Ocean fronts drive marine fishery production and biogeochemical cycling

Significance Fronts in the ocean act as oases in a fluid desert that are not fully accounted for in climate or fisheries model projections. Fronts act to increase production by channeling nutrients through multiple trophic levels, including commercially important fishes and marine mammals, and enhance carbon export to the deep ocean. Fronts consequently have immense effects on the ocean, from base of the food chain up through the dinner table and mediation of global climate change. Here we show how fronts can be incorporated into current models, using a technique from fluid dynamics to improve both climate and fisheries models. Long-term changes in nutrient supply and primary production reportedly foreshadow substantial declines in global marine fishery production. These declines combined with current overfishing, habitat degradation, and pollution paint a grim picture for the future of marine fisheries and ecosystems. However, current models forecasting such declines do not account for the effects of ocean fronts as biogeochemical hotspots. Here we apply a fundamental technique from fluid dynamics to an ecosystem model to show how fronts increase total ecosystem biomass, explain fishery production, cause regime shifts, and contribute significantly to global biogeochemical budgets by channeling nutrients through alternate trophic pathways. We then illustrate how ocean fronts affect fishery abundance and yield, using long-term records of anchovy–sardine regimes and salmon abundances in the California Current. These results elucidate the fundamental importance of biophysical coupling as a driver of bottom–up vs. top–down regulation and high productivity in marine ecosystems.