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A Cold Shoulder from the Fish
The Near and Far of a Warming Lake

Harbor Angler Report, May 27, 2022 Photo

Denizens of a tourism community like Door County understand the meaning of the term “shoulder season”. It is those periods on the calendar that lie between the peak tourist season (aka summer) and the off-season, the dead of winter. In Baileys Harbor that is generally considered to be October and November as well as March and April when the cold winds off Lake Michigan tend to keep the hordes of visitors at bay. The county is pretty void of tourists in those months. Anglers have “shoulder seasons” as well. These are dictated by several factors, the most important of which is whether fish are biting. The beauty of angling in Door County is that we such have a wide variety of fish to pursue, that the “bite” seems to ebb and flow smoothly from species to species: Whitefish and perch through the ice, brown trout and walleye in the cold spring waters, smallmouth bass in the warming shallows, leaping steelhead as the “Big Lake” warms, salmon in the deep summer thermocline, northern pike feeding in the late summer shallows, fall run trout and Chinnok then back on the ice. However, the transitions are not always fluid. There are gaps. Times when fishing is challenging, and other activities more appealing. The last several weeks have been such a shoulder season for me. I had a very successful ice fishing season and the brown trout bite, although short lived, was one of the best in memory. Though the browns have moved off, the weather has stayed cold and wet. One of the huge advantages of being able to fish whenever I want, is that I can choose to not venture out when the weather is miserable. I understand that “weekend warriors” and anglers on vacation don’t have that luxury. They have an allotted time to fish, and damn the weather, they are going! This often leads to very uncomfortable fishing and even hazardous situations. Well, I don’t have to do that. I can just wait out the weather. This spring, I had to wait a lot. Bitter cold temperatures, howling winds and pouring rain (even snow), conspired to keep me off the water for long stretches. I had some distractions as well, specifically turkeys. The quirkiness of how turkey permits are allotted in Wisconsin dictates very specific time frames when you can pursue a big tom. If you are sitting in a blind calling turkeys, you can’t be out on the water. I did bag two toms this spring and had a great hunt, but my fishing time suffered. And anyway, the bite was just not there. The water was slow to warm, and the smallmouth stubbornly waited to move into the shallow waters. Even the walleye bite was tough due to the high winds and storms.

So, I waited. Finally, within the last week the tide has started to turn.  The near shore waters, particularly on the bayside and inland lakes, are warming. I was seeing readings in the 50’s and 60’s on my temperature probe. Smallmouth bass started showing up and becoming active. No more cold shoulder. The sun rises higher in the sky each day creating a magical transformation. Lake flies are hatching, frogs calling, weeds sprouting, schools of newly hatched fry darting in the warming shallows, predators in pursuit. The water was calling, and I answered the call. I had several successful outings for bass including a day on the The Flats in Sturgeon Bay with good friend and former colleague, Steve. It is our “annual” outing that returned after a two-year pandemic hiatus. It was a great day with sunshine, lunch at Waterfront Mary’s and a lot of catching up.  Eventually we found a batch of willing smallies as the water warmed late in the afternoon. Later in the week, Paul and even managed to coax a walleye into the boat. Things are looking up.

In the short term, warming waters increase the activity level of cold-blooded fish. They feed more and are easier to catch. This is the normal cycle of the Lake Michigan eco-system. Each fish species has a preferred temperature range to which they have adapted. They seek out these temperatures as they are available. Smallmouth bass, for example, are most active in temperatures 65°F to 70°F. Walleyes prefer cooler water temperatures, but in a similar range.  Chinook Salmon, steelhead, and Lake Whitefish seek even cooler temperatures usually in the mid 50s to low 60s. Fish will tolerate temperatures out of these ranges for short periods of time, particularly in pursuit of food. If the water temperatures remain out of their preferred range (higher or lower) for longer periods, the fish will become inactive or migrate to other waters with more acceptable temperatures. If they can. What would be the impact on the fish if an entire lake increases in temperature, perhaps out of the range now tolerated by the various fish species?

This past Earth Day, I made a presentation at the Kress Pavilion in Egg Harbor entitled “The Future of Lake Michigan in a Warming Climate – An Anglers Perspective” It was part of the Every Day is Earth Day Festival sponsored in part by the Climate Change Coalition of Door County. I have been learning and teaching about climate change for over two decades. In this presentation, I wanted to specifically explore the impact of a warming Earth on the waters and ecology of our beloved Lake Michigan. To be honest, I first had to get up to speed on the current science on the issue. I researched the latest model projections and scientific predictions related to water temperatures, precipitation patterns, ice cover, timing of lake turnovers and, of course, lake levels. The changes in the water level of the Great Lakes are much more complicated than the ocean. The future of the oceans is clear. Sea levels will rise as the climate warms. There is nowhere else for the water to go. How much it rises and how fast is dependent in large part on humans’ response to increased carbon emissions, but for the foreseeable future, seas levels will continue to rise. The water budget of Lake Michigan is more nuanced. We have inputs, out flows, evaporation, and changes in precipitation. The models are unclear on future lake levels. They may rise, they may fall, they may stay about the same. The most likely scenario is that they will continue their current cyclical nature, but the highs will be higher and the lows lower. In addition, the time between highs and lows may be much shorter than the current 26-38 years cycle. We have already experienced this as we are less that two years removed from record high lake levels which occurred only nine years after record lows. It would be wise not to build any fixed docks or piers going forward, instead opting for floating or adjustable structures.

As unsure as the future lake levels are, the outlook for the temperature of Lake Michigan is quite clear. The lake will get warmer. It already has. The lake is currently warming at a rate of 1 degree Fahrenheit each decade or about .1°F per year. This may not seem like a lot, especially when we see water temperatures change several degrees in a day and tens of degrees in a month.  However, we are talking about the entire lake warming! With Lake Huron, a total volume of over two thousand cubic miles of water. That takes a tremendous amount of energy. Energy that will be stored in the lake for a long time. For as long as any of us will live and much longer. A recent detailed study of the temperature-depth profile of the lake has documented that the entire lake is getting warmer, even at its deepest points. The impact of this warming is also clear. We will have less ice cover in the winter. The spring lake turnover will be earlier and the fall turnover later. In fact, at some point, we may only have a single turnover each year. As the temperatures get warmer, fish currently thriving in the lake must evolve to tolerate the warmer waters or become extinct. Their food may change as well, and they will need to adapt or die out. Some will, some won’t. The faster the changes occur, the less likely the fish will be able to adapt and survive. Species not currently found in the lake may find the warmer water temperatures more desirable, leading to an increase in the already long list of invasive species. Lake Michigan will still be there, but it will be a very different Lake Michigan.

Of course, all these changes will impact anglers and fishing. Will ice fishing on the bay become a mere memory? Will whitefish remain a staple of the Lake Michigan fishery?  Will Asian carp be our new target species? These may seem like rather trivial considerations given the global scope of the problem. Not at all, I would argue. In fact, it is the personal and immediate impact on our daily routines that drives home the critical nature of any issue. Climate change is real. The data shows it, the environment reflects it and our personal experience confirms it.

Frankly, I do not know what the real-world solution is to this existential problem. There may not be one, or at least one that all of society will embrace. The reality is that the atmosphere and waters will continue to warm in our lifetimes, no matter what action is taken. There are actions we can take now that will slow the rate of change allowing humans, plants, and animals a better chance to adapt. We can make it better, if not for us, for future anglers. We all can do something. It is up to each of us to discover what that is.

One thing I know for sure. People will fish. Hopefully they will fish in a responsible manner, but fish they will. It’s only human.

 Stay safe and sane.

 So Long, and Thanks for All the Fish, Bruce