BILLINGS, Mont. — High water last year and warm water this year are complicating an effort to boost sauger numbers in Bighorn Reservoir in northern Wyoming and southern Montana and might prompt biologists to reassess their stocking goals.
Fisheries managers have been hoping to increase fish numbers in Bighorn Reservoir by gathering eggs from the spring spawn in the Bighorn River in Wyoming.
Young fish are raised from those eggs at the Miles City Hatchery in Montana and stocked at the Montana end of Bighorn Reservoir.
The Billings Gazette reports that unusually high water last year made it difficult to catch sauger for their eggs. Biologists gathered 1.5 million fish eggs — a relatively small number — and were able to raise just 60,000 of those eggs into hatchlings.
This year, warm water made many of the fish eggs gathered unviable. The river was much lower but was fed by much less mountain snowmelt. Water temperatures soared into the 70s.
“The eggs basically cooked before we got them,” said Mark Smith, a Wyoming fisheries biologist.
Biologists gathered many more eggs this year — about 6 million — but again, only about 60,000 of those could be raised into hatchlings.
“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.”
Biologists said they may have to push back their fish-stocking goals.
Sauger are closely related to walleye. The reservoir is home to both species, and despite the recent problems with stocking, the population of larger sauger is strong.
The average sauger in the reservoir measured 18.3 inches and weighed 2.5 pounds in 2011, according to the Wyoming Game and Fish Department.
“We have a bunch of big fish, probably as many as we’ve seen in a decade,” Smith said.