Record of Blue tilapiaOreochromis aureus(Steindachner, 1864) in the Eerste River catchment, Western Cape province, South Africa

Abstract

Oreochromis aureus was imported from Israel into South Africa in 1959 but data on its current status in South Africa are lacking. Genomic DNA was extracted and the COI gene amplified at the South African Institute for Aquatic Biodiversity. The identity of the sequences and specimens was determined using the Barcode of Life Data Systems and GenBank. Morphological and genetic assessment demonstrated that 11 specimens collected from two farm dams in the Eerste River System, Western Cape province, were Oreochromis aureus. A MaxEnt model compiled using global distribution, rainfall and temperature data predicted that large areas of southern Africa were climatically suitable for this species, indicating considerable invasion debt in southern Africa. As a result, surveys to assess for the extent of the invasion in South Africa and eradication of existing populations, if feasible, are recommended management actions.

Alien Freshwater Fauna in South Africa

“…Its persistence in the Eerste River catchment was recently confirmed using morphological and genetic identification methods (Marr et al 2018). Impacts on native biota are likely to be similar to those reported for O. niloticus, including hybridisation with, and loss of genetic integrity by, native O. mossambicus (Marr et al 2018). The case of the O. aureus is interesting because it demonstrates the potential for the persistence of other introduced fish species that are presumed to have failed.…”

“…Most severe are the impacts on native minnows that have not coevolved with native predatory fishes (Ellender et al 2018). For example, in the Olifants River system in the Western Cape, predation has fragmented native minnow populations to such an Skelton and Weyl 2011;Marr et al 2018;Khosa et al 2019) extent that most species now only persist in headwater refugia that are isolated from black bass invasion by the presence of waterfalls (van der Walt et al 2016). This has reduced the available habitat for native fishes in the Olifants-Doring River system by more than 700 km of river (van der Walt et al 2016).…”

“…Although several cichlid species have been introduced into the country, there is currently only evidence for the establishment of the Blue Tilapia Oreochromis aureus (Marr et al 2018) and the Nile Tilapia Oreochromis niloticus .…”

“…Oreochromis aureus was imported (as "Tilapia nilotica") for experimental purposes from Israel to the Jonkershoek Hatchery near Stellenbosch in 1959 and released into farm dams in the Lourens and Eerste River catchments in 1961 and 1962 to evaluate its potential to survive the Western Cape winter (Marr et al 2018). Its persistence in the Eerste River catchment was recently confirmed using morphological and genetic identification methods (Marr et al 2018). Impacts on native biota are likely to be similar to those reported for O. niloticus, including hybridisation with, and loss of genetic integrity by, native O. mossambicus (Marr et al 2018).…”

On the Species Identification of Two Non-Native Tilapia Species, Including the First Record of a Feral Population of Oreochromis aureus (Steindachner, 1864) in South Korea

“…The Oreochromis aureus and O. niloticus species that inhabit the Dalseo Stream in Korea are considered to be highly invasive by the ISSG (Invasive Species Specialist Group), and are considered to be and are managed as one of the world’s top 100 disturbing species [ 41 , 48 ]. Many countries, including Brazil, Nicaragua, and South Africa, recognize the seriousness of the habitat disturbances caused by these species and prepare management measures to prevent them from spreading (e.g., physical blocking, population control through direct capture, biological control using potential predators) [ 22 , 49 , 50 , 51 ]. The negative impact that tilapia have in Korea ecosystem may not have detected due to a lack of data, because most of them live only in limited environments with thermal effluent outlets.…”