Clanwilliam Yellowfish
Encyclopedia
The Clanwilliam Yellowfish (Labeobarbus capensis) is a ray-finned fish species
in the family
Cyprinidae. It has long been placed in Barbus
, the "wastebin genus" for barbs, by default; however, the species is increasingly being restored to related yellowfish genus
Labeobarbus which seems a much more appropriate placement. It is hexaploid like the other yellowfish, among which it is more closely related to the Smallscale Yellowfish
(L. polylepis) than to the Largescale Yellowfish
(L. marequensis).
As its relatives, this is a large species. They are silvery with blotchy vertical
barring on the sides when young, and become light brown all over when adult. Males turn golden-yellow in the breeding season, and the common name
refers to this.
, where it is found in tributaries of the Olifants River, namely the Doring River
, and the Biedou, Boskloof, Driehoeks, Groot
, Jan Dissels, Kobee, Noordhoeks, Ratels, Rondegat, Thee and lower Twee Rivers in the Cederberg Mountains. It is not known whether it still occurs in the Olifants River itself in any numbers, and at least above Clanwilliam Dam
and below Olifants Gorge it has apparently gone extinct.
L. capensis is found in large and small rivers, but do not like slowly-moving water. Young Clanwilliam Yellowfish (below 4 cm/1.6 in long) are found in backwater
s and shallow riffle
s. As they grow older they move out of the riffles into deeper water but even adults may still be found in relatively shallow parts of their habitat
. The presence of deep pools and dense riparian stands of Palmiet (Prionium serratum, a Thurniaceae
) that provide shadow will aid its survival if its home rivers run dry in hot summers. The young eat zooplankton
and other small aquatic
invertebrate
s. Adults are omnivore
s, feeding on larger invertebrates and algae. Their breeding season is prolonged and lasts from late spring to summer (about October to December), when the water is at least 20 °C (68 °F). During that time, adults repeatedly move in small groups into shallow riffles where the water is only a few decimetre
s deep, and deposit their non-sticky egg
s there. The hatchling
s initially move away from light and will hide between the substrate
. In the absence of optimal breeding habitat (such as in dam
s), it will use any shallow water with generous rocks on the ground.
(Micropterus dolomieu) was introduced into its range. Though it is still found across a wide area and is plentiful in some places, the bass will eat young Clanwilliam Yellowfish and thus easily lower their stocks to local extinction. Less important as predators of juvenile L. capensis are Largemouth Bass
(M. salmoides), Spotted Bass
(M. punctalatus) and Bluegill
s (Lepomis macrochirus). Largemouth Bass, Bluegills and Tilapia sparrmanii are also food competitors of young Clanwiliam Yellowfish. Habitat destruction
by canalisation and dam
ming as well as water pollution
by pesticide
s and fertilisers in the runoff of agricultural land are affitional threats. Consequently, the species is listed as Vulnerable
by the IUCN.
It is also listed as Endangered by the Western Cape Province Nature Conservation Ordinance, making it illegal to kill it, and to catch it except for supervised translocation and research projects. It occurs in the Cederberg Wilderness Area and in the Greater Cederberg Biodiversity Corridor; the latter was established in 2004 to assist local landowners in sustainable development
. A research station dedicated to captive breeding
was established by the Cape Department of Nature Conservation in 1976; the captive breeding program ran until the 1990s By that time, though water quality
control problems had hampered the work throughout, the station had provided thousands of young L. capensis public and private initiatives for establishing stocks. In a major gaffe, in the 1980s the species was established in the Twee River abvove some waterfall
s which it could not naturally cross. In that region, the rare Twee River Redfin
(Barbus erubescens) had managed to survive; it was subsequently outcompeted by L. capensis and disappeared from some of its remaining range, bringing it to the brink of extinction. The National Yellowfish Working Group was established in 1997 to follow up on the research station's program and to educate the public about the species, which may become of local or even commercial significance as food again if its stocks recover. Under the Cape Action for People and the Environment program launched in 1999, exotic invasive fishes
are to be eradicated from the watercourses of the Cape Floristic Region
. As regards the Clanwilliam Yellowfin former and current range, the eradication program has been slated to include the Krom and Rondegat Rivers.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Cyprinidae. It has long been placed in Barbus
Barbus
Barbus is a ray-finned fish genus in the family Cyprinidae. The type species of Barbus is the Common Barbel, first described as Cyprinus barbus and now named Barbus barbus...
, the "wastebin genus" for barbs, by default; however, the species is increasingly being restored to related yellowfish genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Labeobarbus which seems a much more appropriate placement. It is hexaploid like the other yellowfish, among which it is more closely related to the Smallscale Yellowfish
Smallscale Yellowfish
Smallscale Yellowfish is a species of ray-finned fish in the genus Labeobarbus....
(L. polylepis) than to the Largescale Yellowfish
Largescale Yellowfish
Largescale Yellowfish is a species of ray-finned fish in the genus Labeobarbus....
(L. marequensis).
As its relatives, this is a large species. They are silvery with blotchy vertical
Vertical direction
In astronomy, geography, geometry and related sciences and contexts, a direction passing by a given point is said to be vertical if it is locally aligned with the gradient of the gravity field, i.e., with the direction of the gravitational force at that point...
barring on the sides when young, and become light brown all over when adult. Males turn golden-yellow in the breeding season, and the common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
refers to this.
Distribution and ecology
It is only found in the Western Cape Province of South AfricaSouth Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, where it is found in tributaries of the Olifants River, namely the Doring River
Doring River
Doring River, The Doring River originates northeast of Ceres and joins the Olifants River near the towns of Klawer and Vredendal, Western Cape, South Africa...
, and the Biedou, Boskloof, Driehoeks, Groot
Groot River (Western Cape)
The Groot River of Western Cape Province is a South African river. It should is not to be confused with the Groot River of Eastern Cape and the Groot River of Southern Cape provinces....
, Jan Dissels, Kobee, Noordhoeks, Ratels, Rondegat, Thee and lower Twee Rivers in the Cederberg Mountains. It is not known whether it still occurs in the Olifants River itself in any numbers, and at least above Clanwilliam Dam
Clanwilliam Dam
Clanwilliam Dam is a concrete gravity dam on the Olifants River, near Clanwilliam, Western Cape, South Africa. It was established in 1935, and the wall was raised to its current height of in 1964. The main purpose of the dam is to provide irrigation water to the agricultural region downstream...
and below Olifants Gorge it has apparently gone extinct.
L. capensis is found in large and small rivers, but do not like slowly-moving water. Young Clanwilliam Yellowfish (below 4 cm/1.6 in long) are found in backwater
Backwater (river)
A backwater is a part of a river in which there is little or no current. It refers either to a branch of a main river which lies alongside it and then rejoins it or to a body of water in a main river which is backed up by an obstruction such as the tide or a dam.-Alternative channel:If a river has...
s and shallow riffle
Riffle
A Riffle is a short, relatively shallow and coarse-bedded length of stream over which the stream flows at higher velocity and higher turbulence than it normally does in comparison to a pool....
s. As they grow older they move out of the riffles into deeper water but even adults may still be found in relatively shallow parts of their habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
. The presence of deep pools and dense riparian stands of Palmiet (Prionium serratum, a Thurniaceae
Thurniaceae
Thurniaceae is the botanical name for a family of flowering plants. Such a family has been recognized by most taxonomists.The APG II system, of 2003, also recognizes such a family, and assigns it to the order Poales in the clade commelinids, in the monocots...
) that provide shadow will aid its survival if its home rivers run dry in hot summers. The young eat zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
and other small aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s. Adults are omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
s, feeding on larger invertebrates and algae. Their breeding season is prolonged and lasts from late spring to summer (about October to December), when the water is at least 20 °C (68 °F). During that time, adults repeatedly move in small groups into shallow riffles where the water is only a few decimetre
Decimetre
A decimetre is a unit of length in the metric system, equal to one tenth of a metre, the SI base unit of length. In simple words there are 10 cm in a decimetre....
s deep, and deposit their non-sticky egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
s there. The hatchling
Hatchling
In oviparous biology, a hatchling is the newborn of animals that develop and emerge from within hard-shell eggs. The offspring of birds are often hatched naked and with their eyes closed. The hatchling relies totally on its parents for feeding and warmth. Hatchlings precede nestlings in the chick's...
s initially move away from light and will hide between the substrate
Substrate (biology)
In biology a substrate is the surface a plant or animal lives upon and grows on. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock can be substrate for another animal that lives on top of the algae. See also substrate .-External...
. In the absence of optimal breeding habitat (such as in dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
s), it will use any shallow water with generous rocks on the ground.
Status and conservation
Its stocks have declined precariously between the 1940s and 1970s, after the Smallmouth BassSmallmouth bass
The smallmouth bass is a species of freshwater fish in the sunfish family of the order Perciformes. It is the type species of its genus...
(Micropterus dolomieu) was introduced into its range. Though it is still found across a wide area and is plentiful in some places, the bass will eat young Clanwilliam Yellowfish and thus easily lower their stocks to local extinction. Less important as predators of juvenile L. capensis are Largemouth Bass
Largemouth bass
The largemouth bass is a species of black bass in the sunfish family native to North America . It is also known as widemouth bass, bigmouth, black bass, bucketmouth, Potter's fish, Florida bass, Florida largemouth, green bass, green trout, linesides, Oswego bass, southern largemouth...
(M. salmoides), Spotted Bass
Spotted bass
The Spotted Bass , also called "Spotty", "Leeman", or "Spots" in various fishing communities, is a species of freshwater fish sunfish family of order Perciformes. One of the black basses, it is native to the Mississippi River basin and across theGulf States, from central Texas through the Florida...
(M. punctalatus) and Bluegill
Bluegill
The Bluegill is a species of freshwater fish sometimes referred to as bream, brim, or copper nose. It is a member of the sunfish family Centrarchidae of the order Perciformes.-Range and distribution:...
s (Lepomis macrochirus). Largemouth Bass, Bluegills and Tilapia sparrmanii are also food competitors of young Clanwiliam Yellowfish. Habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
by canalisation and dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
ming as well as water pollution
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
by pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s and fertilisers in the runoff of agricultural land are affitional threats. Consequently, the species is listed as Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
by the IUCN.
It is also listed as Endangered by the Western Cape Province Nature Conservation Ordinance, making it illegal to kill it, and to catch it except for supervised translocation and research projects. It occurs in the Cederberg Wilderness Area and in the Greater Cederberg Biodiversity Corridor; the latter was established in 2004 to assist local landowners in sustainable development
Sustainable development
Sustainable development is a pattern of resource use, that aims to meet human needs while preserving the environment so that these needs can be met not only in the present, but also for generations to come...
. A research station dedicated to captive breeding
Captive breeding
Captive breedingis the process of breeding animals in human controlled environments with restricted settings, such as wildlife reserves, zoos and other conservation facilities; sometimes the process is construed to include release of individual organisms to the wild, when there is sufficient...
was established by the Cape Department of Nature Conservation in 1976; the captive breeding program ran until the 1990s By that time, though water quality
Water quality
Water quality is the physical, chemical and biological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose. It is most frequently used by reference to a set of standards against which...
control problems had hampered the work throughout, the station had provided thousands of young L. capensis public and private initiatives for establishing stocks. In a major gaffe, in the 1980s the species was established in the Twee River abvove some waterfall
Waterfall
A waterfall is a place where flowing water rapidly drops in elevation as it flows over a steep region or a cliff.-Formation:Waterfalls are commonly formed when a river is young. At these times the channel is often narrow and deep. When the river courses over resistant bedrock, erosion happens...
s which it could not naturally cross. In that region, the rare Twee River Redfin
Twee River Redfin
The Twee River Redfin or simply Twee Redfin is a ray-finned fish species in the family Cyprinidae. It is placed in the "wastebin genus" Barbus – the typical barbels and relatives – by default...
(Barbus erubescens) had managed to survive; it was subsequently outcompeted by L. capensis and disappeared from some of its remaining range, bringing it to the brink of extinction. The National Yellowfish Working Group was established in 1997 to follow up on the research station's program and to educate the public about the species, which may become of local or even commercial significance as food again if its stocks recover. Under the Cape Action for People and the Environment program launched in 1999, exotic invasive fishes
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
are to be eradicated from the watercourses of the Cape Floristic Region
Cape floristic region
The Cape Floristic Region is a floristic region located near the southern tip of South Africa. It is the only floristic region of the Cape Floristic Kingdom, and includes only one floristic province, known as the Cape Floristic Province.The Cape Floristic Region, the smallest of the six recognised...
. As regards the Clanwilliam Yellowfin former and current range, the eradication program has been slated to include the Krom and Rondegat Rivers.