Domestication of aquaculture species

Abstract

AbstractDomestication alters genotypes and phenotypes of organisms by changing the selection pressures experienced in captivity compared to those found in natural habitats. Domestication causes significant genetic (and epigenetic) changes in aquatic animals within just a few generations and is often biased towards artificial selection of production traits (growth), but also has potential for reducing the ecological footprint of production and improving animal welfare. Traditional crossbreeding utilizes genetic or physical markers to select for desirable phenotypes (traits), which can be induced by imposing environmental stress on gametes. Stress alters karyotypes (i.e. chromosome structure and ploidy [chromosome copy number]). Genetic engineering represents a rapid way of manipulating genomes with molecular tools that permanently alter the DNA of engineered organisms and their offspring. Two types of genetic engineering are common: 1) insertion of foreign DNA into the genome (random or transposase mediated); and 2) gene targeting/editing (requires specific nucleases). Genetic engineering creates genetically modified organisms (GMOs), which are invaluable models for basic research to establish causality between genotype and phenotype. The commercial production of GMOs has benefits that must be weighed on a case-by-case basis against their pitfalls. Pleiotropy of genes renders assessment of GMO impacts on organisms, ecosystems, and food security difficult and consumer acceptance of GMOs is low. Stock enhancement and sea ranching rely on releasing, rather than confining, hatchery-raised offspring. They require elaborate genetic management plans. Post-release monitoring of genetic diversity of restocked populations is facilitated by physical and genetic markers but restocking impacts are unpredictable.