Michigan DNR: Improving habitat on the Au Sable River's North Branch

Workers arrange woody debris in the North Branch of the Au Sable River.     
Fisheries managers have been adding woody cover, often whole trees, to trout streams for close to a century.
During the 1930s, the federal Civilian Conservation Corps spent countless hours building what have come to be known as “lunker structures” in some of the state’s most notable trout streams.

Over the course of the last two decades, the Department of Natural Resources and fisheries conservation groups have reinvigorated the campaign to increase woody cover in streams, led by efforts along the Au Sable River that use helicopters to drop whole trees into the various branches of one of America’s most famous trout streams.

But the placement of woody debris in streams can provide benefits in addition to giving trout a place to hide. Properly placed, woody cover can improve the function of streams, including helping to manage and move sediment that covers up gravel – valuable spawning and aquatic insect habitat in the stream.

That’s a part of the focus of a $60,000 project underway this summer and next on the North Branch of the Au Sable River near Lovells. A work crew is busily placing logs and trees, as well as rehabilitating old structures, to improve habitat – and fishing – in the stream.

“This is one of our blue-ribbon trout streams,” explained DNR fisheries biologist Neal Godby, who oversees this branch of the Au Sable. “The North Branch is known for its brook trout, but over time, the population abundance has gone down. Our most recent estimates show a small rebound and we hope that will continue, so we’re just trying to improve the habitat and enhance the cover in the river.”

A relatively wide, shallow stream, the North Branch is fairly easy to wade and easy to fish, Godby said. It
was the first stretch of Michigan trout water to have flies-only regulations (1907) and the rules continue to prohibit live bait and restrict the harvest.

Workers secure woody debris in the North Branch of the
Au Sable River. (DNR photos)
The restoration project is being coordinated by the Anglers of the Au Sable, who have hired recently retired
DNR fisheries biologist Steve Sendek to oversee the effort. Sendek, who had worked on the Au Sable River system for much of his career, said the placement of new cover and restoration of aging structures will help manage the sand, which is covering up valuable gravel.

“The Anglers’ main interest here is to improve the brook trout fishing,” said Sendek. “Brook trout don’t live very long and this project is an attempt to get better brook trout survival.”

Much of the best spawning habitat remaining in the North Branch is devoid of cover, Sendek said.

“Brook trout are very vulnerable when they go on the redds in the fall,” he said. “Hopefully, we’re going to give them a little escape cover around their spawning habitat.”

The project “has been a lot of years in the making,” Sendek said. “The area has been surveyed for years, and spawning areas and natural springs have been identified. You have to be careful when you put something in here that it’s done right.”

Part of the project involves building a large woody debris structure just upstream from the Twin Branch
Bridge, which Sendek said was poorly designed and causes increased sedimentation. The new structure will trap sand that is moving downstream and will eventually be an island with vegetation growing on it that will improve stream function.

“There’s wonderful spawning gravel downstream that we’re trying to protect,” Sendek said. “If we lose that, we’re really in trouble.”

Workers cut a branch from a tree to be toppled and
placed in the river (above). Workers carry a toppled tree
to be placed in the river (bottom).
Sendek said the project has “terrific support” among the river’s property owners.

“All the people along the river here have signed easements to allow this work to happen,” he said. “They understand what this project is about and they’re good with it.”

Besides the work crew he’s hired to implement the project, Sendek said, there is a veritable army of volunteers who are helping out.

“We’re going to have weekend work bees up here where chapters of Trout Unlimited are going to come up and work on it,” he said. “Everyone’s trying to help fill the gaps because the state just doesn’t have the funds to do it all itself.”

Not that the state isn’t contributing; Anglers of the Au Sable received an almost $40,000 grant from the DNR’s Habitat Improvement Account.

“We’re counting on our partners because we just don’t have the crews to do it ourselves,” Godby said. “The partnerships here go well beyond this habitat work. There’s temperature logging and help on surveys – everything that goes on here involves our partners. We’re trying to make watershed improvements on a site level.”

Gerry Lake, who works at the North Branch Historical Society and is a member of Anglers of the Au Sable, said he’s been working to improve the stream ever since it suffered a calamitous fish kill back in the 1970s.

Workers and volunteers place woody debris in the
North Branch of the Au Sable River.
“I’m very excited by this project, but we’ve got a long way to go,” Lake said. “We’ve got to be here for the
long haul. This may be blind optimism, but the camaraderie of everyone working together here is what makes it exciting.”

Lake, who described himself as a retired fisherman, says he’s devoting all his energy into restoring the North Branch.

“It’s harder to grow trout than it is to catch them,” Lake said. “Hopefully, 20 or 30 years from now, someone will enjoy the same kind of fishing here that I did.”

Visit Michigan Habitat Improvement Fund Grants for more information.