Two wildly different water years have hampered a cooperative experiment between fishery agencies in Montana and Wyoming to boost native sauger numbers in Bighorn Reservoir.
The idea was to take sauger eggs from fish captured during their May spawn in the Bighorn River in Wyoming. The eggs would be raised at the Miles City Hatchery and stocked as fingerlings on the Montana end of the 70-mile long Bighorn Reservoir, which straddles the border of the two states.
Mother Nature hasn’t cooperated, though.
In 2011, unusually high water made it difficult to capture any sauger. In a month of work, fisheries crews collected only 1.5 million eggs. Out of those eggs, only 60,000 grew to fingerlings for stocking.
The Bighorn River was lower this year, but there was little mountain snowmelt in May. When warm weather hit, the river spiked a fever, with water temperatures rising into the mid to upper 70s. The warm waters killed most of the sauger eggs while they were still in the fish.
“The eggs basically cooked before we got them,” said Mark Smith, a Wyoming fisheries biologist.
So even though the fisheries crews captured about 6 million eggs, only 1 percent hatched – about 60,000.
“We put in a lot of effort and felt really good because we got a lot of eggs,” Smith said. “But by the time we were done collecting eggs, we realized the survival was really low.”
The goal had been to stock 1.5 million eggs over three years on the Montana end of the reservoir and then evaluate the effect of that stocking for three years. That timeline may have to be pushed back.
Species of concern
Montana agreed to stock the sauger in an effort to protect what is listed as a species of concern in the state – meaning its numbers are low and it is restricted to only a few waters. The sauger in Wyoming’s Bighorn River, and also in Bighorn Reservoir, are genetically pure as well as a unique species.
The worry is that sauger have been known to interbreed with walleye. The product of the union is a saugeye. No saugeye has ever been found in Bighorn Reservoir although hundreds of sauger have been tested, Smith said. But there’s still a fear that it could happen, especially if saugeye were inadvertently stocked by FWP, he said.
“If we could have pure walleye, it would be less of a concern,” Smith said. “The concern on our end is the introduction of hybrids inadvertently. We could have this scenario where we have pure sauger and pure walleye break down on us.”
Wyoming quit stocking walleye on its end of the reservoir in 2000 because fisheries staff determined that its more turbid waters were not hospitable to the fish. The state no longer stocks any fish in the reservoir.
To help its neighbors to the south, Montana in 2009 began stocking only sterile walleye, also called triploids, in Bighorn Reservoir. The eggs are collected from Fort Peck Reservoir walleye. With the transition to triploids only, the agency is stocking far fewer walleye, dropping from 500,000 a year prior to 2009 to only 600,000 triploids spread out over six years.
“We don’t want to jeopardize the last-known genetically pure population of sauger,” said Mike Ruggles, an FWP fisheries biologist who has overseen the project.
While water fluctuations in Wyoming’s Bighorn River have caused headaches for fisheries managers attempting to collect sauger eggs, steady water years at Bighorn Reservoir since 2005 have benefited the impoundment’s fish.
“The body condition of these fish in the last few years has been tremendous,” Ruggles said.
The fish are doing well partly because the population of emerald shiners – a main forage fish for walleye and sauger – has been steady.
According to Wyoming Game and Fish surveys, the average sauger in the reservoir measured 18.3 inches in 2011 and weighed 2.5 pounds.
“We have a bunch of big fish, probably as many as we’ve seen in a decade,” Smith said.
Based on twice-a-year nettings as well as spring fish-shocking surveys, Ruggles said his crews are commonly seeing 3-pound saugers in Montana’s section of the reservoir.
“We’re hoping to create this great walleye-sauger fishery,” Ruggles said. “Sauger could easily provide fish 2 to 4 pounds.”
The sauger have the potential to grow from 1- to 1.5-inch fingerlings when planted to about 14 inches in four years in Bighorn Reservoir.
“Sauger have a little bit slower growth rate,” Ruggles said. “These are pigs down here. These are really robust fish.”
How’s the fishing?
According to fish studies, Ruggles said sauger are known to be a more aggressive feeder than walleye. That means they should be easier for anglers to catch. Bob Klein, president of Montana Walleyes Unlimited, has found that to be the case.
“My personal catch rates on sauger are better,” he said. But he added that he sees few of the fish north of Barry’s Landing, a boat launch site near the Montana-Wyoming border.
“My viewpoint is the sauger are a river fish, not a reservoir fish,” he said. “They just don’t travel up the lake as far as everyone thinks they do.”
And since FWP quit stocking fertile walleye, Klein said the walleye fishery at Bighorn Reservoir has declined. Although anglers can still catch a nice walleye in Bighorn Reservoir, Klein said the fish are fewer and catch rates are lower.
So Walleyes Unlimited would like to see changes.
“We’d like to see the triploid project re-evaluated,” Klein said. “Before they consider doing this at other spots, they should re-evaluate it.”
He said the fishery plan may boost sauger populations, but they are just one small part of a very large, 70-mile long fishery that also includes smallmouth bass, channel catfish and yellow perch.
“We’d like to see fertile walleye in there, but it’s probably not politically possible,” Klein said.
The bottom line, he said, is that survival rates of the stocked sauger and walleye seems poor. He sees the triploid stocking as labor intensive and expensive to produce a small number of fish.
“I love (Bighorn Reservoir) because of its scenic beauty,” Klein said. “It’s an absolutely gorgeous body of water. But it used to be a lot better walleye fishing.”