BirdTroutOpen the map Is the Au Sable River good for brook trout?
Not in midsummer, and not everywhere. Michigan's own survey records list brook trout in the Au Sable River, and stocks it as well, but the river's measured July mean of 70.2 °F is above the 68 °F upper limit for this fish, so the water that holds it is the cold tributary mouths and the spring-fed stretches rather than the mainstem in July. Across 8 gauged stretches the July mean runs 66.3–75.5 °F, so the answer changes with where you stand on it. Fish of 6–11 inches are what Michigan reports as typical. The river is designated Type 1, Type 2, Type 3 and Type 4 trout water, which is what sets the size and creel limits.
What the state's records say
- Species
- Brook trout (Salvelinus fontinalis)
- In Michigan
- native
- Record here
- surveyed present, and stocked
- Holds in
- 53–61 °F, stops feeding above 68 °F
- Typical
- 6–11 inches
- Spawns
- October and November, on gravel in groundwater-fed shallows, often at the mouths of seeps rather than in the main current.
Native throughout, and the fish of the Upper Peninsula and the northern Lower's spring creeks. Lake Superior's coasters are the same species run to the lake.
Is the water cold enough
Measured, not modelled: 8 gauged stretches of this river average 70.2 °F in July (66.3–75.5 °F across them), against the 53–61 °F this fish holds in and the 68 °F it stops feeding at.
| Gauge | Now | July mean |
|---|---|---|
| Red Oak | 56.3 °F | 66.3 °F |
| Mio | 57.6 °F | 70.0 °F |
| Mc Kinley | 56.1 °F | 69.5 °F |
| Curtisville | 57.4 °F | 71.8 °F |
| South Branch | 60.4 °F | 74.0 °F |
| Glennie | 60.6 °F | 74.1 °F |
| Sidtown | 63.5 °F | 75.4 °F |
| Au Sable | 64.8 °F | 75.5 °F |
What you may keep
| Reach type | Miles | Minimum | Season |
|---|---|---|---|
| Type 1 Designated | 15.1 | 7″ | Last Saturday in April–September 30th |
| Type 2 Designated | 13.0 | 10″ | Last Saturday in April–September 30th |
| Type 4 Designated | 27.3 | 7″ | January 1st–December 31st |
| Type 3 Designated | 12.1 | 15″ | January 1st–December 31st |
From Michigan's own regulation tables, per designated type, and the current digest is the authority rather than this page. Full regulations for this river →
What to fish for it
- Fish Eggs — October–January and April, #10–16
- Little Black Stonefly — January–April, #16–18
- Little Brown Stonefly — February–April, #12–16
- Blue-Winged Olive — March–May and September–November, #16–22
- Blackfly — April–June, #18–22
- Blue Quill — April–May, #16–18
- Cranefly — April–June and September–October, #6–10
- Grannom — April–May, #14–16
The insects recorded from this river's region, earliest first. The full calendar →
More about Au Sable River
Au Sable River — live water temperature, regulations and access
- Is the Au Sable River good for brown trout?
- Is the Au Sable River good for rainbow trout?
- When to fish the Au Sable River, Michigan
- How to get to the Au Sable River, Michigan
- Au Sable River fishing report
- Au Sable River fishing regulations