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Graptemys pearlensis

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA REPTILIA TESTUDINES EMYDIDAE

Scientific Name: Graptemys pearlensis
Species Authority: Ennen, Lovich, Kreiser, Selman & Qualls, 2010
Common Name(s):
English Pearl River Map Turtle
Taxonomic Notes:

Previously this species was considered the Pearl River population of Graptemys gibbonsi, until G. pearlensis was described by Ennen et al. (2010) as a full separate species.

Assessment Information [top]

Red List Category & Criteria: Endangered A1bcde+4bcde ver 3.1
Year Published: 2013
Date Assessed: 2010-08-01
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.
Contributor(s): Selman, W.
Justification:

While hard quantitative data are absent, available information indicates that populations of Graptemys pearlensis have declined by 80–98% since 1950, a time period probably representing 2–3 generation lengths. While the worst impacts from pollution and habitat destruction may have been ameliorated, habitat quality has not been restored to optimal conditions while impacts from commercial collection, wanton destruction, and hurricane aftermath continue to be of concern. Thus Graptemys pearlensis qualifies as Endangered A1bcde+4bcde, and potentially qualifies as Critically Endangered by the same criteria.

Geographic Range [top]

Range Description: Graptemys pearlensis is restricted to the main stems and major tributaries of the Pearl and Bogue Chitto rivers of Louisiana and Mississippi, USA (Ennen et al. 2010). The occupied section of suitable habitat in the Pearl is about 800 km and the occupied section of the Bogue Chitto about 140 km, for a total estimated length of 940 km of occupied river length.
Countries:
Native:
United States (Louisiana, Mississippi)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population:

Graptemys pearlensis, as part of G. gibbonsi, was considered the second rarest Graptemys species by Lindeman (pers. comm 6 Aug 2009) based on extensive basking surveys.

Graptemys pearlensis used to be observed/captured in the 1950s–1960s in almost double numbers than sympatric G. oculifera (review by Lovich et al. 2009), whereas it had declined severely by the 1990s and it is now being observed in, at best, a one to five ratio (Lindeman 1998, 1999, pers. comm 6 Aug 2009); in context, G. oculifera populations have held stable or locally declined during the same time (Jones and Selman 2009). This steep decline was attributed to water pollution impacting mollusc populations on which pearlensis feed.

Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology:

Very limited ecological data are available for Graptemys pearlensis; in most aspects it is probably similar to those reported for G. gibbonsi in the Leaf-Pascagoula systems.

Females reach up to 29.5 cm carapace length (CL), males to 12.1 cm CL. Average cluch size has been reported as 6.4 eggs, and multiple nesting is likely (McCoy and Vogt in Lovich et al. 2009). Hatchings measure about 23 mm plastron length (PL) (CL apparently not reported).

Females of the analogous and closely-related G. gibbonsi were estimated to mature at an age of 15–20 years (Selman in Lovich et al. 2009). Generation length has not been determined but is unlikely to be shorter than 25 years.

Systems: Terrestrial; Freshwater

Use and Trade [top]

Use and Trade: Map turtles identified as Graptemys gibbonsi have been extensively traded in the global pet trade; collecting efforts for the species have included the Pearl River basin (Selman and Qualls in Lovich et al. 2009), meaning that an unknown but certain proportion of the animals traded as gibbonsi were actually pearlensis.

Threats [top]

Major Threat(s):

Recorded declines in Pearl River broadheaded Graptemys, i.e. G. pearlensis, has been attributed to water pollution impacting mollusc populations on which pearlensis feed, snag and log removal, channelization and impoundment, as well as collection for the pet trade, wanton destruction by fishermen and plinking rednecks, and potentially by subsidized predators (i.e., unnaturally large populations of predators subsidized by easily available resources near human settlements) increasing nest predation rates.

Over 21% of the range of the species had already been channelized by 1986, and 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 to the species’ future (Jones and Selman 2009).

Riverine pollution has been particularly significant in the Pearl River system as a result of 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, a catastrophe somewhere in the river basin will affect the entire turtle population (and/or its prey base) in the downstream parts of that river, increasing the species’ vulnerability to impacts elsewhere in the basin.

Conservation Actions [top]

Conservation Actions:

Graptemys pearlensis, as former part of G. gibbonsi, is protected from commercial exploitation in Mississippi and possession is limited to 4 individuals. Its Louisiana populations are considered an Animal of Conservation Concern. The genus Graptemys is included in CITES Appendix III (United States) since 14 June 2006.

Graptemys gibbonsi has been suggested to qualify for inclusion as threatened under the Endangered Species Act (ESA) (Lindeman 1999, Selman and Qualls 2007), and the taxonomic and conservation status of the split-out taxon pearlensis reinforces this further.

Graptemys pearlensis is likely to benefit from conservation measures in place for sympatric G. oculifera, including turtle-sensitive channel management practices in the 19 km section of the Pearl River designated as ringed map turtle sanctuary (Jones and Selman 2009).

Lovich et al. (2009) stated that appropriate conservation measures for the species include:

  • Protecting and improving the water quality of the rivers and streams it inhabits;
  • Discouraging channelization and removal of snags;
  • Promoting streamside management zones and proper forest management practices within riparian zones;
  • Prohibiting or further regulating commercial collecting;
  • Further population surveys and systematic monitoring densities of known populations
  • Further research on natural history, ecology, and the effects of recovery measures.

Conservation actions for this species should occur in synergy with efforts already underway for the conservation of sympatric Graptemys oculifera.


Citation: van Dijk, P.P. 2013. Graptemys pearlensis. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 16 September 2014.
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