|Scientific Name:||Graptemys oculifera|
|Species Authority:||(Baur, 1890)|
Malacoclemmys oculifera Baur, 1890
|Red List Category & Criteria:||Vulnerable B2ab(iii) ver 3.1|
|Assessor/s:||van Dijk, P.P.|
|Reviewer/s:||Horne, B.D., Mittermeier, R.A., Philippen, H.-D., Quinn, H.R., Rhodin, A.G.J., Shaffer, H.B. & Vogt, R.C|
Graptemys oculifera occurs in two rather small drainage basins (875 and 90 km river length occupied, respectively), where populations appear stable or in some decline, and remain under actual or potential threat from pollution and sedimentation, habitat degradation and loss including channelization, hurricane impacts, and further minor impacts. In the absence of quantitative data that the species has suffered a 50% decline over three generations, or likely to suffer this decline, it appears not to qualify for retention of its previous Red List rating of EN B+2c (criteria 2.3) but the two rivers inhabited by the species represent in effect three populations in a limited range (occupancy less than 2,000 km²) under continuing threat of decline in habitat quality, thus qualifying for Vulnerable B2ab(iii).
Graptemys oculifera inhabits the Pearl and Bogue Chitto rivers of southeastern Louisiana and western Mississippi. The occupied section of suitable habitat in the Pearl is about 790 km and the occupied section of the Bogue Chitto about 85 km, for a total length of 875 km of occupied river length; the Pearl River is fragmented by the Ross Barnett reservoir (Jones and Selman 2009).
Native:United States (Louisiana, Mississippi)
|Range Map:||Click here to open the map viewer and explore range.|
Graptemys oculifera has been reported at densities of 4–340 animals per km of river (review by Jones and Selman 2009). Population monitoring over the past 20 years indicate that some subpopulations are stable while others are in decline (Jones and Selman 2009). No overall decline rates have been estimated.
Graptemys oculifera was considered the overall sixth rarest Graptemys species by Lindeman (pers. comm 6 Aug 2009) based on extensive basking surveys.
|Habitat and Ecology:||
Graptemys oculifera is most abundant in streams with moderate to fast current, numerous basking logs, nearby sand and gravel bars, and channel wide enough to allow sun to reach basking logs. Ringed Sawbacks, both males and females, feed predominantly on caddisflies, diptera, mayflies, beetles and other insects, as well as occasionally scavenging dead fish (Jones and Selman 2009).
Females may reach 22 cm carapace length (CL), males may reach 11 cm CL. Females have been calculated to reach maturity at 13–14 cm CL at 7–16 years of age, while males mature at 7–8 cm CL and 3–5 years. Longevity certainly exceeds 21 years and likely exceeds 25 (males) to 37 (females) years. (Jones and Selman 2009). Generation time has not been estimated.
Females usually produce a single clutch, rarely a second clutch; only 60% of mature females nest in any given year. Clutch size averages 3.66 (range 1–10) eggs (Jones 2006). Hatchlings measure about 35 (range 28–40) mm.
Over 21% of the range of Graptemys oculifera had already been channelized by 1986. Plans for channelization of an additional 28% of the Pearl River and over 160 km of the Bogue Chitto river, while not executed, have not been entirely rescinded and remain as a significant potential threat (Jones & Selman, 2009).
Riverine sedimentation loading and pollution remain particularly significant in the Pearl River system as a result of catchment management infrastructures and practices, riverside paper industries, and riverine gravel mining (review in Lovich et al., 2009). In addition, the river has suffered significant impact from hurricanes in recent years. Because of the connectivity of river mainstem habitat, an impact in the upper reaches of either river inhabited by the species will affect the entire turtle population (and/or its prey base) in that river, increasing the species’ vulnerability to impacts elsewhere. Incidental anthropogenic removal of animals, by pet collection, shooting or incidental take in fisheries, disturbance of basking and nesting sites and behaviour (reducing long-term individual fitness and recruitment), and increased nest predation levels by increasing populations of raccoons, armadillos and fish crows (who together predate 86% of nests – Jones, 2006), represent additional background impacts on remaining subpopulations (Jones & Selman, 2009).
Graptemys oculifera was designated as Threatened under the US Endangered Species Act (ESA) in 1986; a recovery plan has been prepared but no funding has been allocated to implement its recommendations and critical habitat has not been designated; the species was included in a 2005 review of species included under the ESA.
The Ringed Sawback is protected in Mississippi, where it is State-listed as Endangered (http://home.mdwfp.com/License/info.aspx?id=13), while it is listed as Threatened in Louisiana.
The Ringed Map Turtle is included in CITES Appendix III (United States) since 14 June 2006. A section of the Pearl river, 19 km in length, was established as a sanctuary for the Ringed Sawback, resulting in channel maintenance practices consistent with the species’ requirements, and public awareness efforts. The species also occurs in the riverfront sections of Nanih Waiya WMA, Pearl River WMA, and Old River WMA in Mississippi, and Pearl River WMA and Bogue Chitto NWR in Louisiana (Jones & Selman, 2009).
Further desirable conservation measures include implementing the recovery plan, including designation of two Pearl River sections, amounting to 240 river km, as protected habitat, with associated implementation of regulations and funding made available for land acquisition. Further studies of natural history and population dynamics, to complement research already completed or in progress, is desirable.
|Citation:||van Dijk, P.P. 2011. Graptemys oculifera. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 24 April 2014.|