Welcome to the Jungle

Submerged vegetation fuels bluegill and crappie patterns like an elixir, even during seemingly sterile winters. Although plant biomass decreases significantly as ice builds, in many lakes—particularly the clearer ones—certain evergreen plants continue to photosynthesize oxygen throughout the cold months.

Although we’re talking mainly from an ice-fishing perspective here, aquatic plants undergo similar winter cycles in climates where lakes experience cold winters but don’t necessarily freeze up. So these patterns often apply to anglers fishing open waters during the colder periods.

Science tells us that at early- and late-ice, all through winter if snow cover is negligible, sunlight feeds rooted plants, at least intermittently. Despite this, dissolved oxygen (DO) levels in shallow zones continue to erode throughout winter because of decomposition. In milder winters, however, DO replacement via plant photosynthesis can be enough to sustain life. Panfish, in these cases, potentially feed and hold in these littoral zones all winter.

Opposite conditions, on the other hand—turbid water, deep ice, and snow—reduce sunlight penetration and oxygen production by plants, and decomposition depletes DO at an accelerated rate. Eventually, bluegills and crappies fade from flats and reassemble in deep basin holes, where large groups band together. Anoxic conditions can prohibit longterm fish survival, yet we can’t say for certain that all littoral flats lack bearable oxygen levels, as anglers have no simple way to measure oxygen.

We know that panfish, like other species, venture into low-tolerance zones if these areas harbor abundant forage. Some invertebrates eaten by panfish, particularly chironomid midge larvae, thrive in low-oxygen environments outside fish comfort levels, yet these “bloodworms” frequently pack panfish stomachs tight. The same for shallow, decaying weeds that provide food for backswimmers, water boatmen, and certain microcrustaceans. Bluegills love foraging on these critters, even though in winter they often cling to decomposing plants.

Some shallow, weedy flats offer sufficient DO (roughly 6 parts per million and greater) all winter. This is true more often than anglers suspect, even during late-ice. Certain key species of winter-hardy plants continue adding oxygen throughout winter. Groundwater streams percolate through the substrate, creating oxygen-rich microhabitats. Such microhabitats consist of a bubble of highly oxygenated water—a capsule of life in hostile surroundings, an oasis of vegetation with invertebrates and fish packed into a finite area.

Clearly, the well-worn line about green weeds luring flocks of hungry panfish isn’t as simple as it seems. Still, given a little plant knowledge, the process begins to make sense. Some plants wither in fall, some crumple in summer; others, given the right water conditions, remain evergreen throughout winter, continuously producing oxygen. Some of these evergreens actually appear more brown than green.

Finding stands of live plants is a tricky business until you get comfortable with plant identification and corresponding habitat. It requires inspecting the terrain in search of certain species of plants, rather than trying to arbitrarily determine which ones on a weedflat remain alive. Lots of the searching today involves an underwater camera, such as an Aqua-Vu.

Plant vitality can’t always be determined without pulling a strand through a hole, and even then, it can still take a botanist to make the call. Even a seemingly upright stalk of something like pondweed isn’t necessarily photosynthesizing. Until anglers regularly employ and interpret DO meters, camera work remains the best way to help us make judgments about where to fish.

When biologists study aquatic plants, they find a diversity of native species that creates a patchy underwater landscape. Minnesota Department of Natural Resources Senior Research Scientist Paul Radomski is among them. “A patchy field composed of many different plants creates lots of the edges, nooks, and tunnels panfish need to both hide from and pursue prey,” he says. “Multiple fish species and age-classes depend on a diversity of plant habitats for feeding, spawning, and refuge.”

Radomski’s “patchy” concept is key, for a diversity of plants suggests a balanced environment in which each species of plant offers something unique that certain invertebrates or fish require—food, habitat, or both. “We could talk a lot about native versus invasive plants,” he says, “yet of primary importance is that native plants coexist best, while invasives such as Eurasian milfoil tend to overgrow native plants, reducing the patchiness of littoral zones.”

Taking the concept a step further, he adds: “Plant diversity is highest in heterogeneous lakes. These are generally larger or deeper waters with various types of bottom substrate and more convoluted depth variations. Conversely, homogeneous lakes, which are often more turbid, host greater phytoplankton (algae) densities relative to rooted macrophytes. Ideally, you like to see an abundance of submersed plant species, because they increase the probability that at least one is winter-hardy.” But which macrophytes overwinter? Where do they grow? And when do they attract panfish?

The Jungle

Coontail (Ceratophyllum demersum)—This common macrophyte tolerates cold water and low light levels, allowing it to frequently overwinter as an evergreen. “Live winter coontail appears green and bushy, while dying stalks easily fall apart in your hand,” Radomski says. “Unlike most plants, coontail isn’t always rooted to the bottom. Instead, plant masses can drift between different depths—10 to 20 feet—on spacious flats.”

Providing nearly optimal winter habitat for bluegills and occasionally crappies, coontail creates homes for a host of invertebrates, including certain species of mayfly, caddisfly, and midge larvae—critters that make up that gelatinous goo you find in panfish stomachs.

Sometimes you get especially lucky and find swarms of scuds, little crustaceans that crave coontail salads. Likewise, bluegills pop scuds like candy, bulking up rapidly. It’s a sweet weed-prey-panfish link worth the extra detective time. While traveling the winter panfish trail, we’ve found a number of lakes housing this pattern, one that appears strongly tied to clear ponds or small lakes cut into treeless valleys and windswept prairies. The presence of scuds becomes immediately obvious, as they swarm entire plant beds.

Elodea (Elodea canadensis)—Canadian waterweed is another name for a plant anglers encounter often, though rarely identify.

Its stems sprout small waxy-green leaves that crowd together toward plant tips. Typically, waterweed grows in softer sediments enriched with organic matter. Some of these areas lie in shallow water, although this plant often grows to depths beyond 25 feet. Like coontail, elodea tolerates lower light conditions and murkier water, which often allows it to remain evergreen, continuing photosynthesis through winter.

“Waterweed is probably the most common overwintering plant,” Radomski says. “Larger panfish seek it because it produces considerable infusions of oxygen, perhaps in greater abundance than other submersed species. And you usually find lots of midge larvae associated with it, which is a key winter food item.”

Searching for overwintering elodea takes time, as the live plants typically grow in isolated patches. Still, even though it can be more elusive than other species, finding a few live patches can seem like finding treasure, often attracting visits from small pods of real palm-stretchers.

Patches cover areas from the size of a typical kitchen to the expanse of a hockey rink. Shallow bays fed by creeks, river backwaters, and oxbow lakes offer top shots at finding wintergreen elodea fields. Marina bays kept partially open by aerators can host elodea and bluegills all winter. Otherwise, late-ice represents a peak phase for finding ’gills in waterweed, as stems sprout new growth early in the calendar year, inviting fresh infusions of life.

Large-leaf Pondweed (Potamogeton amplifolias)—What fishermen call cabbage remains widely familiar, if slightly misunderstood. Big broad leaves furl away from lanky stems that remind you of giant beanstalks. Pondweed holds fish like few other submersed plants. Under ice, though, it only occasionally remains active. Stems of decaying pondweed break underwater, leaves shriveling like dried tobacco. A live pondweed remains erect and intact, brownish leaves absorbing sunrays that generate oxygen. Turbid water, thick ice, or snow cover cut the probability of encountering living plants.

“Large-leaf and fern pondweed [another occasional overwinterer] often intermix with coontail,” Radomski says. “Finding live winter pondweed, which is a relatively frail submergent, indicates a high probability of other persistent macrophyte life and also a good chance of finding panfish.”

Revisiting the “patchy” concept, multiple living plant types in a given area, such as pondweed in conjunction with coontail, accentuate invertebrate and panfish appeal. Further, the presence of bass and pike in these live weed zones nearly assures that panfish swim somewhere in the neighborhood. Keep popping holes until you find those tight-knit schools of thick-bodied bluegills or crappies clustered around small forests of giant beanstalks. These fish feed a bit like birds—pecking baits aggressively then flitting away to avoid predators.

Curlyleaf Pondweed (Potamogeton crispus)—Even though this overtly abundant aquatic plant is a Eurasian exotic—one capable of overgrowing native species—a couple of elements bear mentioning. “Curlyleaf pondweed is a coolwater specialist,” Radomski says. “It dies back around mid-July, lies dormant during late summer, then produces winter foliage starting in September. When water temps drop into the low-70°F range, plants produce winter foliage, remaining active under snow and ice, often even in murky waters.”

Found primarily in softer bottom sediments, this pondweed sprouts slender, rippled leaves that are easy to identify. Again, even live pondweeds often appear more brown than green.

Beyond the obvious wintertime appeal of live curlyleaf to many aquatic animals, this plant is positively related to populations of large bluegills. “When curlyleaf pondweed dies back in summer, previously hidden juvenile bluegills are exposed to predation, reducing their numbers,” Radomski reports in a study of submersed plants.** “The high lake fertility levels associated with curlyleaf indicate abundant crappie food. Meanwhile the plant’s early spring propensity to overgrow spawning sites potentially limits crappie propagation.”

As you become familiar with those certain submersed plants so attractive to winter panfish, each new lake greets you like your home waters. You soon know right where to look, even if you can’t exactly explain how you know. You’ll find panfish glory sooner rather than later.