Dancing With Grunion: Not A Myth!

Male and female grunion perform an age-old dance on a dark, sandy beach

Along Southern California’s sandy beaches, one of the most remarkable life cycles in the sea is once again in full swing: the California grunion have come ashore to spawn. Grunion runs have been enjoyed by Southern California residents for more than 100 years, but there are still those who are skeptical of their existence. To be invited out in the middle of the night to go “dancing with grunion” does sound a little ridiculous, but in reality it’s the only way to experience this natural phenomenon.

Grunion Spawning and Abundance

The California grunion (Leuresthes tenuis) is a small (up to 7½ inches long), torpedo-shaped fish with blue-green coloring on its upper half and a shimmery silver coloring below. They are found in the surf and in the shallow, near-shore ocean and bay waters of the eastern Pacific Ocean, and normally spawn between March and August each year.

The usual range for grunion extends from Point Conception, California to Point Abreojos, Baja California. Occasionally, they are found in California bays north of Point Conception, and farther south to San Juanico Bay, Baja California.

Grunion are unique in that they are the only fish in California that “surf” the waves up onto sandy beaches where they lay their eggs in wet sand, completely out of the water. After incubating in the sand for about 10 days, the eggs hatch during the next high tide event and the young fish swim out to sea.

In the past, American Indians used grunion, which they called sai sai, for food. Today, human interactions with grunion consist mostly of observing this exciting spawning ritual, rather than capturing them for food. These beautifully colored fish seem to have charmed their way into the hearts of those who have observed their unique spawning behavior, which is now a part of the California beach culture.

Orange grunion eggs (upper right) at a disturbed nesting site

Grunion populations in California are not as abundant as they once were, because their primary spawning habitat (flat, wide areas of sandy intertidal beach) has been reduced by coastal development, sea walls, and erosion. They are also vulnerable during spawning, when the incubating eggs are subject to human disturbance including recreational activities, beach grooming, water pollution, beach sand replenishment projects, vehicle operation, and grading operations that create unnatural beach slopes. These human activities negatively impact adult grunion and their eggs and nests.

The California Department of Fish and Wildlife (CDFW) recommends that people take conservation measures that minimize impacts and disturbances to spawning grunion, eggs, and nests, such as avoiding beach construction activities during the spawning season. Grunion abundance can also be affected by oceanographic conditions (El Niño or La Niña ocean regimes) that may cause unfavorable ocean temperatures or nutrient levels.

Tips for Grunion Observation and Conservation

  • The 2015 grunion run schedule (which lists predicted times and dates for grunion spawning runs from March through August), fishing regulations, and life history information can be found on the CDFW website.
  • Grunion may appear sooner or later than the predicted run times, so stick around for at least an hour before giving up.
  • Grunion may start spawning later in the season on Ventura and Santa Barbara beaches.
  • Wasting fish is illegal, and fish removed from the population will not contribute to future generations. Consider practicing “Observe and Conserve” rather than hunting the fish.
  • No fishing gear is ever allowed to take grunion. Use your hands only to catch grunion in the open season, and do not dig pits in the sand to entrap them, which is illegal. If you catch any grunion, consider handling them gently and then releasing the fish unharmed. Grunion don’t die after spawning–the same fish will spawn more than once if gently handled and released, and may come back to greet future observers.
  • To help conserve grunion populations, don’t disturb the females depositing eggs tail-first in the sand, and don’t disturb the incubating eggs.
  • It may be best to leave dogs at home for wildlife viewing, as dogs will likely scare fish and birds.
  • To help eliminate the harmful effects to fish, birds, and other creatures, please respect the coastal environment while observing grunion runs and avoid leaving garbage on the beach.
  • Do not take or pursue spawning grunion during the closed season of April and May. “Take” means to hunt, pursue, catch, capture, or kill the fish, or to attempt to hunt, pursue, catch, capture, or kill them.
  • During open grunion season, make sure you possess a valid sport fishing license if you are over sixteen and plan to catch grunion.
  • If you plan to take grunion during the open season, review the California sport fishing regulations, including information about marine protected areas (MPAs). Take of grunion may not be allowed in some MPAs. For example, in state marine reserves (a type of MPA with the highest level of protection) take is not allowed during the open grunion season. Spawning grunion can still be observed (without handling the fish) in marine reserves, but no take is allowed there. CDFW produces guides and brochures that provide the locations and regulations for all California MPAs–more information is available on CDFW’s MPA website.

More grunion observation tips and other information can be found on CDFW’s The Amazing Grunion web page, and at www.grunion.org.

post by Loni Adams, CDFW Environmental Scientist    CDFW photos by L. Adams