Influence of Environmental Experience on Response of Yearling Rainbow Trout (Salmo gairdneri) to a Black and White Substrate

Yearling rainbow trout (Salmo garidneri) selected black substrate regardless of size or rearing experience when first introduced into an experimental tank offering a choice of black or white. Differences in the degree of black selection among the various lots of the same strain during the initial 120 min of exposure, under an illumination of 10−2 lx, were correlated only with the level of swimming activity. By 24 hr, only pond-rearsd fish continued to select black while laboratory-reared fish were randomly distributed over black and white. The continuing wariness of only the pond-reared fish reveals the long-term effect of prior experience on juvenile trout behavior. This finding indicates the possible feasibility of environmental conditioning for wariness in the artificial propagation of hatchery-reared fish for live release.