ONAWA, Iowa | D.J. Vogeler wasn’t sure what he was going to find as he eased his aluminum boat up to a net set off the edge of the Missouri River near Onawa.
The Iowa Department of Natural Resources fisheries biologist and his three-person volunteer crew were exploring new territory: A 100-by-50-yard hole carved deep into the riverbank and river bottom during last year’s flood.
Last week, Vogeler and his crew began netting these new off-current areas to determine how fish are utilizing the new habitat. Information from the samplings will be used when state and federal agencies determine what kind of fish habitat to build on public lands.
Formed by floodwaters exploiting weak spots in the bank, the erosion created a pool of slow, deep water sheltered from the swift current of the main channel. This off-current water provides a respite for fish out of the current, which can run as fast as 12 mph, Vogler said.
“The current on the river is moving really fast in most stretches, so those areas that are deep and don’t have any current are few and far between,” Vogeler said.
An altered landscape
The Missouri River wasn't always the fast, relatively straight shot from Omaha to Sioux City that it is today. Thirty-one miles of the river have been removed between the two cities since 1890, turning a meandering river into the channel it is today. Seventy-five miles of river were eliminated from Sioux City to where the river empties into the Mississippi River in St. Louis.
The effort, done by the Army Corps of Engineers, was driven by a desire to make navigating the river easier.
Today, the Corps prevents erosion of river banks by lining sections of shoreline with rock. It also maintains wing dikes -- rocky barriers that stretch from the river bank out into the water, which divert current from the banks out into the channel.
The force of last year's flood was so powerful that the Missouri overcame the manmade flood-control barriers meant to contain it.
The result was devastating for riverfront property owners, but good for the fish.
The same floodwaters that saturated homes and businesses eroded large chunks of shoreline. More fish habitat was formed when saturated river banks gave way, pulling trees into the river as they fell.
Out in the flood plain, slower water that saturated the surrounding land for months served as natural hatcheries for young fish. The result was a very exciting year for area fisherman in 2012.
“I had the best year ever (this year) on the Missouri that I’ve ever had,” said Bobby Walrod, founder of the Big Sioux River Cats catfishing club. “I caught more fish. I caught bigger fish.”
A new fishing hole
On Oct. 15, Vogeler and his crew -- 185th Air Refueling Wing Air National Guard volunteers Justin Menard, Matt Wulf and Lance Larson -- found a variety of fish in the new deepwater area near Onawa. The net strung across the 12-to 23-foot-deep hole contained two paddlefish, a small catfish, a freshwater drum, a smattering of big and small-mouth buffalo fish and a few carp.
Later that week, the team netted near Blencoe, Iowa; Blair, Nebraska; and the DeSoto Bend National Wildlife Refuge.
Over the next few weeks, they'll check sites down by the Missouri-Iowa border.
So far, the nettings produced more paddlefish -- which Vogler said seemed to be doing particularly well this year -- as well as channel catfish, northern pike and shovel-nose sturgeon.
The catches haven't netted enough information for Vogeler to have any theories about how the new habitat fits into the river's ecosystem.
Data from the catches will be analyzed over the winter. However, he says it's clear that fish are using the new underwater landscape.
"Just by looking just at what I’ve collected so far, a lot of the species that we expect or know are doing well in the river, they’re using these habitats," he said.
How long fish will be able to use this new slow, deep water is another question.
The Army Corps of Engineers has awarded $145 million to repair wing dikes, levees, rock revetments along the shoreline and other structures along the river. And the river is also always changing, carving out one place and dumping sand in another.
"We’ve heard some feedback from the corps that some of these sites might only last a year or two, or they might last 10 years," Vogeler said. "I don’t think anybody can say for certain."