An Estimate of Carbon Storage Capabilities from Wild and Cultured Shellfish in the Northwest Atlantic and Their Potential Inclusion in a Carbon Economy

ABSTRACT Bivalve mollusc production has been proposed as a method to reduce carbon emissions as (1) a low-emission protein source, and (2) via carbon stored in their shells. Numerous studies have examined the fate of carbon in bivalve production, estimated carbon sequestration rates, and their role in a carbon economy. To address the fate of shell carbon for the Northwest Atlantic, stored oceanic carbon equivalents (Eq), released CO2via calcification, and hypothetical carbon credit value ($24 tCO2), for both aquacultured and wild-captured bivalves for New England and Canadian Provinces on the Atlantic between 2016 and 2020 were estimated. Bivalve shells do not sequester atmospheric CO2, instead storing oceanic CO2 Eq and cannot be directly included in a carbon sequestration scheme. In the present study, total annual estimates of stored oceanic CO2 Eq were approximately 202,253 and 363,243 tons, with concurrent releases of approximately 121,255 and 217,771 tons of CO2 to the atmosphere, of which only 4% and 8% were from aquaculture production in Canada and the United States, respectively. Even if bivalve shells sequestered atmospheric CO2, current shellfish production levels are inconsequential with regard to current anthropogenic greenhouse gas (GHG) emissions. Stored oceanic carbon Eq for bivalve aquaculture is equivalent to 0.001% and 0.0005% of Canadian and US annual anthropogenic CO2 emissions, whereas wild-capture would store 0.028% and 0.005% of Canadian and US emission, respectively. Bivalve shell will not solve climate change, but the expansion of bivalve production provides a protein source with the lowest GHG emissions, which provides a multitude of environmental services.