Bivalve shellfish aquaculture can provide a variety of ecosystem services beyond food production. Shellfish assimilate nutrients into their tissue and shell, and these nutrients are removed from a waterbody when animals are harvested. In some coastal environments where excess nutrients are causing water quality problems, this service provided by shellfish farms has been formally incorporated into nutrient management programs, and in a few cases farmers have even received payments for nutrient removal services.
Resource managers and industry members have indicated a need for a simple tool, backed by robust science, to predict nutrient removal by harvest of cultivated shellfish. We have synthesized available literature for eastern oyster farms across the US Northeast region (North Carolina to Maine), and applied methodology used by the Chesapeake Bay Program to calculate nutrient removal at harvest. Variability in oyster tissue and shell nutrient content was low, and an assessment of farm location, ploidy, and cultivation practice (with vs. without gear) suggested that a single average value could reasonably be applied across all farms. Evaluation of variation in animal size and weight across these same factors is ongoing and will determine the number of farm input factors needed in the final tool. The harvest nutrient calculator tool will be freely available online, and a preview of the tool will be provided in this presentation. Data gaps will be identified, and data needs for the creation of similar tools for other species and other regions will be discussed.