Biologists study flood's effect on smelt in Lake OaheAs record amounts of water were flushed through Oahe Dam during the Missouri River flooding last summer, biologists and anglers worried about a repeat of 1997, when hundreds of millions of baitfish were sucked through the dam and left Oahe’s walleyes starving and skinny.
By: Chet Brokaw, The Associated Press
PIERRE — As record amounts of water were flushed through Oahe Dam during the Missouri River flooding last summer, biologists and anglers worried about a repeat of 1997, when hundreds of millions of baitfish were sucked through the dam and left Oahe’s walleyes starving and skinny.
State biologists are already trying to determine how many smelt managed to avoid being swept through the dam and whether walleyes are finding enough to eat. The answers are important, not only to local anglers, but also to the bait shops, restaurants and motels that depend on business from the boatloads of anglers from other states who show up every year to pursue those walleyes.
Mark Fincel, a fisheries biologist with the state Game, Fish and Parks Department said a lot of rainbow smelt, the dominant prey fish in lower Lake Oahe, got flushed through the dam last summer, but it’s too early to tell what will happen to game fish and baitfish in the reservoir that stretches from central South Dakota into North Dakota.
Walleyes remained fat and healthy through the summer, and sonar surveys showed a lot of smelt remaining in the lake in mid-summer, he said.
Biologists will learn more from the condition of walleyes caught next spring and further measurements of the smelt population next summer, Fincel said.
“We’ll know for sure next year,” he said.
If the baitfish population was hurt, biologists learned a lot about how to handle such a situation after the 1997 disaster, Fincel said. Fixes could include stocking other kinds of baitfish and raising walleye limits to reduce the number predators gobbling up smelt, he said.
In 1997, the U.S. Army Corps of Engineers ran what was then record high releases through Oahe Dam, and state biologists later estimated that more than 400 million smelt went with the water. Walleyes ran short of food, and the limit on Oahe was eventually raised from four a day to 14 to restore the balance between predator and prey.
“Now we know what to expect. We know what to watch. If we do start seeing the condition of the walleyes start declining, there are some options we can use,” Fincel said.
This year’s peak releases from Oahe and most of the other five dams on the Missouri River were more than double those of 1997 as the corps got rid of runoff from a deep Rocky Mountain snowpack and unexpected heavy rains upstream in May. Releases had to be raised to record levels because the dams were full, and room had to be made for the heavy runoff that continued to pour into the river system.
Emergency levees built in Pierre and Fort Pierre protected most houses in low-lying areas, but some were damaged by rising groundwater.
While attention was focused primarily on protecting lives and property, people began to wonder what would happen to Oahe’s fishery, a key part of the local economy because so many anglers from Iowa, Minnesota, Nebraska and other states visit and spend money on food, lodging and fishing gear.
Sonja Boe, a partner in the River Lodge motel in Pierre, said she’s optimistic that fishing will remain good on Oahe. But a drop in the reservoir’s fishing quality would hurt the motel, where anglers make up two-thirds of the guests.
“If that did happen, it could slow things down,” Boe said
Fincel said conditions on Lake Oahe are different now than they were in the late 1990s.
In 1997, Lake Oahe had large numbers of small walleyes that ate a lot of the remaining baitfish, but that’s not the case now. And most of the smelt that went through the dam this year appear to be young fish from last spring’s extraordinarily good hatch, which should leave a lot of adult smelt to reproduce and replenish the population in future years, Fincel said.
While the reservoir was losing smelt through Oahe Dam, it also appeared to be gaining smelt that were being swept through Garrison Dam upstream in North Dakota, Fincel said.
Hydroacoustic sonar, which can identify fish as small as an inch long, found a lot of smelt still in Oahe in July, the biologist said.
“We are seeing a little bit of a decrease, but it’s nothing to raise alarm yet,” Fincel said.
“Deputy Dan” Miller, owner of Carl’s Bait Shop in Fort Pierre, said anglers and those who make a living off the area’s famed walleye fishery we’re initially “scared to death” that the flushing of Oahe’s baitfish could devastate fishing for years. But he said he’s more optimistic now because anglers continue to report that they see clouds of baitfish on their fish-finding sonars.
“We were very worried about things getting off balance,” Miller said. “We’re very hopeful at this point.”
Fishing guide Dave Spaid said he’s optimistic because Oahe started this year with a much higher smelt population than in 1997. Walleyes remained in good shape through the summer, a sign they were still finding enough smelt to eat, he said.
“I’ve fished probably 120 days on Oahe this year, and I see smelt here yet in the lake,” Spaid said.
The central South Dakota economy relies on fishing not only on Lake Oahe, but also on Lake Sharpe below Oahe Dam. Particularly in the spring, fishing is often better on the lower lake than on Oahe.
Fincel said the cold, fast-flowing water below the dam apparently hurt the hatch of gizzard shad, the major prey species in Lake Sharpe. But the walleyes and smallmouth bass below the dam had plenty to eat because they grabbed the smelt flushed in from Oahe, Fincel said.
Again, however, the full effect on Lake Sharpe won’t be known until next year, Fincel said.