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Austroglanis gilli

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII SILURIFORMES AUSTROGLANIDIDAE

Scientific Name: Austroglanis gilli
Species Authority: (Barnard, 1943)
Common Name(s):
English Clanwilliam Rock Catfish
Synonym(s):
Gephyroglanis gilli Barnard, 1943
Taxonomic Notes: Formerly placed in family Bagridae, but recognized in a separate family by Mo (1991) and de Pinna (1998) (Nelson 2006).

Assessment Information [top]

Red List Category & Criteria: Vulnerable B1ab(iii,v)+2ab(iii,v) ver 3.1
Year Published: 2007
Date Assessed: 2007-03-01
Assessor(s): Swartz, E., Bills, R. & Impson, D.
Reviewer(s): Snoeks, J. (Freshwater Fish Red List Authority) & Darwall, W. (Freshwater Biodiversity Assessment Unit)
Justification:
Bills (1999) established most of the range of this species, especially the lower limits and in some cases upper limits in tributary streams. They occur in more than ten tributaries of the Olifants River system in the Cederberg Mountains, and there are records and unconfirmed reports of their presence in some mainstream areas. Small reductions in range are occurring in the Noordhoeks, Thee and possibly the mainstream Olifants River, but estimated population decline is less than the 30% threshold for qualification for a threatened category under criterion A. The species has an extent of occurrence (EOO) of less than 5,000 km², an area of occupancy (AOO) of less than 10 km², is severely fragmented with continuing decline in AOO, habitat and number of mature individuals. Despite being fragmented, most of the populations are large enough to survive on their own without the need for immigration. However, locations have been identified as sites where alien invasive species and habitat degradation can impact them together: namely the Oudste, Thee, Noordhoeks, Boontjies-Boskloof, Heks, Rondegat, Jan Dissels, Biedou and Matjies-Krom. The Tra Tra-Eselbank is not considered to be large enough. Therefore nine locations are estimated. It therefore only qualifies under Vulnerable for number of locations (>5) (for Endangered it qualifies only under B1b(ii,iii,v)+2b(ii,iii,v), and as Critically Endangered only under B2b(ii,iii,v), which are insufficient criteria to fully qualify for these higher categories). The overall assessment under criterion B therefore is Vulnerable. Provisional indications are that the population size is large enough not to qualify under criteria C or D, and no quantitative analysis has done to be able to apply criterion E.
History:
1996 Vulnerable
1994 Rare (Groombridge 1994)
1990 Rare (IUCN 1990)
1988 Rare (IUCN Conservation Monitoring Centre 1988)
1986 Rare (IUCN Conservation Monitoring Centre 1986)

Geographic Range [top]

Range Description: A. gilli is endemic to the Olifants River system in the Western Cape, South Africa. It occurs in tributaries of the Olifants (Oudste, Thee, Noordhoeks, Boontjies, Boskloof, Heks, Rondegat, Jan Dissels, Dwars) and Doring (Biedouw, Tra Tra, Eselbank, Matjies, Krom and Breekkrans) basins of the Olifants River system in the Cederberg Mountains and occurs in the mainstream Olifants River near the Heks tributary (Bills 1999).
Countries:
Native:
South Africa (Western Cape)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: There are large populations (possibly more than 1,000 mature individuals) in the Oudste, Thee, Noordhoeks, Boskloof, Heks (including the mainstream Olifants nearby), Rondegat, Jan Dissels, Dwars, Breekkrans and Krom tributaries and smaller populations (possibly less than 1,000 mature individuals) in the Boontjies, Biedouw, Tra Tra, Eselbank and Matjies tributaries (Bills 1999).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Common in both lower and headwater sections of tributary streams. They prefer larger pools and deep water within tributary streams associated with cobble and boulder habitat. As juveniles they probably prefer cobble regions, but as they mature they are found in a wide variety of habitats preferring complex structure especially deep cobble and boulder areas (Bills 1999).
Systems: Freshwater

Threats [top]

Major Threat(s): The introduction of alien fishes, particularly Micropterus dolomieu, has caused a major reduction in their range soon after their introduction in the 1940's. Since, then the decline due to alien fishes has become slower due to the inability of Micropterus dolomieu to move above some barriers in tributary streams. Unsustainable water extraction is a major threat that affects almost all the tributary streams and mainstream areas. The effect of insecticides has not been quantified, but could have an increasing impact in the future as more orchards are being established (Bills 1999).

Conservation Actions [top]

Conservation Actions: A river rehabilitation program plans to rehabilitate lower sections of the Rondegat and Krom Rivers that would significantly increase the size of those populations and hopefully secure them against re-invasion by alien fishes.

Citation: Swartz, E., Bills, R. & Impson, D. 2007. Austroglanis gilli. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 28 July 2014.
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