Aquaculture America 2023

February 23 - 26, 2023

New Orleans, Louisiana USA



Darbhi Durvasula*, Emily Buckner, Ryan Crim, Jodie Toft


Tulane University / Puget Sound Restoration Fund

Bainbridge Island, WA 98110


Intertidal shellfish operations are often hindered by biofouling. In Puget Sound, an estuarine fjord in Washington State which hosts many commercial shellfish farms, a particularly interesting form of biofouling can occur. Basket cockles (Clinocardium

nuttallii), a medium-sized bivalve, accumulate in aquaculture cultivation equipment such as PVC piping and mesh tubes (see Figure 1) used for planting geoduck (Panopea

generosa) seed. Farmers sometimes remove and discard cockles from these tubes as they worry that the density of cockles may limit the growth and yield of their target crop, geoduck. However, this ‘nuisance’ species has been a preferred food for many Native American tribes in the Puget Sound region for thousands of years. In fact, some of the earliest forms of aquaculture were “clam gardens” which indigenous people would actively cultivate and care for. Recently, cockles have become increasingly difficult for tribal members to find in their usual and accustomed fishing areas. This presents an opportunity to create a mutually beneficial relationship between shellfish farmers and tribal communities, providing an outlet for this unwanted byproduct of geoduck aquaculture while restoring a preferred indigenous food.

Here we discuss our work to investigate the prevalence and patterns of cockle biofouling on geoduck farms across Puget Sound. We conducted surveys on two large commercial farms in the summer of 2022 to estimate the potential harvestable biomass of cockles per cultivated area. We then looked at cockle abundance and biomass in relation to factors such as geoduck presence, tidal elevation, geoduck tube condition, and geoduck planting date. By developing a more comprehensive understanding of these relationships, as well as the abundance of this fouling species across geoduck farms, we seek to maximize efficiency and success in potential future efforts to harvest and utilize these cockles.