Indigenous versus exotic species in African aquaculture
|
Growing poverty and population in Africa increases the pressure on governments to maximize food production as rapidly and as cheaply as possible. Urgency often results in a failure to carefully review costs and benefits. Policy-makers trying to feed hungry people and investors seeking quick returns are strongly compelled by the perceived magic bullet of importing an exotic species that has proven its worth in other countries or regions. However, the track record of aquaculture-related introductions in Africa (see Table 1) shows that bringing in exotic species to get quick results seldom produces the desired outcome. In reviewing 212 international introductions into Africa of freshwater fishes for aquaculture, only 33 (16%) were found to have resulted in the establishment of an industry with output of more than 10 mt per year in 1997. Of these, 10 (30%) were of common carp (Cyprinus carpio) from Asia and Europe and 7 (21%) were of Nile tilapia (Oreochromis niloticus) from other African countries. Typical is the case of Zambia where 39 introductions resulted in sustained aquaculture of only Nile tilapia and common carp. Production of these two species in 1997 was only 133 and 275mt, respectively, compared to 2 680 and 1 010 mt for the indigenous Oreochromis andersonii and Tilapia rendalli, respectively (see Table 2).
In terms of weight produced, over 99 percent of the total production of exotic species in Africa in 1997 was of common carp in only two countries, Egypt (22 mt) and Madagascar (6 mt). Currently, the common carp industry in Egypt is in serious decline due to reduction of government subsidies and consumer preference for the indigenous Nile tilapia. In total, exotic species account for 15 percent of African aquaculture output. In Asia, the powerhouse of world aquaculture, 517 introductions have resulted in a total contribution of 5 percent to total output.
The main reason why exotics have failed to produce better growth of the aquaculture sector in Africa is because the germplasm being cultivated is only one, and not currently the most important, constraint to development. Africa possesses adequate aquatic biodiversity to sustain aquaculture development. Asia, the world leader in aquaculture, relies on exotics for only five percent of total production and the number of indigenous freshwater fish species in Asia and Africa is approximately the same, 2 943 and 2 660, respectively (Christine Casal, ICLARM, Personal Communication, November 1999). Far more important than lack of species are inadequate inputs, shortage of seed, lack of the necessary research, development and extension (R, D & E) to backstop industrial growth and poor market development. While inadequate inputs affect indigenous and exotic species alike, indigenous species may have an advantage in seed production, R, D and E and markets. Well over 90 percent of the African fish farming sector are smallholders. To be viable and self-sustaining, the smallholder sector needs species that can be reproduced without complicated and/or expensive interventions. Encouraging dependence upon exotic species that require hatchery facilities for propagation will only exacerbate the fingerling supply problem. Inadequate hatchery reserves of broodfish are a major cause of inbreeding depression in cultured stocks. For indigenous species, there are ready reserves of broodstock that are already adapted to local environmental and climatic conditions for their reproduction. New feeds, disease therapies, reproduction techniques and sometimes even pond designs are needed when species additions or changes are taking place. The R & D process, through which new management strategies are developed, is probably the best way to produce both the needed technology and the skilled scientists and extension personnel to support aquaculture development. Exotic species are normally introduced to only one research facility at a time. In situations where high quality human resources are in short supply, this may limit the number of researchers studying the domestication of a particular species to only one or two. With indigenous species, any student, scientist, would-be farmer or extension agent in the country can get involved. Many technology-driven development initiatives introduce complete production systems (including the culture species) more or less without regard to markets. The common carp industry in Egypt is a good example. Carp were introduced as an ideal fish for culture in rice paddies. Millions of carp fingerlings were produced in government hatcheries and delivered at subsidised prices to rice farmers. At give-away prices, these fish were a source of cheap protein to the urban poor, but as government subsidies declined and the price of carp rose to cover costs, consumers with sufficient income switched back to the indigenous tilapias while poorer segments of the market simply didn't buy fish. Carp production in Egyptian rice fields collapsed from a reported 21 000 tonnes in 1996, to less than 7 000 tonnes in 1997. For whatever reasons, the track record shows that indigenous African species are more likely to contribute to local economic growth and put food into African markets faster than exotics. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Prepared by Randall E. Brummett
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
Close-up of a common carp
|
|
|
Aquaculture ponds in Madagascar
|
|
links |
|
further information International
Centre for Living Aquatic Resources Management
(ICLARM) |
|
additional reading Atlas of alien and translocated indigenous aquatic animals in southern Africa. I.J.de Moore and M.N. Burton. South African National Scientific Programmes Report No. 144. 1988.MNB publishers, Port Elizabeth South Africa. |
