Population-dynamics of brown trout (Salmo-trutta) in a breton stream (France) the non-migrant spawners | Dynamique de la population de truite commune (Salmo trutta) d'un ruisseau breton (France): les géniteurs sédentaires

English. Population dynamics of brown trout (Salmo trutta) in a breton stream (France): The non-migrant spawners. The biological factors of the population dynamic of brown trout in a tributary of the Scorff river, have been studied during 4 years. The characteristics of the spawners, present in the stream before the spawning migration from the main river, are described. These spawners were born in the stream and stayed there during their entire life-span. Among mature fish the sex ratio was always in favour of males. During the third and the fourth years of life, annual mortality rate was 70% for males and 50% for females. 1+ spawners were these which had the best 0+ growth rate. A majority of males first matured at 1+ years of age. On an average, 1+ females were responsible for 25% of the total reproductive potential. The number of 3+ and 4+ females seemed to depend on the fishing effort.

French. Population dynamics of brown trout (Salmo trutta) in a breton stream (France) : The non-migrant spawners. The biological factors of the population dynamic of brown trout in a tributary of the Scorff river, have been studied during 4 years . The characteristics of the spawners, present in the stream before the spawning migration from the main river, are described . These spawners were born in the stream and stayed there during their entire life-span . Among mature fish the sex ratio was always in favour of males . During the third and the fourth years of life, annual mortality rate was 70% for males and 50% for females . 1+ spawners were these which had the best 0+ growth rate. A majority of males first matured at 1 + years of age . On an average, 1 + females were responsible for 25 016 of the total reproductive potential . The number of 3 + and 4+ females seemed to depend on the fishing effort .