Giant Fish, Tiny Plastics

By Lesley de Souza  
ASC Microplastics Adventurer
 
I plunge my arm below the surface of the water, feeling the weight of the bottle increase as it fills with our first sample. The sun is relentless here at 3 degrees north of the equator, and my first impulse is to dive in and cool down, but I know black caiman, anaconda, sting ray, electric eels and piranha also take pleasure in these waters.   
 
We are on southern Guyana’s Rewa River studying arapaima, one of the largest freshwater fish in the world. Arapaima often surface to breathe air, and their size—more than 10 feet long and up to 400 pounds—makes them an easy target for sight fishing and overharvest. Despite their threatened status, they are a sought-after delicacy in tropical South America.

​I’ve spent the last three years studying arapaima movement patterns, helping inform managers about the need for protection. I work with the indigenous Rewa villagers and Rewa Eco Lodge, whose ban on commercial harvest has contributed to high arapaima numbers here.

​One of the most remote ecosystems left on Earth, the Rewa is a biodiversity hotspot harboring giant Amazon River turtle, giant river otter, jaguar, harpy eagle, goliath bird eating spider, giant armadillo and tapir. Even so, when I learned of the ASC Microplastics Project, I wondered if plastic was present in these waters. So, during a recent trip, photographer Zachary James Johnston and I collected water samples for ASC.

​In addition to wildlife, the Rewa villagers depend on a healthy ecosystem to hunt, fish and live off this land. Under threat from mining, logging and agriculture, the Amerindians are working to protect their forests. If they can save it and arapaima for future generations, what steps will be needed to protect them from microplastics, too?