As the Columbus Zoo and Aquarium (CZA) prepares to acquire California sea lions (CSL), CZA and The Ohio State University have partnered to conduct a long-term welfare assessment of the focal population in response to relocation from temporary facilities in Myakka City, FL to a permanent habitat at CZA. The project phase presented here aimed to establish baseline measures of hair cortisol concentrations and behavior whilst the sea lions were housed at their temporary facility. Data were analyzed using generalized liner mixed models. Results indicated mean hair cortisol concentrations changed significantly across time periods (p = 0.0152) but found no effect of sex (p = 0.7888), and age was significant only between juvenile and adults (p = 0.0430). Additionally, training staff was significant with hair cortisol concentrations (p = 0.0295). Analysis of behavior through odds ratios indicated that time period (p < 0.0001) and training staff (p < 0.0001) significantly impacted the likelihood of performing inactive behaviors over active behaviors, while sex (p = 0.3865) had no effect. Our results suggest time period and change in training staff were primary predictor variables of both behavior and hair cortisol concentrations. These findings will allow for comparisons to be made against post-relocation measures to assess the impact of relocation on the welfare of zoo-housed animals. We aim to present the studyâ€™s findings to-date and review methodology for upcoming phases. This unique opportunity for a long-term study will contribute to the growing body of literature on marine mammal behavior and welfare in human-care.