Food and Fattening of Oysters¹

Abstract

THE material eaten by an oyster consists of minute organisms and other matter floating freely in the water, and present in the surface soil on which oysters occur. Mr. R. E. Savage has studied qualitatively and quantitatively the contents of the stomachs of oysters in relation only to the organisms and material found floating near the bottom of the sea in two localities, namely, the Main Channels of the River Ore in Suffolk and the adjacent Butley Creek. These situations were chosen because there was reason to believe that oysters fattened much more readily in the Creek than in the Channels. Data were obtained by exhausting the alimentary canals of usually six oysters once a month and taking one ten-minute sample of plankton from each bed once a month for a period of 13 months. From his restricted material, the author has extracted highly interesting facts and results, but the value of the latter is diminished by the absence of continuous contributory—and not necessarily quantitative—observations on the beds. In any estuarine problem the influence of tide and time should not be ignored. The author found that the material ingested by the oysters in the localities examined consisted of 90 per cent, or more inanimate matter (“organic detritus”), and a searching volumetric and numerical analysis of the animate food is given. He also finds that the feeding period extended from July to October or November, with a short season of brisk feeding during August and September, and that in the remainder of the year little food was found. The suggestion adopted that the absence of feeding in winter may be due to the effect of low temperatures on the ciliary and muscular feeding mechanisms is well worth definite examination. There was a definite difference in the quality and quantity of the animate food in the situations chosen.