Abstract
Traditional coarse-scale analyses of population dynamics assume that individuals in a cohort experience identical densities. Yet, juvenile density is commonly influenced by the mother's decision on the spatial location of reproduction. Thus, behavioral decisions taken during reproduction may induce spatial variation in intensity of density dependence, and ultimately the productivity of populations. Furthermore, reproductive behavior determines the habitat characteristics of emerging juveniles and depending on dispersal abilities the availability of suitable habitats. Thus, there is a clear requirement for further advances in our understanding of how maternal behavior may influence population productivity through effects on both abiotic and biotic environments experienced by the resulting juveniles. In the present project we will quantify how spatial decisions taken by Atlantic salmon mothers during reproduction influence variation in reproductive success, and how the sum of such decisions within a population influences its productivity. More specifically, we will use studies of natural populations to test how productivity may vary among populations and within populations over time relative to the spatial dispersion of spawners. Furthermore, we will test how the distribution of spawners relates to availability of breeding habitats and population density and if there is selection against spatial aggregation during breeding. Finally, we will examine how the total amount and the spatial distribution (relative to breeding grounds) of a potentially limiting juvenile resource (shelters) influence productivity. These studies complement smaller scale experimental work that has focused on causal mechanisms, and will give broader insights into how important these issues are for productivity of natural Atlantic salmon populations.
Norway