Tuesday, July 16, 2013

It’s Electric: Triennial Fish Study Returns to Silver Creek

By Caley Gallison, Silver Creek Preserve Intern/Colorado College

Every three years, fishing on Silver Creek undergoes a notable and temporary transformation. Fly rods are exchanged for electroshocking probes and recreational fishermen are replaced by professionals from the U.S. Geological Survey (USGS) and Idaho Fish and Game (IDFG). USGS and IDFG perform separate studies but collaborate in order to correlate their data. Both studies are reliant on volunteer help, engaging Silver Creek Preserve staff and a few locals for help during the scientists’ time on the creek.

Electroshocking is an effective, accurate and largely harmless research method used for gaining insight as to the number and types of fish that are present in a freshwater ecosystem. Basically, electroshocking consists of two positively charged electrical probes that are hooked up to a negatively charged generator on a boat. The positive charge attracts the fish and then temporarily stuns them so they can be scooped up by the nets, put into a water tank with running and oxygen and processed. The fish are carefully released back into the stretch of creek they came from and are watched to make sure they swim off alright. Few fish are harmed by the technique, they are handled with the utmost of care and the data obtained is important for helping to maintain a healthy ecosystem. Even as an avid vegetarian and animal advocate, I was impressed by how careful the handling of the fish was for a relatively invasive technique.

Studying Silver Creek's fish population. Photo ©Terry Maret

It was quite a treat to see all of the fish inhabitants up close. I had started to learn the differences between all the various types of fish but it was not until after looking at hundreds of fish up-close that I could really differentiate a brown from a rainbow trout or a speckled from a long-nosed dace. And each fish within a species is so incredibly different from the next – from their distinct markings to their relative skinniness to their temperament. A number of the fish had bird talon scars on their sides, a testament to a life full of hardship and close calls. And of course, there were a few fish that were of monster size, relics of years of evading predators or of more recent predators like the American white pelicans.

This cold water ecosystem is a haven for rainbow trout. Photo ©Terry Maret

Over the past few weeks, we helped with several studies during the day as well as several at night. IDFG performs some of the electroshocking after dark because it is easier on the fish and they recover quicker. Since we were on the creek during different times, we saw all sorts of wildlife. Nearly every time we were on the water to electrofish, we saw moose! The first day on Silver Creek right before we started, we saw a mother moose, her yearling and baby, and that sighting sure did set a precedent. Once, we had to wait nearly a half hour for the mom and her calves to cross back over the creek so we could proceed. I even had to wait to get into my truck at 3 a.m. after a night session since the moose were right in my way and I was not about to anger them.

A couple of fishing guides and fishermen went along with us during the day shocking; they could not understand why with so many fish in the creek, it was impossible to catch them. I guess the fish here on the Preserve really are smart, and very good at hiding! Hopefully, with the continued aid of these fish studies and other conservation practices, Silver Creek will remain a world-class trout fishery that everyone from humans to animals alike can enjoy for years to come.

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