Full Moon Mutton Spawn Lights Up the Florida Keys Reefs

What's Biting

What's Next

The full moon peaked today (May 31), and the next several days represent the prime tail end of the spawn-aggregation window for mutton snapper. ALL IN Key West notes that May through July is "lights out" for snappers, groupers, sharks, and mahi-mahi throughout the Keys — expect the reef bite to stay strong through at least mid-June as warm-season water temperatures hold.

On the offshore front, mahi-mahi are building as the season shifts toward summer. Trolling weed lines and current edges with live bait or rigged ballyhoo should produce as debris lines push through with Gulfstream influence. The same ALL IN Key West Gulf-side report that highlighted grouper and cobia also noted kingfish in the mix — a species that tends to peak in late spring before tapering off with summer heat, making the next two to three weeks a worthwhile window to target them specifically.

Wind conditions have been exceptionally cooperative. Both NOAA buoys SMKF1 (Sombrero Key) and SANF1 (Sand Key) recorded winds of just 1.5 m/s this afternoon, which opens up the shallow flats for permit and tarpon work alongside easy runs to reef and offshore structure. Light-wind stretches like this are common in the first half of June in the Keys, though afternoon convective storms become increasingly frequent as summer builds — plan morning departures accordingly.

For weekend planning, target reef and bottom structure early before afternoon weather develops. Live pilchards and cut bait on heavier bottom rigs have been working for mutton snapper on the spawn grounds per ALL IN Key West reports. For yellowtail, a steady chum line over the reef edge with light fluorocarbon and small hooks remains the standard approach. On the flats, incoming tide windows during early morning offer the best shots at permit moving across turtle-grass edges, with the strong full-moon tidal swings amplifying current push on productive flat systems.

Context

Late May sits squarely in what Keys regulars consider the year's most reliable combined inshore-and-offshore window. The mutton snapper spawn aggregation — triggered by full moons from roughly May through August — is one of the most predictable big-fish events on the reef, and ALL IN Key West confirms the pattern is running right on schedule this season. The fact that captains are specifically calling out the full moon as the on-switch for this bite aligns exactly with the biological rhythm that has defined this fishery for decades.

Yellowtail snapper historically peak during this same window, with chum-line fishing on the reef producing reliably from late spring through summer. The Gulf-side mix of grouper, cobia, and kingfish in a single trip — as reported by ALL IN Key West — is consistent with what typically materializes once water temperatures climb into the upper 70s and baitfish concentrations build along structure. Buoy 41114 recorded 78°F offshore in late April; by late May that reading would typically sit a few degrees warmer, placing surface temperatures well within the range that keeps this mix of bottom fish and nearshore pelagics active.

Sailfish were already showing strong numbers out of Key West as early as March 1 per earlier ALL IN Key West reports, which may signal a robust overall pelagic season building into summer. Mahi-mahi, typically the dominant offshore target from June onward, should continue ramping up over the coming weeks.

No current benchmark report from Bud n' Mary's in Islamorada is available this week to compare the Upper Keys bite against prior seasons. But charter testimony from Key West aligns tightly with late-May historical norms: this is exactly the window the Keys is built for, and conditions appear to be delivering.