PIERRE - Rainbow smelt, the important bait fish that feeds Lake Oahe's trophy walleye and northern pike, might be on their way back, and in a big way.
Favorable weather and the U.S. Army Corps of Engineers new drought management policy of rotating reservoirs for favorable water-level treatment appears to have paid off for Lake Oahe's fishery.
Rainbow smelt spawned in strong numbers throughout the big Missouri River reservoir in April, according to scientific surveys, and there was steady to rising water since then during the crucial three to four weeks of the incubation and hatching period.
Smelt eggs, which are attached to rocks and branches in water only a few inches deep along the shoreline, quickly die if exposed to air. That is why it's important that water levels rise, rather than fall as has been the case during a drought that now is in its sixth year across the upper Missouri River basin.
Final results won't be known until post-hatch data is fully analyzed this fall, but the spawning data and the conditions look very positive to fishery biologists at the South Dakota Game, Fish and Parks Department.
ADVERTISEMENT
Because of concerns that falling water was hurting fish reproduction, the Corps of Engineers responded to pressure from South Dakota, North Dakota and Montana to hold the water level steady or have it rise on a rotating three-year cycle for each of the three big upstream reservoirs of Oahe, Sakakawea and Fort Peck.
This spring marked South Dakota's turn to be protected during spawning.
"This year, things are looking good on Oahe," Wayne Nelson-Stastny, a senior fishery biologist for Game, Fish and Parks, said Monday during a presentation at the ninth annual Missouri River Natural Resources Conference. He noted that Oahe's level rose about two feet this spring, but Lake Sakakawea fell by about two feet during the same weeks.
"It's hard to be really pleased when you see that," he said.
In a separate interview, Nelson-Statsny said conditions this spring were the best that Oahe has seen during the drought.
The numbers of smelt found in survey nets were up at five of the six of research locations.
At Minneconjou, for example, smelt per net jumped from an average of 10.8 nightly last year to 57.4 this year. At Chantier Creek, the number jumped from 8.8 to 47.2. Sutton Bay rocketed from 0.1 to 53.6. Grand River rose from 2.6 to 39.3, and Indian Creek increased from 3.5 to 4.7.
Only Whitlocks Bay saw a decrease, but that was largely because 2004 was an uncharacteristically strong year with 310.9 smelt per net per night. This spring the nightly average at Whitlocks was 27.2.
ADVERTISEMENT
The overall average in 2004 for Oahe was 56.12, driven primarily by what was happening at Whitlocks. This year the average was 38.24.
Both sets of numbers are far above the four previous years, when few smelt were found to be spawning. The averages were 0.10 in 2000; 0.01 in 2001; 2.0 in 2002; and 0.60 in 2003.
"Given the magnitude of the (spawning) run and good water conditions, I am optimistic about the amount of prey fish production Oahe will see this year," Nelson-Stastny said.
Bob Mercer is a writer for the Mitchell Daily Republic, a Forum Communications newspaper
