Total freshwater-fish consumption provides for the dietary animal-protein needs of the equivalent of 158 million people, with poorer nations especially dependent on this natural and inexpensive source of food.

Credit: Sangkhom Hungkhunthod/Getty

Peter McIntyre at the University of Wisconsin, Madison, and his colleagues used data from the Food and Agriculture Organization of the United Nations to build a global map of river fisheries, which have historically received less attention than their marine counterparts. They found that pressure from fishing was most intense in areas where biodiversity was also highest, raising concerns about conservation. The Mekong (pictured), Amazon and Niger were some of the most heavily fished rivers, whereas rivers in the United States and Europe saw lower than expected catches.

Declines in river fish could be catastrophic for the food security of hundreds of millions of people, the authors say.

Proc. Natl Acad. Sci. USA http://doi.org/bscf (2016)