Water test: Where biology meets geometry in the Great Lakes

By Kurt Williams

Editor’s note: This is the third in a series of stories about profound ecological changes that test our ability to manage the Great Lakes. It’s a test that comes as state and tribal officials negotiate a key agreement affecting fish and fishing for the next 20 years.

How the shape of the Great Lakes now compares with their past is important as negotiators update the consent decree addressing commercial and recreational fishing interests in waters covered by an 1836 treaty.

The deadline is at the end of June, the third such decree covering these contentious waters. The most recent one in 2000 was for 20 years, and it’s overdue for an update.

The Washington Treaty of 1836 was signed between the Ottawa and Chippewa Indian nations and Henry Schoolcraft, commissioner of what was then the Michigan territory. It is the second-to-last treaty signed in a wave of diplomatic activity between non-native and Native Americans.

The 1836 treaty pushed Indigenous people off much of their homelands, paving the way for Michigan statehood the following year.

It covers about 16 million acres, encompassed by points from where the Grand River empties into Lake Michigan, running east along the Grand to a previously established border in present day Ionia County. That border encompasses lands ceded by the Chippewa people in the Saginaw Treaty of 1819.  The shared border then slashes northeast to Thunder Bay.

The Washington Treaty of 1836 carved out much of the northern Lower Peninsula and most of the eastern Upper Peninsula for the United States.

A parting of the waters

But who got the adjoining waters?

No mention is made in the treaty if or how lakes Michigan, Huron and Superior would be divvied up.

That happened much later in the courts beginning in 1976, bringing to a head the tension between the state of Michigan and members of the Indigenous nations over who has the right to fish those waters. For members of the affected tribes, that right was retained in the treaty’s last article.

“That last article was the one that put us where we’re at,” said Kevin Donner, Great Lakes Fisheries program manager for the Little Traverse Bay Band of Odawa Indians. It essentially said, “and by the way, we’re going to continue to have rights to hunt, fish and gather – the usual provisions of occupancy in any lands not called for settlement.”

And since the wording of the treaty only covered settlement of the land, and you can’t settle the lakes themselves, access to the waters was still open to Indigenous people.

“You can’t build a house on the lake, so that fishing practice continues to this day,” he said.

In 1976 the Michigan Supreme Court acknowledged the ”you can’t build a house on the lake” argument when it restored Indigenous people’s sovereign rights to carry on commercial fishing. That reversed a 1930 decision by the court denying them such rights.  And it set the stage for the consent decree process.

The first consent decree, signed in 1985, temporarily settled a looming court case between the plaintiffs – the United States government and tribal governments of the Ottawa and Chippewa Indians – and the defendant – the state of Michigan. It allocated fish between state-licensed commercial fishers, tribal commercial fishers and recreational fishing interests.

The decree provided the first look at what exactly constitutes the 1836 waters – 149 years after the treaty was signed.

The waters of Lake Michigan and Huron wrap around Michigan’s Lower Peninsula like a ringer horseshoe. Today they envelop coastal tourist towns, forests, wineries and fruit farms.  But in the mid-19th century, at the time of the treaty’s signing in Washington, D.C., the land and waters were much different.

Given the bucolic environment found in the adjoining lands today, you might imagine a map of the treaty waters with gentle, sweeping lines artfully delineating their borders.

They’re not.

Instead, they’re divided into variably sized polygons. They look this way because they were borrowed from when the lakes were first subdivided to better understand Great Lakes fish and commercial fishing.

Their shape goes back to the 1920s and 30s, during Great Lakes commercial fishing’s heyday.  Coincidentally, that’s the same period the Michigan Supreme Court ruled that native people had no special rights to fish in the lakes.

Geometry, don’t know much about biology

The maps “prior to the late 60s to early 70s (were) premised on commercial fishing because there just wasn’t sport fisheries out there,” said Kelley Smith, who spent 14 years as chief of fisheries in Michigan’s Department of Natural Resources. He was involved in negotiating two consent decrees for the Great Lakes and one covering Michigan’s inland waters.

The subdivision of the lakes into polygons is a nod to the value commercial fishing used to have in the Great Lakes and of the political power that value brought to bear.

In the 1920s and 1930s, commercial fishing was a driving force in what people did in this part of the world, said Mike Hansen, former chair of the Great Lakes Fishery Commission. The commission is responsible for managing the Great Lakes fishery for the benefit of the people of the United States, Canada and the Indigenous people of the region.

The subdivisions of the 1836 treaty waters look as they do in part because they were adapted from work done by John Van Oosten in the 1920s and later adopted by the fishery commission.

Van Oosten, a federal fishery biologist, is the father of federal fishery involvement in the Great Lakes, Hansen said.

“John Van Oosten basically wanted to get away from just reporting yield.  To understand how fish yields relate to fish abundance, you need to correct for how much you fish,” he said.

And by how much you fish, Van Oosten meant how much time you spent on the water fishing commercially.

“He basically wanted to develop a system to unify reporting across the Great Lakes basin and Michigan was the first to opt in.”

Districts, grids and polygons

Van Oosten’s work divided the lakes into statistical districts. Biologists then built on his work, forming management units for lake whitefish and lake trout that are like Van Oosten’s original districts, polygons used for reporting and for fishery management.

As this approach to managing fish evolved, hundreds of smaller grids based on latitude and longitude were overlain on the lakes. These other reporting units provided more granular detail to the real estate of the lakes for fishery biologists when they talk about locations in the lakes and determine how many fish can be sustainably taken from each.  These myriad grids give maps of the lakes the look of a future housing development.

The 1985 consent decree gave birth to the 1836 waters.

Since the water’s boundaries weren’t stipulated when the treaty was signed, they had to be determined at the time of the first consent decree.

The land-based boundaries of the treaty waters arise from landmarks at the water’s edge that the 1836 treaty describes. From there, the boundaries extend out into the lakes to the state’s boundary.

Within these boundaries the consent decree settlement divides the lakes into variably sized regions. Each region’s use varies based on who gets to fish the waters, what equipment can be used to fish there and what species of fish can be taken.

The arcane lingo that arose from Van Oosten’s work – statistical districts and statistical grids – may make a lay person bleary-eyed. But they’re vital points of reference in negotiating between the parties to the consent decree.

A look at the shape of the future

A key question: Should the future of waters that have undergone such significant biological, chemical and ecological changes caused by invasive mussels and other factors be decided with an approach initially developed in the 1920s?

The lakes’ initial subdivision “had no basis in fisheries biology,” Hansen said. But it has value for understanding fish biology today, providing the foundation to build management plans, imperfect though they may be.

Much information about the Great Lakes fishery continues to be gathered and based around the units, he said. Looking at how fish abundance changed in these zones over time is valuable.

There are probably plenty of reasons to criticize how the zones look on the map, he said. But in the big scheme of things, it was a useful way of describing the lakes on a smaller scale, including understanding how things are changing even now.

Mark Ebener, who worked 37 years for two inter-tribal organizations in the Great Lakes basin, has proposed another way. It would subdivide the lakes based on understanding the genetics and biology of lake whitefish that more closely reflects the reality of life for the fish now.

Most of Ebener’s career was spent in Michigan as an assessment biologist for the Chippewa-Ottawa Resource Authority, a group representing the five tribes with fishing rights in the 1836 waters.

He is the lead author of an expansive 2021 paper published by the Great Lakes Fishery Commission addressing why fewer young whitefish make it to adulthood.

“This paper is my career,” he said.

The way the lakes are currently subdivided doesn’t always consider individual stocks of fish, he said.

Fish stocks are individual groups of fish that spawn in a similar spot in the lake and share similar characteristics like rates of growth, reproduction and mortality.

To understand fish stocks, researchers catch a fish in one location and mark it with a tag.  When it’s caught again, that new location provides information on how much it moved.

This information, combined with the genetic analysis of the fish and repeated with many, many other fish, gives a clearer understanding of the different populations of fish.

Few such studies were ever done to justify the current management units.

Fisheries managers try to protect individual stocks, Ebener said. They know the more stocks that you have, the greater the diversity of the populations and the more resistant they are to over-exploitation and unexpected stressors that may impact those populations.

In the 1836 waters there are eight lake whitefish management areas, he said. The problem is, the fish move freely between these areas, and harvest limits are set not really knowing what stocks of fish are moving into and through them.

“Our management units are too small and need to be larger to encompass all the fish that are there,” he said.

Ebener and other fishery biologists have proposed replacing the polygon pattern of old with ovoid bubbles with names reflecting their geography, like ‘Grand Traverse Bay’ and ‘Muskegon’.

These units more accurately reflect the distribution of distinct groups of whitefish and could prevent over-exploitation of stocks of fish that may be vulnerable under the current system, Ebener said.

About 95% of the whitefish in each individual bubble on the new map spawn in those areas and spend their lives living in its waters, he said.

“It really wouldn’t change commercial fishing that much as it is,” he said. But it would bring clarity to where harvesting limits must occur.

Will the new system be incorporated into the consent decree negotiations currently underway, an agreement that determines the next 20 years of Great Lakes fish management?

“My guess is not,” Ebener said.

“I wasn’t going to sit back and let them decide what was going to happen or not. I was going to put this idea out there because it just seems like the right thing to do. And we’ll see whether they accept that premise or not.”

Water test series:

Day 1: Rending the Great Lakes food web

Day 2: Quagga mussels hijack key Great Lakes nutrient

Day 3: Where biology meets geometry in the Great Lakes

Day 4: One fish, two fish – where are all the whitefish?

Day 5: A long history and hopeful future of human impact on Great Lakes ecology