1251 



Matthiessen, G. C, and R. C. Toner. 1963. 



A study of the marine resources of Barnstable County, Massachusetts. Marine 

 Research Found., Inc., Edgartown, Mass., 31 p. + figs. 



In the past decade (1950s) , Mercenaria msvcenaria was second by value among 

 shellfish resources of the County, accounting for 38% of total landed value 

 of shellfishes. Production in pounds of meats dropped from about 1.0 million 

 pounds in 1907 to about 0.78 million in 1960, a 26% decrease. An increase in 

 "casual" fishermen and natural fluctuations in abundance may account for the 

 decrease. Principal "problems of the shellfish industry were: 1) minimal 

 attention to resource management and improvement; 2) resistance to private 

 planting; 3) effects of dredging and filling; 4) water pollution; and 5) 

 large and increasing harvest by summer visitors. It was recommended that 

 the State establish a shellfish propagation center for mass production of 

 important species, including hard clam; an adequate research facility; and 

 conduct studies of estuarine circulation. - J.L.M. 



1252 



Matthiessen, G. C, and R. C. Toner. 1966. 



Possible methods for improving the shellfish industry of Martha's Vineyard, 

 Duke's County, Massachusetts. Marine Research Foundation Inc., Edgartown, 

 Mass ., 138 p. 



Section 1 treats in some detail the techniques of plankton culture and 

 problems. Most desirable food species for Ueraenaria mevaenavia are 2 

 flagellates, Monochrysis lutheri- and Isochrysis galbana. Section 2 deals 

 with conditioning adults for spawning. It is not uncommon to find mature 

 sperm and eggs in quahogs at any time of year. They do not absorb 

 undischarged gametes. In early spring they can be brought directly from 

 the natural environment and induced to spawn without prior conditioning. 

 In the laboratory, temp for normal development of larvae ranges from 17.5 

 to 32.5°C. Growth is fastest at higher temps. Use of M. lutheri and 

 I. galbana as food precludes higher temps, for these species will not 

 tolerate temps much above 27°C. Optimum density of these food organisms 

 is 10 5 cells/ml at larval concentrations of 10/ml. Sea water was filtered, 

 warmed, and stored in a tank for gravity flow to the culture room. Larvae 

 were reared in 24 gal (90 1) plastic refuse containers with lids. Water 

 temp was maintained at 27 °C by holding containers in a constant temp bath. 

 Water was changed daily; larvae were siphoned onto a stainless steel screen. 

 Larvae were not disturbed until 2 days after fertilization, when they were 

 capable of feeding and had fully formed shells. Only batches with 50% 

 survival from fertilized egg were retained for culture. In addition to the 

 2 flagellates mentioned, quahog larvae lived and grew on a diet of the 

 diatom Cyolotella nana, which was the chief component of blooms in Great 

 South Bay and Moriches Bay, N.Y. in 1958. Optimum density for culturing 

 quahog larvae to metamorphosis is 2.5 to 5 larvae/ml. Quahog larvae are 

 easier to culture than oyster because they are less selective of food and 

 larval life is shorter. Quahog larvae are not hindered in feeding when 

 food is 10 to 12 times as concentrated as in nature. For juveniles a 

 density of 24 clams/in^ was not excessive for culturing up to a length of 

 5 mm; survival was 87% but growth was slow at temps used (16-20°C) . At 

 higher temps (22-29°C) rate of growth nearly doubled but survival was poor 

 because large numbers of Vortioella interfered. Growth of Vortioella might 

 be reduced by eliminating direct sunlight, and forceful spraying of quahogs. 

 Culturing large numbers of quahogs, approximately 2 mm long, at a density 

 of 41/in2 is feasible. Improvements in size and shape of culture vessels 

 are worth investigation. In summer 1963 quahogs 1/4 to 1/2 mm long were 



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