Shift from the Clean Sea to the Bountiful Sea

Osaka Bay Fish Farm

Concept: Obayashi Project Team

II. What is the "Fish Farm"?

In view of the environmental challenges outlined above, the "Fish Farm" concept is intended to ensure that the bounty of the seas surrounding Japan will be available to and even more plentiful for future generations. The concept recognizes climate change and its impacts on surrounding environments to create the aquaculture and fishing grounds of the future.

What Makes the "Fish Farm" Unique?

These are the main ideas behind the "Fish Farm":

(1) Recirculation of Nutrients

The Fish Farm project will use "integrated multi-trophic aquaculture" (IMTA) to make sustainable and low-environmental impact aquaculture a reality. Aquaculture is implemented by combining organisms at different trophic (nutritional) levels in the food chain. Residual aquaculture fish feed, excrement, and other organic matter are circulated as nutrients without wasting this material. In addition, surplus nutrients from aquaculture are supplied to outside of the aquaculture facility for use in the surrounding ocean.

[Figure of Concern for Multi-Trophic Stage Aquaculture]

(2) Creating Rich Fishing Grounds

The first step in creating a rich Fish Farm is to cultivate seaweed beds made up of a variety of seagrasses and seaweeds around the aquaculture facility. Beyond its role in supporting the blue carbon cycle, the facility will serve as a nature-positive environment where fish and shellfish can thrive to create a bountiful fishing ground built on a foundation of cultivated fisheries.

(3) Three Facilities

Facilities will be sited in three locations: in the bay, outside of the bay, and in the coastal zone. In this way, the facilities will take advantage of the respective differences in environment (water, temperature, depth, etc.) to create fish breeding grounds that are in tune with local ecosystems, stages of growth, and seasons of each fish species.

[Environmental Characteristics and Roles of the Three Facilities]

(4) Multi-species Aquaculture

The Fish Farm will preserve for future generations the diversity of Japan's marine products, including the cultural values associated with these products. Rather than promoting the efficiency of large-scale single-product aquaculture, the facility will carefully cultivate and provide a wide range of species with an emphasis on the local fishes that have long been familiar to local residents.

(5) Using Smart Technology

The facility will use information and communication technology (ICT), artificial intelligence (AI), and other smart technologies to address labor shortages and to improve productivity. Robots will do the work of feeding and harvesting fish and shellfish. Also, fish and shellfish growth data, feeding quantities, feed costs, and other data will be digitally managed to ensure stable and efficient aquaculture.

The Role of Seaweed Beds

The key to the success of this project are the seaweed forests and seaweed beds in the vicinity of the aquaculture facility.

Seaweed beds created on the seawall of Kansai International Airport Island Photo by Kansai Air

For many years, it has been widely recognized that seaweed beds play a critical role in the absorption of carbon dioxide, but since seaweed has a shorter life span than land plants, it was believed that most of the carbon taken up would be cycled as carbon dioxide. Recent research, however, has shown that when most types of seaweed die, they settle to the dark depths of the seafloor. The plants do not decompose and in fact are capable of storing carbon over long periods of time. For this reason, seaweed beds absorb no less carbon than forests, and for that reason seaweed beds are receiving a great deal of attention as a critical part of the blue carbon ecosystem.

Seaweed beds also function to promote nature positivity. They are a place that protects fish from waves, currents, and predators, a spawning ground for a variety of fish, and a place for immature fish, fry, and hatchlings to thrive and grow to maturity. Seaweed also provides food for abalone and sea urchins and serves as a home to small benthic organisms such as shrimps and sandworms, which in turn attract the fish that feed on these organisms.

Seaweed beds play a fundamental role in supporting coastal ecosystems by absorbing nutrients like nitrogen and phosphorous and performing photosynthesis. They purify seawater and supply oxygen to the ocean.

The Fish Farm project aims to supply nutrients from the aquaculture facility to the seaweed beds surrounding it, thereby enriching the surrounding sea and contributing to the absorption of carbon dioxide.

[Long-term storage process of blue carbon by seaweed beds]

Using Smart Technology

To transform Japan's fisheries industry into a growth industry, in addition to maintaining and rebuilding natural resources, it is essential that productivity be increased by introducing smart technologies like ICT and AI.

The fisheries industry is facing the same urgent challenges as other industries in Japan: an aging workforce and not enough people to do the work. Furthermore, about 90% of Japanese fisheries workers are self-employed small-scale coastal fisherman and there is a very real danger that the expertise of fishermen, which is a combination of intuition and know-how, will not be passed down to future generations. Smart technology is a way to solve these problems.

In this project, robots will also be used for tasks typically performed by human workers, including the feeding, sorting, and harvesting of fish. The robots will be operated remotely from an onshore control center and will analyze data and images obtained from sensors.

Take the feeding of fish and shellfish as an example, AI will be used to determine the appropriate amount of feed to be delivered at any given time based on the condition of the fish and how well they are eating. The system will be designed to minimize wasteful leftover food.

Sensors placed in the water will monitor seawater temperature, nutrient concentration, phytoplankton quantities, turbidity, and other parameters from the onshore facility. In each area of the breeding tanks, eutrophic ponds, and seagrass beds, nutrient concentrations will be maintained at levels that do not adversely affect fish and shellfish that are being bred, and any abnormalities will be reflected in the amount of water exchange and feeding.

Images from satellites and self-piloted drones will be reflected in more accurate observations and risk management. These images will also be used to quantify blue carbon effects to evaluate seaweed beds for their value as feeding grounds, as well as to monitor fishing grounds to prevent poaching.

High-resolution cameras and AI diagnostics will be used to measure individual fish to predict feeding and harvesting rates with a high degree of precision at all times. The facility will also use ultrasound to count the numbers of individual fish in holding ponds automatically.

[Examples of the Use of Smart Technology]

Feeding and growth management Feeding Feeding robot determines timing based on fish images + Al
Growth management Detects the number of fish and the size and abnormal behavior of each individual fish by using images of the fish, and determines the amount of feeding.
Cleaning and inspection Robot inspects and cleans nets and collects bottom layer residue (reports abnormal detection and records images)
Water quality control Seaweed bed Monitors margins of seaweed beds and stops supplying nutrient-rich water when concentrations are too high
Fish ponds Detects and reports abnormalities in aquaculture and eutrophic ponds
Harvesting Capture Automatic control hoists nets, and robots harvest and sort catches.
Transport Robots transport the fish from the farm to boats, and Al sorts the catch on land.
Seaweed bed assessment and monitoring Monitoring by satellite system and automated drones + radar to assess seaweed bed growth

The issue this article appears

No.63 "Fishery"

Our country is surrounded by the sea. The surrounding area is one of the world's best fishing grounds for a variety of fish and shellfish, and has also cultivated rich food culture. In recent years, however, Japan's fisheries industry has been facing a crisis due to climate change and other factors that have led to a decline in the amount of fish caught in adjacent waters, as well as the diversification of people's dietary habits.
In this issue, we examine the present and future of the fisheries industry with the hope of passing on Japan's unique marine bounty to the next generation. The Obayashi Project envisioned a sustainable fishing ground with low environmental impact, named "Osaka Bay Fish Farm".
(Published in 2024)

Drawn Fishery and Fish

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A History of Japan’s Seafood Culture: Focusing on Fermented Fish

SATO Yo-ichiro
(Director General, Museum of Natural and Environmental History, Shizuoka; and Emeritus Professor, Research Institute for Humanity and Nature)

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The Future of Our Oceans, Marine Life, and Fisheries: Biodiversity and Environmental Conservation

MATSUDA Hiroyuki
(Emeritus Professor and Specially Appointed Professor, Yokohama National University)

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What Will Be on the Table in 10 Years?: The Challenge of Fisheries GX

WADA Masaaki
(Professor, Future University Hakodate and Director, Marine IT Lab, Future University Hakodate)

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Fishery This and That

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OBAYASHI PROJECT

Osaka Bay Fish Farm - Shift from the Clean Sea to the Bountiful Sea

Concept: Obayashi Project Team

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FUJIMORI Terunobu’s “Origins of Architecture” Series No. 14: Seagrass Houses

FUJIMORI Terunobu
(Architectural historian and architect; Director, Tokyo Metropolitan Edo-Tokyo Museum; and Emeritus Professor, University of Tokyo)

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Fish Culture This and That

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