The present study examined the variation in survival, proportion of male morphotypes, female and male proportion, female reproductive status and tag losses in nine crosses from a complete (3 × 3) diallel mating of three populations of Macrobrachium rosenbergii in India. The populations originated from Gujarat (north-west), Kerala (south-west) and Odisha (east), representing different agro-ecological regions in India. Progeny from 60 families (4773 juveniles) were individually tagged and reared for 16–17 weeks in earthen ponds. Binary logistic regression was used to analyse the data.
When different strains or breeds of a particular species are available, the best choice is seldom immediately obvious for producers. Scientists are also interested in the relative performance of different strains because it provides a basis for recommendations to producers and it often stimulates the conduct of work aimed at unraveling the underlying biological mechanisms involved in the expression of such differences. Hence, strain or breed comparisons of some sort are frequently conducted.
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.
The Abbassa selection line (developed by selective breeding) and the Kafr El Sheikh commercial strain (widely used in Egypt), both Oreochromis niloticus, were compared at two stocking densities (two and four fish m-2). Harvest weight, length, depth, width and head length were recorded. The Abbassa line showed a superior harvest weight (28 per cent) over the Kafr El Sheikh strain. Males were heavier than females, but the between-sex difference was greater in the commercial than in the Abbassa line (39 and 31 per cent respectively).
This study investigates the genetic structure and phylogeography of a broadcast spawning bivalve mollusc, Pinctada maxima, throughout the Indo-West Pacific and northern Australia. DNA sequence variation of the mitochondrial cytochrome oxidase subunit I (COI) gene was analysed in 367 individuals sampled from nine populations across the Indo-West Pacific.
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.
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.
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.
This viewpoint paper explores the potential of genomics technology to provide accurate, rapid, and cost efficient observations of the marine environment. The use of such approaches in next generation marine monitoring programs will help achieve the goals of marine legislation implemented world-wide. Genomic methods can yield faster results from monitoring, easier and more reliable taxonomic identification, as well as quicker and better assessment of the environmental status of marine waters.
The aim of this study was to examine genetic variation in reproductive traits and to estimate correlated responses in such traits to selection for high growth rate in the GIFT strain of Nile tilapia (Oreochromis niloticus).