Electrofishing in Wine Country

Rushing through the open van door, the morning air was numbingly cold.

At least it was to this transplanted South Floridian, as none of my fellow students seem to be shivering as much. Nevertheless, all of us are wearing shorts, for soon we would be encased in the damp warmth of our neoprene chest-high waders and thick, almost armored wading boots.  More importantly, later in the day, the northern California sun will have turned this snug, warming suit into an imprisoning cage of suffocating heat.

It was wise to wear the minimum under these blessed and cursed waders.  But the synthetic rubber that forms these waterproof overalls also provides insulation from an element that is most important to our task:  electricity.

*    *    *

We are standing on the beautiful land that is the serene wine country of Anderson Valley, in Mendocino County, California.  If at first you cringed at the tourist-guide description, you will quickly concede to its aptness as you leave the serpentine, locally nicknamed “Dramamine Drive” portion of Highway 128 and enter the lush, magnificent valleys that line the tributaries of the Navarro River.

As you pass by vineyards upon vineyards of wine grapes, you weave through the almost Mediterranean, deciduous landscape and into overwhelming forests of towering redwoods and verdant ferns, and finally you follow the road out of the coastal ranges to be greeted by the Pacific Ocean.  However, not all is as idyllic as it seems:  logging operations throughout the evergreen acres crash the serenity with noise and sediments, and the very same vineyards suck precious water from the nursery tributaries of Oncorhynchus mykiss, the steelhead trout.

If you have dined on rainbow trout in a restaurant, steelheads are fish of the same fin.  “Steelhead” is merely a fishermen’s moniker for rainbows that do not remain inland but migrate out to sea, much like how salmon leave their freshwater birth streams upon adulthood.  In fact, the steelhead is classified as one of the Pacific salmons, a sibling of the famous coho, sockeye, and king salmons. Coho salmon also use the Navarro’s tributaries for their reproduction, but their numbers in this river have declined so much over recent history that the Navarro population is considered to be an endangered species.

More fortunate are the steelheads, for they are only under a “threatened” status.  But there are a multitude of factors that can affect the growth and size of salmon populations, and the state government has been sponsoring a university-run project to further the search for answers.  They want to know how highway construction and other human developments can impact coho and steelhead numbers; we, a lucky group of college undergrads, got summer jobs tagging fish on the redwood streams and sandy beaches of the Mendocino coast.

Our field attire was complete after a few adjustments of the waders and boots, plus a dash of sunscreen here and a joke there to start the morning off with a laugh, hoping for a problem-free final day of sampling and knowing we would not have to wake up at 5 A.M. for a long time.

Various overstuffed totes were unloaded from the van and the truck behind it; only briefly could one identify all of the unpacked equipment before they were quickly reorganized and carried off.  Long-handle nets, aromatic bottles of clove oil and ethyl alcohol, half-dozen buckets, a compactable camping table, portable aerators, and a laptop computer were amongst the gear already lugged down to streamside. “Down” meaning down a hundred feet of disturbingly steep and slick concrete embankment that flanked today’s site, the Rancheria Creek Bridge.  Sprigs of poison oak lined the path, and the felt-bottomed wader boots added no extra insurance with each footstep; it is a wonder how we managed to carry everything down there.  Fortunately, someone else had already descended with the most crucial piece of equipment, the electrofisher.

Looking like an oversized, boxy, metallic hiker’s backpack, the electrofisher also wears like one, as two shoulder straps and a waist belt clamp the twenty-odd pound contraption to you.  Various companies manufacture the device, but all electrofishers share the same plan:  a rechargeable battery pack, a tough casing, exterior dials controlling the voltage output and other electrical parameters, a usage-time recorder, and a sturdy frame to support all the above.

There are two important attachments:  a wire-cable “rattail” cathode on the left and the metallic anode hoop, which looks like an five-foot long, plastic-handled butterfly net missing its netting and plugged into the right side of the backpack via a long telephone cord.   When placed in water, the rattail and the hoop portion form a complete electrical circuit; activate a switch on the anode handle and bursts of electricity are released, startling or temporarily paralyzing any fish present between the anode and the cathode, depending on their size.  Steelheads react with a unique response:  galvanotaxis.  Whereas most fish are merely rendered immobile by a proper shock, steelheads will, as if by magic, gravitate towards the negatively charged anode through involuntary muscle spasms, even out from under the most gnarled submerged tree stumps. You might understand why electrofishing is the preferred collecting method for a project such as this.

Cold as it was, the low temperature and early hours are actually important to steelhead research, since federal regulations do not permit electrofishing for steelhead if temperatures reach over twenty degrees Celsius, for these coldwater creatures become highly stressed and less able to recover from handling at this heat.  Someone’s watch had just beeped eight A.M.; fishing must begin as soon as possible.  We do get a break on this last day, as we are not tagging any fish but are only seeking “recaps,” steelheads containing the rice-sized computer chip implanted into them as long as a year ago by our project.

All steelhead captured are recorded for their weight and length for general natural history data, but it is the recaptures that reveal changes in growth and movement within the stream, data that will help compare steelhead health in streams under various levels of human impact.  To check for tags, we link our laptop to a transceiver-antenna module that detects the unique alphanumeric code of each tag.

In today’s case, we would expect a silent reaction for most fish passed through the circular antenna; a mechanical chirp would be cause for joy, as it announces we have caught a tagged steelhead.  All fish are sedated prior to measuring and scanning to minimize stress, using the pungent clove oil and alcohol solution prepared earlier.  Surprisingly, only two people are needed at the computer station to process the captured fish, and this lends more hands to the electrofishing effort, which is most efficient with a group of four.

To that expedition I joined, as Rick, our fieldwork leader, was armed and ready with the electrofisher.  Soon, we would face-off against the wily steelhead, with Rick at center and a wingman ready at net, while I defended slightly downstream, scooping up any missed fish; a fourth person would be on guard with aerated buckets, and ready to shuttle back to the station with new fish.

Fifteen degrees Celsius exactly, the thermometer read; it was shock time.  Though it was fenced off by a ring of sizeable stones and about as wide and as deep as a kiddie pool for one, nevertheless the small eddy sat at the start of our sampling boundaries, so we began here.  Using the minimum voltage, Rick flipped the switch, and instantly three, foot-long flashes of silver scrambled, but the bordering stones seemed to have blocked off the dazed fish’s escape.

We cranked up the volts for the second sweep to make sure we could get at least one steelhead out of this effort, and sure enough, a shuddering, rainbow flank sat right at my feet.  In a true moment of cartoon irony, I hastily slammed my net in the water to catch the subdued fish.  Continuing the sequence, I scooped my net upwards so hard that the steelhead was fast airborne and with an audible “bonk,” bounced off of Rick’s chest and happily into the next pool.

The quiet redwood creek has never heard such loud, howling laughter, and with trickles of residual giggles and teases, electrofishing resumed.  When the summer field season ended that day, we had measured, weighed, and released almost three thousand juvenile steelheads and had tagged an additional fourteen hundred.  That fish was just lucky.


Originally completed January 23, 2002, for a nonfiction writing course.  This version has been updated with hyperlinks, art, and minor edits.

Image credits, top to bottom: AEAL-UC Davis; Benjamin Landis; Benjamin Landis

Much credit to my writing instructor Scott Herring, a nature writer who is noted for Lines on the Land, essays on the literary and artistic legacies of the National Parks.


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