Arapaima, Largest Fish in the Amazon River Basin Going Extinct

Arapaima Fish

The largest fish in the Amazon River basin is going extinct in some areas, according to a new study. The arapaima measures 10 feet (3 meters) long and weighs more than 400 pounds (180 kilograms) and with their ability to breathe air, it makes them that much easier to catch.

Commonly known as pirarucu, arapaima (Arapaima gigas) are the largest freshwater fish in South America. They’re unique among fishes for their ability to breathe air —  made possible by a primitive lung, which they possess in conjunction with a gill system that allows them to breathe underwater. The fish developed this function because they typically live in oxygen-poor waterways, according to the Tennessee Aquarium, which is home to several arapaima.

The arapaima dominated fisheries in the Amazon a century ago, but three of the five known species of the fish have not been seen for decades, said Donald J. Stewart, professor in the College of Environmental Science and Forestry at the State University of New York at Syracuse, who recently discovered a new species of arapaima.

While commercial fishing of Arapaima has been banned by the Brazilian government, they are still fished by the local Amazonian communities, and it is seldom regulated. The focus of the study was to find out if this unregulated fishing was having an effect on the population.

The research was based on interviews with 182 fishers in 81 communities who were selected by their peers as being experts and on fish counts in 41 of the fishing communities, accounting for 650 square miles of floodplain area.

The results indicate that arapaima populations are extinct in 19 percent of communities, depleted (approaching extinction) in 57 percent, and over-exploited in 17 percent.

“Fishers continue to harvest arapaima regardless of low population densities,” said study leader Leandro Castello, an assistant professor of fisheries at Virginia Tech’s College of Natural Resources and Environment, in Blacksburg.

However, communities that have implemented fishing rules, imposing minimum capture size and restricting gill-net use, density of arapaima is 100 times higher than where there are no rules or the rules are not followed, said David G. McGrath of the Earth Innovation Institute in San Francisco.

“These communities are preventing further arapaima extinctions,” said McGrath.

The results of the study were published online Aug. 13 in the journal Aquatic Conservation: Freshwater and Marine Ecosystems.

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