For the purpose to make a fishing ground in the sea by increasing the primary production, The Ocean Nutrient Enhancer (ONE for short) which rises the nutrient-rich Deep Ocean Water (DOW) and discharges it into the euphotic surface layer has been studied. To establish the concept of ONE, various kinds of the requisite technologies were evaluated from the viewpoint of proposing the extremely new type machine that we have never had before. Especially a choice of energy source for operating the ONE is primarily important to create its concept and outline. The feasibility study on the energy source was carried out in order to establish the prototype of ONE. The result of study was that the most suitable energy system for the ONE is the combination of Ocean thermal Energy Conversion (OTEC) as the main engine and Diesel Engine as the auxiliary engine. This choice can enjoy not only using the property of DOW's low temperature but also adopting submerged floating structure whose performances in the rough sea is very excellent.
The upwelling of Deep Ocean Water (DOW) which has a very dense nutrient salt such as Nitrogen, Phosphorus, etc. can make the sea very rich fishing ground, because the lack of the nutrient salt in the euphotic surface layer of the sea where the photosynthesis can be done is cancelled and growth of phytoplankton as the food of fishes is very remarkable. The fishing ground at the offshore Peru is one of the best sample of the DOW upwelling sea. Many experts are pointing out that if we can upwell the DOW artificially in the sea we can make new fishing ground (Ryther 1969), and this is one of the big solution for the problem of food shortage in 21 st century.
