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The Seaweed Nutrient Removal Calculator (SNRC; https://connect.fisheries.noaa.gov/SNRC/) is a new, publicly available online tool designed to estimate the amount of nitrogen removed by cultivated sugar kelp (Saccharina latissima). This interactive calculator aims to assist seaweed farmers and resource managers in decision-making related to excess nutrient management and coastal aquaculture permitting. The SNRC is a proof-of-concept tool, initially drawing on published data specific to S. latissima grown in the southwestern Gulf of Maine (GoM)—the dominant cultivated species and a key driver of the local seaweed industry. It is designed to be a platform for future expansion to include other species and locations as new data becomes available. Nitrogen (N) is an essential nutrient, but excess levels of N in coastal waters can lead to algal blooms, low oxygen concentrations, fish kills, and other detrimental effects. Like all primary producers, seaweed incorporates nutrients into its tissue as it grows. At harvest, these nutrients are permanently removed from the coastal environment, providing a benefit to water quality and coastal communities. Nitrogen is also an indicator of protein content in seaweed, which may contribute to product quality or nutritional capacity. The calculator is a tool designed for seaweed farmers and resource managers to inform seaweed aquaculture permitting. Resource managers have expressed interest in easy-to-use tools that produce location and operation-appropriate values for the environmental benefits, or ecosystem services, seaweed farms provide. The calculator provides estimated values for nutrient removal in a format that aligns with the seaweed aquaculture permitting process. The nitrogen removal calculations are based on published data measuring seaweed biomass and the average nitrogen concentration in seaweed over a range of harvest dates. This tool estimates the weight and nitrogen concentration of the seaweed based on the day of year it is harvested under typical conditions on a farm in the Gulf of Maine. The weight estimates are based on non-linear generalized additive model (GAM) output of biomass regressed on day of the year. Similarly, the nitrogen concentration estimate is based on GAM output of nitrogen concentration regressed on day of the year. Finally, the nitrogen concentration is multiplied by a dry-weight to wet-weight conversion factor, the total kelp biomass, and the length of line harvested to obtain the amount of nitrogen removed. This repository includes the final GAM models, developed in R and saved as .rds files, alongside the raw biomass and nutrient content data used to create them.