Grunions: See How They Run

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This article is a part of the NASA DEVELOP’s Summer 2017 Virtual Poster Session. For more articles like these, click here

Project Team: Southern California Oceans

Team Location: NASA Jet Propulsion Laboratory ‰ÛÒ Pasadena, California

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Lael Wakamatsu

Sol Kim

Ariana Nickmeyer


Benjamin Holt (NASA Jet Propulsion Laboratory, California Institute of Technology)

Chelle Gentemann (NASA Jet Propulsion Laboratory, California Institute of Technology)

Vardis Tsontos (NASA Jet Propulsion Laboratory, California Institute of Technology)

April 2016 sea surface temperature anomaly for 2002-2017 April climatology, off the California coast. Image Credit: Southern California Oceans Team


The California grunion is an endemic fish species vital to the California coast, acting as a versatile food source for many species such as seabirds, large mammals, and other fish in the food web. This species, known primarily for the unique way in which they spawn, have two specialized regions. Historically, they only occur in Southern California and northern Baja California and are vulnerable to air and ocean temperature changes. In the last 16 years, scientists recorded grunion spawning further north to the San Francisco Bay area. In response to air and ocean temperature increases, the fish migrate to cooler waters they are more adapted to. This is an issue since the grunion found here are much smaller in size, indicating the north coast may not be as suitable for the species. Increased beach activity, beach cleaning practices, and coastal erosion significantly contribute to the decrease in population and the significant shift of spawning areas. This project, in collaboration with the Grunion Greeters Project, used Aqua MODIS satellite data for sea surface temperature (SST) and chlorophyll-a concentration to create a time series of the California coast from 2002 to 2017. Analyzing this product will help predict grunion spawning areas and can be used to develop beneficial management practices as well as establish new protective areas to keep the species thriving and safe.

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