Media outlets, governments, academics, and NGOs are increasingly documenting seafood fraud. This attention has raised public concern over the identity, value, and safety of seafood. Misrepresenting one species, provenance, or production system as another has many potential consequences. Yet, the extent of potential biological, economic, and health impacts from seafood mislabeling is unknown, with evidence largely limited to anecdotal cases. With support from the Paul M. Angell Foundation, ACS is working with the ASU School of Sustainability to develop a systematic understanding of seafood fraud. We are combining theory with empirical data to understand the potential impacts from seafood mislabeling. Informed by our impact framework and synthesis, we are testing hypotheses around specific biological and economic impacts of seafood products involved in fraud that are of global importance. Understanding the mechanisms and feedbacks through which seafood fraud leads to economic and environmental impacts is a critical next step to designing new and improving current interventions to reduce it. Further, identifying the conditions under which seafood fraud is likely to have the greatest impact will help in prioritizing and cost-effectively targeting efforts.