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Lack of rain, extended heat wreaking havoc on fish in area rivers

Arerivers are low — such as downstream Kankakee Dam where dead redhorse suckers were found last week — contributing fish-killing

Area rivers are low — such as downstream of the Kankakee Dam, where dead redhorse suckers were found last week — contributing to the fish-killing impact of the extended heat. | Dale Bowman~For The Sun-Times

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Updated: August 17, 2012 6:46AM

Dead shorthead redhorse suckers send a signal that worries Bob Rung.

The veteran streams biologist is afraid a bigger fish kill might be coming, especially on the Fox River, with another extended heat wave building on top of water levels nearing or at historic lows on area rivers.

Last weekend, Rung had a sense of a building kill. On Monday, he did a survey with fisheries biologist Rob Miller that found some dead fish of specific species on the Fox River, especially in the six pools around South Elgin to Aurora. They found very little indication of a fish kill from Montgomery downstream.

The die-off of specific species is significant. An all species die-off would indicate a kill related to a crash of dissolved oxygen levels. A kill of specific species is more likely to be thermal-related. For example, they only found one dead smallmouth bass, a species tolerant of hot water.

‘‘My concern is the water level continues to go down,’’ Rung said. ‘‘The conditions that killed the fish [last weekend] have the potential to get worse. If we don’t get some rain or a break, we are looking at an expanding kill.’’

My natural next question was did he think Chicago-area fishermen should quit river fishing.

‘‘That would be desirable,’’ he said. ‘‘During the drought, it would be good to put up the rod for a while. Unless you are going to eat what you catch.’’

There’s trouble building.

Miller compares shorthead redhorse to canaries in a coal mine, the signalers of trouble.

Rung used another comparison.

‘‘They are the warm-water equivalent of trout,’’ he said.

That is not good news for the Fox.

In one 200-yard stretch near Indian Trail on the Fox, Miller and Rung counted 130 dead fish, 125 of them suckers (82 shorthead redhorse, 34 silver redhorse, the rest other) with two walleye, one northern pike, one drum and a banded darter.

There are bad indicators from other rivers, too. On Tuesday, wildlife biologist Bob Massey was doing a non-fish survey on the Kankakee River from the Kankakee Dam downstream and noticed dead redhorse along the way.

‘‘It’s such a subtle thing, it is not ringing a lot of alarm bells,’’ Rung said.

A quick survey of one affected area of the Des Plaines River showed two dead muskies and 15 dead white suckers.

This is a thermal kill, as indicated by the dead species.

‘‘Fish were literally being boiled,’’ Rung said. ‘‘I think I lost my taste for bouillabaisse.’’

An apt description for a soup turning bad.

‘‘This is a really bad situation,’’ Rung said. ‘‘There is not a lot that we can do about it. Let’s keep our fingers crossed.’’

Braidwood note

On second thought, Miller is concerned that the fish kill last weekend on Braidwood Lake, the cooling lake in southwest Will County, might be more significant than originally thought. He said we might not know how significant the kill was until the fall survey. In hot weather, dead fish can disappear quickly.

On a more extensive survey of Braidwood, he found more dead species than shad, which is what the kill was originally thought to be.

And of more concern is that the kill might be more extended than thought. Originally, it was thought primarily to be last weekend.

But reader Dan Marzano sent a note that he and a fishing buddy found dozens of dead largemouth bass near the rearing ponds area at Braidwood on July 5, days before the kill was thought to begin. He said they were primarily in the 1- to 3-pound range with some topping 4 pounds.

‘‘If I am seeing this, I am wondering how many are on the bottom,’’ Marzano said.

That might be the question of the summer of 2012.

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