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Something’s in the Water: Pond Die-Offs

Flickr/ Andrea Schwaim

100-degree temperatures and herbicides do not mix well for fish in stocked ponds.

In mid-September, locals in-and-around the Lake Manteno area began reporting strange sightings of fish rising up toward the surface of near-by ponds, gasping for oxygenated air.  And keep in mind that the fish endemically found in the ponds near Lake Manteno are not labyrinth fish—it’s not part of their physiology to breathe via “surface level gulping.” Red flag, anyone? It gets worse, so take a deep breath.

Flickr/ Daniella Vareeken

In just a week’s time from those initial sightings, officials had collected nearly eight-hundred pounds of suffocated, chemically-laden sashimi—I’d pass on it if I were you.

“Heated” Times to Come

What caused the fish in these stocked ponds to belly-up? According to Illinois’ Department of Natural Resources (DNR), locals began heavily using herbicides weeks prior in hopes of mitigating the excessive weed growth. I’m sure the pond looked impeccable—and completely void of life too. Couple this factoid with the documented increase in water temperatures—warmer water contains less oxygen per parts-per-million (ppm) than denser, cold water— from the shallow pond, and the result is an aquatic vacuum.

While yes, small, isolated instances like this occasionally occur, and the ponds affected can potentially recover within a five year window, one can’t help but raise an eyebrow at such episodes. I mean, NOAA did confirm this year’s August was the warmest month it had ever recorded since building the database in 1880. And who’s not to say that—with continual, heavy use—larger quantities of herbicides won’t trickle their way down toward larger waterways, later concentrating in rivers and lakes.

So, aquaculturists and anglers alike, how do we keep our waterways sustainable? Would these chemical customs still remain common practice? I’ll be waiting with “bated breath.”

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Something’s in the Water: Pond Die-Offs