Die Witvis (Barbus andrewi) is 'n vis wat in die Bergrivier en die Breederivier-stelsels in Suid-Afrika voorkom. In Engels staan die vis bekend as die Berg-Breede river whitefish, soms ook as die Cape whitefish.
Die onvolwasse vissies is silwer met onreëlmatige vlekke op terwyl die volwasse visse donker olyfkleurig is aan die bokant, goudkleurig aan die kante en roomkleurig aan die onderkant is. Die vis word tot 60 cm lank en die Suid-Afrikaanse hengelrekord is 3.407 kg.
Die vis leef in diep rotspoele van groter sytakke en hoofstrome. Hulle oorleef ook in die Voëlvlei- en Groter Brandvleidamme. Die vis vreet ongewerweldes wat op die bodem voorkom en ook alge. Hulle broei in die somer. Die eiers word in vloeiende water gelê en broei na ongeveer vyf dae uit.
Die Witvis (Barbus andrewi) is 'n vis wat in die Bergrivier en die Breederivier-stelsels in Suid-Afrika voorkom. In Engels staan die vis bekend as die Berg-Breede river whitefish, soms ook as die Cape whitefish.
The Cape whitefish or Berg-breede River whitefish (Pseudobarbus capensis) is a ray-finned fish species in the family Cyprinidae. It is placed with the South African redfins in Pseudobarbus. It is tetraploid. Its closest living relative was at one time considered the sawfin (P. serra).[3]
It is endemic to the Western Cape Province of South Africa, where it occurs in the Breede River's Brandvlei Dam and Sanddrift Dam, as well as the Hex River. Formerly, it was also found in and around the Berg River, but it seems to have disappeared from there.[2] Populations have also been transplanted to farm water catchments, but it is not well known if these have thrived or failed.[4]
It inhabits the deeper stretches of rivers with rocky shores or riparian trees. While young fish are common in riffles, adults are not rheophilic and will thrive in slow-moving water. Young fish are carnivores, eating zooplankton and small aquatic invertebrates. Adults have more omnivorous diets that consist of benthic invertebrates and algae. The breeding season is in late spring (about October) when the water has warmed to above 20 °C (68 °F). Schools of adults form to migrate to riffles with over one meter/yard deep water and spawn in the late hours of morning. A good-sized adult female produces about 100,000 eggs. In dams, it will use rocky and gravelly substrate in the shallows as a spawning place. The species is long-lived.[4]
This species is considered Endangered by the IUCN as it has declined much in recent decades. The main threat is the introduced smallmouth bass (Micropterus dolomieu), which has killed off the stocks of the fish in the Berg River watershed by eating juveniles. In Brandvlei Dam, where the barb's population is most healthy, the African catfish (Clarias gariepinus) is spreading; its impact will need to be assessed. The common carp (Cyprinus carpio) and Mozambique tilapia (Oreochromis mossambicus), introduced for aquaculture, are competing with the Cape whitefish for food. Water pollution is also a problem.[4]
It is also listed as endangered by the Nature Conservation Ordinance of Western Cape Province. For the time being, it may not be killed and only caught for supervised transfer trials to other habitats. An initiative is aimed at restoring the stocks, so this large fish can be used in fishing and maybe aquaculture as an alternative to the harmful introduced species. [4]
There are many reasons as to why the population of the cape whitefish have recently been declining, with human-related activity being one of them. A severe flood in 2008 as well as invasions of other predatory fish species are a likely cause of the decline as well. In order to prevent further decline, there are conservation actions in place such as managing non-native fish invasions as well as lessening the agricultural impact on aquatic habitat. [5]
The Cape whitefish or Berg-breede River whitefish (Pseudobarbus capensis) is a ray-finned fish species in the family Cyprinidae. It is placed with the South African redfins in Pseudobarbus. It is tetraploid. Its closest living relative was at one time considered the sawfin (P. serra).
Barbus andrewi es una especie de peces de la familia de los Cyprinidae en el orden de los Cypriniformes.[2]
Los machos pueden llegar alcanzar los 60 cm de longitud total.[3]
Es un pez de agua dulce.
Se encuentra en la cuenca del río Breede al suroeste de la provincia del Cabo (Sudáfrica).
Barbus andrewi es una especie de peces de la familia de los Cyprinidae en el orden de los Cypriniformes.
Barbus andrewi Barbus generoko animalia da. Arrainen barruko Actinopterygii klasean sailkatzen da, Cyprinidae familian.
Barbus andrewi Barbus generoko animalia da. Arrainen barruko Actinopterygii klasean sailkatzen da, Cyprinidae familian.
Barbus andrewi è pesce d'acqua dolce appartenente alla famiglia Cyprinidae.
Questa specie è diffusa nelle acque dolci del fiume Breede, nella provincia del Capo, in Sudafrica. Frequenta acque profonde con fondali rocciosi.
Presenta un corpo dalla forma tipicamente barboide, dal corpo allungato, poco compresso ai fianchi, snello ma scattante, ricoperto da grosse scaglie. Il profilo dorsale è convesso, meno quello ventrale. Le pinne sono triangolari. La livrea vede un colore bruno-dorato dai riflessi bronzei, leggermente più scuro su testa e dorso. Le pinne sono brune con riflessi bronzei. Gli esemplari maschili possono raggiungere una lunghezza massima di 60 cm.[2]
La fregola avviene in primavera: gli adulti si ritrovano sotto rapide o immissari e dopo la scelta del partner avviene la deposizione e la fecondazione esterna delle uova, che vengono abbandonate tra la ghiaia di acque correnti. Si schiuderanno dopo 5 giorni di incubazione.
Si nutre di alghe e piccoli invertebrati.
B. andrewi è oggetto di pesca sportiva ma vista la criticità dell sua presenza nell'habitat originario è oggetto di sperimentazioni in acquacoltura per aumentarne il numero.
Barbus andrewi è pesce d'acqua dolce appartenente alla famiglia Cyprinidae.
Pseudobarbus capensis é uma espécie de peixe actinopterígeo da família Cyprinidae.
Apenas pode ser encontrada na África do Sul.
Pseudobarbus capensis é uma espécie de peixe actinopterígeo da família Cyprinidae.
Apenas pode ser encontrada na África do Sul.
