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Water Science Photo Gallery
Shocking fish to collect biological samples

The U.S. Geological Survey (USGS) often works on projects where the ecology and biology of local streams are studied. In these studies, it is often necessary to investigate what fish live in the steam. This picture shows fish being collected as part of a water-quality study in Georgia. Part of this study was to check the fish in different parts of the basin to see if and how they were affected by local pollution and chemicals, such as pesticides. The hydrologists had to come up with a way to collect the fish, and we see them in action. They are actually shocking the water with a strong electrical charge to stun the fish into submission so they can be collected. The hydrologist in the center has a power pack on her back and is holding the electrical wand. At the correct moment she submerges the wand in the creek, presses a button, and the guy downstream will collect the fish for further study.

Credit: Alan Cressler, USGS