Dynamique des populations de poissons.

The author explains that the population dynamics study, descriptive and explicative way, the changes which happen in the structure and the parameters (growth rate, sex ratio, fecundity, mortality etc.) of a monospecific population, by the use of mathematical models which permit prediction and simulation. If the fish population is not exploited, it is necessary to sample it directly and obtain samples representative of the demographical structure by experimental fishing (like electrical fishing) or by selectivity corrections. If the population is exploited, often the exploited phasis of the stock is only studied from samples representative of the whole captures. Now it happens that there is an important difference between the demographical structure of the captures and the structure of the whole population because a part of the population is not always vulnerable to the gear and to the fishing techniques used. But the dynamics of the part of a stock really exploited merit a set apart study because this part is alone overcome to the direct influence of the fishery and because the fluctuations of this stock part have a practical and economical incidence.