• The Great Lakes whitefish collapse is as complex as it is concerning, threatening to unravel an ecosystem, destroy livelihoods and erode regional culture
• Bridge Michigan has been covering the issue all summer, fielding reader questions in the process
• Why is it still legal to fish whitefish? Why can’t we just eat the mussels that are causing the collapse? Read on for answers

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The Great Lakes whitefish crisis is as complex as it is concerning, which is why Bridge Michigan has devoted an entire summer to reporting on it.

We’ve detailed how an explosion of invasive mussels in lakes Michigan and Huron has transformed the lakes, leaving them devoid of the food that baby whitefish need to survive and pushing the species to the brink of collapse. 

We’ve shown how the iconic fish’s demise affects human lives and livelihoods and explored the fish’s link to a global extinction crisis caused by humankind’s destruction of the natural world.

We’ve followed scientists who are searching for ways to kill off the invasive quagga and zebra mussels before it’s too late for whitefish — an effort that has received paltry funding despite its urgency. 

And today, we published a story on Lake Superior, the lone Great Lake where whitefish are still thriving. But a spate of recent mussel outbreaks makes the future uncertain. 

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It’s a lot to digest and readers have asked some great questions that our stories didn’t cover. Read on for answers to some of the most common ones.

If things are so dire for whitefish, why are people still allowed to catch them in lakes Michigan and Huron?

That’s a topic of perennial debate.

A legally binding consent decree dictates how fishing rights are allocated between state-licensed and tribally licensed commercial fishers in much of Michigan’s portion of the Great Lakes. Scientists use computer models to track whitefish populations, then tweak harvest limits based on the results.

Limits have been repeatedly tightened in response to dire findings in lakes Michigan and Huron. Some fishery managers have speculated that in parts of the lakes, regulators may soon ban whitefish fishing altogether. 

New limits have emerged for recreational anglers, too. 

But because whitefish declines are caused by reproductive failures, rather than overharvest, fishing bans would at best slow the disappearance — but not stop it. 

Most baby whitefish in the lakes today are starving to death within days of hatching, a result of food shortages caused by the mussels. Meanwhile, their parents are growing older, meaning that they’ll soon die of old age if humans or predators don’t kill them first.

My favorite restaurant still seems to have plenty of whitefish. How?

Odds are it came from Lake Superior.

Whitefish populations in Lake Superior are stable because invasive mussels remain relatively scarce there. The lake’s lack of calcium makes it difficult for mussels to build their shells, while cold water hinders their reproduction (although the shellfish are making worrisome inroads).

Trouble is, Lake Superior has never been a mega-producer of whitefish, which means it’s not capable of providing enough filets to make up for declines in the lower lakes. 

Prior to 2010, combined catch rates in lakes Michigan and Huron averaged about 6.3 million pounds per year. Last year, the rates dropped to less than 2 million. Lake Superior, by contrast, has consistently averaged less than 1.5 million pounds.

Some restaurants have begun to supplement with other fish, like walleye, while crafting contingency plans for the day when whitefish is off the menu entirely.

Besides Lake Superior, is there anywhere whitefish are doing well?

Sort of.

Whitefish populations in parts of Saginaw and Green bays appear to be holding their own, but scientists say the future in those areas isn’t clear. 

Scientists track fish populations based on the number of young adults that “recruit” into the fishery each year, when they’re about 3 or 4 years old. Big catches of fish born during past baby booms can create a false sense of confidence, hiding reproductive issues that will only become obvious when today’s hatchlings fail to reach adulthood.

In other words, the relatively good whitefish stocks in the bays are a measure of the fishery’s health several years ago — not today.

“We need to be vigilant,” said Michigan Department of Natural Resources fish biologist Steve Lenart. “Especially given what we’ve witnessed in the main basins.”

Why don’t we just harvest and eat all the mussels?

For one, it may not be safe.

Invasive mussels spend their lives clinging to the lake bottom while siphoning food out of the water. They tend to accumulate contaminants that linger in Great Lakes sediments from past industrial dumping, said J Ellen Marsden, an invasive species expert and professor emeritus at the University of Vermont.

“If there’s anything in the way of lead or other heavy metals, or even things like PCBs, they will incorporate it into their shells,” Marsden said during a recent Bridge Michigan panel discussion on the whitefish crisis.

That’s also why nobody has commercialized invasive mussel dog buiscuits or fertilizer, as some entrepreneurs have done with invasive carp.

Beyond the health risks, a person would have to shuck quite a few of the thumbnail-sized mussels to get a meaningful amount of meat. 

Could other issues be causing whitefish declines, such as government-funded stocking of other species?

Not to a significant degree.

State, tribal, federal and academic experts on Great Lakes fish dynamics all told Bridge Michigan that mussels are the driving force behind the whitefish crisis. 

Some onlookers have questioned whether stocked lake trout could be causing whitefish declines by eating juveniles or outcompeting adults for space on spawning reefs. Multiple experts told Bridge Michigan they don’t believe that’s happening.

“These are animals that co-evolved,” Lenart said, and research into lake trout diets has not turned up evidence of trout devouring baby whitefish at an alarming rate.

The federal government and partners have been stocking trout in the Great Lakes since the 1960s to revive populations wiped out by overfishing, pollution and invasive sea lamprey. Only more recently have whitefish populations begun to collapse — a trend that aligns near-perfectly with the mussels’ proliferation.

What’s being done to figure out a solution?

Researchers are scrambling to identify chemicals, bacteria, viruses and genetic engineering tools that could kill or sterilize mussels en masse. But so far, they’ve found no miracle cures for the infestation. 

And whitefish don’t have long to wait: Some experts believe they could disappear from vast swaths of lakes Michigan and Huron within the next few years.

While the search continues, scientists like Harvey Bootsma of the University of Wisconsin-Milwaukee are using paint scrapers, tarps and a large steel contraption called the “mussel masher” to clear invasive mussels from small patches of lakebottom.

It won’t fix the fundamental lack of food that the mussels have caused, but it may give at least a few whitefish a better chance at reproducing.

Despite the grave threat posed by invasive mussels, efforts to eradicate them have received meager funding compared to other Great Lakes threats.

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