245 



Campbell, Robert. 1967. 



A report on the shellfish resources of Raritan Bay, New Jersey. In Proc . 

 Conf. on Pollution of Earitan Bay and Adjacent Interstate Waters, 3rd Sess., 

 Fed. Water Poll. Control Adm. , N.Y., App. A: 653-681. 



This report describes distribution of 2 clam species, Mercenaria mercenaria 

 and Mya arenaria. Prior to this study adequate information on hard clam 

 distribution and abundance was available only for N.J. waters. Information 

 on clams in N.Y. parts of the Bay came from hearsay and assumptions. 

 Samples were taken with a clamshell bucket which covered a bottom area of 

 about 5 ft and dug to a maximum depth of 18 in. In shallower areas samples 

 were taken with hand tongs. Size groups of clams were: "sub-legals" 15 to 

 46 mm long; "necks" 47-66 mm; and "large" over 66 mm. Charts illustrate 

 distribution and density of the three size groups. The boundary between the 

 2 states runs roughly east and west, with N.Y. waters to the north. In 

 general, distribution of hard clams was more even on the New York side, 

 spottier south of the line. The N.Y. sector was far more widely covered 

 with hard clams. General distribution patterns, particularly of "sub-legals", 

 were irregular and were attributed to variations in setting and other factors. 

 Average density of hard clams was 1.05 clams/ft^ in N.Y., 0.47 in N.J. In 

 N.Y. large sizes were 3 times as abundant as necks, in N.J. the two were 

 about equal in abundance. The sub-legal group was least abundant of the 3 

 categories in both states. Total population estimates were made by assuming 

 that "large" size represented 250 clams/bu, "neck" size 850/bu. Total 

 standing crop estimates were: necks- N.Y. 291,200 bu, N.J. 353,000 bu; 

 large - N.Y. 3,153,000 bu, N.J. 1,040,000 bu. - J.L.M. 



246 



Canario, Manuel T., Jr. 1964. 



Rhode Island depuration study. In Proc. 5th Natl. Shellf. Sanitation 

 Workshop, U.S. Dept. Health, Educ . , and Welfare, Appendix I: 99-100. 



Since 19 55, when a peak production of 5,0 20,0 00 pounds were harvested, there 

 has been a gradual decline in amount harvested and in number of diggers, in 

 Rhode Island. Two major areas are closed to shellfish harvesting by pollu- 

 tion. It was estimated that 500,000 bu of quahaugs are in the Providence 

 River area, and 400,000 bushels in Mt. Hope Bay. Some difficulties were 

 encountered with depuration, but it is believed that such purification as 

 is going to take place will occur in the first 24 hrs . The ultraviolet 

 system of water recirculation is a practical method of purifying hard clam. 

 - J.L.M. 



247 



Canzonier, Walter J. 1969. 



Recent studies of hard clam activity and depuration. Proc. Natl. Shellf. 

 Assn. 59:1 (abstract). 



Hard clams were exposed to phage particles in running seawater for 7-18 days 

 at levels of 5-9 particles per mi. . Pooled samples showed clams concentrated 

 particles 10-20 times seawater levels. Some individuals assayed at 50 times 

 the concentration of the seawater. At higher levels (10 3 -10^ particles/m£) 

 titre in clams did not exceed titre in seawater. Clams exposed for 24 hours 

 exhibited no differences in patterns or rates of depuration compared with 

 clams exposed longer. Clams exposed to 90-140 particles/mS. of clam tissue 

 rid themselves of 90% of their viral load, but 10-80% of clams sampled re- 

 mained positive up to 12 days after depuration began. Experiments using 

 E. coli as pollutant had depuration in 12-24 hours. Possibly some viral 

 particles are sequestered and protected outside lumen by adsorption or mi- 

 gration between cells or by phagocytosis by clam leucocytes. - D.L. 



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