Pismo Beach in San Luis Obispo County, California — The American West (Pacific Coastal)

History of Pismo Clams in California

Photographed by Denise Boose, January 30, 2023

1. History of Pismo Clams in California Marker

Inscription. Pismo clams (Tivela stultorum) were harvested by the millions on Pismo Beach and supported a thriving commercial and recreational fishery. Early clammers would use horse-drawn plows to find Pismo clams in the sand. From 1916 to the closure of the commercial fishery in 1947, an estimated 6.25 million pounds of Pismo clams were harvested in the state of California. The majority of these clams were harvested on Pismo Beach and surrounding areas. Annual harvests were nearly 100,000 pounds per year, with the highest harvest recorded at 665,700 pounds. While impressive, this level of harvest was unsustainable and commercial harvesting of Pismo clams was prohibited in 1947. Recreational harvesting of Pismo clams is still legal in California Department of Fish and Wildlife, however the last legal size clam was documented on Pismo Beach in 1993. Clams must bigger than 4.5 inches (114MM) south of the Monterey/San Luis Obispo county line and bigger than 5 inches (125 mm) north of the boundary to legally harvest.

Life History of Pismo Clams
Pismo clams are found on open, sandy beaches from Monterey, California to Baja, Mexico.

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They primarily live in the intertidal or the portion of the beach that is covered during high tide and exposed during low tide. Living in this surfy habitat allows the clams to fee on microscopic algae and detritus floating in the ocean. Having access to this high quality food allows Pismo clams to grow up to 20mm (3/4 inch) per year. Every year Pismo clams create growth rings within their shell, so we can tell how old a clam is by how many rings are in it’s shell. It takes 5 to 8 years for clams to reach a legally harvestable size (4.5/5inches) and the oldest Pismo clam was estimated at 53 years old.

As clams age they grow more slowly since they spend more energy on reproduction. Pismo clams are broadcast spawners, meaning they release eggs, sperm into the water, and fertilization occurs in the water column. It’s only by chance that a baby, larval Pismo clam is created in the ocean. Larval slams float in the ocean feeding and growing their first shell before they settle onto the beach they’ll live on for the rest of their lives.

In 2016 research began at nearby Cal Poly, funded by the City of Pismo Beach, to try to understand

Photographed by Denise Boose, January 30, 2023

2. History of Pismo Clams in California Marker

more about the populations of Pismo clams. This research found that occasionally small clams appear on our beach. If you find a Pismo clam on the beach, rebury it where you found it to help populations recovers.

Erected by City of Pismo Beach.

Topics. This historical marker is listed in this topic list: Natural Resources. A significant historical year for this entry is 1916.

Location. 35° 8.312′ N, 120° 38.642′ W. Marker is in Pismo Beach, California, in San Luis Obispo County. It is on 100 Pomeroy Ave, on the right when traveling south. Located on the Pismo Beach Pier near Pismo Beach Pier Plaza. Touch for map. Marker is at or near this postal address: 100 Pomeroy Ave, Pismo Beach CA 93449, United States of America. Touch for directions.

Regionally, this marker is on the Central Coast

and specifically on the Coast Ranges.

It is also on the American Pacific Coast.

Globally, it is in North America,

on the Ring of Fire,

on the Pacific Rim,

in the Western Hemisphere,

in the Western World,

and in the Anglosphere.

Historically, it finds itself in what was once New Spain

and also Mexico’s Alta California.

Other nearby markers. At

Photographed by Denise Boose, January 30, 2023

3. History of Pismo Clams in California Marker

least 8 other markers are within 2 miles of this marker, measured as the crow flies: The History of Pismo Beach Wharf and Pier (within shouting distance of this marker); Pismo Beach Pier Plaza (about 400 feet away, measured in a direct line); Armed Forces Memorial (about 400 feet away); Joe Rose Memorial Center (approx. 0.3 miles away); Lt. Colonel Juan Bautista de Anza (approx. 0.3 miles away); Mrs. Charis Lee Straw (approx. one mile away); Price Anniversary House (approx. one mile away); Dinosaur Caves Park (approx. 1.6 miles away). Touch for a list and map of all markers in Pismo Beach.

Photographed by Denise Boose, January 30, 2023

4. History of Pismo Clams in California Marker

Photographed by Denise Boose, January 30, 2023

5. History of Pismo Clams in California Marker

Photographed by Adam Margolis, June 1, 2026

6. History of Pismo Clams in California Marker

Credits. This page was last revised on October 6, 2026. It was originally submitted on June 8, 2023, by Denise Boose of Tehachapi, California. This page has been viewed 828 times since then and 137 times this year. Photos: 1, 2, 3, 4, 5. submitted on June 8, 2023, by Denise Boose of Tehachapi, California. 6. submitted on September 30, 2026, by Adam Margolis of Mission Viejo, California. • Bill Pfingsten was the editor who published this page.