GF&P tags keep tabs on trout

By Ryan Woodard, Journal staff | Tuesday, May 08, 2007

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In order to gauge the success of an effort to fight an algae infestation and encourage plant growth in one area of Rapid Creek, hatchery officials are individually tagging and monitoring the fish they stock in that area.

On Wednesday, May 2, McNenny Fish Hatchery assistant superintendent Keith Wintersteen and two state Game, Fish & Parks biologists attached numbered tags to about 150 McNenny rainbow trout, which were stocked in Rapid Creek below Pactola Dam on Monday.

The tagging is being done in preparation for the GF&P’s plan to add low levels of nutrients — mostly phosphorous — to an area within a half-mile of Rapid Creek below Pactola this spring, GF&P biologist Dan James said. The nutrients are expected to filter about two miles down the creek.

The GF&P hopes the nutrients will recharge the growth of plant life that supports the trout food chain and in turn recharge the trout population.

Plant life has been decimated recently by the growth of a single-celled algae called Didymosphenia Geminata, also known as Didymo.

Losing that plant life has also caused a drop in the brown trout population, up to 90 percent in some areas of Rapid Creek.

Wintersteen said the GF&P will keep tabs on the McNenny-stocked rainbows to figure out if the nutrients are doing their job.

“These fish give us living organisms in the stream we can track as the nutrients are released,” he said.

The fish were fixed with blue, yellow and orange tags in their backs. The tags all have different numbers, so GF&P officials will be able to easily identify each fish.

GF&P fisheries biologist Gene Galinat said the GF&P will catch the fish this fall to compare their lengths and weights at that time with the time they were stocked.

“We’ll be able to see how much it’s grown or how much weight it’s gained, and that will give us an idea of how these fish are doing in a Didymosphenia environment,” he said.

James said another benefit will be identifying fish movement, such as whether the fish moved from the nutrient-affected part to a non-nutrient-affected part of the water, and vice versa.

“Say we were to stock fish into a non-affected area and it moved into the nutrient-affected area — we’d be able to see that,” he said.

The fish will be placed in two stretches of Rapid Creek below Pactola Dam. One stretch goes from Pactola to Placerville Camp. The other goes from Placerville to McGee Siding.

A total of 450 of the specially tagged trout will be stocked, 150 at a time over the next three months.

The three-year nutrient project first had to be approved by the state Department of Environment and Natural Resources, which doesn’t usually encourage adding nutrients to waters.

In fact, the federal Clean Water Act is aimed at reducing nutrient loads in public waters.

James said tagging the fish is one of many ways the GF&P is going to monitor the project.

Other methods include monitoring the water quality by measuring it for phosphorous and other substances, analyzing the insect community to see if larger insects are coming back, looking at the fish response to the nutrients and checking for an increase in plant life.

“We’ll probably need quite a bit more data before we can decide if this is a real worthwhile, functional thing,” James said.

GF&P officials hope the nutrients will bring back plant life and larger insects. The lack of larger insects is thought to have caused the decline in the brown trout population.

Brown trout only have the ability to eat larger insects. Small insects go through their gillrakers, or food retaining mechanisms.

Rainbow trout are able to eat the smaller insects, and James said using rainbow trout for the study won’t directly help solve the brown trout problem, but it will help.

“It will give us kind of a relative idea because we’ll be able to see if the condition of the rainbow trout improves or not,” he said. “And that doesn’t necessarily translate into brown trout getting better. But it will be an indication that the stream is becoming more productive and that the fish have more to eat.”

Wintersteen said that although using brown trout would have been better, the hatchery had to use what was available.

“You have to start somewhere and you have to work with the tools you have available,” he said. “Right now we have rainbow trout available.”

James said it would probably be a while before the GF&P can decide if it’s the right time to re-stock the area of Rapid Creek with brown trout. The study may have to go on for a while before those details can be determined.

Before stocking is done, the GF&P wants to see if the brown trout will come back naturally.

“Our overall goal is to bring back the brown trout,” he said. “And that’s going to take several years to see the response in them just because it takes fish so long to grow.”

James and Galinat need the public’s help with the project.

Galinat said people who catch the specially tagged fish are encouraged to let the GF&P know by calling the regional office in Rapid City at 394-2391 or by visiting the GF&P Web site at www.sdgfp.info. The fishing section of the Web site has an area to report a fish tag.

“We’d like to know if people are catching them,” he said. “We have some different colored tags so if they take the color and tag number, that’d be great.”

Galinat said a length report also would help.

James said the public can help by not interfering once the nutrients, which will be loaded into the creek in burlap sacks, are in place.

“In order for this to work, those bags will have to be undisturbed . . . I can imagine (people) mistaking it for garbage or something and cleaning it up. Of course we don’t want that to happen,” he said.

Contact Ryan Woodard at 394-8412 or ryan.woodard@rapidcityjournal.com