Pachnodus fregatensis 

Scope:Global
Status_ne_offStatus_dd_offStatus_lc_offStatus_nt_offStatus_vu_offStatus_en_onStatus_cr_offStatus_ew_offStatus_ex_off

Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Stylommatophora Cerastidae

Scientific Name: Pachnodus fregatensis
Species Authority: Van Mol & Coppois, 1980

Assessment Information [top]

Red List Category & Criteria: Endangered A1a ver 3.1
Year Published: 2009
Date Assessed: 2006-01-11
Assessor(s): Gerlach, J.
Reviewer(s): Miller, R.M., Pollock, C.M. & Seddon, M.B.
Justification:
Secondary poisoning with rodent poison (Brodifacoum) in the year 2001 led to a decline in the popualtion of about 87%, relative to the population size in 1999. The causes of this decline have ceased and future population increases are expected.

Geographic Range [top]

Range Description:This terrestrial snail is endemic to Fregate island, Seychelles. It occupies a single, continuous range of only 2 km² (extent of occurrence (EOO) and area of occupancy (AOO) both calculated at 2 km²).
Countries occurrence:
Native:
Seychelles (Seychelles (main island group))
Estimated area of occupancy (AOO) - km2:2
Number of Locations:1
Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:No
Lower elevation limit (metres):1
Upper elevation limit (metres):100
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Eradication of rats using Brodifacoum poisoning was associated with an 87% population decline in this species between 1999 and 2001. In 2005, the population was estimated to be 7,700 individuals.
Current Population Trend:Unknown
Additional data:
Number of mature individuals:7700
Population severely fragmented:No
Continuing decline in subpopulations:No
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes

Habitat and Ecology [top]

Habitat and Ecology:This snail, the only surviving terrestrial Pachnodus species, is found under logs in lowland woodland, from 1-100 metres above sea level.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:No
Generation Length (years):2

Threats [top]

Major Threat(s): Predation by rats was speculated to be a threat in the 1990s. Eradication of rats using Brodifacoum poisoning was associated with an 87% population decline in this species between 1999 and 2001. The successful completion of the rodent eradication means that neither of these threats remain. Currently no active threats are known. Large-scale agro-industry farming and plantations caused some habitat degradation in the past.

Conservation Actions [top]

Conservation Actions: A captive assurance colony is maintained by the Zoological Society of London, and habitat restoration is in place. Continued monitoring of the population status is necessary.

Classifications [top]

1. Forest -> 1.6. Forest - Subtropical/Tropical Moist Lowland
suitability: Suitable  major importance:Yes
1. Land/water protection -> 1.1. Site/area protection

In-Place Research, Monitoring and Planning
  Action Recovery plan:No
  Systematic monitoring scheme:No
In-Place Land/Water Protection and Management
  Conservation sites identified:Yes, over entire range
  Occur in at least one PA:No
  Percentage of population protected by PAs (0-100):0
  Area based regional management plan:No
In-Place Species Management
  Harvest management plan:No
  Successfully reintroduced or introduced beningly:No
  Subject to ex-situ conservation:Yes
In-Place Education
  Subject to recent education and awareness programmes:No
  Included in international legislation:No
  Subject to any international management/trade controls:No
2. Agriculture & aquaculture -> 2.1. Annual & perennial non-timber crops -> 2.1.3. Agro-industry farming
♦ timing: Past, Unlikely to Return ♦ scope: Minority (<50%) ♦ severity: Rapid Declines ⇒ Impact score: Past Impact 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion

2. Agriculture & aquaculture -> 2.2. Wood & pulp plantations -> 2.2.2. Agro-industry plantations
♦ timing: Past, Unlikely to Return ♦ scope: Minority (<50%) ♦ severity: Unknown ⇒ Impact score: Past Impact 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion

5. Biological resource use -> 5.1. Hunting & trapping terrestrial animals -> 5.1.2. Unintentional effects (species is not the target)
♦ timing: Past, Unlikely to Return ♦ scope: Majority (50-90%) ♦ severity: Very Rapid Declines ⇒ Impact score: Past Impact 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

8. Invasive & other problematic species & genes -> 8.1. Invasive non-native/alien species -> 8.1.2. Named species
♦ timing: Past, Unlikely to Return ♦ scope: Unknown ♦ severity: No decline ⇒ Impact score: Past Impact 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

1. Research -> 1.2. Population size, distribution & trends

Bibliography [top]

Gerlach, J. 2005. The impact of rodent eradication on the larger invertebrates of Fregate island, Seychelles. Phelsuma 13: 20-27.

Gerlach, J. 2006. Terrestrial and Freshwater Mollusca of the Seychelles Islands. Backhuys, Leiden.

Gerlach, J., Matyot, P. and Samways, M.J. 2005. Developing strategies for invertebrate conservation, the case of the Seychelles islands. Phelsuma: 9-12.

IUCN. 2009. IUCN Red List of Threatened Species (ver. 2009.2). Available at: www.iucnredlist.org. (Accessed: 3 November 2009).


Citation: Gerlach, J. 2009. Pachnodus fregatensis. In: The IUCN Red List of Threatened Species 2009: e.T168120A6454444. . Downloaded on 01 June 2016.
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