ABSTRACT:

So far, there are no successful means to upwell Deep Ocean Water (DOW) artificially and to make a fishing ground in the open sea. The five years project of increasing a primary production and making a new fishing ground by upwelling DOW which is very rich in nutrient salt such as Nitrogen, Phosphorus, etc. was commenced in the year of 2000, sponsored by the Fisheries Agency of Japanese Government and Marino-Forum 21. The focus of the project is a creation and proposition of the concept of Ocean Nutrient Enhancer (ONE) to contribute for increasing primary productions and fish productions, furthermore, conducting the experiment in actual sea to confirm the effect of the ONE. The requisite technologies for the ONE such as a density current diffusion, a spar type floating structure, a steel riser pipe, a set-up way of upending, etc. is discussed and integrated to create proto-type of ONE, whose specifications are the DOW upwelling capacity of 100,000m3/day, the displacement of about 1,700tons, Diesel generator of 100kw. The ONE named "TAKUMI" which was set-up with the single point mooring system at the centre in Sagami Bay in the depth of about 1,000m, is now in continuous operation since July 2003.

INTRODUCTION

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 for fishes is very remarkable. And this is one of the big solutions for the problem of food shortage in 21st century. But, so far, there are no practical means to make it.

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