Definitely stop by Gates fly shop (call ahead or honk in the winter since the lodge is closed from October through March or so) and the old Au Sable Fly Shop in Grayling before hitting the upper river system. Linsenman's Au Sable Angler in Mio for the Big Water. They'll get you up-to-date with whatever is going on in the river. Also check out the fishing reports on both websites - updated weekly during the season and whenever the rest of the year.

Get a copy of Seasons on the Au Sable, by Rusty Gates (my mug slipped in there by chance). It's a yearly look at the river based on his river reports. Proceeds go toward the Anglers of the Au Sable, a very worthwhile cause. Would be a nice Christmas present and winter read.

Opening day fishing is usually cold with high water and few fish, but we go anyway. Hit it hard before the aluminus flotilla hatch (aluminum canoes) and then spend sleepless nights chasing the hex hatch (hexagenia limbata mayfly) and listening to the whippoorwills in late June/early July. Late summer can be slow if the weather is hot but this past summer was the best with the cooler temps. Then look forward to the fall when the most beautiful fish in the world, the brook trout, take on their spawning colors. Warmer winter days can be hit or miss streamer fishing for browns.

Parts of the river are closed to fishing at various parts of the year so be sure to get an Inland Trout and Salmon Guide and know where you are.

By the way, the Ausable River is in New York. The Au Sable River is in Michigan.

I've got plenty of tips for the AuSable River in the Adirondack's of NY...I grew up fishing that river...but I can't say I've ever fished the Au Sable in Michigan. I'd suggest bringing the classic trustworthy flies that produce across the country, and then stop at a local fly shop to pick up a few local favorites and find out where some good sections of river are located.