Impacts of Climate Change on Fish Spawning Aggregations

Water temperature sets the large-scale distribution of marine fishes, and the subset of a fish’s range over which adults spawn is often characterized by a more restricted set of temperatures than other life history stages. Climate change is likely to induce significant changes in spatial and temporal patterns of temperature, which in turn, are likely to alter the phenology and distribution of spawning in marine fishes.

Fish spawning aggregations (FSAs), in which all adults from the larger surrounding area migrate to specific locations at specific times to spawn, offer a unique opportunity to use empirical data to realistically model the impacts of climate change on spawning dynamics (both temporally and spatially) and examine the resulting implications for on ecosystem based management (EBM), fisheries, and food security. Using a robust, pre-existing database on the timing and location of FSAs for 12 ecologically and economically important species of groupers and snappers from the Caribbean and Indo-Pacific, this study proposes to combine Earth System Models and Ecological Niche Models to create the first projections of 21st century changes in the distribution and phenology of FSAs. Using these projections, the following questions will be addressed: (1) How may climate change affect the distribution, seasonal timing, and intensity of spawning? (2) How might the spatial scale of climate models, the model used to make projections, and greenhouse gas emissions scenarios affect projected changes in FSAs? (3) Will changes in FSAs act as a “bottleneck” constraining overall shifts in species distributions? (4) How might changes in the timing and distribution of spawning affect the spatial and temporal coincidence between larval fishes and zooplankton (i.e., the primary food for larvae)? (5) Are species with narrower temperature ranges likely to display larger shifts in distribution and phenology? (6) How do evolutionary history (i.e., snappers vs. groupers) and environment (i.e., Caribbean vs. Indo-Pacific) influence expected shifts in spawning under a warming climate?