Multiple Tools and Conceptual Approaches for Evaluating Factors Affecting Fish Habitat Selection

Many empirical field studies in fish ecology identify spatial patterns of fish distribution and density, which are then related to measurements of the physicochemical habitat. Patterns in animal density can be informative in identifying the range of parameters that occupy the basic ecological niche of one or more species; however, these approaches are usually incomplete. Analyses may display high amounts of residual variation, or, more specifically, identify habitats that fall into the range of “ideal” parameters but are unoccupied or underused. Where this is the case, new ecological approaches are necessary.  These include incorporating behavioral and physiological ecology to examine mechanistic drivers of field distributions and densities or incorporation of intra-/interspecific interactions such as predation risk into models of habitat use. Alternatively, fitness correlates such as growth or survivorship can be measured or modeled to estimate the relative performance of individuals across multiple habitat types. Studies of this kind can confirm whether patterns of numerical abundance truly reflect optimal habitat selection patterns, provide insight to under-matching of high quality habitat in light of costs of habitat selection, or determine if life history traits shift in concert with the environment.  Field approaches based on foraging theory can identify the cost of interspecific interactions, particularly the cost of predation risk.  Individual-based models can also assist with pinpointing driving factors shaping fish population dynamics; ultimately, population-level responses emerge from a cumulative impact of individual behaviors.   Mechanistic modeling can provide predictions about future habitat selection decisions, given current food intake, current mortality risk, and a range of decision options that affect future fitness. We introduce these ideas and provide an outline and objectives for this symposium as a forum for discussion of approaches that lend further insight into species-habitat relationships in fish ecology.