USU Researchers Monitor State of State Fish

There’s one sure-fire way to catch fish without the hassle of snags, long debates over fly choice and even a rod or reel. However, you will need a canoe equipped with a generator pumping between 250 and 400 volts of electricity into the water. This works because fish swim toward the electrical field, ultimately getting close enough to be stunned, which makes the fish float to the surface where all you have to do is net them.

 

The technique is aptly named electrofishing. But it is reserved for fisheries management, not weekend warriors. Locally, electrofishing is being used to study Bonneville cutthroat trout in the Logan River. The Bonneville is native to the waters of Logan.

 

The study began in 2001 after whirling disease was found in the Logan, said Phaedra Budy, assistant professor in the Department of Watershed Resources at Utah State and an assistant unit leader for the U.S. Geological Survey’s Utah Cooperative Fish and Wildlife Research Unit. Along with whirling disease, the study is looking at how other factors, like drought and competition from other species, affect the cutthroat population.

 

Home of one of the largest remaining populations of the species in the region, the Logan gives researchers a fairly healthy population to study, making this study an important tool for management of the Bonneville cutthroat trout throughout the region, according to Budy.

 

The number of cutthroat in the higher elevations of the Logan is one of the highest in the region. Budy said they are seeing densities between 1,500 and 2,000 fish per kilometer of river. So far, the study has found the cutthroat population bounces around a bit, and shows a slight decline – possibly because of five years of drought-caused “bad water” – she said. But the population is still fairly strong, Budy added.

 

At a site near Bridger Campground, it’s evident that other exotic fish populations are thriving, as well. Between 200 and 300 brown and rainbow trout – both imports to the Logan – were pulled out in the lower part of the river, which they tend to inhabit, said Jeremiah Wood, a graduate student in fisheries biology at USU.

 

That’s a density of almost a fish per square meter, he noted.

 

“There’s still a lot of fish,” Wood said.

 

This is good news for anglers. To get these numbers, researchers – including fisheries biologists, graduate and undergraduate students from USU and other volunteers – have eight sites along the Logan River, spanning from Franklin Basin to the 10th West bridge in Logan. At each site, 200-meter sections of river are measured out and nets are set up at each end to keep fish in the section.

 

The crew, usually consisting of about 15 people manning the canoe and nets, make three passes through the section – with many of the fish being caught on the first pass. The fish are then transported to sore in five-gallon buckets full of water and dumped into bigger garbage cans full of water.

 

Before being released, each fish is measured and weighed, and those over six inches are tagged with colored, individually numbered tags. A smaller sample is tested for whirling disease, while others are “barfed” to have their diet analyzed. “Barfing” is a term for a process called gastric lavage, which is simply injecting water into a fish’s stomach to force the contents out.

 

Like all of the processes – except the testing for whirling disease – barfing is non-lethal. And although they may seem stressful to the fish, it must not bother many of them much.

 

At the Bridger Campground site, researchers caught 50 fish they had tagged last year, and at other sites, some fish have been captured four or five years in a row, said Gary Thiede, a fisheries biologist at USU.

 

“Fish to have their spot that they always return to,” Thiede said.

 

Some of the frequent captures even have names. One four-pound brown trout is called “LeRoy Brown” by the group, Thiede said.

 

They even find smaller tagged fish in the bellies of bigger fish, he added.

 

Tagging and recapture gives researchers more than an opportunity to give fish nicknames. It tells them a lot about survival rates, growth and movement – all key to population monitoring. This monitoring is an important part of the study, which is a part of a conservation agreement involving state and federal agencies to keep the Bonneville cutthroat from ending up on the threatened or endangered list, which would place management of the species under federal control.

 

Funding for the study comes from federal sport fish restoration money administered through the Utah Division of Wildlife Resources, Thiede said.

 

“Luckily, the native species here is a sport fish,” Budy said.

 

The state also has personnel involved and, through the DWR’s Dedicated Hunter Program, provides volunteers for the study.

 

There’s more to the project than electrofishing, though. Researchers also collect habitat information, including water flow, dissolved oxygen, salinity and pH – anything to give them a better idea about the fish population.

 

All the data gathered allows fisheries managers to make informed decisions about fishing regulations and other things, like stream-side grazing that can affect the population of cutthroat trout or the spread of whirling disease. This could mean many different things, including the consideration of several different options involving brown trout, which outcompete cutthroats and can have a negative impact on their population, Budy said.

 

The Logan River study also provides a basis for other research to come, Wood said. Besides the benefits for researchers and fisheries managers, anglers who frequent the Logan River will also gain.

 

“Basically, the long-term benefit to (anglers) is they’ll always have fish to catch,” Wood said.

 

In the end, that’s all any angler can hope for.

 

 

“USU Fisheries Program Listed Among Top Three in Nation,” Utah State Today, January 2007.