The Council for Scientific and Industrial Research (CSIR) is calling on South Africans to participate in a rapid citizen science survey to source knowledge on the distribution of Nile tilapia in South African watercourses.

Oreochromis niloticus (Linnaeus 1758), commonly known as the Nile tilapia (English) or Nyl kurper (Afrikaans) is an endemic African freshwater fish that is native to the Nile River basin and river systems of West Africa and the south-western Middle East. Since its initial introduction into Lake Victoria in the 1950s, the Nile tilapia is currently one of the most widely distributed invasive fish and has become established and naturalised in many tropical and sub-tropical environments in eastern and southern Africa. The Nile tilapia is known as an ‘aquatic chicken’ due to its high growth rates, adaptability to a wide range of environmental conditions and ability to grow and reproduce in captivity and feed on low trophic levels. Owing to its hardy nature, it has been widely introduced mainly for aquaculture, but also to augment capture fisheries and for sport fishing.

The citizen science survey forms part of a national Strategic Environmental Assessment (SEA) for aquaculture development in South Africa. The SEA was commissioned by the Departments of Environmental Affairs (DEA) and Agriculture, Forestry and Fisheries (DAFF). It forms part of Operation Phakisa and is aimed at promoting and supporting the sustainable growth of the aquaculture industry in South Africa. Nile tilapia is a candidate species being investigated in the SEA as a potential species to be incentivised for farming, but is also known to pose a risk to South Africa’s indigenous fish species.

According to Lizande Kellerman, the CSIR Environmental Scientist coordinating this study, “The survey aims to provide a better understanding of the presence and distribution of Nile tilapia in South African watercourses and will also serve as initial input for a national-scale biodiversity initiative to be undertaken by the DEA in collaboration with the South African National Biodiversity Institute (SANBI).”

This is how you can contribute to the survey: Please visit the Aquaculture SEA Project website: http://aquasea.csir.co.za/nile-tilapia-mapping/ and complete the online submission form providing us with details of your Nile tilapia catches. This online survey needs to be completed by 30 September 2017.

More on Nile tilapia

The Nile tilapia is regarded as the best growing fish species by the global aquaculture community and it has been the focus of much research and development over the past two decades. The Nile tilapia is produced in everything from open ponds fertilised with manure to closed recirculating aquaculture systems (RAS). Production, varying from subsistence culture to high-tech aquaponics, occurs in freshwater and in brackish to ocean salinities at optimal temperatures between 26°C and 30°C. However, South Africa’s Highveld climatic conditions require the use of closed-tunnel systems to provide adequate warmth for this tropical species. This is not necessary in areas that are 1 000 meters above sea level, which experience warmer climatic conditions.

The Nile tilapia exhibits a broad invasive potential over most of southern Africa that overlaps with the natural distribution range of the indigenous species such as Mozambique tilapia (Oreochromis mossambicus) (Mozambique tilapia [English] and Blou kurper [Afrikaans]). The introduction of the invasive Oniloticus into South African river systems that are still free of the Nile tilapia is a cause of concern for the conservation of indigenous tilapia that are at risk of local extinction through hybridisation and competition with the Nile tilapia. Although closed RAS are regarded as the higher yielding and economically more viable production method in South Africa and pose less environmental risk, the risk of escape from open pond culture and non-biosecured RAS into unaffected river systems remains. There are no effective means of controlling this species once introduced, therefore, mitigating efforts should focus on preventing its introduction to new freshwater habitats, especially those that serve as ‘sanctuaries’ for the indigenous Oreochromis species.

For more information contact Lizande Kellerman
Email: lkellerman@csir.co.za