This document represents the report and contributed papers from a workshop of the same name. The workshop was comprised of a group of 30 international experts and representatives of the environmental, fisheries and policy development agencies of the countries in the Volta Basin.
In this study we present estimates of phenotypic and genetic parameters for body size measurements, reproductive traits, and gut length for Nile tilapia (Oreochromis niloticus) selected for growth in fertilized earthen ponds for two generations. Throughout the experiment, ponds were fertilized daily with 50 kg dry matter, (dm)/ha chicken manure. No supplementary feeds were added. For the analysis, 6429 fully pedigreed experimental fish from G0, G1 and G2 were used. Generations were discrete and therefore parameters were estimated separately for each year.
Silver barb (Puntius gonionotus Bleeker 1850) is an Asian carp that is popular as a food fish. It is distributed throughout Thailand in rivers, canals, reservoirs and swamps. It is also cultured in ponds and paddy fields. Its production from aquaculture in 2003 was estimated at 49,066 f metric tons (14 per cent of the total fish production), and valued at 34.6 millions US dollars, ranking third among freshwater fishes cultured in Thailand. However, the performance of many hatchery populations of silver barb is low, mainly due to a lack of improved stocks.
Gathering and recording of biological data vital to experiments in a genetic improvement program should be carried out with efficiency, precision and accuracy. This is important in order to avoid marking erroneous conclusion about the results. The GIFT team has so far standardized the methods of measuring some of the important phenotypic traits in tilapia. These traits are noted and measured during breeding and fry collection, stocking, rearing and harvesting activities. This manual lists the guideline required for sampling and recording of phenotypic traits.
From the history of introductions and the development of successful aquaculture elsewhere, it appears that the use of exotic species to speed up the rate of aquaculture development in Africa is unlikely to be an efficacious strategy. The major sustained aquaculture industries worldwide evolved from close working relationships between pioneering investors and local research-and-development institutions.
Aquaculture is predicted to play a major and ever increasing role in meeting human needs for protein. In terrestrial animal and plant species genetic improvement programs have made a substantial contribution to productivity and viability. By contrast, most aquaculture stocks in current use in developing countries are genetically similar or inferior to wild, undomesticated stocks. Hence, there is ample justification for the planning, design and implementation of genetic improvement programs for aquatic animal species.
The paper presents a brief summary of the available methods to determine connectivity using genetic markers and two examples where they have been applied in Southeast Asia. Recommendations for the more efficient conduct of the research based on the experiences from these projects are presented.
Genetic and phenotypic parameter estimates for tagging and harvest body weights were obtained from the F1 base (377 offspring of 59 full-sib families), F2 (1241 offspring of 52 full- and 33 half-sib families) and F3 (1052 offspring of 55 full- and 25 half-sib families) generations of Oreochromis shiranus. The fish were reared in earthen ponds at three different test environments inMalawi, which were high altitude (Chisitu), medium altitude (Domasi) and low altitude (Kasinthula) fish farms.
In comparison to the rest of the world, aquaculture in Africa is fairly insignificant. The continent as a whole contributed a mere 0.9 per cent (404 571 t) to the total world aquaculture production in 2000. The African continent, however, exhibits considerable potential in terms of land and water and in regard to inland, coastal and offshore resources. Genetic improvement of tilapias has a role to play in order to increase aquaculture production.