In this study, the authors determine the data (dynamics and productivity in carrageenins) which are necessary to the rational management of the C. crispus populations. In the first part, they study the growth of the individual and of the population and the parameters which condition the population evolution. In the second part, they determine the seasonal fluctuations in different carrageenins and the influence of physiological factors. In the third part, they integrate the results to attain a synoptic view of the population states.