population, northwest of Evansville in Vanderburg County, is (or was) threatened (decimated) by a landfill expansion project recently (between 1993-1995).


Page (1994) reported that the mainstay of the Illinois population, the Saline River system, is woefully degraded. The North and Middle forks of the Saline River are extremely polluted and no longer harbor O. indianensis. The contributing factors of the degraded water quality include strip-mining, oil-field pollution, siltation, and desiccation (Smith 1971). A paucity of aquatic life and habitat is patent within this river system (Smith 1971, Page 1985). A proposed project by the Corps of Engineers to construct a reservoir in southern Illinois currently threatens an existing population (Sue Lauzon, pers. comm. 1994).


Although O. indianensis is state protected in both Indiana and Illinois, neither State law is able to provide protection to the species habitat. Therefore, current State protection will not prevent further decline. The only federal law pertinent to the protection of O. indianensis is section 404 of The Clean Water Act. However, as demonstrated above, this law will not preclude the loss of habitat or populations.


Based on existing information, we are not aware of any populations occurring on public lands. It is imperative to recognize that protection of a population will require, at most localities, conservation of the entire waterway (e.g., good conservation practices). This is necessary because activities and practices upstream directly impact the water quality downstream.

Recommendations on Listing:

Retain category 2 status until further trend and threat information can be obtained. Page (1994) contends that the species does not warrant federal protection because the species is more common then once thought and is widespread in Indiana. However, the Illinois population warrants continued State protection because of the much reduced range and the habitat of the mainstay of the population is highly degraded. We believe, however, that many critical questions regarding the stability of Indiana's and Illinois' populations remain unanswered. Therefore, category 2 classification is most appropriate for O. indianensis.


Indiana: The historical distribution is unknown. It is interesting that earlier surveys may not have documented as widespread of a range for the species as reported to date. Although it is thought to be more common then once believed, it is unclear if the range of the species is actually greater than previously documented. Page (1994) did not acknowledge several historical records, therefore, it is possible that the historical range mimics the current range. Page (1994) did add a new county to the range of the species, however, two other historical counties have been eliminated as well. Further, several of the sites searched in 1993 did not show evidence of O. indianensis inhabitance. Presumably these sites were selected for the survey because they contained the essential habitat components and were in close proximity to other known populations. It is not known, however, why these sites were void of the species. It is plausible that these sites may have once harbored O. indianensis, and for whatever reason no longer do.


The paucity of data regarding threats to O. indianensis further obfuscates the status assessment. Since population information for most locations is lacking prior to the 1993 survey, we have no basis for determining the trend of the species in Indiana. For example, if Hay (1896) and Rhoades (1962) were correct in their theory that the Patoka River Valley was the core of the Indiana population, the current condition of the watershed justifiably raises concern. [Note: Based on Rhoades' (1962) and Page's (1985) papers, it is believable that O. indianensis is endemic to southwestern Indiana and Illinois. It is also credible that the Patoka River was the core of Indiana population because Hay (1896) through his statewide survey for crayfishes found O. indianensis only within the Patoka River valley. Rhoades (1962) confirmed Hay's findings]. Currently, the Patoka River drainage is threatened by past and ongoing mining operations, stream channelization, and agricultural practices. It is noteworthy that no individuals were found at historical sites in Gibson and Dubois Counties (the core of the Patoka River Valley). Therefore, if the Patoka River Valley was indeed the core area, the population in Indiana has probably declined and may still be declining.


Illinois: Page (1994) stated that the current range of the species is much smaller than historically known. However, his 1985 and 1994 reports do not reflect this statement. According to the historical records provided by Page (1994), there is only one population considered extirpated from Illinois. It is possible, however, that Reitz's records for the North and Middle forks of the Saline River were not documented within Page's 1994 report, and therefore, the number of populations extirpated was not accurately depicted. Regardless, the range of the species has been restricted by one county only (i.e., historically the species was found in 8 counties and currently is found in 7 counties). However, the range within the extant counties may have been significantly reduced. Without a greater defined map (see Page 1994, Figure 1), it is difficult to infer definitively.


Unlike the Indiana population, population trend data is available for Illinois. Page (1994) stated that the Illinois population does not appear to be declining; its status is the same as it was in the 1970's and 1980's. However, Page (1994) and others have cautioned that the existing threats to several of the populations may precipitate or exacerbate declines in some populations.

Management Actions Needed:

Identify core population areas, and existing and potential threats. Seek conservation agreements with landowners throughout the watershed to minimize, and possibly negate such threats.

Research, Surveys, and Monitoring Needed:

To accurately assess the status of O. indianensis, the following issues need to be addressed: 1) further analysis on the possible historical range in Indiana, specifically address the discrepancy in the reported range; 2) compile trend data, especially for Indiana; 3) clarify the range reduction issue in Illinois; and 4) document past and existing threats to populations in Indiana and Illinois. The identical sampling methodology utilized by Page in 1985 and 1994 should again be implemented; however, sampling intensity (i.e., each site should be visited more often) should be increased. Page's (1994) population status information is limited due to the small sampling period (most sites were sampled on only 2 different dates).


Black, J.B. 1963. Observations on the Home Range of Stream-Dwelling Crawfishes. Ecology 44(3):592-595.


Boyd, J. A. and L. M. Page. 1978. The Life History of the Crayfish Orconectes kentuckiensis in Big Creek, Illinois. Am. Midl. Nat., 99(2):398-414.


Brown, P.L. 1955. The biology of the crayfishes of central and southeastern Illinois. doctoral Dissertation. University of Illinois, Urbana-Champaign, 158p.


Crocker, D.W. and D.W. Barr. 1968. Handbook of the Crayfishes of Ontario. University of Toronto Press.


Eberly, W.R. 1955. Summary of the Distribution of Indiana Crayfishes, Including New State and County Records. Indiana Academy of Science Proceedings 64:281-283.


Hay, W.P. 1896. The crawfishes of the state of Indiana. Pages 476-506 in 20th Annual Report of the Department of Geology and Natural Resources of Indiana.


Page, L.M. 1985. The crayfishes and shrimps (Decapoda) of Illinois. Illinois Natural History Survey Bulletin 33(4):i + vi, 343-393p.


. 1994. the Distribution and Status of the Indiana Crayfish, Orconectes indianensis. Illinois Natural History Survey. Unpubl. Report for Indiana Department of Natural Resources. 25p.

Pennak, R.W. 1978. Fresh-water Invertebrates of the United States. - 2nd ed. 464-487p.


.1989. Fresh-water invertebrates of the United States: Protozoa to Mollusca/Robert W. Pennak. - 3rd ed. p. cm.


Reitz, N.M. 1912. Ecological relations of crawfishes of Illinois. B.S. Thesis. University of Illinois, Urbana-Champaign.


Rhoades, R. 1962. The Evolution of Crayfishes of the Genus Orconectes indianensis Section Limosus (Crustacea: Decopoda). Ohio J. of Sci. 62(2):65-96.


Smith, P.W. 1961. The amphibians and reptiles of Illinois. Illinois Natural History Survey Bulletin 28:1-298.


1971. Illinois Streams: a classification based on their fishes and an analysis of factors responsible for disappearance of native species. Illinois Natural History Survey Biological Notes 76.


Name and Office of Preparer:

Jennifer Szymanski, BFO, Indiana


List of Primary Individuals Contacted:

Lawrence Page, Illinois Natural History Survey (217)333-6846.
Catherine Gremillon-Smith, Indiana DNR (317)232-8160.
Sue Lauzon, Illinois Endangered Species Protection Board, (217)785-8774.


Site Specific Locality Information:
Six extirpated sites = Rock Creek, Hardin County, IL; Rock Branch, Saline County, IL; Brushy Slough, White County, IL; Patoka River, Gibson County, IN; trib of Pigeon Creek, Vanderburgh County, IN; and Robb Creek, Gibson County, IN.


Three declining populations = Honey Creek, Hardin County, IL; Little Saline, Saline County, IL; and South Fork, Williamson County, IL.


September 1997


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