Predicting Grunion Migration Patterns and Spawning Areas in Response to Changes in California's Oceans by Coupling Satellite and In Situ Data

The California grunion (Leuresthes tenuis) is a species of fish endemic to the California coastline that plays an important role in the marine food chain as a consumer of zooplankton and a food source for larger marine creatures. Grunion spawning events documented over the last three decades in the San Francisco Bay suggest a pattern of northern migration caused by changes in ocean conditions and increased human beach activity. With little known about the movement of grunion populations, here we perform a large-scale analysis coupling satellite and in situ data to examine what factors along the coast of California may be forcing the species northward. Earth observation data products, including NASA Multi-scale Ultra-high Resolution Sea Surface Temperature (MUR SST) and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) chlorophyll-a (chl-a), were used to create time series of the California coastline and nearby Pacific Ocean from 2003 to 2018. Upwelling, sea surface current, air temperature, and harmful algal bloom (HAB) data were also considered to derive correlations between the above parameters and grunion spawning events. Analyzing how a changing ocean affects the California grunion will allow for more accurate predictive modeling of spawning behavior. Moreover, this research investigates how satellite data can be employed to reveal migration patterns of species that are difficult to track based on physical and biological oceanographic factors.