Grunion (Leuresthes tenuis) refers to two species of fish known for their unique and fascinating mating habits: the California grunion and the Gulf grunion.

 Found mainly along the Southern California coast in San Diego, Los Angeles, and Orange Counties, these sardine-sized, silver-colored fish are known for their nocturnal mating rituals. The females come ashore to lay their eggs in the sand, and the males fertilize them in a spectacular way under the full glare of the moon’s light.

However, despite grunion’s popularity, its existence is threatened by various human activities. We will talk about these threats in detail in this article. Besides, we will explore other essentials like the biology and behavior of the grunion and its importance in the ecosystem.


Grunions are small fish that grow up to 7 inches in length. They have a silvery color and a distinct, elongated body shape.

Grunion on the beach in San Diego, California, USA
Grunion on the beach in San Diego, California, USA

As you can see, their bodies are adapted for life in the ocean, with a streamlined shape and strong muscles that help them swim and avoid predators.


 Grunions are found along the coast of California and live in shallow waters near the shore. They prefer sandy beaches and sheltered bays, where they can lay their eggs in the sand. During the non-breeding season, they can be found offshore in deeper waters.


 Grunions are so small and lack teeth, so they typically feed on tiny plankton suspended in the ocean. They can also feed on small crustaceans and other microscopic organisms.

Their predators include pelicans and other birds, marine mammals, larger fish, sharks—anything that eats fish. So, grunions are essential to the marine food chain.


Grunions are known for their unique and fascinating mating habits. During high tide, the females come ashore and lay their eggs in the sand. The males then fertilize the eggs buried in the sand and left to incubate.

Grunion laying eggs
Grunion laying eggs

After about ten days or more, the eggs hatch, and the fry swim back into the ocean. This cycle is repeated several times annually and is essential for the species’ survival.


Grunions can live for three to four years. However, their existence is threatened by various human activities, including overfishing, habitat destruction, and pollution. The species is also vulnerable to the effects of climate change, including sea-level rise and ocean acidification.

Overfishing and the destruction of their habitats can lead to a decline in their populations, making them more susceptible to predation and disease.

Despite the challenges, conservation efforts are underway to protect the grunion and its habitats. The California Department of Fish and Wildlife has listed the fish as a species of particular concern, and regulations have been implemented to protect their populations.

According to an official notice that became effective on June 1, 2022, you must acquire a California fishing license to catch grunion. Only individuals aged 16 years and above can successfully apply for it. During the open fishing season, you can use it to take the fish by your hands. It’s an offense to dig holes on the beach to entrap them.

A person taking grunion by the hand according to the law
A person taking grunion by the hand according to the law

In addition, conservation organizations are working to educate the public about the importance of these fascinating fish and their role in the ocean’s ecosystem.

Facts about Grunion

  1. Grunions are small, silvery-colored fish found along the coast of California.
  2. These animals live in shallow waters near the shore and prefer sandy beaches and sheltered bays.
  3. Grunions are omnivores and feed on small crustaceans, plankton, and other tiny organisms.
  4. Grunions engage in a unique mating ritual that takes place under the light of the full moon.
  5. Female grunions come ashore during high tide to lay their eggs in the sand while the males fertilize them.
  6. The grunion’s existence is threatened by overfishing, habitat destruction, pollution, and the effects of climate change.
  7. The California Department of Fish and Wildlife has listed grunions as a species of special concern.
  8. Grunions are a vital cultural and economic resource, playing a role in supporting the local economy through recreational fishing, ecotourism, and other activities.
  9. By protecting their habitats and conserving their populations, we can ensure that this remarkable species will continue to thrive for generations.


What is so unusual about grunion?

The grunion’s spawning behavior and egg survival are so unusual. They are fish but reproduce on land. During high tides in the spring and summer, female grunions come ashore to lay their eggs in the sand, and males follow closely behind to fertilize the eggs. Again, the eggs withstand the harsh conditions of the beach, giving us a reason to save our beaches.

Is a grunion a sardine?

No, a grunion is not a sardine. A grunion is a species of fish native to the Pacific coast of North America. At the same time, sardines are a group of small, oily fish found in the Atlantic, Pacific, and Indian Oceans. Sardines are commonly used for human consumption and are often canned for storage and transport. 

What is grunion dance?

The “grunion dance” is a term used to describe the spawning behavior of the grunion fish. This term is used due to how fish move and interact on the beach during this time. The grunion dance is a unique and fascinating natural phenomenon that has been the subject of scientific study and recreational interest for many years.

Where do you catch grunion?

Grunions are caught along the Pacific coast of North America, from Baja California to southern California. Regulations regarding the catch of grunions vary by state, so it is crucial to familiarize oneself with local laws before attempting to catch them. Some states allow for the harvest of a limited number of grunions during designated fishing seasons, while others prohibit the taking of grunions altogether.

What happens to the grunion eggs after they are fertilized?

After fertilizing grunion eggs on the beach during a high tide, they are left to incubate in the sand. Once they hatch, the small, newly-formed grunions return to the ocean to continue their development and growth. As the fish mature, they eventually return to the beach to lay their eggs and continue spawning.

Can grunion breathe air?

No, grunions cannot breathe air in the same sense as land animals. They are a species of fish, and, like other fish, they obtain oxygen from the water through their gills. So, whenever these fish come ashore to lay their eggs, they are essentially “stranded” on the beach and cannot breathe until they return to the water.

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