Variability in performance in wild Atlantic Salmon, Salmo salar L., fry from a single redd

Dispersal and growth were studied in Atlantic salmon, Salmo salar L., fryfrom a natural isolated redd. The distribution of fry leaving the redd was stronglypeaked, 80% being caught within a 2-week period. Early in the dispersal period, all fryleaving the redd had remnants of yolk sac and had not fed; by half way through thedispersal period, no fry had any visible yolk, but 35% still had empty stomachs. Fryleaving the redd during the first half of the dispersal period tended to settle in differentfirst feeding sites than those dispersing later. Predation on fry by larger salmonids wasfrequent, especially during dispersal. Coefficients of variation for length, weight andcondition factor increased significantly over the study period and for individuallyrecognised fry, growth rates varied markedly. Thus, individual salmon fry differ inphysical status on emergence from the redd and these differences are amplified during thefirst few weeks after emergence.