415 



416 



dredge, were used. Meraenaria sp. were found in greatest abundance 

 between Cape Lookout and a point about 4 mi west of Beaufort Inlet in 

 depths of 3 1/2 to 7 1/2 fath. Simulated commercial dredging produced an 

 average catch of 7 1/2 bushels live clams/hr fished and a max catch rate 

 of 13 bu/hr. Most clams were chowder-size (3-5 in long), yielding an 

 average of 1 gal meats/90-lb bu. Dead clams were taken as frequently as 

 live. Small numbers of hard clam were taken near Bogue In. and near the 

 mouth of Cape Fear R. , and abundant dead shell but no live clams near 

 Drum In. It apparently was not determined whether the species was 

 Meraenaria meraenaria, M. campechiensis , or both. - J.L.M. 



Cunliffe, James E., and Michael J. Kennish. 1974. 



Shell growth patterns in the hard-shelled clam. Underwater Nat. 8(4) : 

 20-24, 47. 



Meraenaria meraenaria adds a small increment of aragonite bounded by a 

 thinner layer of conchiolin to its shell every day. The aragonite incre- 

 ments are deposited at night and the conchiolin by day. Thus, shell forma- 

 tion in M. meraenaria appears to coincide with light and dark cycles of the 

 solar day. The thickness of daily increments varies during the year, 

 thickest in summer, thinnest in winter. Other patterns suggest that shell 

 deposition is also controlled by the fortnightly tidal cycle, thin incre- 

 ments deposited during neap tides, thick increments during spring tides. 

 Periods of stress may also interrupt growth for one to several days . These 

 interruptions or breaks are characterized by indentations of the outer shell 

 layer, the most severe of which is the winter break. Less severe breaks may 

 also be caused by spawning events, and by storms. Clams from creeks with 

 heated effluents show a higher number of breaks and slower summer growth. 

 There also appear to be three phases of growth according to age, each dif- 

 fering in the pattern of daily increments. During old age, clams sometimes 

 appear to be able to resume the pattern of the middle period if transplanted 

 from deep to shallow water. Counting surface rings has previously been used 

 to determine age of clams. The new method suggests that such estimates are 

 high by a factor of about 2. In fossil clams of several species it appears 

 that the earth's rate of rotation is slowing down. During the Late Pennsyl- 

 vanian Period (about 300 million yrs ago) there were about 18 more days per 

 yr than at present. - J.L.M. 



Curley, John R. , Robert P. Lawton, John M. Hickey, and John D. Fiske. 1971. 



A study of the marine resources of the Waquoit Bay-Eel Pond estuary. 

 Mass. Dept. Nat. Resour., Div. Mar. Fish., Monogr . 9, iv + 40 p. 



Quahog (Meraenari 

 species in 1967. 

 Growing season is 

 32°F to max of 79 

 15 ft 2 of bottom h 

 clams averaged 36 

 August 1967. In 

 clams was 1 . 2/f t 2 

 averaged 42 mm an 

 commercial harves 

 production was 17 

 - J.L.M. 



a meraenaria) was the principal commercial shellfish 

 Areas of major concentration are illustrated on a chart. 

 six months, April to October. Temp range was from below 

 F. Salinity ranged from 23°/°° to 33°/°°. Samples of 



ad an average of 3 and max of 8 quahogs/ft2. Sublegal 

 mm and legals 55 mm, and 31% were of legal size, in 



June 1968, 64 ft 2 samples were taken. Average number of 

 and range was to 12 clams/sample. Sublegal clams 



d legals 57 mm. Samples were 32% legal size. Most 



ting was with tongs, some with hand rakes. Average 

 bu/acre. Total quahog harvest in 1967 was 2,459 bu. 



417 



Curley, John R. 

 1972. 



Robert P. Lawton, David K. Whittaker, and John M. Hickey. 



A study of the marine resources of Wellfleet Harbor. 

 Resour., Div. Mar. Fish., Monograph 12, 37 p. 



Mass. Dept. Nat. 



Wellfleet once produced more Meraenaria meraenaria than any other town in 

 Mass. Commercial production in the late 1800s ranged from 1,800 bu to 

 2,500 bu/yr. Annual production in 1906 was 33,000 bu. In 1957 harvest 



115 



