Variations in Size and Composition of Fish Populations in Recently Stocked Ponds

During the past decade or so fisheries biologists have used various terms when referring to the total weight of a fish population. Among those so used, productivity, fish production, carrying capicity, standing crops, yield and others have been prominent in the literature. In some instances terms which should imply different aspects of the dynamics of the population have been used synonomously. In others, obscure meanings have been inferred that have further confused an already difficult picture. More recently Clarke ('46) included ". . . All the ideas and measurements of productivity which have an ecological application, . . . under the following three fundamental concepts . . ." (1) standing crop, (2) material removed, and (3) production rate. For purposes of the present and related work the following definitions are proposed: 1. Productivity and production. The word productivity should be used as a general term following the proposal of Clarke. There it embraces all the concepts of the dynamics of production. Productivity is not merely the rate of production of organic material in a body of water as suggested by Riley ('40) and Lindeman ('41, '42). Rather, the rate of production is only one phase of productivity as outlined by Clarke. Further, Clarke wrote (p. 324) ". . . To avoid