Pismo Clams in California: Recovery of an iconic species
Pismo clams were once an abundant recreational fishery species throughout California and on Pismo Beach in particular. They are iconic, and were important to Californians over the last century and to the Chumash people for many centuries before that. Their abundance declined statewide over the last several decades, but populations on Pismo Beach have shown strong evidence of a comeback in recent years.
Our research aims to understand the current status of Pismo clams, the mechanisms that impact their abundance, and how we can collaborate with local organizations to ensure that the current population recovery is a lasting one. This research is made possible by Cal Poly undergraduates, the City of Pismo Beach, the Santa Rosa Creek Foundation, our agency partners, and community support.
We've published a few papers so far (led by lab alum Alex Marquardt as part of her MS degree), with several more in the works, led by current student Marissa Bills. Recent undergraduates have also finished many senior projects on Pismo clams, including reproduction (Park; published below), age and growth (Clark and Maietta; published below), poaching (Moon), spatial distributions (Ross), Public knowledge (Ippoliti; Key), sand as habitat (Gianni), and the importance of predators (birds, Bloom; otters, Mattioli), among others.
Marquardt AM*, Park SK**, Clark NM**, Maietta EG**, Waltz G, Needles LA, Ruttenberg BI. 2023. Distribution, abundance, and drivers of population variability of a large sandy intertidal bivalve (Tivela stultorum) across California. Regional Studies in Marine Science 65:103063. https://doi.org/10.1016/j.rsma.2023.103063
Marquardt AM*, NM Clark**, EG Maietta**, SK Park**, BI Ruttenberg. 2022. Reproduction, body condition, age, and growth of a large sandy intertidal bivalve, Tivela stultorum, Mawe 1823. Aquatic Biology 31: 19-30. https://doi.org/10.3354/ab00749
Our research aims to understand the current status of Pismo clams, the mechanisms that impact their abundance, and how we can collaborate with local organizations to ensure that the current population recovery is a lasting one. This research is made possible by Cal Poly undergraduates, the City of Pismo Beach, the Santa Rosa Creek Foundation, our agency partners, and community support.
We've published a few papers so far (led by lab alum Alex Marquardt as part of her MS degree), with several more in the works, led by current student Marissa Bills. Recent undergraduates have also finished many senior projects on Pismo clams, including reproduction (Park; published below), age and growth (Clark and Maietta; published below), poaching (Moon), spatial distributions (Ross), Public knowledge (Ippoliti; Key), sand as habitat (Gianni), and the importance of predators (birds, Bloom; otters, Mattioli), among others.
Marquardt AM*, Park SK**, Clark NM**, Maietta EG**, Waltz G, Needles LA, Ruttenberg BI. 2023. Distribution, abundance, and drivers of population variability of a large sandy intertidal bivalve (Tivela stultorum) across California. Regional Studies in Marine Science 65:103063. https://doi.org/10.1016/j.rsma.2023.103063
Marquardt AM*, NM Clark**, EG Maietta**, SK Park**, BI Ruttenberg. 2022. Reproduction, body condition, age, and growth of a large sandy intertidal bivalve, Tivela stultorum, Mawe 1823. Aquatic Biology 31: 19-30. https://doi.org/10.3354/ab00749
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Current Pismo Clam Research
Photo Credit: CDFW
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Population Status
To understand how Pismo clam populations are changing over time, we conduct quarterly surveys on Pismo Beach. We sample from the top of the beach into the intertidal as far as the tide will allow us to get by digging trenches of specific sizes called transects. We count and measure all clams found in each transect and then rebury them on the beach. This monitoring effort began in 2014 and continues today, helping us build a robust, long-term dataset. Such a dataset provides us with important information on Pismo clam abundance and size, essential to understanding population trends and informing management. Interested in joining us for a survey? Fill out our volunteer form here Read more about our Pismo clams survey project in the news: KCLU The One Oh One Podcast (April 2022) Monterey Herald (Jan 2022) LA Times (Front Page! 11/2021) Community Science - Have you seen this clam?
In the summer of 2021, we started a mark and recapture study for Pismo clams on Pismo Beach. We collect clams, measure them, and tag them with a unique number, metal washer and a QR code. The unique number allows us to identify individuals, and the washer helps us find marked individuals with a metal detector. Recapturing marked individuals allows us to measure growth, survival, and movement of individual clams, critical data for understanding key ecological processes. This project is ongoing, and we hope to continue it for many years. The QR code allows members of the community to be a part of this study! If you find a clam with a QR code, please scan the code with a smartphone. It will open a short data form; answering a few short questions will help us collect important data! More about this project in the San Luis Obispo Tribune (Oct 2021) Pismo Clam Poaching
Poaching has become an increasingly large problem for Pismo clams on the Central Coast. In 2020, law enforcement officers intercepted over 25,000 poached clams on Pismo Beach alone! We work with the California Department of Fish and Wildlife enforcement division to understand and track Pismo clam poaching. While the recreational fishery is still open for Pismo clams, clams must be over 4.5 inches in San Luis Obispo county and south, and over 5 inches in Monterey County to be collected legally. Additionally, clamming is only permitted between sunrise and sunset, there is a limit of 10 clams per day, and fishers must have a valid fishing license. If you are witnessing poaching, call Cal Tip at (888) 334-2258 to report your sighting to CDFW. Learn more about the state of Pismo clam poaching from KSBY (Aug 2021) Aquaculture Potential
Recently, we have begun examining the aquaculture potential of Pismo clams at the Cal Poly pier marine facility. We are exploring ways to spawn them in captivity and rear their larvae in an effort to develop ways to create baby Pismo clams. If successful, these methods could be used to culture Pismo clams for commercial and/or restoration aquaculture. Learn more about our aquaculture research |
Want to get involved in our research or learn more?
Contact master’s student Marissa Bills
If you are a Cal Poly undergraduate, we are always looking for more students to get involved in our research!
Email Marissa to learn about current opportunities
Contact master’s student Marissa Bills
If you are a Cal Poly undergraduate, we are always looking for more students to get involved in our research!
Email Marissa to learn about current opportunities