Genus Delectopecten Stewart 1920 



Delectopecten vitreus (Gmelin 1791). Vitreous scallop. Figure 

 41. 



Johnson (1934). La Rocque (1953). Morris (1973), and 

 Abbott (1974) reported the distribution of this species for U.S. 

 waters as ranging from Newfoundland and Nova Scotia to 

 Martha's Vineyard. Mass. In addition. Abbott (1974) stated 

 that it is also found in northern Europe and at Clipperton 

 Island in the eastern Pacific. Ockelmann (1958) listed the 

 Arctic distribution, Clarke (1962) listed the worldwide dis- 

 tribution, and Tebble (1966) listed the northern European 

 distribution for this species, he also mentioned the Indo- 

 Pacific as a site of habitation. 



This small, uncommon scallop is represented in the NEFC 

 collection by 12 specimens from 3 samples (Table 5). 



Our samples, two of which occurred at one sampling site, 

 are from the edge of the continental shelf off the Northeast 

 Peak of Georges Bank (Fig. 41 ; Theroux and Wigley footnote 

 4, table 68). 



The vitreous scallop is a deep water scallop, ranging in 

 depth from 28 to 4,258 m (Clarke 1962; Morris 1973). 



The depth range of our samples is 4 1 2 to 549 m with a mean 

 of 458 m. The 200-499 m depth range grouping contains 66% of 

 both samples and specimens ; the 500-999 m grouping contains 

 the remaining 33% of each (Table 116). 



Only one of our samples contains information regarding 

 sediment type, it was obtained in till and contained four 

 specimens (Table 117). The remaining two samples with eight 

 specimens are unclassified with regard to bottom sediments. 



of all specimens: these are from 164 samples accounting for 

 nearly 2% of the samples in the bivalve collection (Table 5). 



The NEFC samples are from the continental shelf in the 

 northeastern region around the periphery of the Gulf of 

 Maine, with large series of collections on the northeast peak 

 of Georges Bank, extending south over the Southern New 

 England Continental shelf into the Mid- Atlantic Bight region 

 south to approximately the mouth of Chesapeake Bay (Fig. 

 90; Theroux and Wigley footnote 4, table 155). 



This species inhabits the Boreal and Virginian provinces 

 (Coomans 1962; Gosner 1971). 



The depth range for the Atlantic deepsea scallop extends 

 from offshore to moderately deep waters which range be- 

 tween 6 and 183 m (Johnson 1934; Abbott 1968). 



Our samples are from depths which range from 36 to 293 m 

 of water with a mean of 96 m. The majority of both samples 

 and specimens are in the depth range groupings of the middle 

 shelf regions. Sixty percent of the samples and 62% of the 

 specimens are in the 50-99 m depth range grouping, while 31% 

 of the samples and 33% of the specimens are in the 100-199 m 

 grouping; significantly smaller amounts of both samples and 

 specimens are in the 25-49 and 200-499 m groupings (Table 

 118). 



Sea scallops were found in all sediment types considered in 

 this report with the exception of till. The majority of both 

 samples and specimens were obtained from sand substrates 

 where 39% of the samples and 30% of the specimens oc- 

 curred. Table 1 19 shows the distribution of both samples and 

 specimens with regard to the other sediment types. There are 

 66 samples containing 603 specimens which are unclassified 

 with regard to sediment type. 



Genus Placopecten Verrill 1897 



Genus Propeamussium Gregorio 1884 



Placopecten magellanicus (Gmelin 1791). Atlantic deepsea scal- 

 lop. Figure 90. 



Placopecten magellanicus is one of the most valuable com- 

 merical shellfish resources of the U.S. east coast, especially 

 in the northeast and middle Atlantic coastal regions, which in 

 1978 yielded approximately 3 1 million pounds of meats valued 

 at $76.4 million in the United States, while Canada's catch 

 was 26.7 million pounds (Pileggi and Thompson 1979). 



The natural history of this species has been well 

 documented in the literature, especially by investigators at 

 the NEFC where, for many years, an investigation of the sea 

 scallop fishery was active (see Merrill 1959b, 1960, 1961; 

 Merrill and Burch 1960: Merrill and Posgay 1964: Merrill et al. 

 1966: Posgay 1957. among others). There is also extensive 

 information from Canadian researchers. 



It must be pointed out that the dta for this species contained 

 in this report are solely based on collections which are cur- 

 rently, physically present in the NEFC collection. No data 

 from the extensive sea scallop data base here at NEFC have 

 been included in this analysis. 



The Atlantic deepsea scallop is distributed from New- 

 foundland to North Carolina with a questionable record from 

 Labrador (Johnson 1934: Morris 1951. 1973: La Rocque 1953: 

 Abbott 1968. 1974: Emerson et al. 1976. 



There are 1,225 specimens of the sea scallop in the NEFC 

 Specimen Reference Collection representing slightly over 1% 



Propeamussium thalassinum (Dall 1886). Figure 95. 



This species ranges from off Martha's Vineyard, Mass., to 

 the West Indies (Johnson 1934; Abbott 1974). 



There are 28 specimens from 6 samples of Propeamussium 

 thalassinum in the NEFC Specimen Reference Collection 

 (Table 5). 



Our samples are from the outer continental shelf and the 

 upper continental slope between Cape Cod. Mass., and 

 Atlantic City, N.J. (Fig. 95: Theroux and Wigley footnote 4, 

 table 168). 



Gosner ( 1971 ) placed Propeaumussium thalassinum in the 

 Virginian zoogeographic province. 



The depth range for this species as reported by Abbott 

 (1974) is 40 to 580 m. 



Our samples are from water depths which range between 84 

 and 201 m with a mean of 149 m. The 50-99 m depth range 

 grouping contains 17% of the samples and 7% of the spe- 

 cimens; the 100-199 m grouping contains 67% of the samples 

 and 50% of the specimens, and the 200-499 m grouping con- 

 tains 17% of the samples and 43% of the specimens (Table 

 120). 



Both gravel and sand sediments contained 25% of the sam- 

 ples, but 8 and 46%, respectively, for specimens, while silty 

 sand sediments contained 50% of the samples and 46% of the 

 specimens (Table 121). There are two samples containing two 

 specimens which are unclassified with regard to sediment 

 type. 



22 



