Why do lake whitefish move long distances in Lake Huron? Bayesian variable selection of factors explaining fish movement distance

Understanding fish movement patterns is vital for stock assessment and fishery management. We used a variable selection procedure in a Bayesian framework to understand what factors most likely affect the net movement distance of individual fish based on a conventional tag-recovery study of lake whitefish populations in Lake Huron during 2003-2011, where fish of this species with spawning site fidelity were tagged during the spawning season and recovered throughout the year. We found that fish with greater total length, and those that were tagged and released from tagging sites near Cheboygan and Alpena, Michigan, moved longer net distances than fish from other tagging sites. Habitat conditions also had a profound effect on net movement distance. We found that shorter movement distances by lake whitefish can be expected if the relative density of the benthic amphipod Diporeia spp. was higher near the tagging site during the recovery year. We also found evidence that lake whitefish may start their annual spawning migration runs earlier during warmer years. More generally, our Bayesian framework for analysis of conventional tagging data has potential for wide applicability, and model details and our code are provided to facilitate this.