Sena S. De Silva, Rohana P. Subasinghe, Devin M. Bartley, and Alan Lowther; from the Food and Agriculture Organisation of the United Nations (FAO) authored a review (FAO Fisheries Technical Paper. No. 453. Rome, FAO. 2004. 65p.) on tilapia as an alien aquatic species, available online.
Tilapias are not native to Asia but have been a significant component of inland fisheries and aquaculture in the region for over half a century. They have been introduced into over 90 countries worldwide, with a global distribution second only to common carp. The contribution of tilapias to global aquaculture production has increased over the past three decades with production in 2002 exceeding 1.5 million tonnes with an estimated value of US$1.8 billion. The average annual growth rate in aquaculture and capture fisheries production of tilapias from 1970 to 2002 has been 13.2 percent and 3.5 percent, respectively. In the present context of development, success of a species is determined not only by its contribution to production per se, but also by its social, cultural, economic and environmental impacts. Although tilapia has been associated with adverse environmental impacts, detailed analysis of the literature suggested that other factors, such as overfishing, environmental degradation from land-based activities, and changes in hydrological regime have probably been more responsible for adverse impacts. It is clear that numerous factors working together can impact biodiversity. It is also clear that tilapias, as a group of alien species, have made a significant contribution to food production, poverty alleviation and livelihoods support in Asia and the Pacific. In spite of the wide-scale introduction into Asian waters, there is scant explicit evidence to indicate that tilapias have been overly destructive environmentally.