Greenback cutthroat trout comeback continues on edge of Colorado Springs

Jun. 7—Colorado Parks and Wildlife teamed up with the U.S. Forest Service Tuesday morning to spawn one of the rarest breeds of fish in the United States — the greenback cutthroat trout.

Adopted as the Colorado state fish in 1994, the species of cutthroat trout was thought to be extinct in 1937, succumbing to the consequences of mining pollution and overfishing.

However, about 75 years later, the species was rediscovered in 2012 in the Bear Creek watershed on the southwest edge of Colorado Springs — nearly 100 miles south of the species' ancestral waters in the South Platte River drainage basin.

With the watershed residing on both Pike and San Isabel National Forests and city property, a joint effort of Colorado Parks and Wildlife and the Forest Service is involved in efforts repopulate the greenback cutthroat trout.

"It's super-rare for a species to be recovered that were believed to be extinct," said Janelle Valladares, a fisheries biologist with the Forest Service.

According to Bill Vogrin, a spokesperson for CPW, the population of greenback cutthroat trout in Bear Creek is believed to have been brought to the area in the late 1800s for a tourist fishing enterprise. Through genetic testing using fish tissue samples from the Smithsonian National Museum of Natural History, officials were able to confirm the last population of pure, wild greenbacks to be in the Bear Creek watershed.

Cory Noble, Parks and Wildlife's aquatic biologist covering the Pikes Peak region, has been responsible for recovering the greenback cutthroat trout population since starting with the organization in 2016. He said that although biologists have been able to establish several populations in the wild over the years, the Bear Creek population remains a top priority.

"Having this wild population here, where they're naturally reproducing and doing reasonably well is extremely important," Noble said.

A team of 10 aquatic technicians split up in pursuit of covering a 3-mile portion of the creek Tuesday. Armed with backpacks looking to be straight out of "Ghostbusters," biologists used an electro-fishing method to catch possible specimens.

"We use electricity to put a current into the water which briefly stuns the fish. We then net them up and stick them in buckets to spawn them later on," Noble said, "I'm checking to see if they're ready to spawn. The males will be expressing milk, and we should be able to squeeze a few eggs out of the females."

Teams spent just over an hour traversing the rough creek terrain, then collecting and tracking greenbacks in the process. Ripe greenbacks were brought back to a live well near a spawning tent, while "green" fish were recorded and released.

"It looks like we have some nice ripe females today, and the eggs are precious," Valladares said, "It'll be a big deal if we can collect a lot (of eggs)."

According to Valladares, the term "ripe" is used by aquatic biologists and technicians to describe a female carrying unfertilized eggs. If a fish is "green" that means it has not reached maturity and is incapable of reproducing.

Over four females and four males were brought back to a tent near a separate portion of the stream to be spawned. Noble, surrounded by his team, led the process.

Starting with the females, Noble handled one fish at a time, physically squeezing, or "milking" the fish's lower torso to retrieve the eggs, or "rows."

Noble estimated a total of 100-150 eggs were retrieved in the process — a successful first round of female spawning this June, considering last year's efforts resulted in finding a single ripe female trout.

He then began milking the male's "milt" or semen in with the petri dish of freshly harvested eggs. The eggs are then fertilized through the addition of stream water. Goose feathers are used to stir and clean the eggs.

"They're soft," Noble said of the feathers, "but firm enough so we can manipulate things and move them around. They're slightly water resistant so they don't get too saturated.

"Once we get them fertilized, I'll be stirring and mixing them. We'll pour some water after the sperm, and that makes the sperm become active, they start swimming and the pores on the eggs open up allowing the sperm to go through. Any contaminants we'll be picking out with a feather as well before we get them in transport."

The eggs are then sent to the state's hatchery in Salida, where they'll incubate. Within two to three weeks, the eggs will hatch and will then be sent to the Leadville National Fish Hatchery, where they will be raised into adulthood to help replenish the broodstock of greenbacks.

A broodstock refers to the reproductively mature adults in a population that breeds, or spawn, to further the growth of a population, according to the Fish and Wildlife Service.

This is the first of three scheduled spawning sessions in June that are tedious processes and full of unknowns, Noble said. Only 10%-20% of eggs collected this year will survive into adulthood.

This past September, Parks and Wildlife announced a second population of greenback cutthroat trout to be naturally reproducing at Herman Gulch — an incredible feat for Noble, Valladares and the team behind their efforts.

"It's wonderful anytime you see any good news in this species. It's reassuring that we have a second population where we have reproduction happening, but it doesn't diminish the Bear Creek population by any means," Noble said.

The greenback cutthroat trout population decreased from 2017 to 2020, the last time Parks and Wildlife did a population survey for the fish, Noble said last year.

This year, CPW said the greenback population is stable.

"We had that decline and have taken several steps to reduce stress on the fish," Vogrin said, including use of a 360-degree underwater video camera that allows folks like Noble to survey the fish without having actually touch them. "We also decided not to spawn them in 2020 which allowed them to lay eggs and fertilize them in the creek. That may have helped boost the population in Bear Creek."