Caitlin R Fong, Melanie Frazier, Gage Clawson, Haley Epperly, Halley E. Froehlich, Benjamin S. Halpern
Science of the Total Environment
Climate change threatens food production, yet gaps remain in our understanding of these threats to aquaculture, the fastest growing food production subsector. To build climate-resilient practices and policies we need to quantify and map current and future climate threats to aquaculture. Here, we explore how downscaled climate change [SSP 2 (eq. RCP 4.5) and SSP 5 (eq. RCP8.5), CMIP6] threats – including water scarcity, flooding, and increasing temperature – may directly affect United States (US) freshwater farmed fish (N = 7) based on their biological thermal tolerances and indirectly challenge the operations required for production, including to the human workforce. Aquaculture in the US is dominated by catfish, trout, and tilapia production and is widespread, with some form of finfish aquaculture present in every state and nearly half of all counties across the country. Given the current location of catfish, tilapia, bass, and carp in the US and their tolerance to warmer conditions, we find increasing temperatures are less likely to biologically impact these species negatively. In contrast, current trout, sturgeon, and perch production will be biologically threatened by rising temperatures. With respect to operational needs for facilities, increases in ‘wet bulb’ temperatures in the Southeast will regularly challenge human physiological limits and constrain worker capacity. Drought in the Southwest will also limit an intrinsically water dependent system, affecting nearly all taxa. While current areas of aquaculture will tend to become increasingly challenging for farmed fishes, new potential habitats will open up for nearly all species. Overall, in the absence of immediate greenhouse gas mitigation, there are several non-mutually exclusive climate adaptations, yet these adaptations can be extremely costly. Ultimately, freshwater aquaculture in the US is going to be under intense climate pressure, which may drive out small operations and cause the country to further increase dependence on international aquatic food imports.