On Wednesday, my watershed ecology class went electrofishing. For someone not from this area, when this field trip was listed on our syllabus, it read to me like the stuff of fiction. It is in fact the stuff of science, but there are many fictional allusions that can be drawn from some of the details of the day, as you will see.
But to begin, electrofishing (in a nut shell) is the use of electricity in water to stun fish such that you can net them, record data about them, and then re-release them. We were part of a research team for the day at Winton Park to aid in the Lower Kings Annual Trout and Non-Game Fish Population Survey. The survey is organized and run jointly by the Kings River Conservation District, the California Department of Fish and Wildlife, and the Kings River Water Association (along with volunteers, like the students in our class). They conduct the survey on different portions of the river for 6 days, and we helped out on the final day.
Here is how the process goes:
1. Set up an upstream and downstream block seine net across the width of the river to quarter off a section of the river to gather the fish from. You drape the net over tripods set up on the river bed, and let the leadline (bottom part of the net has lead weights) fall with the direction of the current and weigh down the leadline with large cobble to keep the net in place.
2. Suit up in a pair of waders, and put on a pair of rubber gloves (both keep the electricity from shocking you when you are in the water).
3. Set up the backpack electroshockers. These packs have an anode on a long rod with a flat net at the bottom (helps to scoop up fish) and a cathode (called a “rat tail”) that is a simple wire that trails behind the backpack wearer (called the “shocker”) in the water.
4. Distribute nets and buckets to the rest of the crew (those not shocking) to collect the fish. Each shocker should have one netter shadowing then with a bucketer close behind.
5. Have a few large, plastic garbage cans with holes out in the water behind the netters / bucketers. Once a few fish are added to the small buckets, they should be poured into the large cans. The large cans have holes so that fresh water can circulate. If the fish are left in the small bucket (without holes) too long, then they will use up the dissolved oxygen in the water and die.
6. Walk in a line spanning the width of the transect so that all areas are covered. You begin by shocking downstream and walk upstream (against the current), otherwise the shocked fish would be swept away with the current.
7. Once the first pass is completed, bring the collected fish to the data collection team on the shore line. There the fish will be recorded for their weight, length, and species before being re-released into the water.
8. Wait 30 minutes after the first pass and then do a second pass. Wait 30 minutes after the second pass and then do a third pass.
My first thought upon becoming acquainted with a backpack electroshocker was Ghostbusters…if you look at the picture, I think you shall quite agree. The electroshockers are calibrated to release the level of voltage desired, for us it was 575 volts. The electricity isn’t dangerous to humans as long as you have your waders and gloves on, but we were given a thorough safety brief before beginning the project just the same.
The whole idea of putting electric currents into the water to gather fish seemed a whimsical collaboration of a futuristic sci-fi novel (for the use of electricity instead of hook and line to fish) meets Little House on the Prairie (for the fact that we were wearing waders, walking in a river, and using a big-ol’ net to scoop up fish).
Scooping up the fish is more challenging then you might expect. I felt an inner competitive drive, long grown dormant from my high school sport days, rise up inside me as I’d see the silver gleam of a stunned fish…and then see it slip into the crevice between two cobbles, out of reach of my net, and out of sight.
Most of the fish caught were small guys, but we got one larger fish. Overall, there seemed a general agreement from those who have done the survey before that there are far fewer fish this year. The speculation is that this is largely due to the higher water temperature of the river and the drought.
I think my favorite of the species (and also seemingly the most abundant out in our cross section, although I don’t yet know what the data collection reflects) was the the sculpin. They are quite prehistoric looking which made me reminisce of my many viewings of The Land Before Time as a child.
Honestly, the whole experience was a thrill and just good fun. It was quite a privilege to get to work along side folks from three different organizations that study water quality and ecology of river areas. It was also incredibly peaceful, working down by the river all day was such a great reminder of the beautiful music running water makes.
And, there is the fact that I can now say I have gone electrofishing, which is certainly something to break the ice at a cocktail party…for all those many cocktail parties I attend 😉