22 Sep Electrofishing: The Easiest Way To Catch Fish
At Dinosaur I’ve had the great fortune of participating in numerous opportunities. I can now say that I’ve drawn blood from a Prairie Dog and tagged a Monarch. Yet, electrofishing was by far one of the most interesting experiences I’ve had, especially since it tested my hand-eye coordination. In the morning, I had the opportunity to meet the staff from the Utah Division of Wildlife Resources (DWR) that would be guiding us on our mission. On the excursion, were one biologist, two boat operators, and two technicians who have worked their way through the Green River surveying for native and nonnative fish. To monitor and manage the river’s fisheries and ensure that endangered native fish populations are healthy.
Before we could set off, the group had a safety discussion with a focus on electricity and water. So, the safety discussion mostly focused on electrofishing and how it works. Essentially, electrofishing is a tool to capture large quantities of fish for scientific research. It works by transmitting a charge of electricity between two metal balls that act as a cathode and anode, hanging off the bow of the boat. The amperage of electricity discharged between the cathode and anode is determined by the boat operator. It’s set to a level that temporarily shocks the fish allowing a technician enough time to scoop it into the boat. The shock is not strong enough to affect fish that are more than a couple of feet away from one of the balls. On larger fish, the shock would leave them shaking for a couple of seconds after pulling them out of the water. However, all the fish are safe and alive and return to the water once they’re processed.
Once on the river, the generator turned on and electricity flowed through the water. While standing on the bow of the boat with net in hand I assured that my feet were fully placed on a black mat. This mat acted as a kill switch incase someone were to go off the mat, it would turn off the electricity preventing someone from getting shocked. So, as I consciously tried to stay atop the mat my eyes were focused on the water below. As we moved down the river the water was mostly cloudy with only a few shallow areas that provided clarity. So, that required fast reactions when you saw a fish emerge shocked from the murky waters below as you attempted to net it as the fish, and you are both moving. This usually led to missing a lot of fish, especially when passing over a large group that shocked 5+ fish at once. Yet, we were still able to catch a large amount of native and nonnative fish.
When the boat collects enough fish it stops on a riverbank or sandbar and begins to process them. Usually 10-15 fish would be caught before stopping, to ensure that they would survive. Some of the native fish that were caught were Blue-Headed Suckers, Flannel mouth Suckers, and the endangered Razorback Sucker. The nonnative species that were caught included Smallmouth Bass and White Suckers. The process for the native fish began with checking fish for a PIT tag, if they have one it will read out a unique identifier. Once that data is collected the fish is then weighed, measured, and released. If the fish doesn’t have a PIT tag one is put in and recorded, the PIT tags act as an electronic identifier of individual fish. If endangered species like the Razorback Sucker don’t have a PIT tag one is injected, and a sample of the fine bone is taken for genetic testing. Nonnative fish have a different fate they are checked for a PIT tag, and then weighed and measured. After that they are killed to manage their populations and prevent dominance over native species. It is a sad fact of conservation that sometimes the best thing we can do for an ecosystem is to remove the flora and fauna that humans introduced.