Trout Roe: FWP harvests, Fish Roe to stock trout population at aspect tanks

In a peaceful cove on Holter Reservoir, almost 90 rainbow trout burst in two huge cages A net swept with, scooped up three females bulging with eggs and swung them aboard a watercraft where Fish, Wildlife and Parks fisheries biologist Eric Roberts and fish culturist Josh Culver waited.

In three nights of live netting rainbows, FWP crews recorded over 900 trout, and then chose the finest fish from those efforts to collect for eggs. The 88 rainbows divided by gender into 2 cages.

rested motionless below the water's surface area until the net entered their domain. The cages turned into a whirling tornado of fins and tails prior to falling back into a lull.

Holter Reservoir has practically no natural spawning rainbows. Biologists see generating in the Missouri River below Hauser Dam and in tributaries, but hardly any with hatchery fish in the lake itself, Roberts stated.

To keep the trout fishery, FWP harvests and fertilizes eggs, then cultivates the brood at Big Springs Trout Hatchery in Lewistown. The state uses eggs from Holter to stock Canyon Ferry and Hauser tanks, plus some lakes near Great Falls, Roberts said.

In the past, FWP stocked fingerlings, but increasing walleye populations starting in the mid-1990s in the reservoir system made fast meals of the tiny trout. FWP began stocking bigger trout in response, and rainbow populaces have actually rebounded.

FWP stocks two strains of trout in Holter: the Arlee and Eagle Lake pressures. The Eagle Lake strain is wilder and will travel into the river and generate. The Arlee is a more tamed strain that tends to grow bigger and faster and have a more aggressive bite, Roberts stated.

Fisheries specialist Chris Hurley dropped the 3 ladies into a water-filled bin containing an FDA-approved anesthetic. Within a few minutes, the fish calmed and Roberts reached in, plucking one out by the tail. He placed it on a ruler and check out off the measurements.

"Twenty-two point one. Female. Hatchery," Roberts sounded off.

Fisheries specialist Troy Humphrey entered the information on his clipboard, then held up a Dixie cup as Roberts placed his fingers near the rainbow's opening, and with a delicate press fluid shot into the cup. Culver did the very same with the next lady. The state checks the ovarian fluid to consider for different conditions that can pass from mommy to egg.

Holding the fish over a decontaminated metal bowl, the two began "stripping" the ladies by making long, pressing runs with their fingers down the fishes' tummies. Eggs shot out in an orange coagulation of almost 3,000 raindrop-sized eggs blended with mucus. The fish appeared like deflated balloons as the last couple of eggs dropped in the bowl.

As soon as completed, Roberts and Culver launched the fish over the side. It took a minute for the dazed trout to find their bearings before a few tail flicks sent them back into the deep.

Once the roe of six rainbows filled the bowl, four males were plucked from the container. A press fertilized the eggs, and with a couple of swirls from Culver's finger, the spawning was almost complete. The eggs were transferred to a cooler to be disinfected in an iodine option prior to making their journey to Big Springs.

The crew prepared to return a minimum of 2 even more times over the spring to collect a mix of eggs from trout that generate at different times.

Three fishermen in a passing watercraft swung by the borders of the cove and peered intently at the sizeable fish.

"What's the greatest trout?" one of the fishermen screamed.

"About 25," Roberts yelled back.

Individuals have a big interest in fisheries, and Roberts and other biologists regularly field concerns about exactly what they're seeing and doing, he stated. The questions are simply part of the task and something to which they're quite accustomed.

The males met a different fate than the ladies. The scene played out like the Pike Place Fish Market in Seattle, with male rainbows flying with the air back into Hurley's web. He swung them into a bin on shore, where FWP fish wellness expert Amanda Bryson had erected a mini lab loaded with test tubes and a cutting board.

"It's a shame to have to kill all these fish, however it's the only means to test for pathogens," she stated.

Each test tube held the organs of five males to be examined at the state fish lab in Bozeman. FWP tests 60 fish from the spawning population.

2 males received a reprieve from the cutting board when Bryson attacked her quota. Humphrey made use of a hole punch to mark a fin so the males would not be utilized to spawn again.

Eggless females moved back into much deeper water. Without the human help, the eggs are never ever laid and the trout eventually absorb them back into their bodies, Humphrey said.

The fish utilized for the generate are mature and in the 3- to 4-year-old variety. FWP occasionally documents a 5-year-old trout, but most hatchery fish do not make it that long, Humphrey stated.

By lunch, no even more trout swam in the traps and a looming thunderstorm stuck around over the back of the Sleeping Giant. An approximated 264,000 fertilized eggs sat in coolers aboard the FWP watercraft. After screening, they will return on trucks in about a year as 6- to 8-inch trout.

"Holter is the very best location to capture fish for the spawn due to the fact that they just travel up and down the coastlines," Humphrey stated. "If we let the males go, they go right back to travelling and we just wind up catching them again."