Results from recent investigations into shellfish resources in San Diego Bay
Map of 11 rip rap survey and oyster collection sites.We already know a lot about the finfish that are commonly caught in San Diego Bay, including information about the types and amounts of bay fish that are safe to consume (see OEHHA advisories for San Diego Bay here; see a recent study on San Diego Bay anglers here). But, there is still a lot to learn about the bay's shellfish resources.
In July 2018 and January 2019, our team conducted rip rap surveys in 11 publicly-accessible locations throughout the bay (between -1 and 3 ft above MLLW) to determine what types of shellfish are available to potential harvesters along the waterfront. We also collected oysters from each of these sites that will be analyzed for contaminants, so we can better understand the potential risks of consuming shellfish from the bay.
Shots of 3 rip rap survey sites (from left to right): Shelter Island West, Shelter Island East, and NTC Channel.
Species richness (number of species) was highest at the two Shelter Island sites, Embarcadero, and Harbor Island (12-16 species per site), while the other seven sites were each populated by 3-8 species. Most of these species would likely not be of interest to harvesters for food, however some are of interest for other uses, such as bait (e.g., lined shore crabs).
Of the species found in our sites, Pacific and Olympia oysters and Mediterranean mussels are the three species that would likely be of the most interest for food harvest. Oyster density ranged from an average of 10-63 oysters/m2 at each site (see figure below). Mussels were less abundant, with most sites featuring an average of <1 mussel/m2, and only 2 sites (the Shelter Island sites) with abundances close to (or surpassing) those of oysters (28/m2, 112/m2).
Average density of oysters at each survey site.
As we talk to people about their seafood harvesting habits on piers throughout the bay, we are also conducting pier trapping surveys with hoop nets, to understand what shellfish species are available to pier anglers. Stay tuned for further information on shellfish availability and contamination in the bay!