But there are significant populations of fish in river systems.
People tend to think of freshwater fish as being in ponds, reservoirs and lakes.
Rivers and streams were fished by 13.7 million anglers nationwide compared to 20.9 million on the nation's lakes and reservoirs, according to a 1991 survey by the U.S. Fish and Wildlife Service, the latest figures available. This portion of the Brazos was chosen for the study because it is still somewhat in its natural state with no impoundments as are common along the more northern part of the river. The researchers and their students gathered samples and collected data on water levels, water chemistry, sediments, fish, zooplankton and phytoplankton in the river and nearby oxbows. The two-year study found fish abundant in both the main river channel and 10 oxbows, or lakes that form when the course of the river changes and creates a natural levee. They all came from a river at some point.