Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Photo of fisheries employee holding a sturgeon © Michael Kienitz

DNR fisheries staff works below the Prairie du Sac dam to estimate the number of sturgeon in the 92-mile river stretch.
© Michael Kienitz

February 2012

A state for sturgeon

Restoring an ancient fish species to its ancestral waters.

Lisa Gaumnitz

SUPERIOR – The inch-long lake sturgeon are not much to look at – all head and bulbous eyes – but they are small wonders.

Scooped up in a fine mesh net in July 2011 on the St. Louis River forming the Wisconsin-Minnesota border, the fish are the first documented offspring of lake sturgeon stocked in the 1980s and 1990s by the two states.

The four sturgeon followed nature's clock and beat cruel odds to wind up in the net. Female sturgeon don't reproduce until they are in their 20s or 30s, spawn only every three to five years, and lay up to 500,000 eggs at a time, only eight to 12 of which will make it through their first growing season.

Photo of sturgeon offspring © Brian Borkholder
Documenting stocked sturgeon offspring is a monumental first step.
© Brian Borkholder

"There are many more years ahead before we know if these young sturgeon can survive, reproduce and help build a self-sustaining population," says Peter Stevens, Wisconsin DNR's fish supervisor in Bayfield. "But this is a monumental first step. So many people worked so hard a long time to get us to this day."

It's hard not to get excited about this discovery, or about efforts elsewhere in Wisconsin to restore this ancient species to its ancestral waters.

While other states' sturgeon stocks dwindle, the state supports in Lake Winnebago the world's largest self-sustaining population of lake sturgeon and a unique winter spear fishery; offers a hook-and-line season on major inland waters with small but stable populations; and, as on the St. Louis River, works to rebuild sturgeon populations from scratch on other waters.

Several factors mesh to make the 21st century one of the most promising for a species that's been cruising Wisconsin waters for tens of millions of years and whose continued existence depends on humans successfully managing their populations within razor thin margins. Harvesting just 5 percent of an adult population is regarded as safe, compared to the 35 percent typical for walleye and other shorter-lived species.

"It's a good time to be a sturgeon in Wisconsin," says Ron Bruch, a DNR fish supervisor, lead sturgeon scientist on the Winnebago system for the last 20 years, and co-leader of the agency's sturgeon team.

"We have the information, the public interest and understanding, and the agency commitment to managing restoration but also maintaining local fisheries to keep public interest and support high. That's what's needed to see the fruition 30 years down the road of efforts to restore the population and allow local fisheries to develop."

It's good to be a sturgeon in Wisconsin

The state has long been regarded as a national and international leader in sturgeon protection, restoration and research, a reputation built since Wisconsin started regulating sturgeon harvest on the Winnebago system in 1903.

"You ladies and gents have done such a good job that you're helping other states restore their populations," says Ed Scott, a volunteer from the Tennessee Valley Authority who came to Lake Winnebago last spring as part of a multi-state and federal effort to collect eggs to jump start their reintroduction programs. "It wouldn't be possible otherwise."

The research and leadership coming out of Wisconsin has only grown in the last decade as the Winnebago system gained a dedicated and growing funding source. State law now directs sturgeon spearing license fees back to the Winnebago system. Conservation groups like Sturgeon for Tomorrow and Shadows on the Wolf have also poured in money and labor, leading to an information explosion.

Radio transmitters surgically implanted into hundreds of fish revealed that fish move out of Lake Winnebago in the fall and into the rivers where they'll make their spawning runs the next spring. Those findings helped propel a 60-inch minimum length limit for the hook-and line-season statewide and a shortened season to protect potential spawners.

New techniques of aging fish revealed that the longtime practice of counting rings on fish fin bones consistently underestimated true age by as much as 10 to 30 years. So now DNR biologists apply a correction factor in their calculations, allowing them to continue using fin bones to age fish and to draw on older information gleaned that way. That's particularly important because the newer technique, counting rings in the fish's ear bone, or otolith, requires killing the fish.

Photo of syringe and microchip © Michael Kienitz
Microchips, called PIT tags, are implanted in sturgeon to estimate population size and harvest.
© Michael Kienitz

Individual electronic microchips called PIT tags are injected with a needle into fish DNR collects during surveys, a process that eliminates the loss of tags that used to occur with traditional external tags. These tags, the same microchip technology people now use to permanently mark their dogs and cats, carry individual numbers, and when the fish are subsequently caught during DNR surveys, staff can run a scanner over the fish to detect its number. The information gathered through this modern tagging technique allows DNR to more easily and accurately track individual fish and their age, key information to calculate growth, mortality and exploitation rates, and other vital information for sound management.

"Although the sturgeon research we do on Winnebago addresses an important management question in the system, we try to design our studies to give insight into sturgeon population dynamics in fisheries elsewhere in the state," Bruch says.

A new project with a University of Wisconsin- Milwaukee Freshwater Institute geneticist seeks to develop a test that will determine sturgeon sex and age by looking for DNA protein sequences in fluids in the fish. Now, it's very difficult to determine that information except when the fish are spawning or after they've been harvested and cut to have their internal organs examined.

Another new project seeks to use the sound male sturgeon make during spawning season to get a more accurate count in waters where sturgeon populations are low.

"Males make a sound when they spawn to attract females that sounds like a grouse drumming," Bruch says. University of Wisconsin – Madison audiotechnicians have analyzed that sound and the Department of Natural Resources hopes to be able to use acoustic equipment to listen for spawning fish and document spawning activity without seeing the fish.

This technology would have widespread application for documenting successful spawning activity, especially in small recovering populations. That recent research is now driving efforts to update Wisconsin's statewide sturgeon management plan, says Karl Scheidegger, who co-leads DNR's sturgeon team with Bruch. "It's a total overhaul (of the previous plan) because the information we gained in the last 10 years is so amazing."

"Where the old plan was a bit of pie in the sky – this is what we'd like to do – the new plan is more practical. This will give our biologists and other states a lot of good information on the best stocking, assessment, evaluation and other methods to use."

The Department of Natural Resources has made other changes that are benefitting sturgeon, and ultimately anglers. The statewide 60-inch minimum limit and shorter hook-and-line season has helped protect potential spawning adults. Harvest has dropped from about 225 fish statewide every year to one-tenth that level.

The Wild Rose State Fish Hatchery renovations have greatly increased the capacity for restoration through stocking using artificial propagation techniques developed in the late 1970s in Wisconsin by the Department of Natural Resources and Fred Binkowski of the University of Wisconsin-Milwaukee WATER Institute. Streamside rearing facilities along the Kewaunee and Milwaukee rivers are helping supply sturgeon for those areas and, biologists hope, will help the fish imprint to their native waters so they will one day return to spawn there.

Plans are underway to help sturgeon get over dams on the Lower Wisconsin River and the Menominee River to allow sturgeon to reach potential spawning grounds.

"Ultimately, the goal of all the sturgeon restoration work in Wisconsin and the Great Lakes is to produce viable fisheries," Bruch says. "We're very positive that will happen. We just have to have the commitment and patience over time."

Three waters – the St. Louis River, the Lower Wisconsin River, and the Winnebago system – represent the different status of sturgeon populations in the state, how the Department of Natural Resources and partners are using the new information to maintain or build populations, and some of their key challenges.

Starting from scratch on the St. Louis River

Lake sturgeon originally inhabited the St. Louis River in western Lake Superior, but the population disappeared, along with other species, during the early 1900s due to overharvest, water pollution and habitat changes, says Steve Schram, a retired DNR fisheries supervisor stationed in Bayfield and a driving force behind restoring lake sturgeon to the St. Louis River.

Starting in the 1970s, federal Clean Water Act regulations forced wastewater dischargers to meet tougher standards and poured money into upgrading municipal treatment plants. The Western Lake Superior Sanitary District went online in 1979 and water quality improved significantly in the St. Louis River.

"After water quality improved, fish could stay in the estuary year around instead of being forced out to Lake Superior just to stay alive," Schram says. "I have always felt the real credit for the success of this program belongs to the people that pushed for passage of the 1972 Clean Water Act and the people that were instrumental in establishing the Western Lake Superior Sanitary District."

With the water quality improving so much, Schram and colleagues knew the time was right to begin a long-term project to re-establish native species such as lake sturgeon in the St. Louis River. From 1983 through 2000, the Wisconsin and Minnesota DNRs stocked 762,000 fry, 143,000 fingerlings and 500 yearling lake sturgeon into the St. Louis River and set no-kill regulations to prevent anglers from harvesting the stocked fish.

The Wisconsin Department of Natural Resources has been monitoring adult abundance below the Fond du Lac dam (Minn.) on the St. Louis River during spawning time since the early 2000s. They have documented good numbers of fish, an increase in spawning numbers and fish as large as 59 inches, Schram says. Until this year, however, no offspring were found there.

Biologists with the Fond du Lac Band of Lake Superior Chippewa found the four inch-long survivors while sampling for such tiny, larval fish.

Wisconsin and Minnesota will continue monitoring in the river and Lake Superior to follow abundance of naturally produced fish. Schram says that the current no-kill regulation on the St. Louis will likely remain in effect until successful reproduction by parents produced naturally is documented.

Schram calls the discovery of the young sturgeon "wonderful news" but cautions against declaring victory. "We need to keep in mind it's just another step in the long process of rehabilitating a degraded river system and managing a long-lived species," he says. "So we need to keep the Clean Water Act intact and continue to educate the public about the value of clean water and the value of a healthy St. Louis River ecosystem."

Sustaining fishing on the Lower Wisconsin River

On the Lower Wisconsin River, the inland water with the highest hook-and-line fishing pressure and harvests, the challenge is to keep the population stable while continuing to allow fishing for sturgeon.

That's why DNR Fish Supervisor Dave Rowe and technicians Mike Rennicke and Dan Fuller from the Poynette office launch their boats on the river below the Prairie du Sac dam on a crisp, sunny October day. They're here to collect information to estimate the number of sturgeon in the 92-mile river stretch so they can understand next fall if the fish harvested during the hook-and-line season are under the safe 5 percent limit.

In 2005, anglers harvested 75 sturgeon below the dam – 26 percent of the estimated population, and well over the safe level. Since the 60-inch minimum length limit and the shorter season started in 2006, harvest of large fish has dropped to just under eight sturgeon, for a 4.8 percent harvest rate.

They set four gill nets below the Prairie du Sac dam and, 90 minutes later, check them with Kate Strom Hiorns, a fisheries analyst from Madison recruited to help out that day. Hand over hand they haul in the nets, carefully remove fish caught in the widely spaced mesh and place them in an aerated tank until they can reset the nets and motor back to shore to process the fish.

There, they lift a sturgeon out of the tank, hold it down along a measuring board on the floor to check its length, run a microchip reader over the fish to detect an electronic tag, and then put the fish in a net. Rennicke hoists it onto a hanging scale and Fuller records the information. Rennicke gently returns the sturgeon to the water.

Photo of fisheries staff collecting sturgeon roe © Michael Kienitz
Fisheries staff collecting sturgeon roe.
© Michael Kienitz

"One of the biggest challenges is trying to define what the entire Lower Wisconsin River population is," says Rennicke. "It's a continuous process of building up the database and getting more confident in the numbers."

Getting solid numbers is literally a moving target. Fish move into and out of the Lower Wisconsin from the Mississippi River; Wisconsin research shows some sturgeon swimming up to 30 miles a day on the river.

So every fall they capture more fish and conduct other research to better understand this population. In recent years, Rennicke and others have implanted 16 adult sturgeon with radio tags to help them understand fish movement, critical spawning habitat and other important information. They've also done spine age estimates for nearly 200 fish, and last spring started surveys to detect larval fish, evidence of natural reproduction.

One of the biggest questions is whether natural reproduction is occurring below the dam, Rowe says. We know that fish come over the dam from Lake Wisconsin when water levels are high. Are they the source of fish that is keeping the population stable, or are the fish that live below the dam naturally reproducing, or both?

The answer won't matter as much in coming years when Alliant Energy is required to build a fish passage at their Prairie du Sac dam. The design calls for an elevator to lift fish that migrate upstream to get over the dam. Biologists will raise the tank to the top of the dam and sort through the fish, sending any native fish on their way upstream. A downstream passage is also being built to make sure the fish can pass safely back to the lower river as well.

"You have these systems that over time developed to be a connected thread so the organisms evolved to utilize the best spawning habitat at one time of the year and feeding and resting habitat at other times of the year," Rowe says. "The whole point of the elevator is we want fish interested in swimming up the river to spawn to be able to do so while keeping invasives out."

Maintaining enthusiasm on the Winnebago system

On a cold, windy April day, a crowd gathers at Bamboo Bend on the Wolf River near Shiocton. Men, women and children, many of them with cameras, a local TV crew, and a Discovery Channel TV crew swarm as DNR staff carry a writhing sturgeon up from the rocks in a big net.

"Somebody, get the head," Bruch yells as he helps wrestle the fish out of the net and onto the measuring board on the ground below him. "Oh, is he huge! Look at that guy. It's a nice big male. He's bigger than you, Jack (Bruch says to one of the fisheries technicians at his side) 71.8 (inches)."

Though the crowds can slow the work, Bruch is glad to see them. Later he says, "Key to our success is not only effective control of harvest, but also proactively involving the public in our sturgeon management program – the public has great ownership and pride in this program."

Regulation changes developed since 1993 through a joint Department of Natural Resources and Winnebago Citizens Sturgeon Advisory Committee effort have led to an increase in the Winnebago lake sturgeon stock and the number of trophy-size fish in the population.

Trophy lake sturgeon are typically considered to be any fish 100 pounds or larger, and historically fish this size have made up less than 1 percent of the total annual harvest. In the last decade, the percentage of trophy fish has gradually increased to 6 percent in 2011.

License sales for the 2012 season set a new record at 12,860, up 48 percent since 2007, reflecting the growing interest in recent years by a wider range of people attracted by the big fish, the growing success of spearers and the Winnebago sturgeon program.

Despite this growing popularity, Bruch considers one of the biggest challenges to be "maintaining the enthusiasm for the fishery that results in the license sales that keep the whole thing running," he says.

"If you look at the trends in outdoors activity, the proportion of people who fish has stayed steady or gone down a little in Wisconsin. We're always aware we're not just in this business for the fish.

"Whenever I give a sturgeon presentation, the last slide I show stresses the two things we're trying to do on the Winnebago system," he says. "One is to keep the sturgeon population healthy and flourishing. The second is to keep Winnebago sturgeon spearing a vibrant part of our Wisconsin outdoor culture."

Lisa Gaumnitz is the public affairs manager for the DNR's Water Division.

Sign up to guard sturgeon

Each spring, hundreds of volunteers guard sturgeon at their spawning sites on the Wolf River and protect the fish from poaching. When the sturgeon spawn along the rocky shorelines of the Wolf, they are fairly oblivious to nearby human activity and are very susceptible to illegal harvest.

The volunteers of the "Sturgeon Patrol" guard the spawning fish 24 hours a day throughout the spawning season which is typically in late April and early May. While it is impossible to predict the exact dates that spawning will occur, guards are routinely scheduled from April 15 through May 5. Spawning generally occurs over a seven- to 10-day period within that time window.

If you would like to sign up, contact the DNR sturgeon guard coordinator at the DNR Oshkosh Service Center at DNR Sturgeon Guard or call (920) 303-5444. A representative will call you to schedule a day.