Mozambique tilapia (Oreochromis mossambicus) are hardy and can easily establish in natural waters near aquaculture ponds or cages, from which they may escape during loading-harvesting or via containment failures. Mozambique tilapia are particularly hardy, resistant to wide varieties of water salinity oxygen and pollution levels, and can migrate long distances. They are difficult to catch by angling. They occupy a wide range of habitats, and reproduce rapidly and successfully. Removal from natural water resources where they have established may be impossible. The most effective management is complete isolation of individuals from natural waters to prevent introductions. Established populations may require intensive fishing to prevent overpopulations from affecting native populations (Jeffrey McCrary pers.comm May 2005).
Preventative measures: The use of potentially invasive alien species for aquaculture and their accidental release/or escape can have negative impacts on native biodiversity and ecosystems. Hewitt et al, (2006) Alien Species in Aquaculture: Considerations for responsible use aims to first provide decision makers and managers with information on the existing international and regional regulations that address the use of alien species in aquaculture, either directly or indirectly; and three examples of national responses to this issue (Australia, New Zealand and Chile). The publication also provides recommendations for a ‘simple’ set of guidelines and principles for developing countries that can be applied at a regional or domestic level for the responsible management of Alien Species use in aquaculture development. These guidelines focus primarily on marine systems, however may equally be applied to freshwater.
Copp et al, (2005) Risk identification and assessment of non-native freshwater fishes presents a conceptual risk assessment approach for freshwater fish species that addresses the first two elements (hazard identification, hazard assessment) of the UK environmental risk strategy. The paper presents a few worked examples of assessments on species to facilitate discussion. The electronic Decision-support tools- Invasive-species identification tool kits that includes a freshwater and marine fish invasives scoring kit are made available on the Cefas (Centre for Environment, Fisheries & Aquaculture Science) page for free download (subject to Crown Copyright (2007-2008)).
Location Specific Management Information
Mozambique tilapia (Oreochromis mossambicus) aquaculture is restricted to southern California below the Tehacapi Mountains in San Bernadino, Los Angeles, Orange, Riverside, San Diego and Imperial counties.
In 2003, there were several unsuccessful attempts to eradicate Mozambique tilapia (Oreochromis mossambicus) using various techniques (chlorine, explosives, etc.). In December 2003 the President of Palau declared a Quarantine Emergency, and several agencies under the leadership of the Bureau of Agriculture developed a plan to eradicate the tilapia in four artificial ponds, the only known infested sites. These four ponds were treated with rotenone by a multi-agency team led by staff of the Palau Environmental Quality Protection Board (EQPB). Please follow this link for a Tilapia Eradication Effort – Phase I Final Report on this effort. The eradication was apparently successful, and in January 2006, almost two years after the treatment, the Declaration of Quarantine Emergency was lifted and the President declared that there were “no known infestations” of tilapia in Palau.
In August-September 2006 the National Invasive Species Committee received reports that there were again tilapia in the sedimentation pond at the national rock quarry, operated by Palau Transportation Company (PTC). Investigation showed that there were indeed tilapia present in the pond. The other three ponds were also checked and found to be tilapia-free.
It is not clear whether this is a new infestation or whether a few tilapia survived the earlier rotenone treatment. This pond has a small spring at its base and it is possible that a few tilapia survived at the opening of the spring and were not subsequently detected until their population had again built up. In any case, it was decided to take action immediately to destroy these fish.
On September 21, 2006, staff of the EQPB, Bureau of Agriculture, the Division of Fish and Wildlife Protection, and the Division of Fire and Rescue acted to destroy these fish, using the naturally-occurring, plant-derived fish poison, rotenone. This is the same fish poison which was used in the previous eradication efforts. Over 300 dead fish were recovered. A second application is planned before the end of 2006, to be certain that all the fish in the pond have been killed.
The government has received the full cooperation and support of PTC in this effort. PTC adjusted their blasting schedule, and provided application equipment at no charge. Without this support, the eradication effort would have been delayed, providing opportunities for these highly invasive fish to escape into the wild (Joel Miles., pers.comm., November 2006).
1. Aguirre, W. and Poss, S. 1999. Oreochromis mossambicus (Peters, 1852). University of Mississippi, College of Marine Sciences, Gulf Coast Research Laboratory Museum.
Summary: Chapter on Oreochromis mossambicus from a list of non-indigenous species in the Gulf of Mexico ecosystem.
2. Baird, R. 1976. Historical review of the SPC fisheries activities. South Pacific Commission, Noumea. 5 pp.
3. Centre for Environment, Fisheries & Aquaculture Science (CEFAS)., 2008. Decision support tools-Identifying potentially invasive non-native marine and freshwater species: fish, invertebrates, amphibians.
Summary: The electronic tool kits made available on the Cefas page for free download are Crown Copyright (2007-2008). As such, these are freeware and may be freely distributed provided this notice is retained. No warranty, expressed or implied, is made and users should satisfy themselves as to the applicability of the results in any given circumstance. Toolkits available include 1) FISK- Freshwater Fish Invasiveness Scoring Kit (English and Spanish language version); 2) MFISK- Marine Fish Invasiveness Scoring Kit; 3) MI-ISK- Marine invertebrate Invasiveness Scoring Kit; 4) FI-ISK- Freshwater Invertebrate Invasiveness Scoring Kit and AmphISK- Amphibian Invasiveness Scoring Kit. These tool kits were developed by Cefas, with new VisualBasic and computational programming by Lorenzo Vilizzi, David Cooper, Andy South and Gordon H. Copp, based on VisualBasic code in the original Weed Risk Assessment (WRA) tool kit of P.C. Pheloung, P.A. Williams & S.R. Halloy (1999).
The decision support tools are available from: http://cefas.defra.gov.uk/our-science/ecosystems-and-biodiversity/non-native-species/decision-support-tools.aspx [Accessed 13 October 2011]
The guidance document is available from http://www.cefas.co.uk/media/118009/fisk_guide_v2.pdf [Accessed 13 January 2009].
7. Courtenay, W. R., Jr. 1989. Exotic fishes in the National Park System. Pages 237-252 in L. K. Thomas, editor. Proceedings of the 1986 Conference on science in the national parks, volume 5. Management of exotic species in natural communities. U.S. National Park Service and
George Wright Society, Washington, DC.
8. Courtenay, W. R., Jr. and Robins, C. R. 1989. Fish introductions: good management, mismanagment, or no management? CRC Critical
Reviews in Aquatic Sciences 1(1): 159-172.
12. Hogan, A. and Vallance, T. (undated). An assessment of an NHT project to re-establish riparian zones as a
Tilapia control measure. Queensland Department of Primary Industries, Walkamin QLD.
Summary: A management plan that aims to reduce tilapia numbers by improving stream habitat quality.
13. Mendoza, R.E.; Cudmore, B.; Orr, R.; Balderas, S.C.; Courtenay, W.R.; Osorio, P.K.; Mandrak, N.; Torres, P.A.; Damian, M.A.; Gallardo, C.E.; Sanguines, A.G.; Greene, G.; Lee, D.; Orbe-Mendoza, A.; Martinez, C.R.; and Arana, O.S. 2009. Trinational Risk Assessment Guidelines for Aquatic Alien Invasive Species. Commission for Environmental Cooperation. 393, rue St-Jacques Ouest, Bureau 200, Montréal (Québec), Canada. ISBN 978-2-923358-48-1.
Summary: In 1993, Canada, Mexico and the United States signed the North American Agreement on Environmental Cooperation (NAAEC) as a side agreement to the North American Free Trade Agreement (NAFTA). The NAAEC established the Commission for Environmental Cooperation (CEC) to help the Parties ensure that improved economic efficiency occurred simultaneously with
trinational environmental cooperation. The NAAEC highlighted biodiversity as a key area for trinational cooperation. In 2001,
the CEC adopted a resolution (Council Resolution 01-03), which created the Biodiversity Conservation Working Group (BCWG),
a working group of high-level policy makers from Canada, Mexico and the United States. In 2003, the BCWG produced
the “Strategic Plan for North American Cooperation in the Conservation of Biodiversity.” This strategy identified responding to
threats, such as invasive species, as a priority action area. In 2004, the BCWG, recognizing the importance of prevention in addressing
invasive species, agreed to work together to develop the draft CEC Risk Assessment Guidelines for Aquatic Alien Invasive
Species (hereafter referred to as the Guidelines). These Guidelines will serve as a tool to North American resource managers
who are evaluating whether or not to introduce a non-native species into a new ecosystem. Through this collaborative
process, the BCWG has begun to implement its strategy as well as address an important trade and environment issue. With increased
trade comes an increase in the potential for economic growth as well as biological invasion, by working to minimize the potential adverse
impacts from trade, the CEC Parties are working to maximize the gains from trade while minimizing the environmental costs.
Available from: English version: http://www.cec.org/Storage/62/5516_07-64-CEC%20invasives%20risk%20guidelines-full-report_en.pdf [Accessed 15 June 2010]
French version: http://www.cec.org/Storage/62/5517_07-64-CEC%20invasives%20risk%20guidelines-full-report_fr.pdf [Accessed 15 June 2010]
Spanish version: http://www.cec.org/Storage/62/5518_07-64-CEC%20invasives%20risk%20guidelines-full-report_es.pdf [Accessed 15 June 2010].
14. Ranoemihardjo, B. S. 1981. Nauru: eradication of tilapia from fresh- and brackish-water lagoons and ponds with a view of promoting milkfish culture. FI:DP/NAU/78/001 Field Document 1, FAO, Rome.
15. Trewavas, E. 1983. Tilapiine fishes of the genera Sarotherodon, Oreochromis and Danakilia. British Museum (Natural History), London, UK: 292-315.
Summary: Taxonomic account and compilation of other biological data available for the mouth-brooding tilapias.
Results Page: 1