Manipulação cromossômica em curimatã-pacu Prochilodus argenteus (Spix e Agassiz, 1829) : indução à triploidia

Abstract

Chromosomal set manipulation is a promising tool for breeding programs and biological conservation. Triploidy induction provides benefits that increase fish production and reduces the impact of escapes from fish farming on wild populations. These benefits are due to the most probable characteristics of triploid fish: sterility; because of its assumed ability to increase yield by conducting the energy required from gonadal development to somatic growth, leading to better growth rates and fillet quality. The curimatã-pacu (Prochilodus argenteus) is an endemic migratory fish species of the São Francisco River, which abundance have been compromising by the hydroelectric dams along the river and is known for its highly appreciated meat, with a great potential for extensive aquaculture, In this study, the efficiency of thermal shocks (cold and heat) to triploid production was evaluated. Cold shocks (0-4ºC) were tested at 2.5 min, 5 min, 10 and 12 min postfertilization (mpf), lasting for 10, 15, 20 and 25 minutes. Heat shocks were alsoinvestigated at 5 mpf, lasting for three minutes at 39 and at 41ºC. In each treatment, a control group was maintained to analyze egg quality. No hatches were observed for the heat shock treatments. For cold shock treatment applied at 5mpf and lasting for 25 minutes, 100% triploids were obtained. For others cold shock treatments also applied at 5mpf, but lasting for 20, 15 and 10 minutes, triploid rates were 89.12, 76.92 and 63.33%, respectively. Although fertilization rates were statistically different between diploid and triploid, survival, weigh and size were similar between triploids and control groups after being reared for 21 days in tanks. This is the second protocol for a Brazilian native species with 100% triploidization yield and the first one to achieve this by means of thermal shocks.