The United States seafood sector is susceptible to shocks, both because of the seasonal nature of many of its domestic fisheries and its global position as a top importer and exporter of seafood. However, many datasets that could inform science and policy during an emerging event do not exist or are only released months or years later. Here we synthesize multiple data sources from across the seafood supply chain, including unconventional real-time datasets, to show the relative initial responses and indicators of recovery during the COVID-19 pandemic. We synthesized news articles from January to September, 2020 that reported effects of COVID-19 on the US seafood sector, including processor closures, shortened fishing seasons, and loss of revenue. Concerning production and distribution, we assessed past and present landings and trade data and found substantial declines in fresh seafood catches (-40%), imports (-37%) and exports (-43%) relative to the previous year, while frozen seafood products were generally less affected. Google search trends and seafood market foot traffic data suggest consumer demand for seafood from restaurants dropped by upwards of 70% during lockdowns, with recovery varying by state. However, these declines were partially offset by an increase (270%) in delivery and take-out service searches. Our synthesis of open-access datasets and media reports shows widespread, but heterogeneous, ramifications of COVID-19 across the seafood sector, implying that policy-makers should focus support on states and sub-sectors most affected by the pandemic: fishery-dependent communities, processors, and fisheries and aquaculture that focus on fresh products.