Cal Poly surveys Pismo clams for growth


SUPPORTING SCIENCE A group of Cal Poly students, from undergraduate to graduate students, volunteered to pick, tag, and release clams for research. - PHOTO BY BULBUL RAJAGOPAL
  • SUPPORTING SCIENCE A group of Cal Poly students, from undergraduate to graduate students, volunteered to pick, tag, and release clams for research.

The pandemic made sure people can find QR codes everywhere, from restaurant menus to billboards, and San Luis Obispo County just added them in an unusual new location—the shells of live Pismo clams.

Cal Poly's biology department organized a clam tagging session on Oct. 8 at Pismo Beach to monitor the growth, mortality, and migration patterns of Pismo clams. A major mascot of Central Coast marine life, Pismo clams barely made visits to its namesake beach for decades.

That's changing now. But even though they're returning to Pismo Beach, the clams fall below the legal 4 1/2 inch size to make them ripe for recreational picking. If they are harvested while undersized, it's considered to be illegal poaching.

Marissa Bills, the Cal Poly graduate student who led the clam survey, said that one of their goals is to give clams the best chance of reaching their growth potential.

"It would be unrealistic to name thousands of clams. We actually use super glue [to stick QR codes on clam shells], it works really well. It's standard practice in marine science to use these for different invertebrates. We assume it'll be successful but we're not a 100 percent sure, but it's something we'll hopefully find out in time," Bills said.

The best way to keep tabs on each clam involves a data-calculating trifecta of QR codes, washers for metal detectors, and clear nail polish. The latter helps to seal the QR code sticker, and washers make sure beach visitors with metal detectors can find clams.

Bills devised the plan with her advisor and professor Ben Ruttenberg. They concluded that people could scan the QR codes on clams using their phones to help the research team with their study. The code opens a short survey sheet that asks for the clam's ID (a serial number sticker is also put on the shell), its dead-or-alive status, and where it was found. Participants can also upload pictures of clams.

"The awesome thing about Pismo clams is that community members get really excited about them," Bills said. "The more people who are aware that the clams are here, and getting invested in keeping them around will hopefully help curb some of the poaching we are seeing."

Vehicles driving on wet sand threaten clam life, too. A YouTube video recorded in August showed several trucks driving over hundreds of Pismo clams. Bills said that future plans could involve looking into these issues that impact clams.

While measuring clams after tagging, Cal Poly students told New Times that some of the larger ones measured almost 3 inches. This was the group's second clam tagging session since their first one over the summer. Clams were roughly the same size then, too.

"The biggest we found is around 88 to 90 millimeters, which is still less than 4 inches," Ruttenberg said.

But Bills and her team look forward to helping these clams thrive.

"This past year, we've been finding more clams than we have in the past six," she said. "So we know that the populations are growing and the clams are getting larger. It's a very exciting time to do Pismo clam research."


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