Oysters in the raw

The San Dieguito River in its renaissance continues to serve up surprises, not the least of which are clumps of Pacific oysters (Crassostrea gigas) clinging to old pilings of the Grand Avenue Bridge on the south side of the lagoon.

One of the most globalized marine invertebrates, these four- to six-inch, non-native bivalves with their rounded, fluted shells can also be spotted at low tide on pilings in the river channel just east of the Interstate 5 bridge as well as on the concrete abutments of the bridge itself.

The Pacific oyster begins its life as a male but after a year or so functions as a female, living up to 30 years unless consumed by crabs, fish, or wading birds. They breed in the warm water of the lagoon with fertilization occurring when free-swimming larvae group together to find habitats to settle.

It’s not as if oysters are newcomers to the region though. Some 8,500 years ago the Kumeyaay, the original native inhabitants of what is now San Diego County and Northern Baja, Mexico, foraged for oysters among other food sources, primarily in the San Elijo Lagoon region, as evidenced by shell middens in the estuary. Today, in Baja, delicious Pacific oysters known as Kumiai are commercially farmed both in Ensenada and further south in Guerrero Negro Lagoon.

But are these oysters for eating? Probably wisest to enjoy them from a distance. As filter feeders, feeding on phytoplankton and detritus in water, even if some fool survived a waist-deep (and illegal) foray through the mud to pluck an oyster from the pilings near the Grand Avenue viewing platform, only the same fool would attempt to eat one without knowing the quality and toxicity of the water, even this long after the lagoon’s restoration.