Electrofishing works well for bass, but the survey has to be very well-timed, especially for smallmouth bass. Max Wolter is shown with a smallmouth bass on a Hayward area lake.
Electrofishing is not a very efficient way to capture big muskies, but once and a while we do get lucky. Volunteer Randy Neumann, left, and Evan Sniadajewski , DNR fisheries technician, are shown here with a musky on the Chippewa Flowage.
Electrofishing works well for bass, but the survey has to be very well-timed, especially for smallmouth bass. Max Wolter is shown with a smallmouth bass on a Hayward area lake.
Electrofishing is not a very efficient way to capture big muskies, but once and a while we do get lucky. Volunteer Randy Neumann, left, and Evan Sniadajewski , DNR fisheries technician, are shown here with a musky on the Chippewa Flowage.
Electrofishing captures the public’s imagination more than any other Department of Natural Resources activity.
There’s plenty of reason for intrigue. Very few people get an up-close view of this method for capturing fish, since most surveys are done in the deep of the night. But as you’ll see, when it comes to electrofishing, the truth is not actually stranger than the fiction.
The idea of using electricity to capture fish is almost as old as our understanding of electricity itself. Still, the premise for how electrofishing works is somewhat bizarre. When fish enter an electrical field they become immobilized. With some forms of electrofishing, the fish even swim towards the source of electricity involuntarily.
These opportunities allow fisheries staff to scoop up the fish with fiber-glass handled dip nets (a process known as “dipping”). Electrofishing can be done with either AC or DC current, depending on the waterbody. Over time, electrofishing units have been adapted to almost any environment, from backpack setups for small streams up to full size electrofishing boats for lakes and large rivers. There are even submersibles capable of conducting electrofishing remotely.
There is a long list of misconceptions people have about electrofishing. One of the most common is about how shocked fish behave. Shocked fish do not float up to the top of the surface. Nothing changes with the physiology or density of the fish that would make them suddenly float when they encounter electricity. Rather, electricity immobilizes their muscles. So most fish actually “roll” in place in the water column.
“Dippers” — those with the nets scooping up fish — will usually see a flash as the fish rolls which shows them where to scoop. An experienced dipper can tell the species of fish just from the way that it rolls, as each species has its own unique movement. Some fish do not get shocked enough to become fully immobilized and they keep swimming or even launch out of the water. This is very common with big muskies and pike. We still try to net these fish, but it can be a real challenge.
Which is, in effect, another misconception. Catching fish in an electrofishing survey is not easy. Even fish that are fully immobilized require skill to gauge how deep in the water column the net must plunge. Often there are rocks or logs to work the net around.
The act of netting itself is very physically demanding on the back and arms. The fine-mesh nets produce a tremendous amount of drag if left in the water because the boat is continuously in motion. To get an idea of what this is like, try holding your landing net in the water for several minutes while the boat idles along. Now do that repeatedly for six hours.
By now you are getting a clearer picture of the reality of electrofishing, so this next misconception may be more obvious. We do not capture all the fish in the waterbody. Not even close, in fact. Boat electrofishing is only effective in water less than about six feet deep. In water deeper than that the electricity diffuses too quickly and the fish are too far down to net anyway. This makes the timing of our surveys crucial to their success.
We need to be there when the fish we want to target are up shallow. This is also one reason why most of our lake electrofishing is done at night, a time when certain species like walleye will come into the shallows. Conductivity, or the amount of dissolved ions in the water capable of carrying an electrical current, is another important factor that limits electrofishing. There are some lakes in the Hayward area with such low conductivity we don’t even attempt to electrofish them. Even on lakes with good conductivity, our capture rate is not perfect for many other reasons.
Fish get missed by dippers all the time. Many fish swim away from the electrical field before it can fully affect them. And then there are all the fish that happen to be in deep water or a part of the shoreline we are not shocking. As a result of all those factors, we typically capture less than 1% of all the fish in a lake. In a big lake like the Chippewa Flowage it is undoubtably less than 0.01%. From a data collection standpoint, that’s OK. These are samples, not censuses. After capturing a few hundred of a species we have a large enough sample to make conclusions about what the total population looks like (similar to how a poll doesn’t need to sample every person to gauge public opinions).
Another misconception is that electrofishing is going to screw up your fishing because it changes fish behavior. This is not true for several reasons. First, as we just discussed, often 99% of the fish are completely unaware that a lake electrofishing survey even happened. Secondly, studies have shown that even fish that are shocked and captured return to their normal behavior pretty quickly. A study of electrofishing on sunfish found they returned to normal in under 5 hours and similar results have been observed for bass.
The last thing people should know about electrofishing is that it is safe, as long as the people involved are safe. The DNR places a lot of emphasis on electrofishing safety. We have safety courses and certifications before we can operate electrofishing boats. We have technicians that work diligently on maintaining our equipment to keep it safe. The boats and stream shocking units are all loaded with safety features.
We take public safety very seriously too, and there are things people can learn here that can help them be safe and help us do our jobs. First off, stay on shore. Many people see the electrofishing boat coming down the shoreline and run down to the end of their dock to watch. As soon as we see that happening, we turn off the electricity. That means you won’t see any fish, and our survey will be slightly compromised. Watch from a safe distance and keep hold of your pets so they don’t go in the water either.
Similarly, if you are out on the water at night, make sure your navigational lights are on and don’t come close to the electrofishing boat while it’s operating. Lastly, please don’t leave unattended lines at the end of your dock. It’s illegal, and it creates a hazard for us as we make our way down the shoreline.
Electrofishing provides a lot of valuable data that we use to manage the fish populations in the area. It is a tool. And like all tools it has a place and a purpose. Also like other tools, it has to be operated safely.
Wolter is the Department of Natural Resources senior fisheries biologist in Sawyer County and a lifelong angler.
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