Bunker gets thrown early. The schools show up, the water warms, somebody marks a big pod off the beach in late June, and the bunker spoon comes out of the bag for the rest of the summer.
The stomachs of striped bass sampled off Massachusetts tell a different story, and the number that starts it is zero.
Zero, then most of the diet
Nelson's population-consumption work put figures on what Massachusetts bass actually ate, and the seasonal split is about as sharp as fisheries data gets:
0% of June–July stomachs. 29–81% of August–September consumption.
Not "less in summer". None. Then, within a few weeks, the single largest item in the diet for most age classes — 81.7%, 73.0%, 73.7%, 55.0% and 31.9% by age in August–September.
Across the North Shore population over the June–September season of 2000, menhaden came to roughly 29% of all prey eaten, by weight. Almost all of that is compressed into the back half of the season.
The bait is there before the eating starts
This is the part that makes the early-summer bunker session so persuasive: you are not imagining the pods. The largest adult menhaden reach southern New England by May and the Gulf of Maine by June (ASMFC 2017). You can see them. You can snag them.
Presence and predation are different questions, and the stomachs answer the second one. For most of the summer the bass are eating other things — the region-by-region diet work is full of crabs, sand eels, silversides, squid and hake — while the bunker swim past.
Something changes in August. The authors tie it to young-of-the-year menhaden, 30 to 145 millimeters long, moving seaward out of the estuaries in late summer (Nelson et al. 2003).
And it is not the same coast to coast
Averaged over the season, menhaden's share of the diet varies enormously by where you fish:
| Region | Menhaden, % of diet by weight |
|---|---|
| North Shore | 22.6% |
| Cape Cod Bay | 17.2% |
| Nantucket Sound | 5.5% |
Four times the dietary importance on the North Shore that it has in Nantucket Sound. A more recent Salem Sound study, sampling 2012–2016, put its own pooled figure at 7.0% by weight — a reminder that these numbers move with the years sampled as well as the place.
If your bunker confidence came from someone fishing a different piece of this coast, that may be all the explanation the difference needs.
What to do with it
Do not stop fishing bunker in June. Big bass do take big baits — prey fish up to twenty inches turned up in the Massachusetts stomachs (Nelson et al. 2003) — so a live bunker in front of a cow can still work in June. The data is about what fills stomachs across a population, not about whether one presentation can work on one fish.
But stop treating early-summer bunker as matching the hatch. Through June and July you are offering something the population is measurably not eating. That is a legitimate tactic — a big obvious meal among smaller ones — just not the same tactic as showing them what they are already on.
And in August, believe it. The transition is real and quantified: from August, bunker is what the population is eating most.
How StripedLines uses this
StripedLines is built for striped bass. The app's bait calendar puts menhaden's peak in August through October, where the stomach data puts it.