Short answer: yes, but less than the squid-run stories suggest. When Massachusetts biologists opened striped bass stomachs from June to September, 1997 to 2000, squid and their relatives (cephalopods) made up 1.3 percent of the diet by weight on the North Shore, 2.1 percent in Cape Cod Bay and 3.4 percent in Nantucket Sound. A newer study around Salem Sound found 2.9 percent.
The exception: big bass in open water south of the Cape, where squid-type prey was nearly a fifth of the meal.
What the stomachs held
Nelson, Chase and Stockwell of the Massachusetts Division of Marine Fisheries collected 3,006 stomachs, and 1,720 of them held food. Their table splits the cephalopods into what they could name and what they could not:
| North Shore | Cape Cod Bay | Nantucket Sound | |
|---|---|---|---|
| All cephalopods, share of diet weight | 1.3% | 2.1% | 3.4% |
| Named as longfin squid | 0.9% | under 0.1% | 0.1% |
| Not identified | 0.4% | 2.1% | 3.3% |
| Share of stomachs with food holding any | 2.1% | 2.5% | 8.4% |
Most of the weight could not be identified. The only cephalopod named to species anywhere in the study was the longfin inshore squid, so the rest were most likely squid too. That is our reading; the paper does not say it.
For scale, fish and crustaceans together made up 90 to 95 percent of the diet by weight in every region. Squid was a side dish.
A second look came 12 years after the first one ended. Murphy, Nelson and Grabowski caught 158 bass on rod and reel around Salem Sound from 2012 to 2016. They found seven cephalopods in six stomachs, about one in seventeen of those with food, weighing 138 grams together: 2.9 percent of the diet by weight.
Where squid mattered: big fish, open water, south of the Cape
Nelson's team also grouped stomachs by place, habitat, season and fish size. In Nantucket Sound one group stands out: 36 stomachs from bass of roughly 32 to 40 inches (825 to 1,025 mm) caught offshore, more than about half a mile (900 m) from shore, over the whole summer. Cephalopods were 18.4 percent of their diet by weight, behind only lady crab (33.6 percent) and sea robins (20.2 percent). Estuary bass of about 15 to 23 inches in the same sound, 89 stomachs, carried 0.05 percent.
It is the same group behind the lady crab numbers in do striped bass eat crabs, with the same caution: 36 stomachs is a small sample, and size and place are tangled: the big fish came from open water and the small ones from estuaries, so the table cannot say whether squid follows the size of the bass or the water it was caught in.
North of the Cape, big fish in open water did not show it. In Cape Cod Bay, 112 stomachs from offshore bass of about 29 to 38 inches (725 to 975 mm) held 0.7 percent cephalopods; their meals ran to silver hake, bivalves, rock crab and sand eels. On the North Shore, 175 stomachs from rocky-shore bass of about 27 to 38 inches held 0.6 percent.
Where the squid are
The squid's own survey record helps explain that map. A NOAA Fisheries habitat report on longfin inshore squid (Cargnelli and colleagues, 1999, updated by Jacobson in 2005) summarizes the Massachusetts inshore bottom trawl survey, in its spring and autumn tows from 1978 on:
- Spring: high catches in Buzzards Bay and around Martha's Vineyard and Nantucket, low numbers in and around Cape Cod Bay, and none north of Cape Cod.
- Autumn: high catches in Buzzards Bay and around the islands, and squid throughout Cape Cod Bay, Massachusetts Bay, and north and south of Cape Ann.
Two qualifications from the report itself. The authors think the spring survey ran before the main inshore migration, so "none in spring" partly means "not yet." And the map describes young squid, about 3 inches (8 cm) in body length or less, taken at the bottom.
The report also says the inshore movement starts in the south and works north, with the larger squid off Massachusetts coming inshore in April and May. Longfin squid are generally found in water of at least 48°F (9°C). Off Massachusetts the survey found most of them at 50 to 55°F (10 to 13°C) in spring and 61 to 68°F (16 to 20°C) in autumn.
They also move at night. Jacobson's update records that longfin squid rise in the water column at night and drop by day, that the pattern depends on squid size and season, and that off-bottom habitat is poorly known because nearly all sampling is done with bottom trawls.
What the stomachs cannot tell you
They stop at the end of September. Nelson's sampling ran June through September. The autumn squid the trawl finds up to Cape Ann have no matching stomach record, and we found no month-by-month squid diet study for Massachusetts bass.
They are mostly morning fish. 77 to 90 percent of Nelson's bass were caught between 6 a.m. and noon, most on rod and reel, some by gillnet and long-line. A squid that rose at night and was eaten after dark has had hours to digest by a morning capture. Our inference: that would push the measured share down, and help explain why so much could not be identified. Nobody has measured it.
What to do with it
Inference from the diet and the squid surveys, not a tested rule:
- South of the Cape, with big fish, squid earns a place. Offshore in Nantucket Sound it was one of the three main foods of 32- to 40-inch bass.
- North of the Cape in summer, it is a side dish. About 1 to 2 percent of the diet by weight; sand eels, menhaden, crabs and lobster carry far more.
- Expect squid from the south first. The survey finds them around the islands and in Buzzards Bay in spring, and up to Cape Ann by autumn.
- After dark, think about the whole water column. Squid rise at night. Whether bass follow them up has not been measured in Massachusetts.
How StripedLines uses this
StripedLines is built for striped bass. Longfin squid is one of the baits the app can suggest, May through October, more at night than by day. In late spring and summer, deeper ledges, drop-offs, holes and channel edges can carry a "Squid season over deeper structure" label. That label names the calendar, not squid seen at the spot.