Disclosed herein are methods for mixing of carbon dioxide (CO2) and/or other nutrients in an ocean, wherein surface water CO2 is decreased to reduce or slow acidification of the ocean, and increases in fish populations are advantageously promoted. Also disclosed herein are methods and systems for recovery of nutrients, for example, phosphorus, from an ocean floor in the form of fish biomass, which may be used to make such useful products as fish fillets, fish meal, fish oil, biofuel or fertilizer.
