Hatchery prepares salmon for Oahe
RAPID CITY -- It's a monotonous job, but somebody has to do it in order to keep track of Chinook salmon in Lake Oahe.
Staff and volunteers at Cleghorn Springs State Fish Hatchery in Rapid City have been busy preparing 50,000 4-inch-long fingerling Chinook salmon for stocking in the massive Missouri River reservoir in May. Staffers mark the tiny fish one by one, clipping their adipose fins and implanting a tiny segment of coded wire into the cartilage in their nose.
The hand-operated injection machines are efficient, if boring to operate.
"One person can average 1,000 tags or better per hour," hatchery manager Will Sayler said. "And we run three taggers. One of our volunteer students was able to inject 1,300 tags per hour, which is very quick."
Baby salmon are pretty quick, too, which is why a chemical sedative is used in the water to knock them out, temporarily.
"It just makes the whole process a lot easier," Sayler said.
In years to come, those grown-up marked fish -- part of a total salmon stocking of 210,000 in Oahe this year -- will be caught by anglers or captured by Game, Fish & Parks Department fish crews in a salmon spawning station at Whitlock Bay on Lake Oahe. And the coded wire will tell biologists when, where and at what age the fish were stocked. Such data will help determine how well salmon survive and grow and how many are caught by anglers in South Dakota's largest reservoir.
It's important information to a salmon-management program that began about 30 years ago on Oahe. Salmon stocked in the Missouri River in North Dakota started turning up at the end of anglers' lines downstream in Lake Oahe. South Dakota began stocking its own salmon soon after.
Eventually, the state built the spawning station at Whitlock Bay west of Gettysburg, which became the center of salmon operations. Salmon stocked as fingerlings in that area return in three or four years to spawn, and die -- or be caught by anglers in the process. An artificial fish ladder allows many to swim up into the spawning station, where GF&P fish crews take their eggs.
Those eggs are then transported to Cleghorn Springs, and the McNenny State Fish Hatchery near Spearfish, where they hatch and produce salmon fry that will grow in hatchery tanks to stocking size.
Most are stocked as fingerlings, slightly longer than 4 inches. A smaller number will be kept in the hatchery for stocking this fall, when they will be about eight inches long.
Oahe Chinooks will grow to 12 pounds to 15 pounds, and sometimes even bigger. The state record Chinook, caught in Oahe in August 2003, weighed 23 pounds, 12 ounces.
These 4-inch fish have a ways to go to approach trophy size.
But when some of them get there, thread-thin bits of coded wire in their snouts will help biologists better understand their journey.
The fish will be collected at the spawning station after they are spawned out or taken from collection boxes on boat ramps along Lake Oahe, where anglers leave the heads of the fish. Reading that wire back in the laboratory is an interesting process in itself. First, they have to find the salmon heads that contain the wire tags.
"They're able to slice off the nose, and they have a magnetic detector that beeps when the metal tag is passed through," Sayler said. "That identifies the fish with the coded wire. Then, you section the flesh until you get to the piece with the little wire. It has hash marks etched into the tag. Under a microscope, you can read it."
That information helps fisheries teams adjust stocking rates or size or location to improve survival and increase return to sport anglers. This year, most of the salmon will be stocked in the Whitlock area, as usual.
But fish crews also will stock about 30,000 salmon at Spring Creek closer to Oahe Dam, hoping the fish will return there in three or four years.
"We're trying to see if we can get some of them to come back to Spring Creek, so we can establish a fall fishery there," Sayler said.