Growth and Production of Mussels Mytilus edulis from Two Populations

Gompertz growth curves for Mytilus edulis (L.) from two populations were derived from size-class analysis.By the incorporation of time and temperature as day-degrees, and of the results of length/dry weight regressions, estimates were made of seasonal changes in weight, and of fecundity as mantle weight loss on spawning.The results agreed well with independent estimates of growth made by integrating the results of physiological measurements of energy balance.Differences between production estimates for individual mussels at the two sites are discussed and related to various physiological differences, chiefly the seasonal pattern of the efficiency of absorption of energy from the ingested ration.Somatic production is shown to be similarly dependent on temperature in both populations, but seasonally abnormal temperatures and a reduced quality of available food at one site caused a marked reduction in the production of gametes.