RIVERDALE There have been cisco sightings this summer from the Garrison Dam Tailrace to Bismarck and beyond. Thousands of ciscos that didn't survive a tumbling ride through one of three release tunnels or hydro-electric power generating turbines have been floating lifeless downstream. While the sight of so many dead fish floating on the river may be startling, the loss is likely not large enough to significantly alter the cisco population in Lake Sakakawea.
A few short decades ago there were no ciscos in Sakakawea, but they were stocked into Fort Peck Reservoir farther up the Missouri River in Montana. Biologists introduced cisco into Fort Peck as a cold water forage fish for lake trout. In time, enough ciscos came downstream to create a viable population in Lake Sakakawea.
"We were doing a study prior to possibly introducing them into Lake Sakakawea in the '80s," said Greg Power, North Dakota Game and Fish Department fisheries division chief. "Then we started recovering them in Sakakawea and Lake Audubon. All of our cisco came from Fort Peck."
Kim Fundingsland/MDN - - Fishermen have returned to the Tailrace which was closed during a lengthy period of high releases from Garrison Dam. Note the number of birds that have been feeding on fish, including small cisco, that were suctioned from Lake Sakakawea above to the Tailrace below.
Kim Fundingsland/MDN - - This adult cisco found floating below the Garrison Dam Tailrace is typical of those that perished after passing through the dam’s release tunnels. The release tunnels, spillway and power generating turbines have all been utilized to pass water through Lake Sakakawea this summer.
The Montana cisco originally took hold in Sakakawea at a time when smelt numbers were declining in the late 1980s and early '90s. At that time young cisco helped fill a void in the forage base created by the loss of smelt.
"The first year or two they can be used for forage," said Dave Fryda, Game & Fish fisheries biologist. "Salmon can stay on top of those cisco for a year or two. Their niche is pretty similar to smelt."
Similar yes, but the two species live in competition with each other. When smelt are reproducing well and increasing in numbers, cisco populations decline. The cisco currently seen floating in the Tailrace are likely those from a large year class of 2007 that was 15 percent above the norm. Since that time smelt have rebounded and the number of young cisco has dropped correspondingly. Smelt are known predators of cisco eggs and young.
"Smelt will out compete cisco," Fryda said. "The cisco fishermen are seeing are actually looking thinner than normal, just reflective of a good smelt population."
Cisco are a member of the salmon family. The North Dakota state record is 2 pounds, 8 ounces. A "whopper club" cisco is 1-3/4 pounds.
"The term cisco refers to one species basically," said Scott Gangl, Game & Fish fisheries management section leader. "In Minnesota they are called tullibee or lake herring. They are different from lake whitefish."
Many of the dead cisco in the Tailrace appear to be in the 1-1/2- to 2-pound range, too big for most walleyes or salmon to eat but good food for large northern pike. Lake Audubon, which has a history of struggling to maintain a forage base, has seen an increase in the average size of gamefish the past few years. Much of the credit goes to young ciscos.
"Audubon has always lacked in suitable forage," said Power. "Cisco have been good for the fishery. In the big picture I'd say cisco is a positive rather than a negative. Twenty-pound pike love cisco."
Muskies love cisco too. It was a growing population of adult cisco that helped encourage recent stockings of Tiger muskies into Lake Audubon. As the Tigers increase in size they will feed on adult cisco. That should lead to some fast growing muskies for fishermen to tangle with in a few years.
In some lakes fishermen target ciscos. Ciscos can provide plenty of action and, if your taste permits, can be smoked and eaten. Sometimes ice fishermen report catches of cisco from Lake Audubon.
"They're kind of a component, but overall not a big component of the cold water forage," Fryda said. "They live throughout the system and push down the reservoir as the summer goes on."