Short answer: yes, and often. The shrimp in question is the sand shrimp, a small, sand-colored bottom shrimp of bays and estuaries (Crangon septemspinosa, also called the sevenspine bay shrimp). When Massachusetts biologists opened striped bass stomachs from June to September, 1997 to 2000, sand shrimp were about one in five of all the prey items they counted north of Cape Cod, and turned up in about one in five stomachs that held food.
Who ate them is the useful part. For school bass in estuaries in early summer, sand shrimp were more than half the meal by weight. For big bass on rocky shoreline, they were almost nothing.
How much shrimp
Nelson, Chase and Stockwell of the Massachusetts Division of Marine Fisheries collected 3,006 stomachs, and 1,720 of them held food. Their summary table gives three measures for sand shrimp:
| North Shore | Cape Cod Bay | Nantucket Sound | |
|---|---|---|---|
| Share of diet weight | 7.7% | 6.6% | 3.9% |
| Share of prey items counted | 19.8% | 24.2% | 12.9% |
| Share of stomachs with food holding any | 19.3% | 20.1% | 9.3% |
The gap between the rows is the point. A sand shrimp weighs little, so weight makes it look minor beside a menhaden or a small lobster. By count it was nearly a quarter of everything eaten in Cape Cod Bay. The authors list it first among the main crustaceans in the diet, ahead of rock crab and lobster.
Small bass, estuaries, early summer
The team also grouped stomachs by place, season, habitat and fish size. Sand shrimp follows one kind of water.
| Group (stomachs with food) | Sand shrimp, share of weight |
|---|---|
| North Shore estuary, June–July, about 15–17 in (32) | 55.3% |
| North Shore estuary, Aug–Sept, about 15–19 in (85) | 15.7% |
| North Shore rocky shore, June–July, about 17–25 in (239) | 0.9% |
| North Shore rocky shore, June–Sept, about 27–38 in (175) | under 0.1% |
| Cape Cod Bay estuary, June–July, about 13–32 in (159) | 23.8% |
| Cape Cod Bay estuary, Aug–Sept, about 17–29 in (198) | 2.1% |
| Nantucket Sound estuary, June–Sept, about 15–23 in (89) | 14.9% |
| Nantucket Sound offshore, June–Sept, about 32–40 in (36) | none |
Two things stand out. Shrimp is estuary food: rocky shoreline barely shows it, even for fish of similar size. And it is early-summer food. In the North Shore estuaries the same size of bass went from 55 percent sand shrimp in June and July to 16 percent in August and September, when menhaden took over at 43 percent. Cape Cod Bay's estuaries ran the same way: 24 percent shrimp early, 2 percent late, with menhaden at 53 percent. More on that switch in menhaden are an autumn bait.
Nelson's team pointed out that state trawl surveys had found sand shrimp among the most abundant crabs and shrimp in North Shore estuaries, and suggested estuary bass may have been eating what was locally abundant.
Two cautions. The 55 percent rests on 32 stomachs. And size and place are tangled: small bass mostly came from estuaries and big ones from rock and open water, which the authors themselves flag. The rocky-shore rows, one habitat and two sizes, show shrimp scarce for both.
The fly-rod study: shrimp in every season
Ferry and Mather sampled 797 bass from 13 Massachusetts estuaries in 1999, mostly 15 to 19 inches (375 to 475 mm). The fish came on flies, four hours at first light on the ebb, and their stomachs were flushed and the fish released. Unlike Nelson, they sampled from May into October.
Their summary is plain: sand shrimp "were eaten in all locations and seasons." In spring and summer it made up nearly a third of the diet by weight in some estuaries. In Buzzards Bay, the spring diet was mainly sand shrimp and smaller crustaceans. North of the Cape, spring was juvenile herring, summer a mix that included shrimp, and autumn juvenile menhaden.
In the paper's own summary, summer stomachs were also the lightest: under 5 grams of food per fish, counting the empty ones, against more than 10 in spring and 13 in autumn. A shrimp diet is a light one.
Big bass: almost none
Murphy, Nelson and Grabowski caught 158 bass on rod and reel around Salem Sound from 2012 to 2016, averaging about 30 inches. They found two sand shrimp, in two stomachs, weighing about 1 gram out of 4,716 grams of food. They noted that sand shrimp swim up off the bottom and are taken differently from crabs, so they kept them out of their crab-and-lobster group.
That fits the rocky-shore numbers above. Big Massachusetts bass eat a lot of crustaceans, but the crustaceans are crabs and small lobsters. See do striped bass eat crabs.
Grass shrimp and mysids: not measured here
"Shrimp" in a tackle shop often means grass shrimp. In Nelson's 1,720 stomachs, grass shrimp (the family Palaemonidae) appeared only in Nantucket Sound, under 0.1 percent of the diet by weight and in 0.4 percent of stomachs. Mysids, the tiny opossum shrimp, were under half a percent by weight in every region, though one North Shore estuary group in late summer carried 4 percent. Ferry and Mather lumped grass shrimp with unidentified crustaceans and mysids with amphipods and isopods, so their data cannot single them out. We found no Massachusetts study that measures either as striped bass food.
What the stomachs cannot tell you
They are mostly morning fish. In Nelson's study 77 to 90 percent of bass were caught between 6 a.m. and noon, most on rod and reel, some by gillnet and long-line. Ferry's were all fly-caught at first light. A soft shrimp eaten overnight may be hard to find by mid-morning; that is our inference, and nobody has measured it.
Weight hides small prey. By weight, sand shrimp looks like a side dish; by count, it is one of the main foods. Read both.
Big fish after September are unmeasured. Nelson stopped in September, and Ferry's October fish were school-sized.
What to do with it
Inference from the diet, not a tested rule: nobody has compared catch rates by fly or lure against these stomachs.
- For school bass in estuaries, June and July, think shrimp. Small, sand-colored patterns near the bottom match what the stomachs held.
- Expect the switch in August. As juvenile menhaden leave the estuaries, the same size of bass turned to them.
- On the rocks, or after big fish, shrimp is the wrong match. Crabs and small lobsters carried those diets.
How StripedLines uses this
StripedLines is built for striped bass. Sand and grass shrimp are among the baits the app can suggest in estuaries, back bays and flats over mud, sand, marsh and eelgrass, mostly in June and July. Ferry's fish carried it in May and October too, so the app's window is narrower than the evidence. The app does not know what size of bass you are after.