"Warming Rivers Threaten Iconic Michigan Fish"

"A beloved, cold-loving state fish is in danger of overheating."

"GRAYLING, Mich. — If the word 'tricos' means anything to you, the Au Sable River is the place to be in late summer.

Tricos are tiny mayflies, hatching abundantly in August. The imitations tediously tied by fly anglers are, of course, just as tiny. On a clear Sunday earlier this month, I was lobbing these pinky fingernail sized flies on particularly productive stretch of the river known locally as the 'Holy Waters.'

For some the name rings true, as this is akin to church. The speckled, cosmic colored brook trout, Michigan’s native river trout and official state fish, pop all along the watershed at tricos—real and fake.

The river is cold—Michigan’s brook trout, a sensitive species, prefer water between about 43 degrees and 53 degrees F and can get stressed in water in the high 60s. The Au Sable, Michigan’s most fabled trout stream, has strong groundwater recharge, clear water and all kinds of springs and seeps that provide the cold-water brook trout need to survive.

While the Au Sable might be buffered against rising air temperatures, that’s not true across the state. And, in some streams, climate change could spell big trouble for the little fish."

Brian Bienkowski reports for the The Daily Climate August 21, 2017.