Abstract

Data on reproductive traits in a cultured population of brown trout (Salmo trutta L.) in southern Chile were collected over three consecutive reproductive seasons: 1999, 2000 and 2001, corresponding to the first (at 3 years), second and third spawnings in females. Data were collected from individual females (n = 238, 273 and 169 respectively). The reproductive season lasted mainly from June to August. The peak (July) tended to increase with each season (55.46%, 62.27% and 80.81% of total spawning fish respectively). Female body weight (470.8 ± 102.5, 735.0 ± 150 and 1263.9 ± 263.4 g), total fecundity (1182 ± 344,1904 ± 595 and 2744 ± 605) and egg diameter (4.64 ± 0.11, 4.67 ± 0.27 and 5.24 ± 0.12 mm) increased significantly (P < 0.01) over successive reproductive seasons, particularly between the second and third spawnings. Relative fecundity, on the other hand, decreased significantly with each season (3577 ± 471, 2591 ± 900 and 2181 ± 360). Following analysis of the variables over the three seasons, the correlation pattern of female body weight with total fecundity (r = 0.91, n = 458; P < 0.001) and relative fecundity (r = -034, n = 451; P < 0.001) proved similar to that described in other salmonid females. Fertilization rate and survival to the eyed egg stage were also positively correlated (r = 0.73, n = 453; P < 0.001). The systematically high values obtained for these latter variables over the seasons evaluated (consistently above 90%) are clearly greater than those we registered in other species of salmonids bred in Chile under similar conditions and suggest highly efficient biological variables that determine the gamete fertilization of this species. The brown trout is, therefore, an interesting potential aquaculture resource in Chile.