of Cape Cod during the late 1800's to northern 

 New England in the 1940's and 1950's. By 1954, 

 green crabs had extended their range northeast- 

 ward to Wedgeport, Nova Scotia, Canada, and 

 were also very numerous in Massachusetts, New 

 Hampshire, and Maine. Glude (1955) and Tay- 

 lor, Bigelow, and Graham (1957) considered an 

 increase in air and surface sea-water temperatures 

 north of Cape Cod to be an important factor in the 

 increase in abundance and extension of tlie green 

 crab's range. 



The green crab was reported to be tlie most prob- 

 able cause of the decline in soft-shell clams by 

 Smith and Chin (1953), Glude (1955), Medcof 

 and Dickie (1955), and Smith, Baptist, and Chin 

 (1955). MacPhail, Lord, and Dickie (1955) and 

 Dearborn ^ observed the feeding of green crabs 

 in laboratories where they were restricted to cer- 

 tain foods, but only a few observations were avail- 

 able on the feeding of green crabs in nature. Smith 

 and Chin (1953) first reported a green crab ac- 

 tually feeding on a soft-shell clam that it had ap- 

 parently just dug out of the sediments. Hence, a 

 study to determine feeding habits under natural 

 conditions was needed for a broader understanding 

 of the impact of this predator on its environment, 

 and particularly on the soft-shell clam. 



I studied the feeding habits of green crabs while 

 at the field stations of the Bureau of Commer- 

 cial Fisheries in Newburyport, Mass., and in the 

 Narragansett Marine Laboratory, University of 

 Ehode Island, Kingston, R.I., from 1954 through 

 1956. The stomach contents of green crabs collected 

 from Plum Island Sound, Mass., and Hampton 

 Harbor, N.H., were examined to determine the rel- 

 ative importance of their foods ; I also made some 

 observations on the relation of feeding behavior txD 

 the environment. 



MATERIALS AND METHODS 



Green crabs occurred and were collected in two 

 distinct zones at low tide — the upper int«rtidal 

 zone and the shallow subtidal zone. Crabs were 

 caught at the edges of salt marshes in Plum 

 Island Sound, Mass., and Hampton Harbor, N.H. 

 (fig. 1) , by opening caves in the banks of cordgrass 



^ De-arborn, John H. 1957. A preUmlnary study of the food 

 habits of the green crab, Carcinifles maenas (L.) with particular 

 reference to the soft-shell clam, Mya arenaria L. M.S. thesis, 

 Mich. State Dnlv. Agr. Appl. Sol., 48 pp. 



184 



{Sparfi7iii) and searching through seaweeds at the 

 ui)per edges of the banks and beneath sods that 

 had fallen onto the clam flats (table 1). Crabs were 

 collected from the subtidal zone by dragging a 

 scallofj dredge at the edges of channels in Plum 

 Island Sound, Mass. (table 2). The net was 76.2 

 cm. wide and 20.3 cm. high at the mouth and had 

 a 51 -mm. mesh (stretched measure) netting bag 

 76.2 cm. deep. A weighted line at tlie leading edge 

 of the net scraped over the bottom; probably crabs 

 buried in the sediments were missed, and active 

 crabs were most likely to be captured. All dredge 



Table 1. — Number of green crabs dug from the banks at 

 Plum Island Sound, Mass., and at Hampton Harbor, 

 N.H., 1954-55 



Table 2. — Number of green crabs dredged from the subtidal 

 zone at Plum Island Sound, Mass., 1964-66 



Plum Island River 



Lufkins Flat 



Date 



Crabs 



Date 



Crabs 



1951, Number 



Oct. 5 124 



Oct. 28 10 



Nov. 5 -. 62 



1955 



Apr. 18 20 



May26 47 



June 13 54 



July 18 S5 



Aug. 15 -_- 64 



Sept. 10.. 52 



Sept. 23- 68 



Oct. 9 54 



Oct. 21 74 



Nov. 7 49 



Nov. 23 -, 



1956 



May 11.- 2 



June 11 40 



June 11 22 



July23 -. 27 



July23 27 



Aug. 6 26 



Aug. 6 27 



Sept. 4 10 



Sept. 5 67 



Sept. 21 26 



Sept. 22 61 



Oct. 5 62 



Oct. 19 67 



Oct. 20 -. -.. 61 



Nov. 5.-- 24 



195i Number 



Oct. 5 69 



Nov. 2 60 



1955 



Apr. 18 20 



May 18 33 



June 13 37 



July 18 67 



Aug. 15 61 



Sept. 10 128 



Sept. 23 44 



Oct. 9 67 



Oct. 21 44 



Nov. 7 69 



Nov. 23 



1956 



May 11 58 



June 11 48 



June 11 16 



July23 59 



July23 46 



Aug. 6 49 



Aug. 6 43 



Sept. 4 52 



Sept. 5. 64 



Sept. 21. 44 



Sept. 22 46 



Oct. 5 49 



Oct. 5 42 



Oct. 19 53 



Oct. 20 98 



Nov. 5 71 



' Two crabs not used for stomach analysis. 



U.S. FISH AND WILDLIFE SERVICE 



