Fish & Wildlife - Region 6
Mon Nov 19 12:09:00 MST 2012
Montana Fish, Wildlife & Parks staff collected 574,229 Chinook salmon eggs this fall from adult fish that were attempting to spawn in Fort Peck Reservoir.
That didn’t beat the record of 610,230 eggs collected in 2010, but it came close, said Heath Headley, the reservoir’s fisheries biologist. The number also was about double the eggs collected last year.
FWP began stocking Chinook, also called king salmon, into Fort Peck Reservoir in 1983. They were introduced to offer a unique angling opportunity and to utilize the coldwater habitat, as well as to feed on a growing population of cisco -- also known as lake herring -- that inhabit the reservoir.
Roughly 75 percent of the anglers that visit Fort Peck Reservoir target walleyes, but creel surveys show that Chinook salmon are the next most targeted species there -- beating out other popular fish like northern pike, smallmouth bass and lake trout.
Currently, this is the only Chinook population in Montana. Headley noted that anglers will travel as from the Dakotas, Wyoming, and western Montana to partake in this unique fishery.
Shortfalls in habitat conditions in the reservoir prevent the fish from successfully spawning on their own, so their eggs and milt must be collected and mixed manually when the adult fish congregate each fall near the Flat Lake boat ramp, the dam and the nearby marina.
“We rely exclusively on an electro-fishing boat to capture the spawning adults,” Headley said. “It involves intentionally sending an electric current into the water where the fish are congregating, which stuns them and makes them easier to net. That’s proven to be most effective because it allows us to easily locate and collect a lot of salmon at once.”
The salmon in Fort Peck Reservoir typically show up in shallow areas near their original release sites once water surface temperatures hit 60 degrees. Peak spawning activity doesn’t occur until surface temperatures hit about 55 degrees.
After collection the eggs are disinfected, counted and placed into incubation jars or heath trays, said Wade Geraets, manager of the Fort Peck Multi-Species Hatchery.
“The incubation jars are clear plastic jars that allow water to up-flow through and gently roll and oxygenate the eggs” Geraets explained. “The heath trays are a group of trays set up in a vertical rack system that allows gravity-flow water to move over the eggs and oxygenate them.”
After a month, eye pigmentation begins to develop in the live eggs. At this ‘eyed stage’ the eggs are then physically shocked before picking. This is done by siphoning eggs from their incubation vessel and striking them against the side of another container.
“Infertile or undeveloped eggs are tender, and the shocking causes water to enter the ruptured egg and coagulate the egg yolk turning the egg white,” Geraets said. “These eggs are then picked out with a tool that separates the live eggs from dead eggs. The live eggs are then placed back into the incubator or heath trays until they have hatched and the young have used up their egg yolk.”
Chinook salmon eggs at the Fort Peck facility typically start to hatch the week of Nov. 19, and egg batches will continue to hatch through the first two weeks of December.
“Once the Chinook salmon have used up the nutrition found in their egg yolk, we’ll begin feeding them a processed fish food,” Geraets said. “The management goal and stocking requirements are to grow the fish to 4.5 to 4.75 inches long at the hatchery prior to releasing them into the reservoir in early June.”
To help supplement the Fort Peck egg take, the facility this year received 69,000 eyed eggs from the Garrison Dam National Fish Hatchery in North Dakota. Headley said that Montana and the Dakotas are currently the only source for disease-free Chinook eggs in the Lower 48 states. That’s why the annual egg-taking effort on Fort Peck is critically important to the continued existence of a healthy fishery.
“Condition of the adult salmon in Fort Peck in 2012 was excellent due to an abundance of cisco in the reservoir,” Headley said. “Males averaged 10 pounds, and females averaged 15 pounds. The largest salmon collected during the operation was 27 pounds. Younger salmon were also present, which indicates improved growth and survival over the last few years and a positive sign of things to come in the near future.”