Genetic identification and stock improvement of Tilapia in Malaysia and Fiji

• Ministry of Agriculture, Fisheries and Forests, Fiji
• Institute of Advanced Studies, Malaysia

Malaysia and Fiji face a problem currently confronting many countries - a decline in inshore marine fisheries due to over-exploitation. In the past few decades, they have responded by establishing aquaculture industries to help meet the demand for fish for human and livestock consumption.

Both countries have chosen to farm tilapia, a group of cichlid fishes considered pests in Australia but widely used for food in many parts of the world.

Tilapia have many attributes that make them suitable for fish farming in the tropics and subtropics. These include general hardiness, resistance to disease, the potential for high yield under sub-optimal conditions, the ability to utilise a wide variety of natural and artificial foods, and good eating qualities.

Tilapia species have proved attractive both for low technology, subsistence aquaculture to provide needed protein and for sophisticated, market-oriented fish farming.

However, they also have a number of drawbacks. Some species can reach sexual maturity at a very small size; such early maturation coupled with uncontrolled spawning can lead to a major proportion of the yield comprising unacceptably small fish.

Another problem is the ease with which hybridisation occurs between species and strains; the result can be reduced productivity due to the incorporation of unwanted traits.

Until recently, efforts to improve tilapia culture have concentrated on managing these problems by population control, but cost considerations and reliability problems have limited the success of this approach. The emphasis has now shifted to selection for improved performance and the establishment of genetically improved lines maintained as broodstock. A major development has been the initiation, by the International Centre for Living Aquatic Resource Management (ICLARM), of a research program, based in the Philippines, on genetic improvement of farmed tilapia. The ACIAR project - which arose from approaches from Fiji and Malaysia for assistance with stock improvement - will collaborate with that program.

It aims to genetically characterise existing Fijian and Malaysian tilapia stocks and strains and their hybrids; evaluate the productivity of the existing Fijian and Malaysian strains; and enhance expertise in fish culture and stock improvement in the participating nations (Fiji, Malaysia and Australia) via personnel exchange and consultation.

The work on genetic characterisation of existing stocks will provide baseline information on stock composition and the degree of genetic mixing that has occurred to date. The productivity evaluations, involving application of standardised experimental procedures by the research teams in Malaysia and Fiji, will permit comparison of stock performance under identical environmental conditions within each country. Replicated experiments will compare fry production and survival, growth performance, stocking rates, integrated versus non-integrated farming, and relative pathogen load.

If possible, the performance of in-country strains will be compared with that of a potentially genetically superior reference strain provided by ICLARM. This comparison, if it can be made, will assist Fijian and Malaysian authorities in deciding whether to develop their own indigenous broodstock or import broodstock. The links established with the ICLARM project will facilitate the development of tilapia breeding programs in both countries.

By identifying superior stock and developing local expertise, the project should result in a major increase in the productivity of tilapia used for aquaculture in Fiji and Malaysia. The resulting boost to the productivity of inland fish farming should lead to an easing of pressures on coastal and reef fisheries.

In Fiji, the number of farms producing tilapia increased from 33 to 160 between 1989 and the end of 1991, and similar growth is occurring in Malaysia. The potential for expanding the area devoted to aquaculture is large in both countries, with authorities suggesting 1200 ha in Fiji and 20 000 ha in Malaysia could be made available.

Areas that could be turned over to tilapia farming in the near future are put at 200 ha in Fiji and 2000 ha in Malaysia. Combined with increased productivity, the growth in size of the fish farming industry offers the prospect of very large increases in production of a high-grade, protein-rich food.

The project's focus on stock evaluation will have important spin-offs for the development of the Australian aquaculture industry, which is based on marine and freshwater native species. This industry, which as relied on wild, captured fish, will benefit from the expertise developed in applying advanced husbandry techniques to the farming of fish.