Shocking Fish to Collect Ecologic Data

Science Center Objects

Collecting samples of water isn't the only way to test water quality. The USGS actually collects fish to see if and how they were affected by local pollution and chemicals in the water, such as pesticides. Read on to find out more.

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Electroshocking for lamprey larvae

Electroshocking for lamprey larvae (Credit: USGS, Public domain)

One example of a local study where electrofishing was used was in Georgia where the ecology of a river basin was being analyzed. One 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 this picture shows 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 has a power pack on his back and is holding the electrical wand. At the right moment, he submerges the wand in the creek, presses a button, and then... zap 'em and bag 'em.

Just as the name implies, specialized equipment is used to emit an electrical pulse into the water and stun nearby fish. Think of it as a “stun gun” but much less powerful. In fact, a boat-mounted unit used in this study runs on only 4 amps and 60 volts of direct current. This provides an immobilizing shock that is considered non-lethal and only stuns the fish for a brief period. Essentially, it gives the boat operator just enough time to turn around and the netter to collect the fish.