Fish food for thought

When the fish aren’t biting, find out what they bite. That’s the motto I live by. For me, fish are often not biting, at least not biting frequently enough to keep me engaged.

Anticipation does not motivate me whenever I’m casting a lure redundantly or watching a bobber interminably. So, I grab my dip net (a long-handled tool equipped with a fine mesh net) and off I go to discover all sorts of aquatic critters.

I first discovered the dip net while job-shadowing biologists from the Illinois Environmental Protection Agency whose goal was to monitor water quality at locations downstream of a sewage treatment plant. On that day, the biologists took the dip nets in hand, extended one to me and waded into the stream. They were looking for aquatic macroinvertebrates.

Certain macroinvertebrates (a term indicating immature insects, for the most part) are intolerant to pollution. Such species are not capable of surviving within an aquatic environment tainted by pollutants nor within water bodies depleted of oxygen. Among macroinvertebrates, there are degrees of tolerance. Some species, such as rat-tailed maggots and mosquito larvae, can thrive in yucky water.

If the intolerant, or highly sensitive, species are discovered within the mix of organisms in the dip net, the water is considered good quality. It suggests the body of water can support a complex and diverse aquatic community. For example, a pond community in Illinois will include plants such as algae, water willow, and arrowhead; as well as animals, such as leeches, snails, giant water bugs, predaceous diving beetles, mayfly larvae, flathead minnows, bluegill sunfish, largemouth bass, and the list goes on!

This is the chance to gain insight into the underwater world. The dipper gets a peek at the food chain. One can infer that the tadpole ingests algae (often called pond scum or moss). The tadpole is nabbed by the extendable jaws of a dragonfly naiad. The naiad becomes the prey of a bluegill. Meanwhile, a snail scrapes away at the photosynthesizing tissues of coontail. Then a redear sunfish cracks the snail’s shell, and a bass gulps the sunfish.

By the end of that day, the biologists’ dip nets held stonefly larvae, which require high dissolved oxygen levels. The stream had been deemed healthy. I was then hooked, and since then I carry a dip net when near a body of water.

Along the shore of a lake, I extend my reach, dip my net down through the shallows, skim it along the bottom and tug it back. As I lift the net, water drips through. Aquatic species assemble at the bottom of the net. Some wiggle and squirm, some shimmer and sparkle reflecting sunlight, and some jump and flip. At that moment I am no different than a child. I giggle at the little chubby tadpoles, the backward-scooting crayfish and the shiny-sided fry (baby fish). I tip the net over a bucket, and in they go.

I easily spot whirligig beetles and water boatmen swimming in the bucket’s water. I focus to detect small damselfly nymphs with three tiny paddle-like tails extending from delicate elongated abdomens. I find crawling naiads with eyes large and prominent, much like those of their adult winged version called dragonflies. I look at salamander larvae with flared feathery gills. I observe and release the organisms back to their watery home.

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