Polyploids can be defined as organisms with one or more additional chromosome sets with respect to the number most frequently found in nature for a given species. Triploids, organisms with three sets of homologous chromosomes, are found spontaneously in both wild and cultured populations and can be easily induced in many commercially relevant species of fish and shellfish. The major consequence of triploidy is gonadal sterility, which is of advantage in the aquaculture of molluscs since it can result in superior growth. In fish, the induction of triploidy is mainly used to avoid problems associated with sexual maturation such as lower growth rates, increased incidence of diseases and deterioration of the organoleptic properties. Triploidy can also be used to increase the viability of some hybrids, and is regarded as a potential method for the genetic containment of farmed shellfish and fish. This review focuses on some current issues related to the application of induced polyploidy in aquaculture, namely: 1) the artificial induction of polyploidy and the effectiveness of current triploidisation techniques, including the applicability of tetraploidy to generate auto- and allotriploids; 2) the performance capacity of triploids with respect to diploids; 3) the degree and permanence of gonadal sterility in triploids; and 4) the prospects for the potential future generalised use of triploids to avoid the genetic impact of escapees of farmed fish and shellfish on wild populations. Finally, directions for future research on triploids and their implementation are discussed.

This review originated following the presentations and subsequent discussions made at an international workshop on the "Genetics of domestication, breeding and enhancement of performance of fish and shellfish", organized within the EU-funded project "Genimpact" (RICA-CT-2005-022802. http://genimpact.imr.no), held in Viterbo, Italy, 12–17 June 2006.

Studies in the laboratory of M.F. discussed here were supported in part by grants MSM6007665809 and GACR 523/08/0824. Research at the laboratory of F.P. is partially funded by the Consolider-Ingenio 2010 project "Aquagenomics".

32 pages, 8 figures, 6 tables.-- Printed version published Aug 16, 2009.

Peer reviewed