Food and Growth of Fishes.: I. A Growth Curve Derived from Experimental Data

Abstract

A general equation for growth of fishes is obtained through use of the relations among body weight, metabolic rate, and growth efficiency that have been found in laboratory experiments. The curves show an early inflection point and gradually decreasing growth rate thereafter, without a theoretical asymptote. When growth efficiency is constant this equation indicates that growth becomes nearly exponential and is fitted exactly by the Parker and Larkin (1959) equation. When growth efficiency decreases with increasing rations the curves become more complex, as described here.Growth curves having an asymptote, such as the von Bertalanffy curve, have often been fitted to growth data. When the estimated asymptote can be related to the inflection point of the early part of a growth phase, it is proportional to a physiological time scale suggested by the food–growth relations. Truly asymptotic growth would appear to result only from complex changes in metabolism, growth efficiency, or interactions with mortality of the sort suggested by Lee's phenomenon.Some consequences of these results of food–growth experiments are discussed in relation to studies of biological productivity, especially their bearing on objectives of fisheries management. They suggest that, in general, highest sustained yield from a particular growth phase or stanza is obtained from a type of cropping which results in a population of fish having an average size near that of the smallest fish in the stanza.