Grand River bass go post-spawn; late-spring salmon window still open

What's Biting

What's Next

**River conditions** — The Grand River at 3,330 cfs (USGS gauge 04119000) sits near the upper edge of comfortable wading but remains fully fishable by drift boat and kayak from the lower river down to the Grand Haven pier mouth. Absent meaningful rainfall over the next several days, flows typically ease as late-May snowmelt contribution trails off, which should gradually open wading access and improve water clarity through the first days of June. Anglers should carry a thermometer, as gauge readings at this station currently lack water temperature data.

**Post-spawn bass window** — Late May into early June is the prime post-spawn transition for both largemouth and smallmouth in this system, and the Full Moon timing reinforces that shift. Tactical Bassin's post-spawn breakdown describes the bite moving from shallow beds to isolated offshore structure and outside flats: the crew found chatterbaits and swimbaits drawing reaction strikes on moving presentations, with neko rigs and drop-shots filling in when fish went lockjawed. Wind-drifting outside flats — the specific technique the post-spawn piece highlighted — translates well to the lower Grand River's broad pools and the rock structure flanking the pier mouth where the river meets Lake Michigan. Start with reaction baits covering water on the drift; slow to finesse once fish are marked but not committing.

**Lake Michigan trolling building** — As late-May nearshore temperatures continue climbing, early Chinook and coho begin positioning along the thermocline off the eastern Michigan shore. The WI DNR Lake Michigan Fishing Report confirmed that the 2024 Chinook class posted the strongest numbers since 2012 on the back of healthy alewife forage; if forage conditions have held through the 2025–2026 stocking cycle, the early-summer trolling window off the Grand Haven and Muskegon port corridor should be productive. Flasher-fly rigs and spoons in the top 20 to 30 feet are the standard setup for this phase; board-and-diver spreads can probe the thermocline transition as it sets over the coming weeks.

**Full Moon timing** — Today's Full Moon typically compresses peak feeding into tight windows at dawn and dusk rather than spreading activity through the day. River anglers targeting post-spawn bass should plan sessions around first and last light. Open-lake trollers at depth are less affected by surface lunar pressure and can fish through midday with consistent results.

Context

Late May on the Lake Michigan eastern shore and Grand River mouth is a well-defined seasonal pivot. Spring steelhead returns, which peak through April and into early May, are in their final weeks by Memorial Day. The coho run often stretches slightly later but is similarly tapering by late May. In their place, summer-mode bass and the early vanguard of the Chinook trolling season take over the calendar. It is not a slow stretch so much as a changeover, and anglers who adapt technique rather than waiting for one run to end before heading out typically do well in this window.

The WI DNR Lake Michigan Fishing Report's 2024 harvest summary is instructive as backdrop. The record coho return of more than 210,000 fish and the strongest Chinook tally since 2012 (over 160,000) were credited to above-average survival among alewife, the forage species that stocked salmonids depend on in Lake Michigan. Michigan Sea Grant's ongoing research into zebra and quagga mussel impacts on the Great Lakes food web provides longer-term context: these species have altered nutrient cycling and offshore productivity for more than three decades, increasing water clarity while reducing the energy available to prey fish like alewife. The result is genuine year-to-year variability in how stocked salmon classes perform, meaning the 2024 benchmark does not translate automatically to 2026.

On river flows, a reading of 3,330 cfs at USGS gauge 04119000 for late May is within the expected range for this time of year — above typical summer base flow but well below the elevated conditions that accompany peak April runoff. No current-season catch-rate data or Michigan-specific angler reports were available in this reporting cycle to benchmark conditions against prior years. If conditions are on schedule, the next meaningful shift to watch for is the late-June arrival of Chinook concentrating along the thermocline as surface temperatures push into the upper 50s and low 60s in the southern Lake Michigan basin.