Effect of Initial Size on Daily Growth and Survival in Freshwater Chondrostoma Nasus Larvae: A Field Survey

Effects of initial size on the growth and survival of a freshwater fish, Chondrostoma nasus, were tested in a field survey, where individually tagged larvae were introduced into a potential nursery habitat. Characteristics of individual daily growth trajectories were utilized as a basis to explain growth, as well as survival patterns, in relation to ontogeny. Initial size only affected growth rates during the larval phase. Survival patterns could not be explained solely based on size-selective mortality processes because prey-predator interactions played a major role as well. This is confirmed by the Lande-Arnold selection model because directional, as well as stabilizing gradients, showed significant values. Thus, for the 0+ year freshwater fish, inherited size-specific effects were a significant advantage for growth performance and survival in early ontogeny. As fish grew older, however, other effects such as compensatory growth and prey-predator interactions apparently gained in importance.