An investigation of model transportability: Is thermal optical habitat area relevant to Canadian walleye

This thesis investigates the question of model transportability across space and across scale using a model developed by Lester et al. (2004). Lester et al. (2004) presented a new definition of preferred walleye habitat and defined it as the intersection of preferred thermal and optical conditions within the water column, termed "Thermal Optical Habitat Area" or TOHA. TOHA was incorporated into a model predicting walleye harvest for a group of Ontario lakes. Here, I test the predictive ability of the model by Lester et al. (2004), as well as the relevance of the TOHA term to walleye populations outside of Ontario. I also increase the scale of analysis from the individual lake to the tertiary watershed to assess the contribution of TOHA to predictive models at this scale. I found that Lester et al.'s model in its totality does not transport well to other locales, yet the TOHA term improves the accuracy of models predicting walleye occurrence at both the lake and tertiary watershed level.