NEW FAO PUBLICATIONS

Tave, D. 1999. Inbreeding and brood stock management. FAO Fisheries Technical Paper. No. 392. Rome, FAO. 122 pp.

This manual, written for extension workers, aquaculturists, and
those who work with natural resource m a n a g e m e n t
programmes, primarily deals with the problems caused by unwanted inbreeding in cultured fish populations and describes management techniques that can be used to prevent or minimize inbreeding.

The manual also describes how inbreeding can be used to improve captive populations of fish. The manual contains chapters on: basic genetics and the genetics of inbreeding; how to determine individual inbreeding values when pedigrees are known; how to determine the average inbreeding value in a population when pedigrees are not known; genetic drift, which is random changes in gene frequency; how inbreeding programmes can be used to improve cultured populations of food fish; how to prevent inbreeding depression and loss of genetic variance in farmed populations; and recommendations on how to manage cultured populations of fish to prevent unwanted inbreeding and genetic drift from depressing productivity, profits, and survival.

One of the most important aspects of managing a closed population offish at a fish farm or fish culture station is the management of the population's effective breeding number, because inbreeding is inversely related to the effective breeding number.

Techniques to determine and manage the effective breeding number are described, and recommended mininum effective breeding numbers are provided for a variety of farm sizes and fish culture goals. A number of culture techniques can affect inbreeding, and ways to modify them so there is minimal impact on inbreeding are discussed. Finally, ways to minimize inbreeding during selective breeding programmes are described.

Pullin, R.S.V., D.M. Bartley and J.Kooiman, Editors. 1999. Towards policies for conservation and sustainable use of aquatic genetic resources. ICLARM Conf. Proc. 59, 277pp.

FIRI is pleased to announce the publication, Towards policies for conservation and sustainable use of aquatic genetic resources, edited by R.S.V. Pullin, D.M. Bartley and J. Kooiman (ICLARM Conference Proceedings 59, 1999). The publication represents the proceedings from the ICLARM/FAO Bellagio Conference held in Bellagio Italy, 14 to 18 April 1998. As Dr Louise Fresco, currently Assistant Director General of the Agriculture Department FAO states in the Foreword to the proceedings, "... the development of sound policies governing the use of aquatic genetic resources has, in general, lagged behind the impressive technical developments . ... this volume represents one of the first efforts at bringing together the diverse information necessary for the development of policies for the sustainable use and conservation of aquatic genetic resources." The proceedings include a wide range of disciplines, such as aquatic biology, aquaculture, population genetics, fish breeding, governance of natural resources, fisheries, public awareness, intellectual property rights, and law, that will all play a role in policy formulation. For information on how to order please contact Devin M. Bartley ([email protected]) or ICLARM Publication Unit Manager PO BOX 500, GPO, 10670
Penang, MALAYSIA ([email protected]).

NEW FAO PUBLICATIONS

Fernando, C.H. and M. Halwart. 2000. Possibilities for the integration of fish farming into irrigation systems. Fisheries Management and Ecology,
Vol. 7, p. 45-54.

Abstract: Harvesting fish in irrigation systems, sometimes involving some form of husbandry or even culture, is a practice which dates back at least two millennia. Although seldom recorded, it seems to have been widespread in the tropics and subtropics, especially in rice fields. In the present century, improved management for land-based crops and the demands for the successful raising of aquatic organisms were not generally compatible, but with the advent of integrated crop protection, this situation has changed drastically. Moreover, irrigation systems using stored or diverted water have increased exponentially during the past 50 years, but fish farming within these irrigated systems has not expanded equally, and therefore, there is now a huge potential for this integrated enterprise. A systematic approach to fish farming development at irrigation system level which will make this integration a viable enterprise is proposed.

The whole range of aquatic habitats created by irrigation systems can be integrated with fish farming. Small and large irrigation reservoirs, the extensive network of irrigation canals, the irrigated fields themselves, as well as adjacent ponds or aquatic refuges of various sorts are all potentials sites for nursing or grow-out fish. In many countries, there is now relatively easy access to fish seed, even in inland areas. Permanent water bodies should be stocked with a central pool of culture species harvested from short-lived habitats which serve as nurseries. A flexible system of moving culture fish within the system of habitats should be feasible. For example, stocking material for reservoirs can be obtained from irrigated rice fields where the short maturation period of the crop only permits the harvest of fingerlings. If a pragmatic and flexible approach is made to use all habitats for fish production, there could be a year-round supply of fish and a minimum wastage of stocks of cultured fish.

The use of high-yielding fish of good quality is essential for economic viability. In areas where a high diversity of fish with a requisite biomass of

desirable species already exists, these indigenous fish can be harvested, but their yields may only be adequate for low-income rural areas. Common carp, Cyprinus carpio L., has traditionally been a preferred cultured species. Tilapia are proposed as an alternative because these fish are cheap to raise, give high yields and are also quite palatable.

Aside from economic revenues, this type of integration also involves ecological and social benefits. High densities of fish in irrigation systems enhance the yield of land crops, alleviate the pressure of terrestrial and aquatic pests, and lower the populations of vectors of diseases of man and domestic animals.

Full paper available upon request from authors: C.H. Fernando, Department of Biology, Faculty of Science, University of Waterloo, Ontario, Canada, e-mail: [email protected]

M. Halwart, Fishery Resources Division, Food and Agriculture Organization of the United Nations, Rome, Italy. e-mail:[email protected]

Abstract and cover photo used with permission.