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Abstract Seaweed farming in the United States is gaining significant financial and political support due to prospects to sustainably expand domestic economies with environmentally friendly products. Several networks are seeking appropriate synthesis of available science to both inform policy and substantiate the sector’s sustainability claims. Significant knowledge gaps remain regarding seaweed-specific food hazards and their mitigation; a resource-intensive challenge that can inhibit sustainable policies. This is particularly concerning for rapidly expanding Saccharina latissima (sugar kelp) crops, a brown seaweed that is known to accumulate heavy metals linked to food hazards. Here, we present baseline information about concentrations of arsenic, cadmium, lead, and mercury, in both wild and farmed sugar kelp from the New England region. We interpret our findings based on proximity to potential sources of contamination, location on blade, and available heavy metals standards. Contrary to our expectations, high concentrations were widespread in both wild and farmed populations, regardless of proximity to contamination. We find, like others, that cadmium and arsenic consistently reach levels of regulatory concern, and that dried seaweeds could harbor higher concentrations compared to raw products. We also share unique findings that suggest some toxins concentrate at the base of kelp blades. Our results are one step towards aggregating vital data for the region to expand its seaweed farming footprint.

Abstract Seafood farming is heralded for its economic opportunities and its potential to reduce the greenhouse gas emissions associated with food production. Yet the persistent lack of awareness among the US public about these potential benefits of seafood farming is often cited as a barrier to social acceptance and industry growth. We employed two exploratory online surveys of residents of western and northeastern US coastal states and a unique message‐testing approach to explore: (1) how existing opinions about seafood farming vary across sociodemographic attributes, geography, and prior familiarity with aquaculture; (2) the malleability of opinions about seafood farming; and (3) what benefits of marine aquaculture broadly and of seaweed farming specifically were viewed as the strongest reasons to support industry expansion, and what messengers are most trusted to share that information. We found that baseline attitudes about seafood farming strongly correlate with prior familiarity and that opinions about both marine aquaculture and seaweed farming were highly malleable, at least in the short term. If confirmed by further studies, our results suggest that messages emphasizing benefits in terms of environmental sustainability, as opposed to economic benefits or social benefits, may be an important tool to better engage residents of western and northeastern US coastal states with seafood farming expansion.