A mysterious sight: What is causing hundred of fish to appear on the shoreline?

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(Photo courtesy of Dept of Natural Resources)

CHICAGO — The Illinois Dept of Natural Resources says it believes it knows what’s causing a number of fish to appear on shorelines of Lake Michigan.

(Photo courtesy of Dept of Natural Resources)

It’s called “upwelling” which is when deep cold water rises toward the surface and pushes fish up.

The DNR says it happens from time to time, but it is rare.

Fishermen at various locations along the lake noticed the number of yellow perch coming up by the shorelines at the 87th Street slip and elsewhere.

It becomes a feast for seagulls and fish-eating ducks which make quick meals of them until they’re gone.