WorldFish annual report 2011/12

This year's report contains the Director General's and Chairman's statements. Also highlighted in the reports, are stories of projects with different partners: 1) CGIAR Research Program on Aquatic Agricultural Systems (AAS) in Zambia. 2) Wetland Alliance project in the Mekong delta. 3) Projects with CARE, the humanitarian organisation in Egypt. 4) Tilapia breeding program with Water Research Institute (WRI) in Ghana. 5) Partnerships with the private sector on sustainable aquaculture enterprise in developing countries.

Selective breeding in fish and conservation of genetic resources for aquaculture

To satisfy increasing demands for fish as food, progress must occur towards greater aquaculture productivity whilst retaining the wild and farmed genetic resources that underpin global fish production. We review the main selection methods that have been developed for genetic improvement in aquaculture, and discuss their virtues and shortcomings. Examples of the application of mass, cohort, within family, and combined between-family and within-family selection are given.

Indirect genetic effects and inbreeding: Consequences of BLUP selection for socially affected traits on rate of inbreeding

Social interactions often occur among living organisms, including aquatic animals. There is empirical evidence showing that social interactions may genetically affect phenotypes of individuals and their group mates. In this context, the heritable effect of an individual on the phenotype of another individual is known as an Indirect Genetic Effect (IGE). Selection for socially affected traits may increase response to artificial selection, but also affect rate of inbreeding.

Growth and survival rate of three genetic groups fed 28% and 34% protein diets

The strain by nutrition interaction in body weight and survival rate was examined by testing three genetic groups (Selection and Control lines of the GIFT strain, and Red tilapia) at two levels of protein in the diet (28% and 34%). The GIFT strain of Nile tilapia (Oreochromis niloticus) has been selected for high-breeding values for body weight, whereas the Control was contemporaneously maintained and selected for breeding values of body weight close to the population mean. The Red tilapia (Oreochromis spp) was unselected at the time of the experiment.

Genetic improvement of farmed tilapias: Genetic parameters for body weight at harvest in Nile tilapia (Oreochromis niloticus) during five generations of testing in multiple environments

The main objective of this paper was to report more reliable estimates of the genetic variation and the genotype by test environment interaction for harvest body weight in the GIFT population in the Philippines than could be obtained from the base population by using the data from the five generations following the base population and that covers a wider span of test environments than the later experiments referred to above. Included are also estimates of the genotype by sex interactions for body weight.

Quantitative genetic parameter estimates for body and carcass traits in a cultured stock of giant freshwater prawn (Macrobrachium rosenbergii) selected for harvest weight in Vietnam

Benefits derived from selective breeding have been demonstrated in livestock and in some fish species, but by contrast, there have been few systematic selection programs reported for shrimps. Improving growth rate has been identified as the most important trait in the breeding objective for cultured shrimp species. In the present study we analyzed a four generation data set from a fully pedigreed selective breeding program for giant freshwater prawn (GFP in Vietnam. We estimated phenotypic and genetic parameters for body and carcass weight traits.

Inbreeding and effective population size in a coho salmon (Oncorhynchus kisutch) breeding nucleus in Chile

A commercial breeding nucleus of coho salmon (Oncorhynchus kisutch) was established in Chile in 1997. This nucleus consists of two independent populations corresponding to different year-classes (even and odd, depending on the spawning year), which have been successfully selected for harvest weight (approximate genetic gain per generation of 10%). In order to constrain the buildup of inbreeding a strategy based on avoiding full-sib mating in each generation was used.

Genotype by production environment interaction in the GIFT strain of Nile tilapia (Oreochromis niloticus)

Three discrete generations of GIFT fish (Nile tilapia strain, Oreochromis niloticus; a total of 10,065 fish with pedigree and phenotypic information) were tested in pond and cage culture environments to determine genotype by production environment interaction between both environments in Malaysia. Live weight (selected trait), standard length, body depth and width were recorded. A bivariate animal model was used to estimate variance and covariance components, whereby the homologous body traits in pond and cage environments were treated as genetically distinct traits.


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