A diffusion model has been used to estimate the spring cross-shelf flux of nitrate and its rate of biological uptake in the southeastern Bering Sea during 1976 to 1979. Vertical fine structure of temperature and salinity and a cross-shelf salt balance were used to estimate eddy coefficients in the diffusive fluxes of nitrate. A combination of the computed physical resupply of nitrate and its observed local time rate of change was then used to predict the rate of nitrate utilization by phytoplankton. Agreement of this model with independent 15N estimates of formation of phytoplankton particulate nitrogen allowed further analysis of the possible fate of the spring bloom in the outer shelf of the Bering Sea. A comparison of the utilization of spring phytoplankton production is made at the same isobath and similar latitude of the Bering and North seas.