Shocking habitat projects help increase native Cutthroat populations

Wednesday , May 14, 2014 - 12:07 PM

Dylan Brown

With a snap, a dry-fly follows the lead of a rod and lands above a swirling pocket of water. A moment later, the nose of a fish surfaces and the fly disappears from the angler’s sight.

The struggling fish fights the tension of line and before long, the fish is netted and the angler sees orange flashes, signifying he has landed a native Bonneville Cutthroat trout.

He is standing in the center of the Weber River near Mountain Green.

He may not know it, but the fish he is holding is somewhat of a rarity. Upon closer inspection, he realizes that the fish is missing his adipose fin.

He unhooks it and watches it dIsappear from sight.

According to Paul Thompson, the northern region aquatics manager for FWP, the adipose fin, which is the small fin behind the dorsal fin, does nothing for the fish.

But for anglers and scientists, it signifies that this fish has been shocked. Yes, as in shocked with electricity.

“Basically when we put electricity in the water it stuns the fish. They become immobile, allowing us to net them,” said Thompson. “As soon as they are released to fresh water they return to normal.”

Since 2011, Division of Wildlife Resources, along with support from Trout Unlimited and Utah State University, have been shocking Bonneville Cutthroat trout by using a wand that pulsates a low voltage current in the water.

“It does a good job in streams that are five to 10 feet wide,” Thompson said.

When a fish comes in contact with the electrical current, they are temporarily paralyzed. Biologists then record their weight, length, population and using microchips, migration.

After a fish has been tagged, biologists cut off the fish’s adipose fin, making it easy to identify that the fish has a microchip.

The shocking began after DWR scientists discovered a rare population of fluvial Bonneville Cutthroat trout living in the Weber River water system.

A fluvial fish is one that lives in a large, free-flowing body of water and then migrates to headwaters to spawn. Cutthroats typically don’t become fluvial until they are more than 12-inches in length.

At one time thought to be extirpated, the Bonneville Cutthroat trout is proving to be a resilient and resourceful fish.

Using the microchips that are injected into the underside of the fish, biologists have been able to track these fish in specific tributaries. But because of human development in the area, many of these streams pose serious obstacles for the fish.

Antennas are placed near the mouth of select tributaries, below red-flagged obstacles and in some cases, above the said obstacles. When a tagged fish passes these antennas, it is recorded in a database. This database is then downloaded, logged and later analyzed.

There are currently nine antennas in place throughout the Weber River basin, with a tenth going in shortly.

In Jacobs Creek, which is located south of Mountain Green, there are two.

One is located below a road crossing and another above. The obstacle is composed of roughly 10 vertical feet of riprap, followed by a two-foot vertical jump into a circular conduit.

“This one kind of surprises us," said Matt McKell, northern region streams biologist for DWR. “Even though it looks pretty rough for a fish, about two-thirds of the tagged fish that we had come through the lower antenna last year also hit the upper.”

According to Paul Burnett, project coordinator for Trout Unlimited, there are 196 impassible obstacles across the entire Weber River basin.

“When you start doing the numbers, it’s obvious it’s impossible to get to all of them,” he said.

These monitoring sites are important because it helps scientists prioritize streams.

“Based on the number of cutthroat (in certain streams) and looking at the proximity to mainstem river populations … If we can reconnect habitat for those populations, then generally we can have a bigger bang for the buck,” he said.

In coordination with non-profit groups, some federal and state grants,

Trout Unlimited has been fixing some of these impassible obstacles.

“By reconnecting all of these tributaries to the mainstem for spawning purposes, we’re building what is known as population resiliency,” said Burnett. “So if all of the fish are spawning in one spot and there’s a bad year in that one area then that will affect the population that we fish for in the Weber River.”

If DWR can reconnect all of the spatially separated streams in the Weber River basin, then that would potentially strengthen the Bonneville Cutthroat numbers, resulting in better angling opportunities.

To further protect this limited resource of Bonneville Cutthroats, starting in 2013, the DWR enacted a new regulation from the Great Salt Lake to Echo Dam for catch and release on all Cutthroat trout.

“The goal there is to keep as many fish in the river as we can, so there’s more fish to go up these tributaries to spawn,” said Thompson. “And through habitat projects; increase connectivity through these tributaries; increase areas they can spawn; build populations in the Weber. And maybe even get to a point where we will allow harvesting of Cutthroat in the Weber River.”

But for now, when the line goes taught and the reel winds tight, if there is orange flashing, the fish must be returned to weather another day. 

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