ABSTRACT:

TAKUMI the prototype of Ocean Nutrient Enhancer, which upwells and discharges Deep Ocean Water (DOW) in the euphotic layer and increases a primary production in the sea, was set up in Sagami bay in May 2003. Since then, TAKUMI has been continuously upwelling the DOW of 100,000m3/day from the 200m depth, even in the case of rough sea condition. In this paper, the design concept and three years operation experience of TAKUMI is reported briefly. It seems that TAKUMI is the world first successful device for artificial upwelling and increasing primary production in the real sea.

INTRODUCTION

To increase a primary production in the sea, Upwelling and discharging a Deep Ocean Water (DOW) which has very rich nutrient salts into the euphotic surface layer has been proposed by many oceanologists as a "Fishing ground of artificial DOW upwelling" (Liu, 1999). Table 1 shows the comparison of the area and the productions in the sea in case of the ocean, the coastal and the upwelling area (Ryther, 1969). The world half fish production is made in the upwelling area which is only 0.1% of the whole sea area, for example, offshore Peru, Canary Islands, etc. But, so far, there are no successful means to make it artificially, because of the problems of the large amount of upwelling DOW, the dilution of nutrient salts in the sea, enduring the rough sea condition, the strength of very long riser pipe for upwelling, etc. MARINO-FORUM 21, a subsidiary of The Fisheries Agency of Japanese Government, established the budget of about USD 6 million and organized the research and development project to create Ocean Nutrient Enhancer (ONE for short) which upwelles and discharges DOW into the euphotic layer to increase primary production of the sea and make a fishing ground.

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