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Ensuring sustainable fishing with satellite data


Japanese schoolchildren are taught that fishermen use satellite data to search for the best fishing grounds. Many fishermen, especially of the younger generation, have become experts at using information and communications technology (ICT). Analyzing the latest satellite data on marine and meteorological conditions is now an integral part of their job as the seafood supply chain undergoes major changes with the dwindling catch of species like saury. For more on the subject we talked to Katsuya Saito of the Japan Fisheries Information Service Center (JAFIC), an organization dedicated to fostering change in the fishing industry by encouraging the use of satellite data.

Dr. Katsuya Saito
Director, System Planning Department, Japan Fisheries Information Service Center (JAFIC)

After graduating from the School of Marine Science and Technology of Tokai University in 1989, Katsuya Saito joined the Japan Fisheries Information Service Center in 1990. He obtained a PhD in fisheries science from the Graduate School of Fisheries Sciences, Hokkaido University, in 2003. Before assuming his present post in 2015, he served as director of JAFIC’s Department of Fishing and Oceanic Conditions. An expert in satellite oceanography and fisheries oceanography, he studies the application of satellite data and geographic information systems (GISs) to fisheries oceanography. He is a member of the Oceanographic Society of Japan and a member and councilor of the Remote Sensing Society of Japan.

-Where does the Japanese fishing industry stand today? What challenges does it face?

SAITO: A lot of people have probably heard about how poor the p saury catch is this year. In the waters around Japan, saury, Japanese flying squid, salmon, and other species can no longer be harvested in the same numbers as in the old days. There are other problems too. Japan’s fishermen are getting older, and the number of fishing boats has declined.

In response to these developments, the Japanese Fisheries Agency revised the Fishery Act in 2018 — the first revision to the law in seventy years. A new resources management system is being brought and the system of fishing licenses and fishery rights is being overhauled in under the revised act, The idea is to reinvigorate the fisheries sector as a whole, and turn it into a growth industry, while fostering a resource management-based fishery — one that sustainably exploits fisheries resources. A resource management-based approach means operating more systematically and efficiently. That in turn will require promoting “smart” fishing and leveraging ICT. The use of ICT is also crucial to making fishing more attractive to newcomers and turning it into a growth sector. And satellite data is a key part of the picture.

By sharing information with each other, fishermen are able to gather a broader range of data on where the fish are. But the decrease in the Japanese fishing fleet has reduced their ability to search for shoals of fish in this fashion. The dwindling number of fish only exacerbates the situation. Satellites can observe a large expanse of ocean in an instant. They thus have the potential to make up for this loss of capacity.

But fishery resources aren’t going to recover just because you have satellite data. Restoring resources, and reinvigorating the fishing industry, will need to be done by leveraging a wide array of data, including data from satellites.

-How can the satellite SHIKISAI (GCOM-C) be put to good use in the Japanese fishing industry as it increasingly adopts ICT? It lets you see the Earth in color. How can that help the fishing industry?

SAITO: SHIKISAI has potential applications in many different areas of the industry. At the global level, the volume of phytoplankton inferred from SHIKISAI tells you how rich the oceans are. The more phytoplankton, the more zooplankton. Small fish then come to eat the zooplankton, and bigger fish come to prey on them. Phytoplankton are at the bottom of the ocean food chain, so they’re an indicator of how rich the oceans are.

Two areas where we think SHIKISAI’s capabilities could be put to good use are inshore fishing and aquaculture. Inshore fishing and aquaculture, which take place close to the shore, require fine-grained data on the marine environment. Where are red tides located? How does river water spread as it flows into the ocean? Are the waters further offshore approaching the coast? That requires fine-grained data. With SHIKISAI, the coastline can be observed at a spatial resolution of 250 m, which is far superior to the resolution of the satellites previously used in the fishing industry.

Also important in assessing the state of the coastal marine environment is the color of the seawater. The water’s darkness is generally determined by the concentration of phytoplankton, but it also varies under the influence of other factors such as river water or household wastewater. These variations in water color are extremely subtle. It takes a sensor with highly sensitive spectral characteristics to detect them.

Coastal waters are an amalgam of many different types of water. The color of the water changes depending on the type and concentration of phytoplankton, as well as the inflow of turbid river water and household wastewater. Determining the water’s state requires making inferences based on these subtle variations in color: “This must be a red tide.” “It’s not a red tide, but there’s a lot of phytoplankton.” “This is a plume of river water.”

To take one example, changes in seawater color affect nori farms. Nori, a type of edible seaweed, competes with phytoplankton for nutrient salts. If phytoplankton proliferates and produces a red tide, the nori is steadily deprived of nutrition. SHIKISAI’s SGLI sensor tells you precisely which wavelengths of light the seawater most reflects and absorbs. That might make it possible to identify the water’s characteristics based on its color. Does it contain lots of phytoplankton? Is it a red tide? Is it turbid water clouded by suspended matter like mud washed from dry land into the sea?

-So knowing the color of the seawater enables you to detect red tides. What kind of damage does a red tide do?

SAITO: We refer to red tides as “harmful algal blooms.” Red tides, or harmful algal blooms, do a lot of damage, particularly to fisheries in coastal waters. There are many different types of red tides, or harmful algal blooms, and a wide variety of fish and industry sectors are affected. A typical example is a diatom*1 bloom, which causes nori to lose its color. The price of nori drops if the color is faded, so the occurrence of diatom blooms in the Ariake Sea of Kyushu, one of Japan’s biggest nori-producing regions, has a devastating effect on nori farming.

Red tides caused by algae like raphidophytes and dinoflagellates*2 are a threat to buri (Japanese amberjack) and red sea bream farmers because they suffocate the fish. Among the culprits are Chattonella, a type of raphidophyte, and the dinoflagellates Cochlodinium and Karenia mikimotoi. When they strike fish farms, they inflict millions of dollars in damage.

Alexandrium, a genus of dinoflagellates, causes shellfish poisoning. Toxic plankton accumulates in bivalves, making the shellfish itself poisonous. Unlike Chattonella, which harms fish, Alexandrium directly affects the person eating the shellfish, so you need to beware.

*1 The largest group of phytoplankton, characterized by their glass-like cell walls.

*2 A group of phytoplankton inhabiting both fresh and salt water. Possessing an organ called a flagellum, they are able to swim.

-How can satellite data from SHIKISAI help in the fight against red tides?

SAITO: The Japanese fishing industry has long been plagued by red tide. As soon as a prefectural fisheries experimental station is notified of a red tide, it’s ready to send out a research vessel to assess the situation. If as a result it’s found that the cell count and density of the red tide plankton exceed the benchmark, an alert is promptly issued. That much can be done without satellite data, but a ship-based survey just provides isolated scraps of information; it doesn’t really tell you whether the red tide is spreading to the waters just offshore or how it’s moving. Satellite data gives you a clear picture of its spatial distribution: it’s extended quite close to the waters offshore, say, or judging from the current it must be spreading eastward. That’s the role that satellite data can be expected to play.

Studies using satellite data to detect red tide have been done before, but the satellite resolution used was around one kilometer, which wasn’t really accurate enough to get a detailed look at a red tide. With SHIKISAI, on the other hand, which has a 250 m resolution, it may be possible to detect red tides with surgical precision. While there are higher-resolution satellites, most of them typically take observations less frequently, so they fail to offer immediacy. SHIKISAI strikes the right balance between resolution and observational frequency — once every one to two days. It’s an extremely high-performance satellite, even by global standards. Certain aspects are still at the research stage right now. The next thing we’ll need to do is get actual fishermen to look at the SHIKISAI data so we can verify it.

-How is the data obtained by SHIKISAI delivered to actual fishermen?

SAITO: The existing workflow basically goes like this. JAXA receives the satellite data and does the initial processing; then JAFIC further processes it for ease of use and promptly sends it out to fishermen and prefectural fisheries experimental stations. The same procedure is followed when supplying data from SHIKISAI. Thanks to improvements in maritime communication since the 2000s, more and more fishermen now make use of ICT: they have a computer on board that they use for receiving and manipulating information. To serve their needs, JAFIC has developed an information device for PC called Ebisu-kun. Recently a lot of them have told us they’d like to be able to access the information on smartphone and tablet as well; in response we’ve developed a tablet version of Ebisu-kun designed for ease of use on cellphone and tablet, as well as an inshore version for fishermen operating in coastal waters. Ebisu-kun is currently used on about 700 vessels. Many boats that fish pelagic species use it. We’re now getting ready to supply data from SHIKISAI as part of the content delivered by it.

One of the big advantages of Ebisu-kun is that it gives you both marine information like water temperature and meteorological information, all in one go. It even lets you check the market price of fish. That way you can use it to decide which port to unload your catch at by checking each port’s prices while still at sea.

-How will the Japanese fishing industry change as more fishermen learn to make effective use of satellite data and ICT?

SAITO: Instead of relying solely on experience and intuition as in the past, today’s fishermen also keep track of the latest marine conditions. As they search for the best fishing grounds, they analyze a full range of data, including water temperature readings taken aboard ship and temperatures observed by satellite. But the fact is that fishermen in their boats are finding that fish have disappeared from waters where they previously caught them — that the sea isn’t the same as it was last year. It’s at times like this, more than ever, that data needs to be leveraged and analyzed so that solutions can be devised. More and more fishermen will start putting data to good use. The fishing industry and the fisheries sector will, I believe, become smarter and more ICT-savvy as a result. And that will demand an even more sophisticated level of data.

Another thing: it will also be important to develop people who know how to use ICT. Japanese schoolchildren are taught that fisherman use satellite data on water temperatures to analyze where the fish may be when they go fishing. Satellite data is coming to be taken for granted in the fishing industry. Classes on the use of ICT in the fishing industry will soon begin at high schools that specialize in training students for a fisheries career. I believe that increasingly, people who enter the fishing industry will be regular ICT users who are receptive to the latest technology.

-The fourteenth of the Sustainable Development Goals (SDGs) is, “Conserve and sustainably use the oceans, seas and marine resources for sustainable development.” How can that be accomplished as the Japanese fishing industry evolves?

SAITO: Turning the entire fishing industry into a growth industry by making it ICT-savvy, while preserving fisheries resources for the next generation — that, I think, is JAFIC’s mission. It’s also consistent with the SDGs. We want to promote effective use of satellite data to that end.

Working with fisheries experimental stations in each prefecture will be important, especially when it comes to supporting inshore fishing and aquaculture. The personnel at those stations, though, often complain of being unable to make full use of satellite data and not knowing how to use it. It will therefore be important, in my view, to offer a service providing easy access to satellite data over the Internet and make data available in a form that’s user-friendly for researchers who have no expertise in satellite technology.

On our own, there’s only so much that we at JAFIC can do to promote the use of the latest satellite data and the latest technology in the fisheries sector. Partnering with JAXA and people at companies like NEC is essential for us. We hope to help promote further technological advances by informing those in the business of developing satellite technology what kind of satellite data people in the fishing industry require, and what observational capabilities they’d like to have.

Interview and article by Ayano Akiyama
Published Nov. 4, 2020

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