found only in more sheltered and shallow bays and rivers, where its 

 distribution parallels that of American oyster. Distribution is limited to 

 P.E.I, and Northumberland Strait shores of N.B. and N.S. It is now absent 

 from some places where it formerly existed along the north shore of P.E.I. 

 Quahaugs usually live just under the surface of the sea bottom, but sometimes 

 on hard bottom of intertidal zone the dorsal portion of the valves and the 

 ligament are uncovered with substrate. Siphons are very short and project 

 only a few mm beyond the posterior edges of the valves. Large quahogs (6 to 

 8 cm long) are inactive although they have a powerful foot. If placed on the 

 surface of the sea bottom large quahaugs bury in a short time, but once below 

 the surface there is no horizontal movement. Smaller animals are more active. 

 At 2 to 3 cm long they can travel up to 1 ft horizontally in 2 months in 

 summer. At 5 cm they have a larger foot relative to size of valves and are 

 more active in burrowing, but move little horizontally. All sizes can regain 

 the surface if buried under several inches of bottom in summer. Quahaugs are 

 inactive at low temps. In May 1939 when water temp was 10°C clams left on 

 the surface of the sea bottom did not bury for several days. In midsummer 

 they disappeared from view in less than 1 hr. In Bideford River spawning in 

 1939 and 1940 was in late June and early July at a bottom temp of 23°C and 

 continued until Sept. In 1939, length of free-swimming period was about 12 

 days. A single-thread byssus is used for attachment of small clams under 10 

 mm long. Growth rates in Canada are slow. Five yrs or longer are needed to 

 reach minimum legal length of 1 3/4 in. Clams up to 2 5 yrs old are found 

 frequently. Commercial fishing is done with rakes from anchored dories or 

 with tongs. In intertidal zone clams are hand picked or taken by treading. 

 Heavy rakes and tongs damage clams, but they can survive considerable damage. 

 An experiment showed that clams with considerable pieces of shell broken away 

 to expose mantle did not survive. .When shells were cracked right across, or 

 valve edges chipped without exposing much mantle, breaks were filled in. 

 Growth was studied by notching shells. Fifty were planted in each of 8 beds 

 4x2 ft from near high water in hard sandy bottom to below low water in a 

 mixture of sand and mud. Some were planted in wire screen boxes sunk in the 

 bottom, but these became clogged with algae and growth was retarded. Growth 

 rings on external shell appear to be reliable indices of age. Lighter colored 

 new shell increased in width during summer. Clams late in summer had a final 

 band of lighter color of about the same width as previous bands. In general, 

 larger clams had narrower bands. Notched clams had lines on shells at the 

 position of the notch, but always fainter than annual lines. Similar 

 indefinite lines were seen between definite check marks, but check marks were 

 always distinguishable, especially at edges of shell. Some shells had so many 

 lines that age reading was difficult, but these made up less than 5% of all 

 clams. Large numbers of rings may have been caused by frequent disturbance by 

 oyster raking. Clams in harder bottom, where they would be less disturbed, 

 did not have such rings. Chief difficulty in reading age from lines was in 

 identifying first season's growth, because shell wore away near the umbo, and 

 because the first-formed shell inturned with increase in size. It was possible 

 to detect the check line produced at the end of the first growing season in 

 most cases when it became clear that the line was much nearer tip of umbo than 

 first expected. A light check line is produced on shell at the time of 

 notching. The most convenient dimension for measuring size of clams was 

 height (greatest distance from umbo to ventral margin) , but length and 

 thickness also were measured. Attempts to spawn quahaugs in the laboratory 

 were only partially successful. Quahaugs do not spawn in marked bursts like 

 oysters and mussels, but produce larvae gradually over a long period when 

 water temp is high enough. Thus it is not often possible to follow broods of 

 larvae in nature. In 1939 about 70% of the season's growth was between 13 

 July and 6 Sept. There was no evidence that salinity limited growth on 

 Bideford River beds. During most of the growing season salinity fluctuations 

 there are usually slight. The same is true for Tatamagouche Bay. Bideford 

 growing season is short. Usually there is no growth before 1 June and little 

 if any after 15 Sept in either of 2 study areas. Growth rate is not 

 controlled by temp alone; other factors are operative. Growing season is 

 limited by min bottom temp of about 10°C. In Bideford River the area suitable 

 for good growth above low water is very small because tidal amplitude averages 

 only 3 ft. Intertidal zone is exposed for long times at low spring tides. In 

 Tatamagouche tidal amplitude is about 8 ft and exposure on low spring tides is 

 much shorter, therefore growth is good over wide areas of the extensive 

 intertidal zone. In Bideford River growth below low water is not influenced 

 by depth up to 10 ft deep. Growth rate is much reduced in eelgrass, and 



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