SANBI

Rationale (Changed due to Same category but change in criteria)

The species is currently known from five to eight locations based on the major threat which is the distribution of invasive alien species: the Bloukranz Pool in the Kowie River System, the Koonap and Kat river catchments in the Great Fish River System, the Keiskamma River System, the Gxulu River System, the Igoda River System, the Buffalo River System, and the Nahoon River System. Only two specimens of Eastern Cape Rocky (Sandelia bainsii) were sampled from Bloukranz Pool during extensive surveys of the Kowie River System in 2014. A longitudinal survey conducted in 2017/18 revealed no specimens. The Kowie River population is thus either extirpated or at extremely low abundance. Recent comprehensive surveys of the Great Fish River System revealed that the Edge Hill Farm population in the Koonap River is most likely extirpated, whereas severe decline in population size was recorded in eNyara River (only six individuals were sampled despite extensive sampling of the river reach where the species was historically common). The present distribution pattern of this species in the Kat River is similar to the historical pattern, indicating that this population has remained fairly stable. The Kat River population is however severely fragmented due to presence of several weirs as well as the Kat River Dam, which may affect gene flow between the remnant populations, and hence potentially affect their long-term evolutionary potential or persistence. The Kat River population is potentially threatened by the presence of non-native species, particularly the African Sharptooth Catfish (Clarias gariepinus) which has successfully invaded the lower and middle sections of the Kat River. African Sharptooth Catfish, Common Carp (Cyprinus carpio) and Bass species (Micropterus spp.) have also been introduced into Kat River Dam where they pose a threat to the Sandelia population in the upper Kat River. Small populations in the Gxulu and Igoda river systems are threatened by agriculture, and the population in Yellowwoods River of the Buffalo River System is threatened by an inter-basin transfer from Wriggleswade Dam (Kubusi River System) as this may facilitate the translocation of alien invasive species. The Nahoon River population is almost extirpated. The estimated area of occupancy (AOO) is 168 km². The species is experiencing ongoing decline due to habitat loss and spread of alien invasive species. More than 50% of the populations are small and isolated with only three viable subpopulations (the Kat, Keiskamma and Buffalo) and five non-viable subpopulations (the Kowie, Koonap, Gxulu, Igoda and Nahoon). The remnant populations are thus severely fragmented. The species is assessed as Endangered under criteria B2ab(ii,iii,iv,v).

Distribution

Eastern Cape Rocky (Sandelia bainsii) is endemic to the Eastern Cape Province of South Africa, where it occurs in small sections of the Kowie, Great Fish, Keiskamma, Igoda, Gxulu, Buffalo and Nahoon river systems (Skelton 2001). Genetic studies have revealed existence of two lineages within this species, a southern lineage that occurs in the Kowie, Great Fish and Keiskamma river systems, and a northern lineage that occurs in the Igoda and Buffalo river systems (Roos 2005, Chakona et al., in prep). No samples have been collected from the Gxulu and Nahoon for genetic analysis to determine their placement.

Habitat View more ecological information

Population trend

Trend

Ongoing decline in population sizes is likely. The Kowie River population is almost extirpated, the Koonap River population has severely declined and the population at Edge Hill Farm, in the Koonap is likely extinct because no specimens were found despite extensive surveys in 2017 ( Chakona unpublished data), whereas the eNyara River population is represented by only a few remaining individuals. More than 50% of the populations are small and isolated with only three viable subpopulations (the Kat, Buffalo and Keiskamma) and five non-viable subpopulations (Kowie, Koonap, Gxulu, Igoda and Nahoon). The remnant populations are thus severely fragmented. The Kowie, Koonap, Gxulu and Nahoon rivers populations are almost extirpated. Regular surveys are required to monitor the status of these remnant populations and to inform conservation actions.

Threats

Major threats are habitat alteration, potential competition from and predation by invasive alien species particularly predators such as Largemouth Bass (Micropterus salmoides) and African Sharptooth Catfish, excessive water abstraction, interbasin transfer that may introduce non-native species, siltation and water pollution. The Kowie River System, the eNyara River and lower Kat River have been severely impacted by agricultural activities that have modified instream habitat as well as pollution from urban settlements situated in the upper catchments of these rivers.

Conservation

Educational resources have been developed and distributed in the past. These awareness campaigns need to be revived. Genetic studies are urgently required to assess the genetic diversity and determine the long-term evolutionary potential and viability of the severely fragmented populations of this species. This information is crucial for identifying populations with low levels of genetic diversity and may thus need to be considered for potential genetic rescue. Habitat restoration and reintroduction would also need to be considered, but all conservation actions should be informed by scientific data generated through dedicated ecological and genetic studies. Immediate conservation efforts should be aimed at securing the remnant populations against potential invasion by non-native species, while long-term efforts are needed, particularly focusing on eradication of alien fishes from critical habitats and habitat restoration.

References

[@article{18475,
 author = {Skelton, P.H.},
 title = {A Complete Guide to the Freshwater Fishes of Southern Africa},
 year = {2001}
}
,@electronic{2573,
 address = {www.iucnredlist.org},
 author = {IUCN},
 title = {The IUCN Red List of Threatened Species. Version 2018-1},
 year = {2018}
}
,@article{19889,
 author = {Roos, H.},
 title = {Genetic diversity in the anabantids <i>Sandelia capensis</i> and <i>S. bainsii</i>: a phylogeographic and phylogenetic investigation},
 year = {2005}
}
,@article{19889,
 author = {Cambray JA},
 journal = {Environmental Biology of Fishes},
 pages = {293--306},
 title = {The spawning behaviour of the endangered Eastern Cape rocky, Sandelia bainsii (Anabantidae), in South Africa},
 volume = {49},
 year = {1997}
}
,@phdthesis{19889,
 author = {Mayekiso M.},
 school = {Rhodes University},
 title = {Some aspects of the ecology of the Eastern Cape Rocky Sandelia Bainsii (PISCES: ANABANTIDAE) in the Tyume river, Eastern Cape, South Africa. MSc thesis},
 year = {1986}
}
,@article{19889,
 author = {Mayekiso M. & Hecht T},
 journal = {Rev Hydrobiology trop},
 number = {3},
 pages = {219--230},
 title = {The feeding and reproductive biology of a South African Anabantid fish, Sandelia bainsii},
 volume = {23},
 year = {1990}
}
,]

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