Early development and survival in brown trout (Salmo trutta fario L.):: indirect effects of selection for growth rate and estimation of genetic parameters

Some components of the response to selection for growth in the PROSPER program on brown trout (Salmo trutta fario L.) (+30% in three generations) were investigated. A correlated response on growth during yolk-sac resorption was looked for, and we estimated the genetic parameters on growth-related traits at the end of endogenous feeding. For this purpose, a diallel cross between selected and control fish was designed, including 200 full-sib families (20 males X 10 females), each of them being represented by four individually recorded fish. A positive-correlated effect of selection was seen on survival and percent weight gain at swim-up, and a negative one was shown on dry weight and dry matter content. No effect was seen on final wet weight. A putative interpretation is that selected individuals have a higher development rate, inducing a higher consumption of yolk reserves by the end of the experiment, and therefore, a decrease in wet weight, dry weight and dry matter content. Significant sire heritabilities were seen for final wet weight and percent weight gain (h(s)(2) = 0.28 +/- 0.13 in both cases). For all traits except percent weight gain, maternal effects were strong, and an important part of them was related to the initial weight of eggs. Significant dominance effects were reported for wet weight, dry weight and percent weight gain. (C) 2002 Elsevier Science B.V. All rights reserved.