The regulations for recreational harvest of Pismo clams and clams in general are found on the Ocean Sport Fishing regulation webpage and in California Code of Regulations (CCR), Title 14, Sections 29.20 and 29.40.
Summarized regulations as of 2024:
To harvest clams, anyone 16 years of age or older must possess a valid sport fishing license, and a Sport Ocean Enhancement Validation is required in ocean waters south of Point Arguello (Santa Barbara County). Clams may be harvested one-half hour before sunrise to one-half hour after sunset 29.20(b). Gear restrictions are listed in section 29.20(c).
Anglers are allowed to possess a maximum of 10 Pismo clams. The minimum size is five inches in shell diameter measured at the widest part for the area north of the boundary between San Luis Obispo and Monterey counties, and four and one-half inches south of that boundary line (29.40 (c)). Pismo clams must be immediately measured, and any undersize clams shall be immediately reburied in the area from which they were taken (29.20 (d)). The proper way to rebury a Pismo clam is shown in this short video clip.
Pismo clams may be taken in Santa Cruz and Monterey counties September 1 through April 30. In all other counties, Pismo clams may be taken any time of the year. No clams shall be taken within state marine reserves or other marine protected areas which prohibit the take of clams (CCR, Title 14, Section 632).
No, Pismo clams are not allowed to be harvested commercially. Historically, there was a commercial fishery for Pismo clams from the early 1900s through 1947. Commercial harvest was prohibited after 1947.
Pismo clam abundance has increased in recent years both locally and in other regions of southern and central California, primarily due to strong recruitment events in recent years.
A recent study from Cal Poly researchers published in the journal Aquatic Biology(PDF) estimated that Pismo clams reach legal size (south of the San Luis Obispo and Monterey county line) of 4.5 in (114 mm) between 9 and 15 years of age based on analysis of growth rings. Several factors can influence their growth rate and thus the age at which they reach legal size including water temperature, food availability, and other environmental factors. Estimates of growth from ongoing Cal Poly survey data suggest that they may reach legal size closer to the lower end of that range, and possibly at 8-10 years, but ongoing work will provide more detailed information.
Clammers can take Pismo clams statewide, but you won’t be able to find them north of Half Moon Bay. The heart of the clam population is south of San Franscisco on the Central Coast, near Pismo Beach; and at various beaches in Santa Barbara, Ventura, Los Angeles, Orange, and San Diego counties. Please use our mobile Ocean Sport Fish Map to find out the specific regulations for your location.
Yes, there are legal sized clams being harvested in the Pismo Beach area. While sub-legal sized clams far outnumber legal clams, many clammers are finding legal clams. Prior to recent years, the last time legal sized clams were seen in this area was in the early 1990s.
There are several signs posted along the beach at various locations on both State Parks property and the City of Pismo Beach. The signs posted by the City of Pismo Beach are posted at walkways along the coastline and at various spots at Pismo Pier. State Parks have posted several interpretive signs about Pismo clams near the entrances to the Oceano Dunes on Grand and Pier Avenues as well as at campground areas. The Department of Fish and Wildlife posted notice signs about recreational Pismo clam regulations and some of the concerns associated with illegal harvest of undersized clams.
There have been several instances over the past few years where large numbers of Pismo clams have become unburied during low tide events. These events appear to be localized and have occurred in several locations along Pismo State Beach.
The cause of these events remains unclear. Several possibilities include harmful algal blooms that produce domoic acid, bacterial and fungal infections that degrade muscle and visceral tissue, stress from environmental changes such as temperature fluctuations, and overcrowding. In the last five years, the Pismo clam population has increased, and some unburying events are in these densely populated areas.
The Department of Fish and Wildlife is working collaboratively with State Parks, California Department of Public Health, and researchers at California Polytechnic State University in San Luis Obispo to investigate possible causes.
These large unburying events appear to happen more often between the Pismo Beach Pier and Grand Avenue. High clam concentrations mostly occur north of the Pismo Creek outlet, and this is where some of the larger unburying events have been noted. Large surfacing events have also occurred directly north of the Pismo Beach pier up to the area of the bluffs.
To date, unburying events have been observed during summer. The first of these large events reported to the Department of Fish and Wildlife and State Parks occurred in August 2020. Two additional events were reported in August 2021 and 2022, and so far, four major events have been reported for 2023. The events in 2023 began earlier in summer during June.
Samples of Pismo clams have been sent to the California Department of Fish and Wildlife’s Shellfish Health Laboratory to assess the general health of the animals, look for any abnormalities on a cellular level that may indicate recent injuries or illness, and test for the presence of known bivalve pathogens. These tests can determine whether an animal was infected prior to its death and allow researchers to determine whether an infectious agent--such as a virus, bacteria, or fungus--may be the cause of an unusual behavior or illness. While several known marine shellfish pathogens have been eliminated as the cause of this unusual unburying behavior and no obvious signs of injury or illness has been observed in the unburied clams, the health investigation is ongoing.
Additional samples of the clam meat and viscera were sent to the California Department of Public Health to be tested for marine biotoxins—specifically domoic acid and paralytic shellfish poisoning. These naturally occurring toxins are produced by phytoplankton and can accumulate in filter-feeding shellfish, posing a public health threat for those people who consume shellfish. While trace amounts of these toxins were detected in these clams, the amounts of these toxins were well below the threshold levels that would trigger human health concerns.
To learn more about health advisories and warnings of contaminated shellfish from marine biotoxins please visit the Health Advisories website by the Department of Fish and Wildlife, and for more information about biotoxin monitoring visit the Marine Biotoxin Monitoring Program website by the Department of Public Health.
If you notice people collecting clams or engaging in illegal harvest activities, please report it to CalTIP (Californians Turn in Poachers and Polluters) immediately. CalTIP is a confidential reporting program that encourages the public to provide the Department of Fish and Wildlife with factual information that could lead to the arrest of poachers and polluters.
The toll-free telephone number operates 24 hours a day, 7 days a week, and you do not have to give your name. The CalTIP number is 1-888-334-CALTIP (888 334-2258).
Researchers at both Cal Poly and at Concordia University in Irvine, CA have been studying Pismo clams both locally and in other areas of central and southern California for the past few years. These efforts are being led by Dr. Benjamin Ruttenberg at Cal Poly and Dr. Sean Bignami at Concordia and their students who have examined aspects of their reproductive biology and population abundance.
Three publications so far have come out of this work. The first paper dealt with reproductive aspects of Pismo clams in central and southern California and appeared in the journal Aquatic Biology(PDF). The second article provided updated information on population density and recruitment in central and southern California and appeared in the California Fish and Wildlife Scientific Journal. The third article provided an updated status of Pismo clam populations across their range in California and appeared in the journal Regional Studies in Marine Science.
In addition to these Cal Poly is conducting research on several aspects regarding Pismo clams. Some of these include mark-recapture studies to track growth and movement, evaluation of spatial variation in sand grain size and its importance as habitat for Pismo clams, impacts of predation by gulls and otters, and ongoing monitoring of population abundance and size structure around Pismo Beach and Morro Bay.