UC Santa Barbara

Marine aquaculture is the most rapidly growing food sector and has great potential for expansion as part of a sustainable vision for seafood production in the future. Marine spatial planning for aquaculture is crucial to identify the best areas for productivity and profitability and to avoid conflict with other uses of the space. Given that climate change will likely change the answers to these spatial planning questions, effective marine spatial plans for aquaculture must assess expected changes and identify efficient adaptation strategies. To this end, we propose a novel approach to define climate change responsive marine spatial planning of aquaculture. We use the Southern California Bight (SCB) as a case study. First, we focus on understanding the effects of interannual variability over site selection. In Chapters I and II, we use a historical reanalysis of environmental data to run aquaculture models of Mediterranean mussels, striped bass and giant kelp (mussels, fish, and kelp). We use empirical orthogonal functions and principal component analysis to identify spatial and temporal patterns of variability. We found that decadal variability has significant impacts on the productivity and profitability of farms. The different farmed species had quite different responses. Mussels had good productivity regions spread along the coast with the highest productivity in the northern region. By contrast, fish had highest productivity sites in the south given warmer temperatures, but differences among southern sites were small. Kelp production is limited to the northern-most region and productivity differences among sites were striking. Finally in Chapter III, we look to the future and incorporate climate projections up to year 2100 to understand the effects of future climate change on site selection for mussels, kelp, and fish species. Given that mean conditions and interannual variance are both relevant components of climate, we analyzed both effects on future aquaculture productivity. Variability in production is projected to be most striking for kelp, followed by mussels. Fish production actually benefits from warming temperatures, and the increasing trend in the mean predominates over interannual variability. General lessons from historical records and future forecasts suggest that kelp and mussels are more prone to variability given their dependence on nutrients and plankton controlled by ocean conditions. By contrast, since fish are fed in aquaculture, the long term trend in temperature is the biggest driver of fish production. Ignoring variability, therefore, might have greater consequences for the profitable siting of kelp and mussel farms. Monitoring systems are valuable to both characterize productivity variation and to enhance the empirical foundation for better forecasts that can help create climate resilient marine spatial planning. Our results show that spatial patterns of productivity remain consistent despite growing climate variability and climate change until optimal thresholds for growth are reached. Selection of species and sites resilient to current and upcoming environmental conditions are important steps in the planning process. Although this work focuses on a single coastline region, it provides an analytical framework that can be expanded to other regions of the globe to help design optimal adaptation strategies tailored to each region’s specific climate dynamics.