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Freshwater Fisheries

Tools of the Trade

Backpack Electrofisher Backpack electrofishers are primarily used to sample small to medium sized freshwater streams. Modern backpack electrofishers run on rechargeable batteries and the settings can be modified to effectively sample for different species and age classes of fish. The electrofisher stuns the fish by causing electrotaxis, allowing the fish to be collected, weighed, and measured. Stunned fish recover very quickly and mortality is extremely rare.			Electrofishing Boat Electrofishing boats are used to sample impoundments and major rivers across the state. The boats are powered by generators and the most powerful boats can sample in high salinity water. Electrofishing boats can effectively sample in 8-10 feet of water for any species of fish. Mortality is also very rare when sampling using electrofishing boats.			Seine Seine nets are typically used to assess fish reproduction in ponds, lakes, and rivers. The net hangs vertically in the water and either end is pulled by a biologist. Fish trapped in the net are analyzed and then released back into the water.
Anesthetic Anesthetic is commonly used on fish collected during an electrofishing survey. Using an anesthetic allows for easier handling and decreases stress on the fish, reducing chances of mortality. Fish usually recover in less than five minutes and are then released.			Electrofishing Barge Electrofishing barges are used to sample medium to large freshwater streams that are wadeable. A gas powered generator is connected to an electrofishing box which regulates the current going into the water. This current can be increased or decreased based on water conductivity. Electrofishing barges need a minimum of 5 biologists to operate effectively.			Telemetry Receiver Radio Telemetry Receivers allow biologists to detect fish that have been implanted with a radio tag. Tag frequencies are programmed into the receiver and the unit cycles through all active tag frequencies. Once an implanted fish is located, GPS coordinates are recorded to identify the location and evaluate fish movement within a watershed.
Water Temperature Logger Water temperature loggers are used to record stream temperatures during the hottest months of the year. Temperature loggers are usually deployed in late spring and recovered again in the fall in order to assess the temperature profile of coldwater streams.			Radio Tag Radio tags are surgically implanted into fish and the incision is then closed with sutures. These tags allow biologists to track, record, and evaluate fish movements in targeted watersheds.			Water Quality Meter Water quality meters provide field biologists with valuable water quality data; Temperature, pH, Conductivity, Salinity, and Dissolved Oxygen are the most commonly measured features. This information allows biologists to evaluate the “health” of the waterbody along with providing information on how to effectively operate electrofishing units.