The victim has been identified as 39-year-old Benjamin Z. Mei of Brooklyn, New York.
The incident happened around 10:40 a.m. in the area of Market Street and Route 45 in Mannington Township.
Investigators say Mei was fishing with two friends when something fell in the river and he tried to retrieve it. He fell in the water and, not knowing how to swim, drowned.
His body was recovered a short time later.