Induction of triploidy and gynogenesis in teleost fish with emphasis on marine species

The induction of triploidy and gynogenesis by chromosome set manipulation has traditionally been studied more intensively in freshwater than in marine fish. In the last years, however, several studies have applied these manipulations in about a dozen marine species, including mainly sparids, moronids and flatfishes. This paper focuses on the methodologies used to induce, verify, and assess performance of both triploids and gynogenetics of these marine species. Since many of them are batch spawners and have small and fragile eggs and larvae, peculiarities relating to broodstock management, gamete quality and mortality assessment during early larval stages are also taken into account. However, data show that if handling is correct and the treatments are optimized, triploid and gynogenetic rates of 100% can be easily achieved. Survival of triploids with respect to the controls is about 70-80%, whereas in gynogenetics it is generally low and more variable, depending on the species considered. In the marine fish investigated so far, triploidy has not resulted in significantly higher growth rates. On the other hand, the induction of gynogenesis has resulted in the production of both all-female and mix-sex stocks. Throughout the paper, special reference is made to the European sea bass (Dicentrarchus labrax L.), a species of both basic and applied interest, for which a comprehensive study has been carried out on the induction, verification and performance of triploids and gynogenetics.