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> > Measuring the Health of a Trout Stream using the Hilsenhoff Biotic Index

WiflyfisherFebruary 9th, 2023, 5:28 am

Posts: 663
I thought Jason might like this.

John S.
Jmd123February 12th, 2023, 12:30 pm
Oscoda, MI

Posts: 2611
Not just for trout streams...we used it on Little Otter Fork in southern IN. I do wonder what exactly is the source for the tolerance values...opinions? Hard data?

No matter how big the one you just caught is, there's always a bigger one out there somewhere...
WiflyfisherFebruary 16th, 2023, 4:52 am

Posts: 663
Hilsenhoff compiled data from more than 2000 sample sites collected in the 1979-1980 cooperative study with the Wisconsin DNR to reevaluate the tolerance values by comparing the tolerance values of each species with the average biotic index value of streams where that species was commonly found.

The HBI is used all over the World. I see it as an alternative option to doing a chemical analysis to estimate the health of a stream. I do believe mayflies, caddisflies and stoneflies are the canaries in the coal mine.

I recently found a stream where there is tons of farm sediment and runoff. Mayfly larvae are virtually non-existent, as samplings have shown, but the brown trout are doing fine. The stream is actually in poor health, which proves brown trout are more tolerant to organic pollution than mayflies.

John S.

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