Lake Oahe has a national reputation for some of the finest fishing in the country, but the past several months have been exceptional even by standards set by the popular Missouri River reservoir.
Boat ramps and fish-cleaning stations along the central South Dakota lake have been very busy with anglers enjoying a walleye bite that began last year, continued through record flooding, and is still going strong.
Some anglers are wondering what changed on the big lake.
“We currently have a lot of 13- to 16- inch fish in Lake Oahe that were produced since water levels rose at the end of the drought in 2008,” said Mark Fincel, senior fisheries biologist for the Game, Fish and Parks Department. “Fish over 20 inches were common in angler catches this spring, but as the water has warmed, the young fish are now dominating the catch.”
Fincel said providing answers to angler’s questions about how the fishery in Lake Oahe is fairing can be complex.
“The system is very dynamic,” he said. “It’s not uncommon for Lake Oahe to experience periods of high fish production when water levels continually rise for a few years following a drought. The system is very productive then, as the influx of water brings in a lot of nutrients and flooded vegetation makes great spawning habitat and places to hide for young fish.”
The most complex and unknown factor in the environment of Lake Oahe is the fallout from the record flooding of 2011. A lot of smelt were lost from Lake Oahe when they were flushed in heavy downstream flows into Lake Sharpe. GFP biologists have found that most of the lost smelt were young fish hatched in the spring of 2011.
“We still have some adults left to spawn next year and smelt could bounce back,” Fincel said. “Unfortunately, the run in 2012 was one of the smaller ones we have monitored. However, Lake Oahe is very productive right now because of the high water and flows of 2011. There is a lot of food for bait fish and young fish of other species, which all serve as food for walleyes. Those young fish should start to enter walleye diets soon.”
GFP staffers have added to the potential food base for game fish in Lake Oahe by placing about 1,800 adult gizzard shad into the lake this past spring.
“The plan was to stock pre-spawn adult shad with the idea that their offspring could provide food resources in localized areas of Oahe. The adults began spawning in June and newly hatched, or larval, shad are being caught in small-mesh trawls, (nets towed behind a boat) at most locations where adults were stocked,” Fincel said.
GFP staffers have spoken with some anglers who report seeing walleyes that they consider to be skinny, but other anglers think the fish look fine.
“When you look at the whole reservoir and all the fishing trips that occur on it, fish caught at some locations on a specific angler trip may be skinnier than fish caught elsewhere on a different trip. This range in fish condition indicates food resources are adequate in some locations and more sparse in other locations. Anglers also report seeing clouds of baitfish on their graphs,” Fincel said.
GFP has received inquiries from anglers on the possibility of raising the daily and possession limits for walleye on Lake Oahe. Daily limits as high as 14 fish were used in the early 2000s in an attempt to reduce walleye abundance and thus reduce predation on a low density of rainbow smelt, to help increase smelt abundance.
“You hear rumors at fish-cleaning stations, bars, and coffee shops up and down the reservoir about GFP raising the limits, but there are no immediate plans to do so,” Fincel said. ”Raising the limit is not always needed if you want to harvest a lot of fish. In 2011, we harvested almost as many walleyes with a four-fish daily limit as we did in 2001 with a 14-fish limit because of the high number of fishing trips and the high percentage of anglers keeping a daily limit of four fish. Walleye harvest estimates for April through June this year have been the highest recorded, surpassing the harvests in 2001 and 2011.”
Fincel summed up fishing conditions on Lake Oahe by noting that the current level of fishing is providing exciting opportunities for anglers of all ages and all experience levels.
“The Oahe walleye fishery currently has a lot of fish that are easy for anglers to catch, and they are abundant enough that keeping them will not hurt the fishery,” Fincel said. “We have learned a lot about the current status of this fishery since the flooding, but there are still some important surveys that need to be completed to help determine the current status of the Lake Oahe fishery.”