Cal Poly researchers, students, and 130 volunteers surveyed nearly 40 sites in California over a two-year period to create the first and most comprehensive survey of Pismo clams on record today. “This is the first time anyone has evaluated the status of Pismo clam populations across California,” says Ben Ruttenberg, biological sciences professor, and director of the Cal Poly Center for Coastal Marine Sciences. The research is focused on the life history, population ecology and habitat associations with Pismo clams. The team is conducting scientific surveys on beaches locally and throughout California to learn more about where the clams are, how they live, what they need to thrive. “We are looking at how abundant they are, how quickly they grow, and what time of year they reproduce,” said Alex Marquardt, the Cal Poly biological sciences graduate student leading the project.
Initial observations show high numbers of clams on local beaches relative to the early 2000s, but nothing close to the levels seen throughout much of the 20th century. Although these clams are too small to legally harvest, the question of where they are coming from remains. “We're trying to understand, specifically with regards to reproduction, what is it in that environment that may be driving the patterns that we see,” said Marquardt.
Traditional wisdom would suggest that the Pismo clam population declined because of over-harvesting by humans and over-predation by otters. However, according to Ruttenberg, the data collected in this research effort suggests a much more complex set of factors may have contributed to the population decline of the species across the state.
“If we want to restore the population of Pismo clams, we must first understand what factors contributed to the population decline,” says Ruttenberg. “Currently, we have data to suggest that the size of sand grains are critically important to where Pismo clams live.”
The research team will continue to collect data to give them a more holistic view of how the species interacts with its environment over time. The eventual hope is to have a clear enough picture that Pismo clams can once again be harvested in California. According to Marquardt, the methods used in surveying are helping restore formative experiences in clamming for many community member volunteers.
“The act of digging for clams is a historic part of the Pismo Beach community's cultural identity, and reconnecting with that experience is incredibly valuable for our volunteers,” said Marquardt.
The initial study was funded by the City of Pismo Beach. Ruttenberg is hopeful that the study will continue on an ongoing basis in the future. “We are so thankful for the generous funds that we’ve received thus far that have allowed us to conduct this important work. With continued support from the local community and those interested in the fate of Pismo clams, we will keep answering key questions needed to restore Pismo clam populations, and provide outstanding hands-on research and learning opportunities for our students in the process,” he said.
Photographs by Cal Poly alumna Maya Vavra (Biological Sciences, ’18)
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