The Orange River is the longest watercourse in Southern Africa. Lying south of the Zambezi River, The Orange River rises in the Drakensberg Mountains and flows westward to discharge into the Atlantic Ocean. The river has a length of 2208 kilometres and drains 48 percent of the land area of South Africa and forms the national boundary between that country and Namibia. The total drainage area amounts to 896,368 square kilometres, and the discharge at the mouth is about 11.5 cubic kilometres per annum.
Excessive nutrient loading from overly intensive fertilizer usage in agricultural areas in the Vaal and middle reach Orange River is the major water quality issue in the basin. Headwaters areas of the basin support high endemism in flora and reptiles, while the middle reaches of the basin boast significant endemism in small mammals. Lower reaches of the basin support high endemism in both reptiles and small mammals.
The chief water quality concerns are within South Africa, and more specifically in the densely populated areas of Johannesburg, Pretoria and the Vaal Triangle. Exacerbating the issue are insufficiency and ageing of the wastewater treatment plants of that locale, and the fact that discharges from that high population density region is at a higher elevation than the principal dams along the Orange River; thus, inevitably polluted discharges from the densely populated area reaches these warm termperature reservoirs, which are then poised to generate elevated bacterial levels.
Within the Orange River system 21 different fish taxa have been recorded, most of which are benthopelagic. The three largest benthopelagic native species are: the 170 centimetre (cm) long North African Catfish (Clarias gariepinus), the 122 cm Flathead Grey Mullet (Mugil cephalus) and the endemic 92 cm Vaal-Orange Largemouth Yellowfish (Labeobarbus kimberleyensis). Other noteworthy native benthopelagics are the basin endemic 56 cm Orange River Mudfish (Labeo capensis), the 56 cm basin endemic Smallmouth Yellowfish (Labeobarbus aeneus), the 45 cm Redbreast Tilapia (Tilapia rendalli). L aeneus may be useful in algae control in the Orange basin, since this omnivorous bottom feeder consumes considerable algae in its diet. The 146 cm Wild Common Carp (Cyprinus carpio carpio) is the largest introduced benthopelagic alien species in the Orange River.
The largest fish species in the Orange River system is the 200 cm pelagic-neritic Leerfish (Lichia amia), which is a true aquatic apex predator, functioning at trophic level 4,5. Native demersal fish are the 40 cm South African Mullet (Liza richardsonii) and the near endemic 37 cm Rock Catfish (Austroglanis sclateri).
Die grootbek-geelvis (Labeobarbus kimberleyensis) is 'n varswatervis wat voorkom in die Oranje- en Vaalrivier-stelsels in Suid-Afrika. In Engels staan die vis bekend as die largemouth yellowfish.
Die vis is lank en silwerkleurig wanneer dit jonk is en word olyfkleurig soos hy verouder. Die vis kan tot 80 cm lank word en weeg dan 22 kg. Dit het 'n groot bek met twee paar baarde onderaan. Die wyfie word groter en leef langer as die mannetjie. Dit is die grootste van die inheemse geskubde visse in Suid-Afrika. Die Suid-Afrikaanse hengel rekord is 22.2 kg.
Die vis leef in die Oranje- en Vaalrivier opvanggebied, is 'n roofvis en eet klein vissies, insekte en skulpvis. Die vis groei stadig en die mannetjie bereik volwassenheid wanneer hy ses jaar oud word en die wyfie eers op agt jaar. Die wyfie lê haar eiers gedurende die somer op gruisbeddings in vinnig vloeiende riviere. Die larwes broei uit na 2-3 en begin vreet na 3 -4 dae. Hulle is 100 mm lank na twee jaar en 300 mm na vyf jaar.
Die grootbek-geelvis (Labeobarbus kimberleyensis) is 'n varswatervis wat voorkom in die Oranje- en Vaalrivier-stelsels in Suid-Afrika. In Engels staan die vis bekend as die largemouth yellowfish.
Labeobarbus kimberleyensis és una espècie de peix pertanyent a la família dels ciprínids.[5]
Es reprodueix des de mitjans de l'estiu fins a finals de la mateixa estació sobre fons de grava.[6]
Com a juvenil menja insectes i crustacis petits, mentre que a partir dels 30 cm de llargària es nodreix de peixos.[6]
És un peix d'aigua dolça, potamòdrom, bentopelàgic i de clima subtropical (24°S-30°S).[6][8]
Es troba a Àfrica: les conques dels rius Orange i Vaal (Namíbia i Sud-àfrica).[6][9][10][11][12][13][14][15][16]
És exportat als mercats dels Estats Units i del Canadà.[17]
És inofensiu per als humans.[6]
Labeobarbus kimberleyensis, im englischen Largemouth Yellowfish oder Vaal-Orange Largemouth Yellowfish genannt, oder auf Afrikaans Grootbek-Geelvis, ist eine große Barbenart, die nur in Südafrika vorkommt.
Die Fische werden bis 120 Zentimeter lang und 22 Kilogramm schwer, was durch ein mit der Angel gefangenes Exemplar aus dem Vaal-Stausee dokumentiert wurde. Ein kommerziell gefangener Largemouth Yellowfish wog sogar 52 Kilogramm.[1]
Labeobarbus kimberleyensis ist endemisch im subtropischen Oranje-Vaal Flusssystem und dessen Nebenflüssen wie dem Riet River, in Lesotho, Namibia[2] und Südafrika heimisch und gehört dort zu den größten einheimischen Fischarten zwischen dem 24° und 30° Breitengrad südlicher Länge.[3] In Südafrika findet man den Largemouth Yellowfish in den Provinzen Ostkap, Freistaat, Gauteng, Mpumalanga, Nordwest und Nordkap. Adulte Exemplare bevorzugen strömungsreiche Gewässerabschnitte, über zwei Meter tiefe Pools hinter Stromschnellen, finden aber auch im langsam fließenden Wasser der Stauseen vor Wehren und Staudämmen wie dem Sterkfontein-Staudamm einen geeigneten Lebensraum.[3] Eine reiche Wasservegetation, dicht bewachsene Uferpartien und oberflächenbedeckende Wasserpflanzen sind für das Überleben ihrer Art von großer Bedeutung.
Der Largemouth Yellowfish ist ein Spitzenprädator und steht in seinem Habitat an der Spitze der Nahrungskette. Während sich Jungfische von Labeobarbus kimberleyensis noch von Krebstieren und Wasserinsekten ernähren, werden sie ab einer Länge von 30 Zentimetern überwiegend zu piscivoren Raubfischen.[3] Im Sommer in den Monaten Dezember bis Januar laichen sie in sauerstoffreicher Strömung auf Kiesbetten ab.[3] Große Weibchen können dabei bis zu 60.000 Fischeier ablegen. Largemouth Yellowfish sind langsam wachsend, erreichen mit fünf Jahren erst eine Länge von 30 Zentimetern, in Ausnahmefällen können sie bis 12 Jahre alt werden.
Labeobarbus kimberleyensis gehört zu den Karpfenfischen. Lange Zeit wurde L. kimberleyensis in die Gattung der Barbus eingruppiert, bis sie später in die eigenständige Gattung Labeobarbus klassifiziert wurden. Labeobarbus kimberleyensis hat vermutlich einen hexaploiden Chromosomensatz. Sie weist einen ähnlichen Haplotyp der mitochondrialer DNS wie Labeobarbus aeneus auf, unterscheidet sich aber morphologisch. Dies ist typisch für Arten, die in ihrer jüngeren Stammesgeschichte eine Divergenz oder hybride Introgression erfahren haben, oder für Morphen, die fälschlicherweise als unterschiedliche Arten beschrieben wurden. Letzteres ist im Fall dieser beiden Arten aber unwahrscheinlich, da sie sich nicht nur in ihrer Größe unterscheiden. Die molekulargenetischen Gemeinsamkeiten beider Arten sind bisher unerforscht.[4]
Labeobarbus kimberleyensis ist ein Speisefisch, Filets vom Largemouth Yellowfish werden aus Südafrika teilweise für den nordamerikanischen Markt exportiert.[3] Überfischung können lokale Bestände an den Rand des Aussterbens bringen und außerdem vermutet man, dass der Largemouth Yellowfish als Spitzenprädator größere Mengen von Schadstoffen in seinem Fleisch anreichert. Verglichen mit anderen südafrikanischen Süßwasserfischarten gilt der Bestand von Labeobarbus kimberleyensis vor allem am Unterlauf des Oranje-Flusses als derzeit noch nicht bedroht. Aufgrund der zunehmenden Degradation und Verschmutzung durch Abwassereinleitung ihrer Lebensräume könnte sich diese Situation in Zukunft ändern. Da der Largemouth Yellowfish in seinem Ökosystem die Rolle des Spitzenprädatoren einnimmt, glaubt man, dass seine Population wenig individuenreich ist. Als Sportfisch ist der Largemouth Yellowfish bei Anglern beliebt, wobei man in Südafrika weitgehend das Catch and Release praktiziert. In den Nationalparks Augrabie und Richtersveld gelten für Angler bestandsschonende Verordnungen beim Fang dieser Fische.[5]
Labeobarbus kimberleyensis, im englischen Largemouth Yellowfish oder Vaal-Orange Largemouth Yellowfish genannt, oder auf Afrikaans Grootbek-Geelvis, ist eine große Barbenart, die nur in Südafrika vorkommt.
The largemouth yellowfish or Vaal-Orange largemouth yellowfish (Labeobarbus kimberleyensis) is a ray-finned fish species in the family Cyprinidae. This large freshwater barb is found in southern Africa.[2]
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 probably hexaploid like the other yellowfish. L. kimberleyensis shares mtDNA haplotypes with the sympatric smallmouth yellowfish (L. aeneus), but is morphologically distinct. This typically indicates either species that have recently diverged, or hybrid introgression, or morphs that are mistakenly considered distinct species. The latter does not seem likely in this case, as the two differ much in size alone, but the actual cause for the genetic similarity remains unstudied.[3]
The largemouth yellowfish occurs in the Orange and Vaal Rivers and their larger tributaries (e.g. the Riet River) in Lesotho, Namibia and South Africa. In the latter country, it is found in Eastern Cape Province, Free State, Gauteng, Mpumalanga, North-West Province and Northern Cape Province.[2]
L. kimberleyensis is predominantly found in deep pools (deeper than 2 metres/yards) of large rivers, as well as in the slow-moving water before weirs and river dams (e.g., Sterkfontein Dam). Abundant water weeds, overhanging riparian vegetation and other forms of plant cover seem to be essential for its well-being. They are predators of aquatic large invertebrates and small invertebrates; adults feed almost exclusively on fish. Spawning occurs in riffles during summer (around December/January); a large female can lay more than 60,000 eggs. They are slow-growing and long-lived and reach a total length of 30 cm (12 in) only after five years.[2]
Compared to some of its relatives, the stocks of the largemouth yellowfish are still relatively healthy and it is not considered a threatened species. It is listed as Near Threatened by the ICZN though, as many ecosystems in which it occurs are severely degraded, and if this does not change, it probably cannot maintain viable populations for long. In the lower Orange River, considerable numbers are still found. Damming may cut off local populations from spawning sites. The Vaal River is highly laden with pollutants from sewage outside the wet season, and fish kills have been reported due to this. As it is an apex predator, its population density cannot be high. It is popular with anglers and theoretically a valuable food species, but it is recommended to catch and release it until the water quality is improved – for one thing, catching them for food may deplete local stocks to the point of extinction, for another, as an apex predator it accumulates toxins and may not be safe to eat. Whether significant introgression with the smallmouth yellowfish (Labeobarbus aeneus) occurs and yields less viable hybrid offspring (which would also serve to decrease its stocks) needs to be determined.[2]
L. kimberleyensis is found in the Augrabies Falls and Richtersveld National Parks. Anglers are being educated about this flagship species and encouraged to practice catch and release, which is mandatory in Free State. The species has also been successfully transplanted to dams within its range that have nearby shallow-water regions for spawning.[2]
The largemouth yellowfish or Vaal-Orange largemouth yellowfish (Labeobarbus kimberleyensis) is a ray-finned fish species in the family Cyprinidae. This large freshwater barb is found in southern Africa.
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 probably hexaploid like the other yellowfish. L. kimberleyensis shares mtDNA haplotypes with the sympatric smallmouth yellowfish (L. aeneus), but is morphologically distinct. This typically indicates either species that have recently diverged, or hybrid introgression, or morphs that are mistakenly considered distinct species. The latter does not seem likely in this case, as the two differ much in size alone, but the actual cause for the genetic similarity remains unstudied.
Labeobarbus kimberleyensis Labeobarbus generoko animalia da. Arrainen barruko Actinopterygii klasean sailkatzen da, Cyprinidae familian.
Labeobarbus kimberleyensis Labeobarbus generoko animalia da. Arrainen barruko Actinopterygii klasean sailkatzen da, Cyprinidae familian.
Labeobarbus kimberleyensis is een straalvinnige vissensoort uit de familie van eigenlijke karpers (Cyprinidae).[2] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1913 door Gilchrist & Thompson.
De soort staat op de Rode Lijst van de IUCN als Gevoelig, beoordelingsjaar 2007. De omvang van de populatie is volgens de IUCN dalend.[1]
Bronnen, noten en/of referenties
Labeobarbus kimberleyensis é uma espécie de peixe actinopterígeo da família Cyprinidae.
Apenas pode ser encontrada na África do Sul.
Labeobarbus kimberleyensis é uma espécie de peixe actinopterígeo da família Cyprinidae.
Apenas pode ser encontrada na África do Sul.
Labeobarbus kimberleyensis là một loài cá vây tia trong họ Cyprinidae. Loài cá nước ngọt lớn này được tìm thấy ở southern Africa.[1] Chúng đã được đặt trong chi Barbus một cách mặc định, tuy nhiên đang có xu hướng ngày càng tăng đưa nó vào chi Labeobarbus.
Loài này phân bố ở sông Orange và sông Vaal và các nhánh lớn của nó (như sông Riet) ở Lesotho, Namibia và Nam Phi. Trong những năm gần đây, Loài này có ở tỉnh Eastern Cape, Free State, Gauteng, Mpumalanga, tỉnh North-West và tỉnh Northern Cape.[1]
L. kimberleyensis chủ yếu được tìm thấy ở hồ sâu hơn 2 mét của các sông lớn cũng như ở vùng nước chảy chậm.
Bài viết về Họ Cá chép này vẫn còn sơ khai. Bạn có thể giúp Wikipedia bằng cách mở rộng nội dung để bài được hoàn chỉnh hơn. Labeobarbus kimberleyensis là một loài cá vây tia trong họ Cyprinidae. Loài cá nước ngọt lớn này được tìm thấy ở southern Africa. Chúng đã được đặt trong chi Barbus một cách mặc định, tuy nhiên đang có xu hướng ngày càng tăng đưa nó vào chi Labeobarbus.
Loài này phân bố ở sông Orange và sông Vaal và các nhánh lớn của nó (như sông Riet) ở Lesotho, Namibia và Nam Phi. Trong những năm gần đây, Loài này có ở tỉnh Eastern Cape, Free State, Gauteng, Mpumalanga, tỉnh North-West và tỉnh Northern Cape.
L. kimberleyensis chủ yếu được tìm thấy ở hồ sâu hơn 2 mét của các sông lớn cũng như ở vùng nước chảy chậm.
大口魮（学名：Labeobarbus kimberleyensis）为輻鰭魚綱鯉形目鲤科的其中一種，分布於非洲橘河流域，體長可達82.5公分，棲息在流動快速的水域或水庫，屬肉食性，以昆蟲、小型甲殼類及魚類等為食，繁殖期在夏季，可做為遊釣魚。
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