Abstract

The tambaqui, Colossoma macropomum, is the most popular fish species used for aquaculture in Brazil but there is no study comparing genetic variation among native and farmed populations of this species. In the present study, we analyzed DNA sequences of the mitochondrial DNA to evaluate the genetic diversity among two wild populations, a fry-producing breeding stock, and a sample of fish farm stocks, all from the region of Santarém, in the west of the Brazilian state of Pará. Similar levels of genetic diversity were found in all the samples and surprisingly the breeding stock showed expressive representation of the genetic diversity registered on wild populations. These results contrast considerably with those of the previous study of farmed stocks in the states of Amapá, Pará, Piauí, and Rondônia, which recorded only two haplotypes, indicating a long history of endogamy in the breeding stocks used to produce fry. The results of the two studies show two distinct scenarios of tambaqui farming in the Amazon basin, which must be better evaluated in order to guarantee the successful expansion of this activity in the region, and the rest of Brazil, given that the tambaqui and its hybrids are now farmed throughout the country.

Highlights

  • The natural range of Colossoma macropomum Cuvier, 1818, known locally as Tambaqui, includes the Amazon and Orinoco river basins (AraujoLima and Goulding 1998)

  • A further 39 specimens were obtained from the fry-producing breeding stock maintained at the Santa Rosa Aquaculture Station in Santarém, and 63 (21 pure C. macropomum, 39 Tambatinga hybrids, and 3 Tambacu hybrids) were collected from 22 fish farms located in municipalities neighboring Santarém

  • The Amazonian tambaqui (Colossoma macropomum) is the most popular fish species in Brazil for freshwater aquaculture, and the understanding of the genetic variation should be a priority for the development of management strategies capable of reducing the erosion of the genetic diversity of wild populations and minimizing the risks of inbreeding depression in captive stocks

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Summary

Introduction

The natural range of Colossoma macropomum Cuvier, 1818, known locally as Tambaqui, includes the Amazon and Orinoco river basins (AraujoLima and Goulding 1998). This species is one of the most important fishery resources in the Amazon region, where it is a staple of the diet of traditional riverside populations. In recent years, increasing pressure on the wild stocks of this species has led. In contrast with wild stocks, supplies of tambaqui from aquaculture are increasing, and the species is the most important farmed fish in northern Brazil, where it corresponds to more than 70% of the production of the region’s inland aquaculture operations (Ostrensky et al 2008). A major potential problem is the interaction between farmed specimens and wild population through accidental escapes or intentional releases from fish farms, in particular if the farmed stock is composed by hybrids

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