I take a number of different routes when I go on my daily bicycle rides. All of them pass through the marsh, then head off in different directions. This autumn I’ve been using the northern loop more often than usual, mostly because it hugs the Mississippi River and I want to see where the fishing boats are. Last Wednesday, for the first time since last spring, I didn’t see a single boat on the water. It wasn’t windy and it wasn’t raining, so it means the fish aren’t biting.
Every autumn a time comes when the fish either relocate or stop feeding aggressively. Some people think it is because of the annual turnover. I am not so sure. Turnover is when water at the surface cools from contact with cold air, becomes denser than the warmer water below, and sinks to the bottom.* The water on the bottom gets displaced, and it has to move upward. This rotation alters oxygen levels and nutrient distribution, which then affects fish behavior. I understand the basic concept, but in my experience, good summer fishing comes to a halt several weeks before any of this happens.
There is a second kind of annual turnover on the river, one also linked to air and water temperature. At least for me, the reasons for fishing reverse themselves. While it is always more fun to catch fish than not catch fish, having fish on the line is less a factor in the summertime than at other times of the year. The primary goal in the summer is to be outdoors. However, as soon as the wool hat and long underwear come out, the joy of simply communing with nature lessens. When the temperature first turns chilly, then bitter cold, fishing needs to include fish. In the summer, I can be skunked time after time and still go out on the water at least once a week. In the dead of winter, a couple of outings without a half dozen perch strewn on the ice and I might be done for the season.
Except for a special steelhead trip this past October, I haven’t fished in over a month. In contrast, I will keep biking until first snowfall. That could be a month and half from now; it could be tomorrow.
* One of the miracles of nature is that liquid water is most dense at 39º Fahrenheit, then gets less dense if colder. If water was most dense at 32°, the very coldest water would sink to the bottom just prior to freezing. Lakes would freeze from the bottom up and most likely freeze solid. Instead it is the water on top of the lake that freezes first, and a blanket of ice on the surface insulates the water below.