Using DNA barcoding to conserve tropical freshwater fish

The fish commonly referred to as "Acara" in the Amazon is actually 7 species. Credit, Alba Ardura et al.Scientists have developed a DNA barcoding tool to help with the conservation of freshwater fish in the Amazon. They presented their research in the journal Biological Conservation.

In DNA barcoding, scientists use "short DNA sequences of standardized and agreed-upon position in the genome" as a kind of molecular fingerprint for identifying species.

This can be a very valuable tool because successful conservation relies on having a standardized way for telling species apart from one another.

The Amazon is an extremely diverse place for freshwater fish. Over 3000 species of fish occupy tributaries of the Amazon River. Numerous fish are exploited commercially, and they play an important role in the regional economy and diet.

However, over-fishing and other disturbances such as climate change pose a risk to these economically and ecologically important species.

Alba Ardura and the fellow study authors believe that DNA barcoding could help resolve some logistical issues that make the monitoring and regulation of freshwater fisheries in the Amazon very difficult.

One issue is that in the Amazon, the commercialization of fish is based on common names, which can vary widely for a given species depending on the region (or the person).

Another complicating factor is that fish are often sold in a processed form (e.g. fish slices) in which the species is not easily recognizable.

To develop a tool that is specifically suited to the fisheries of the Amazon, the researchers created the DNA barcoding sequence by looking at 23 main commercial species directly purchased from local markets. These species made up 63% of the fish production in the Brazilian Amazon in 2006.

One of the study findings exemplifies the usefulness the DNA barcoding tool - the researchers found that the fish generically sold as "Acara" actually includes seven different species.

"Thus estimation of exploitation rates was not possible until now," the authors write.

This study represents the first successful attempt for creating a DNA barcode for the main commercial fish in the Amazon and one of the first efforts of its kind in Latin America. The approach in this study is likely applicable to freshwater fisheries in other tropical regions.

--by Rob Goldstein

Ardura, A., Linde, A., Moreira, J., & Garcia-Vazquez, E. (2010). DNA barcoding for conservation and management of Amazonian commercial fish Biological Conservation DOI: 10.1016/j.biocon.2010.03.019