Nutritional Sustainability of California (Zalophus californianus) and Steller Sea Lion (Eumetopias jubatus) Diets Under Future Climate Conditions

Abstract

Marine species’ distributions are predicted to shift due to rising ocean temperatures under climate change. The bottom-up control of prey species on sea lions under future climate conditions is an important factor to consider when evaluating their populations and the entire Pacific oceanic ecosystem. This study utilized the program AquaMaps to develop species distribution models of California and Steller sea lions (Zalophus californianus and Eumetopias jubatus, respectively) and their common prey items under the predicted climate scenario for 2050 to determine how their diets may be affected by changing prey distribution. Additionally, the nutritional compositions of commercially available prey were analyzed to understand the impacts that a dietary shift may have on meeting the sea lions’ nutritional needs. Results suggest that while common prey items may remain available in the future, more energetically dense options such as Pacific jack mackerel, Pacific salmon, and Pacific sardine could increase in importance in the diet of both sea lion species, especially as currently predominant prey becomes less available at the furthest extents of their ranges. The results inform not only actions that may need to be taken in their native habitats to maintain steady populations, but also in the zoos that maintain these animals as species ambassadors.