Sheridan Region fisheries biologists and other WGFD personnel recently conducted electrofishing surveys on the North Tongue River. Other surveys that were completed this summer and fall include the South Little Tongue and Little Tongue rivers, as well as Bull, Lick, Red Gulch, Wagon Box, Little, Big and Goose creeks.

Electrofishing can be done by boat or wading and the North Tongue sampling was done by wading, assisted with a raft carrying a generator. Biologists hold a probe that conducts electric current into the water while walking slowly upriver.  They scan the probe from side-to-side, reaching around rocks and in small pools to access every fish possible. The probe releases a small electric current that temporarily stuns the fish and other personnel walk behind with nets to collect them.

Several passes are made on the same designated stretch of stream with fish collected on each pass held in separate live-hold containers. They are later counted, weighed and measured before being released. By keeping track of how many fish are caught on each pass, which pass they are captured on and how many total fish are captured, biologists can generate population estimates to compare one sampling event to another. These data show if the population is going up or down, what size the fish are and how healthy they are. These data are then used to evaluate potential changes in stocking strategies or regulations. All fish collected and sampled are released back into the creek.

Anglers are usually interested in this unique sampling technique when they see personnel in the field and often ask what is happening, how the operation works and if the process injures fish or impacts their fishing. If you are fishing close by when we are electrofishing, please stay clear until we shut the equipment off. Once off, we welcome you to come over to visit and see the fish we’ve caught.