Pedro Luiz de Castro

Monitoramento e conservação genética de populações naturais de Prochilodus lineatus dos rios Pardo, Mogi-Guaçu e Tietê, São Paulo

ABSTRACT The aim of this study was to determine the genetic diversity and structure of six wild populations of Prochilodus lineatus in Hydroelectric Power Plants (HPP) of the Pardo (HPP Limoeiro – LMO), Mogi Guacu (HPP Mogi-Guacu – MOG), and Tiete (HPP Promissao – PRO, HPP Barra Bonita – BAB, HPP Nova Avanhandava – NAV and HPP Bariri – BAR) rivers. A total of 47 alleles, ranging in size from 118bp to 330bp were found. The results of observed heterozygosity average (0.490 to 0.625) reflected a high intra-population genetic variability. The values of genetic distance (0.149 to 0.773), Fst (0.006 to 0.218), and Nm (1.2 to 4.2) showed that between the populations there is genetic similarity. According to AMOVA there was higher variation within populations than between them. The dendrogram demonstrated the formation of two groups (LMO-PRO-MOG and BAR-BAB-NAV). It was concluded that wild populations had high genetic variability with genetic similarity between them, possibly caused by the restocking program performed in these rivers. Keywords: curimba, microsatellite markers, fish, preservation, genetic variability

Parental contribution of Curimba offspring in different reproductive system

The knowledge of appropriate reproductive managements is fundamental for the management and orientation of activities in restocking centers. The aim of the present study was to evaluate the influence of artificial and semi-natural reproductive systems and sex ratios on parental contribution progeny of Prochilodus lineatus. Samples of caudal fins from 25 breeders subjected to the artificial reproductive system and 10 breeders subjected to the semi-natural reproductive system were collected in different sex ratios (1♂:1♀ and 2♂:1♀, and 1♂:1♀, respectively). Two hundred and eight fingerlings from these matings were evaluated. Breeding mortality was recorded shortly after reproductive procedures. For paternity analysis, 10 microsatellite loci were amplified. Three breeders died in the artificial reproductive system (two in the 1:1 ratio and one in the 2:1 ratio). In the 1:1 ratio in the artificial reproductive system, one male (M1.4) had a higher contribution in the progeny formation (41.8%), whereas in the 2:1 ratio, four males contributed from 14.5 to 21.7%. Lower reproductive dominance was identified in the semi-natural reproductive system, with values ranging from 22.86 to 25.71% for four males. In the formation of families, both systems demonstrated a reproductive dominance of some couples. So, the semi-natural reproductive system allowed greater homogeneity in the contribution of progeny without losses due to mortality.

Genetic variability of Prochilodus lineatus in artificial and semi-natural reproduction

Abstract Prochilodus lineatus is a South American fish of great economic and social importance that is impacted by high fishing pressure. Restocking programmes have tried to be effective in recovering natural populations; however, genetic and reproductive methodologies are necessary to make feasible the survival of released fingerlings. The genetic variability of P. lineatus subjected to semi-natural and artificial reproduction was evaluated. Caudal fin samples from 25 breeders subjected to an artificial reproduction were collected at different sex ratios (1♂:1♀ and 2♂:1♀), and 138 fingerlings originated from these spawning. Similarly, samples were collected from 10 breeders (1♂:1♀) subjected to a semi-natural reproduction, and 70 fingerlings were generated from this spawning. Ten microsatellite loci were evaluated, producing 142 alleles. High interpopulation variability for broodstock and fingerlings was observed in both reproductive systems. A deficit of heterozygotes through the inbreeding coefficient (Fis) was obtained. Moreover, a deviation in the Hardy–Weinberg equilibrium of the fingerlings in both systems was detected. Fst values indicated a moderate genetic differentiation in 1:1 artificial reproduction system and low differentiation in 2:1 artificial and 1:1 seminatural reproduction system. Despite the high genetic variability, genetics analyses in the next generations of fingerlings will be necessary considering the likelihood of a decrease in genetic variability.