Hendrickson Hatch on Michigan Rivers

Late April through mid-May emergence on the AuSable, Pere Marquette, and Manistee. Timing, fly selection, and where to fish.

The hendrickson hatch is the first significant mayfly emergence of the Michigan trout season and the one that draws serious dry-fly anglers back to the AuSable and Pere Marquette every year. Chris Izworski covers what to expect, when to be on the water, and how to fish it.

Ephemerella subvaria identification

The hendrickson (Ephemerella subvaria) is a medium-sized mayfly, hook size 12 to 14, with a reddish-brown body, gray to dun-colored wings, and three tails. The dun (subimago) stage hatches in late afternoon from silt-and-gravel bottomed water. The female spinner (imago) returns to the river in the evening, lays eggs, falls spent, and provides a second feeding opportunity as a spinner fall. Both stages are eaten by trout, often within the same two-hour window.

Hendrickson nymphs are dark brown, medium-sized swimming nymphs that live in moderate-speed gravel runs. In the week before the hatch, trout key on the nymphs, which makes a pheasant tail nymph in size 14 or 16 highly productive subsurface. Once the duns start emerging, fish move to the surface and feeding behavior shifts accordingly.

When the hendricksons emerge

On the AuSable mainstem and the Holy Water section, hendricksons typically begin in the last week of April and run through mid-May. Peak hatches happen during the second week of May in most years. The hatch follows water temperature: emergence begins when water hits the low fifties and tapers when water passes the upper fifties. Cooler springs delay the hatch into late May; warmer springs push it earlier.

On the Pere Marquette, hendricksons start a few days earlier than the AuSable. On the lower Manistee below Tippy Dam, the hatch runs about the same time as the AuSable. On the Boardman, the upper Sturgeon, and the smaller cold-water rivers, hendricksons run a week or two later and continue into the third week of May. The daily emergence window is typically 2:00 PM to 4:00 PM in cool weather and shifts earlier as the day warms.

Patterns for the hendrickson hatch

For the dun, carry a parachute hendrickson in size 14 with a dun (gray) post and a reddish-brown body. The Roberts Yellow Drake is an old AuSable pattern that still works. A comparadun hendrickson in size 14 fishes well on flat water where a parachute might be too visible from below. For the spinner stage, carry a Rusty Spinner in size 14 with rust-colored body and clear poly wings tied flat. Spinner falls happen at dusk and visibility gets tough, so consider an orange or pink hi-vis post to keep track of the fly.

Nymph fishing in the week before the hatch is highly effective. A tungsten-bead pheasant tail in size 14 fished on an indicator rig or tight-line drift through the heads of pools and gravel runs will catch fish reliably in the seven to ten days leading up to the surface emergence. Use 4X tippet for the nymph and step down to 5X or 6X for the dry fly.

Hendrickson water on Michigan rivers

The classic hendrickson water is the AuSable Holy Water, the seven-mile catch-and-release section between Burton's Landing and Wakeley Bridge. The hatch is dense, the wild brown population is high, and the river has dozens of named pools and runs that hold rising fish during the emergence. Below Wakeley Bridge and downstream through the McMasters Bridge section, the hatch continues with similar density.

The South Branch of the AuSable, especially the Mason Tract from Chase Bridge downstream, produces strong hendrickson hatches with smaller wild brook and brown trout. The North Branch has a hatch but the river is generally smaller and more brushy. Outside the AuSable system, the Pere Marquette flies-only water from M-37 to Gleason's Landing produces excellent hendrickson fishing in late April and early May.