Abstract The objective of this study was to evaluate the weight and body yield of two families of selectively bred tambaqui farmed in different environments. Two families (FA and FB) were reared in the municipalities (environments) of Santo Antônio de Leverger (MT) and Campo Grande (MS) for 431 days. Pre-bleeding weight, body yield, and the interaction effect between families and environments on these traits were investigated. No interaction effect between the evaluated families and environments was detected on the evaluated traits. Pre-bleeding weight did not differ significantly between the families in MT (FA: 2,421.7g; FB: 2,478.0g) or in MS (FA: 1,138.7g; FB: 1,389.8g), but the fish from MT had a higher (P<0.05) pre-bleeding weight than those farmed in MS. The visceral fat yield (considering the two environments) was higher (P<0.05) in FB family (3.8%) than in FA family (3.3%).Fish from MS showed higher (P<0.05) offal yield (10.6%) and visceral fat yield (3.9%) but a lower clean-trunk yield (70.6%) than the tambaqui farmed in MT (offal: 7.7%; visceral fat: 3.1%; and clean trunk: 72.6%). In conclusion, the MT environment provides higher pre-bleeding weight and clean-trunk yield and lower offal and visceral-fat yields than the MS environment.

Abstract The aim of this study was to evaluate the growth curve of selectively bred and non-selectively bred tambaqui (Colossoma macropomum). The experiment involved 388 fish (weight: 65.38 ± 20.00 g; age: 217 days), consisting of 252 fish from seven selectively bred families (18 fish per family) and 18 non-selectively bred fish (control group). Groups were placed in two 800-m² tanks. Biometric measurements were taken on nine occasions at 30-day intervals, for a period of 254 days. Weight and morphometric traits were evaluated. To describe the tambaqui growth behavior, we adopted the Gompertz nonlinear regression model. Greater growth (p < 0.05) was observed in selectively bred families compared with control group. Four families stood out with higher (p < 0.05) asymptotic values for weight (F1: 2448.7 g; F7: 2284.7 g; F5 2180.1 g; F4: 2080.5 g; and control: 1808.4 g) and other morphometric traits. None of the selectively bred families (except F5) had a higher growth rate and age at inflection point than the fish from control group. In conclusion, selectively bred and non-selectively bred fish present distinct growth curves, but some families have greatly superior growth.

RESUMO Foi avaliado o padrão de crescimento entre fêmeas e machos de tambaqui por meio do modelo de regressão não linear de Gompertz. Foram mensuradas cinco características de importância econômica em 145 animais durante os três anos, totalizando 981 de dados morfométricos analisados. Curvas diferentes foram ajustadas entre machos e fêmeas para peso corporal, altura e comprimento da cabeça e apenas uma curva para a largura e comprimento do corpo foi ajustada para ambos os sexos. O peso assintótico (a) e taxa de crescimento relativo à maturidade (k) foram diferentes entre os sexos nos animais com ± 5 kg; peso de abate praticado por um nicho específico do mercado, muito rentável. No entanto, não houve diferença entre machos e fêmeas de até ± 2 kg; peso de abate estabelecido para abastecer o maior mercado consumidor. As fêmeas apresentaram maior peso do que os machos (± 280 g), sendo estas mais indicadas para fins de piscicultura definidos para o nicho de mercado de animais maiores. Em geral, os machos apresentaram menor taxa de crescimento (8,66 g / dia) do que as fêmeas (9,34 g / dia), entretanto, alcançaram a taxa máxima de crescimento mais rápido do que as fêmeas, 476 e 486 dias, respectivamente. A altura e comprimento do corpo são as características que mais contribuíram para o peso aos 516 dias (P <0,001).

ABSTRACT Was evaluated the pattern of growth among females and males of tambaqui by Gompertz nonlinear regression model. Five traits of economic importance were measured on 145 animals during the three years, totaling 981 morphometric data analyzed. Different curves were adjusted between males and females for body weight, height and head length and only one curve was adjusted to the width and body length. The asymptotic weight (a) and relative growth rate to maturity (k) were different between sexes in animals with ± 5 kg; slaughter weight practiced by a specific niche market, very profitable. However, there was no difference between males and females up to ± 2 kg; slaughter weight established to supply the bigger consumer market. Females showed weight greater than males (± 280 g), which are more suitable for fish farming purposes defined for the niche market to larger animals. In general, males had lower maximum growth rate (8.66 g / day) than females (9.34 g / day), however, reached faster than females, 476 and 486 days growth rate, respectively. The height and length body are the traits that contributed most to the weight at 516 days (P <0.001).

Objetivo. Evaluar la diversidad genética de cuatro lotes de reproductores y un lote de juveniles de curimba Prochilodus lineatus en una hidroeléctrica en São Paulo - Brasil, utilizados en el programa de repoblamiento del río Tietê. Materiales y métodos. Cinco primers RAPD se utilizaron para amplificar el ADN extraído de 150 muestras de aleta. Resultados. Cincuenta y nueve fragmentos fueron polimórficos, 52 tuvieron frecuencias con diferencias significativas (p<0.05), 45 tuvieron bajas frecuencias, 54 fueron excluidos, y dos fueron fragmentos limitantes. Se observaron altos valores de fragmentos polimórficos (71.19% a 91.53%) y de índice de Shannon (0.327 a 0.428). Los valores de divergencia genética dentro de cada lote fueron mayores al 50%. La mayor variación genética se encontró dentro de los grupos a través del análisis de AMOVA, el cual fue confirmado con los resultados de identidad y distancia genética. Los altos niveles de descendencia (F ST) entre los grupos indicaron una alta y moderada diferenciación genética. Los cálculos del número de emigrantes por generación (Nm) indicaron bajos niveles de flujo génico. Se observó alta y moderada divergencia genética entre los grupos (0.58 a 0.83). Conclusiones. Los resultados indicaron una alta variabilidad dentro de los lotes y baja diferenciación entre ellos. Los lotes de peces analizados representan una amplia base genética que permitirá a los productores liberar juveniles sin riesgos genéticos para las poblaciones naturales presentes en el río. Estos procedimientos genéticos pueden ser utilizados como modelos para otras especies migratorias, inclusive en aquellas en peligro de extinción.

Objective. Assess the genetic diversity in four brood stocks and one juvenile stock of curimba Prochilodus lineatus in a Hydropower plant in São Paulo - Brazil, using the Tietê River stocking program. Materials and methods. Five RAPD primers were used to amplify the extracted DNA from 150 fin-clip samples. Results. Fifty-nine fragments were polymorphic, 52 had frequencies with significant differences (p<0.05), 45 had low frequencies, 54 were excluded, and two were fixed fragments. High values for polymorphic fragments (71.19% to 91.53%) and Shannon index (0.327 to 0.428) were observed. The genetic divergence values within each stock were greater than 50%. Most of the genetic variation was found within the groups through the AMOVA analysis, which was confirmed by the results of the identity and genetic distance. High ancestry levels (F ST) among the groups value indicated high and moderate genetic differentiation. The estimates of number of migrants by generation (Nm) indicated low levels of gene flow. High and moderate genetic divergence between groups (0.58 to 0.83) was observed. Conclusions. The results indicate high variability within the stocks, and genetic differentiation among them. The fish stocks analyzed represent a large genetic base that will allow the fish technicians to release juveniles without genetic risks to wild populations present in the river. These genetic procedures may be used as models for other migratory species, including those threatened by extinction.