Changing Waters | Door County Pulse
How Door County’s fishing industry is navigating a new normal
by CHARLES HENRIKSEN, owner/founder Henriksen Fisheries
Extreme weather is the new normal. Here in northeast Wisconsin, we do not have the devastating floods, wildfires, tornadoes or hurricanes that plague much of the country, but other changes greatly impact our lives. Of particular interest on our peninsula is the warming weather. It does prolong our summer tourism and boating seasons, but its effect on our waters is concerning.
I am a food producer and take great pride and care in providing healthy, local products. I believe in science, but my life is ruled by the unpredictability of Mother Nature. Weather is changing, and so is our environment, and many of these changes occur with astonishing speed.
Invasive species from sea lamprey to quagga mussels, with many others in between, have plagued our food-producing industry and recreational fishers for decades. In recent years, persistent warm weather has created warmer water that has profound effects for many here in Door County and around the Great Lakes.
An obvious example is the recent decline in ice fishing opportunities. After two years of almost no stable ice in Green Bay, a small amount of decent ice allowed some success this year. It did not last long.
“Little more than two weeks of some of the best winter conditions for snow sports in years melted in unseasonably warm air this week, and thoughts of ice fishing into April are only a fool’s dream now,” wrote Kevin Naze, reporter and avid sportfisherman, in a recent Peninsula Pulse Wild Things column.
Successful whitefish guide JJ Malvitz offered similar sentiments when he told me that, from his perspective, “Weather is volatile and unpredictable; it really affects people’s ability to work with Mother Nature.”
He did add that the fish look healthy and there appear to be lots of them.
While this winter showed more ice, information from last year shows trends in ice cover across the Great Lakes have been on the decline – roughly a 5% overall average decline each decade since satellite tracking of ice began in the early 1970s. The average ice cover through March 11 this year across the lakes was 5.3%, the lowest on record, according to the National Oceanic and Atmospheric Administration (NOAA). The agency says the long-term average for the same period is about 30% ice cover.
The Whitefish Recruitment Issue
There is a serious decline in whitefish stock in much of the Great Lakes, and it is having a very noticeable effect on our Lake Michigan harvest. Commercial fishers in Door County have seriously curtailed their efforts in the lake.
Scott Hansen, Wisconsin Department of Natural Resources (DNR) fisheries biologist, said recent research has shown that longer egg incubations, coupled with larval hatching times that coincide with an abundance of zooplankton, are both important for the survival of larval whitefish emerging in spring.
“If they hatch too early and the timing doesn’t ‘match up’ with an adequate spring zooplankton abundance, survival will be impacted,” he said. “The changing climate is disrupting their normal cycles.”
Clearer water due to invasive mussels means less impeded UV rays, causing more algae growth. The incredible research done by Canadian filmmakers Yvonne Drebert and Zach Melnick in their recently released documentary, All Too Clear, highlights a lot of this, but in particular details research that indicates UV rays are damaging larval whitefish soon after hatching.
Hansen also spoke about UV damage on larval whitefish, with the lack of ice on the lakes another disruptive factor.
“Ice cover can also protect from the harmful effects of UV light,” Hansen said. “Studies have suggested that without ice cover, UV light can stimulate eggs to hatch earlier than they should.”
Tribal biologist Jason Smith, who is involved in multiple projects in the Upper Peninsula, said that not long ago, clear water was the sole factor contributing to the whitefish recruitment issue – specifically, how well young whitefish are surviving into adulthood.
“Even as little as two years ago, I think almost every fish biologist would have said this whole problem was about dreissenids [invasive mussels],” Smith said. “I think climate is playing a larger role than most of us would have said two, three, four years ago.”
He noted there is still a significant gap in current research in this area.
“Good quantitative analysis of the impact that climate warming is having on whitefish is a gap in current research,” he said.
Pockets of Resilience
There are pockets of resilience in these sad stories, notably far southern Lake Huron and right here in southern Green Bay. Today, whitefish are known to spawn in bay tributaries – the Fox, Oconto, Peshtigo and Menominee rivers – that had not been waterways of significant spawning for over 100 years. There is also ongoing research into identifying spawning reefs in the bay, as there is not enough habitat in these rivers to account for the massive whitefish population that has appeared in the last 20 years. The Green Bay story has inspired efforts among Michigan Tribes, conservation groups like The Nature Conservancy, and the Michigan Department of Natural Resources to stock whitefish eggs in tributaries including the Carp and Jordan Rivers. They are also rearing whitefish in ponds to augment existing populations.
Our Door County commercial fishery works closely with all interested parties to understand and enhance these issues. In recent years, we have tagged Sturgeon with the U.S. Fish and Wildlife Service (USFWS), and collected chub eggs for incubation and planting in Lake Ontario.
We worked with our DNR to tag whitefish in Lake Michigan to support their early tagging of the emerging stocks in the Bay Rivers. We worked with and partially funded a catch composition study with the University of Wisconsin-Green Bay to assess impacts on sport fish so we could harvest a fair share of the Bay’s burgeoning whitefish stock. We are also involved in continuing work with UW-Stevens Point with acoustic tagging for telemetry studies that record a vast array of acoustic receivers to track fish movements and possible latent mortality in released fish. Ice guides were also able to help tag some fish this winter.
Avoiding Hypoxic Kills
Another recent development we are planning to help track is the hypoxic area in Green Bay. Will Henriksen, my son and partner, had some fish die in his nets southwest of Sturgeon Bay in August 2023, which is well north of past documentation of the dead zone – an area in a body of water where dissolved oxygen levels are so low that most marine life cannot survive.
We have talked extensively with Val Klump, former dean and retired professor of the School of Freshwater Sciences at UW-Milwaukee, and Associate Dean and Professor Michael Zorn at UW-Green Bay, about extending their ongoing research further north in the bay. Their monitoring includes real-time data being transmitted through a Cellcom tower; the company is working with them to install a receiver in the proper place. We plan to deploy a monitor, which the professors think will serve as an early warning system.
“In 2024, we were able through an abundance of caution and closely monitoring water temperatures to avoid any hypoxic kills,” Will said. “We had to shut down some of our best fishing nets when the local demand was greatest, but we pride ourselves on sustainability and do whatever is necessary to supply our customers while protecting fish stocks.”
Adaptability and Evolution
Our observations are that whitefish are proving to be one of the most adaptable animals in nature. They have become piscivores, voluntarily inhabit warmer water than they ever did before, and have recolonized Green Bay.
“It’s truly remarkable to see their evolution over the 25 years I have been involved, 18 full time,” Will said.
It is important to mention that a huge reason for improved conditions in the bay is the massive PCB cleanup effort. While everything is impacted by the mussel’s upset of the lower food chain, many species in Green Bay and Lake Michigan are doing well. In the lake, important commercial species – perch and chubs – are struggling, but top predators are thriving. Judicious planting strategies are maintaining a healthy salmon and other silverfish stock.
Salmon have established a partially self-sustaining spawning stock on the eastern shore in wild rivers in Michigan. Lake trout are also doing well and have established a robust ability to naturally reproduce after 60 years of massive planting with puzzling difficulties. Shockingly, it has been discovered that eating alewife, which contains an enzyme (thiamaze) that inhibits successful reproduction, is the culprit. The conundrum is that the lakes are being managed to maintain a sufficient alewife abundance to feed salmon, which show no interest in other food sources.
All of this information becomes hard to keep track of.
“It would be better if there was a little better coordination amongst all the researchers and a central place to see it,” Will said.
To succeed in the modern fishery, you need to be able to adapt, be open to new ideas, and have the wherewithal to try them. Managing the resource is a bit of a crapshoot because things do not go as planned, and Mother Nature is in charge. My longtime observation is that the only sure thing in our business is that things are gonna change.
Whatever you believe or whatever label you want to put on these changes, respecting nature and our environment is of paramount importance.
Charlie Henriksen started commercial fishing in 1975, founded Henriksen Fisheries in 1987, and branched into a retail operation in 2022, Henriksen’s Fish House, with his son, Will, and daughter-in-law, Kristie. They employ between six-and-12 people in Northern Door County to supply whitefish products to over 30 Door County businesses. He currently chairs the Lake Michigan Commercial Fishing Board and also currently serves on the board of the Door County Maritime Museum.
