SCALLOP IXDUSTRY OF NORTH CAROLINA 181 



The oyster drill (Urosalpinx) is named by Beldinsx as one of the 

 principal enemies of the .scallop. Comparatively little evidence of 

 destruction by this form has been noted in North Carolina. Tlirough 

 a laroe portion of the scallop-producing areas it is distinctly un- 

 common. Large gastropods destroy commercial bivalves but are 

 relatively harmless to the scallop because of the latter's quickness and 

 swinuning ability. 



Ducks and other water birds sometimes are destructive of small 

 scallops. "Whether this destruction is ever serious in North Caro- 

 lina is not known. One bird, the herring gull, destroys many large 

 scallops, which it catches at low tide. The scallop is cracked open 

 by being dropped from a considerable height onto the beach. From 

 fall to spring it is a common sight to see herring gulls in flocks wait- 

 ing over the scallop beds or busily catching and cracking them 

 when the water over the flats has become sufficiently shallow. 



Scallop embryos and larvse are preyed upon by the usual predatory 

 microscopic forms associated Avith them and by plankton feeders. 

 Destruction by enemies presumably is much greater in these stages 

 than later, but is unavoidable, unless in artificial culture. 



It is probable that .some fish are somewhat destructive of small 

 juvenile scallops, but the principal enemy of the bay scallop is man. 



Destructive agencies other than enemies are freshets and cold. 

 Heavy freshets may be very destructive. Severe cold weather, es- 

 pecially if accompanied by low ebb tides, sometimes does much 

 damage. Trade wastes or heavy sewage discharges are not yet 

 serious factors in destruction in North Carolina scallop w^aters. 



FOOD VALUE 



Because only the adductor muscle is eaten, the nutritive proper- 

 ties of scallops ditfer considerably from those of oysters and claiiis. 

 Protein content is higher — more than twice as high as that of oysters 

 and the highest of any of the food mollusks of real commercial im- 

 portance in this country. The content of glycogen or '' animal 

 starch " generally is good, about equal to that of oysters. Fats, never 

 prominent in bivalves, are very low in analyse.s of scallops. Many 

 substances present in small amounts in various parts of the body, 

 including vitamins, are lost with the parts discarded. 



The accompanying table of analyses by Atwater and Bryant is 

 taken from Marine Products of Connnerce (Tressler). The total 

 solids content is thus seen to vary from 17 2 j)er cent to 22.2 

 per cent and to average 19.7 per cent, Avhich probably is fairly rep- 

 resentative for North Carolina scallops. However, a great decrease 

 in salinity may be accompanied by a decrease in total solids to 

 about 14 per cent. Examination of the table shows that on a dry 

 basis the protein content varies from about 65 per cent to about 90 

 per cent and averages 75 per cent. Thi.s abundance of protein makes 

 the relative gh^cogen content (excellent on a wet basis and indica- 

 tive of the food value to the consumer) low. On the assumption 

 that substantially all the carbohydrate content is glycogen it works 

 cut at about 5 to 25 per cent, with an average of 17 per cent. 



