Fish’s hearing is sensitive to the frequency of underwater sound generated by offshore wind turbines, ranging from tens to hundreds of hertz. Marine organisms living near these turbines experience prolonged exposure to underwater sound. In this study, we developed a system for measuring underwater sound pressure levels and analyzed the effects of low-frequency sound on the behavior of Pagrus major (red sea bream). Low-frequency sound (100 Hz pure tone) was emitted at 15-min intervals from an underwater speaker installed in the experimental tank. Prior to low-frequency sound emission, the fish were swimming in proximity to the speaker; however, during the initial low-frequency sound emission, the fish refrained from entering the area near the speaker. In subsequent experiments, no difference in swimming area with or without low-frequency sound was observed. Although temporary avoidance behavior was observed, these findings suggest that red sea bream gradually habituated to continuous underwater sound.

As a countermeasure against color fading of seaweed, which has been regarded as a problem in recent years, we used steelmaking slag and ammonium sulfate to perform a “composite fertilization” that elutes nutrients and trace elements and verified its effect in Nori aquafarming grounds. As a result, compared to the control area, the iron concentration in the seawater and the nitrogen, phosphorus, and iron contents in the Nori thalli were higher in the test area, and a significant color maintenance effect was observed. Conventional fertilization often involves supplying only nitrogen. However, in this study, we found that the composite fertilization provided not only nutrients such as nitrogen and phosphorus, but also trace elements such as iron, which are easily deficient in the natural environment, and had a successful effect on the growth of Nori.

The 2023 JSFE Fall Symposium “Current Status and Technical Challenges on Effective Use of Fishing Ports for Aquaculture and Propagation of Marine Resources for the promotion of Umigyou” was held on 2 December 2023. At the symposium, there were two sessions after the introduction on the outlines and purposes of this symposium. In the first session, eight resource persons gave presentations on current policies, current status and case studies on utilization of fishing ports for aquaculture and propagation of marine resources. In the second session, we had a general discussion about technical challenges on aquaculture and propagation of marine resources in sea and land areas of fishing ports to promote “Umigyou” which is once again gaining attention as the development concept of fishing villages and local fisheries mainly based on new central government policies. This paper reports the outlines of the 2023 JSFE Fall Symposium by symposium organizers.

In recent years, the environment surrounding the fisheries industry and fishing villages has continued to be challenging due to a decrease in fishery production resulting from the depletion of fishery resources, the aging of fishermen, population decline in fishing villages, and changes in the marine environment due to climate change. In this context, there is an expectation that initiatives such as UMIGYO which capitalize on the value and allure of abundant nature and unique regional resources inherent to fishing villages and respond to diverse needs, will contribute to improving regional income and securing employment opportunities. Among the expectations for UMIGYO, there is a growing demand for aquaculture. Therefore, this paper introduces case studies of aquaculture utilizing fishing ports and reports on the policies implemented by the Fisheries Agency to promote aquaculture.

Tsushima City is located on an island located between mainland Kyushu and the Korean Peninsula, serving as a border island. The surrounding waters of Tsushima are where the Tsushima Warm Current and coastal waters of the continent intersect, creating favorable fishing grounds due to the undulating seafloor topography. The diverse rias coastline is suitable for marine aquaculture. Osaki Fishing Port continues to expand as one of the premier aquaculture base ports on the island. This report introduces the synergistic effects of breakwater development aimed at securing calm areas within the port.

Utilizing existing assets such as infrastructure and value chains in fishing ports to expand aquaculture operations holds significant potential for future growth. However, if aquaculture is to compensate for the decline in fishing vessel fisheries, it requires production on a certain scale, securing large-scale fishing grounds, introducing adapted production facilities and systems, and addressing labor shortages, among other challenges. The large-scale offshore aquaculture system we are advancing excels in adapting to rough fishing environments, automation, labor-saving techniques, and data-driven production management, making it effective in addressing challenges in aquaculture operations at fishing ports. From this perspective, we examine how large-scale offshore aquaculture systems can expand the possibilities of increased aquaculture operations in fishing ports.

In recent years, the vitality of fishing villages has declined due to population decrease and aging, while diminishing aquatic resources and environmental issues have dampened fishery production. The Fisheries Agency aims to revitalize regional fisheries and enhance the vibrancy of fishing villages by promoting the development of the Umigyou. This paper reports on a method for creating breeding grounds for Japanese sea cucumbers (Apostichopus japonicus) using fishing port facilities, with the goal of revitalizing fishing villages. Sea cucumbers are important not only for domestic consumption but also as export commodities to countries like China. However, there are challenges within fishing port facilities, such as the occurrence of low-oxygen water masses and issues with release methods. This paper focuses on case studies highlighting improvements to breakwaters into seawater-exchanging structures and enhancements to sea cucumber seedling release techniques.

Seaweed beds play various roles, but they are facing decline and changes in distribution due to factors like global warming. Additionally, there is global attention on blue carbon, with hopes for climate change mitigation. Amidst this, there is a need for the development of seaweed cultivation systems resistant to damage such as grazing. Utilizing the Green Innovation Fund established last year to achieve carbon neutrality by 2050, a consortium has been formed to initiate efforts on seaweed bank systems in fishing ports. In this report, we summarize the initiatives to date, technical challenges, and compile an overview of challenges in fishing port and marine area utilization to contribute to the promotion of maritime industries.

The fishery resources are becoming scarce as the demand for fishery products rises. Consequently, the aquaculture industry will likely support the worldwide expansion of fishery product demand. However, the expansion of marine aquaculture is limited due to restrictions on suitable aquaculture areas. Therefore, land-based aquaculture is expected to expand significantly, as it is projected to have higher productivity than marine aquaculture and can be conducted almost anywhere. Consequently, the use of seawater is expected to increase. Until now, surface water intake has been most often adopted, as the equipment is simple and the construction costs are relatively low. However, this conventional method faces several problems: Surface water temperature is too high for aquaculture, while the temperature of deep ocean water is too low, leading to significant expenses in adjusting water temperature. Under these circumstances, underground seawater is being reconsidered due to its cost-effectiveness and relatively low temperature. We present a variety of seawater intake options and their methods, analyze the feasibility of underground seawater intake, and report on the planning methods for its intake.

Submarine groundwater is a water source that is less susceptible to the effects of rising seawater temperatures due to recent concerns about global warming and red tide. The Tottori Prefecture Cultivation Fisheries Center utilizes submarine groundwater for the production of juvenile fish used in aquaculture and fish farming. Since around 2012, Tottori Prefecture has been actively promoting land-based aquaculture utilizing submarine groundwater and has conducted well drilling to attract aquaculture businesses. However, the high concentrations of iron and manganese found in the submarine groundwater obtained through these efforts have posed challenges, resulting in few examples of seawater suitable for aquaculture. Nevertheless, aquaculture operations for species such as Pacific saury and flatfish have been conducted in some locations. Land-based aquaculture utilizing submarine groundwater incurs higher costs such as electricity expenses compared to offshore aquaculture. However, it offers advantages such as no offshore operations and ease of labor. Therefore, it is expected to be a less risky aquaculture method in the face of challenges such as climate change and labor shortages.

The Hashiri Fishing Port is located approximately 6 km offshore from Hashiri Island in Fukuyama City. A majority of the island’s residents are engaged in fishing, making it one of the leading fishing areas in Hiroshima Prefecture. The main catches include sardines and cultivated nori seaweed, with processing facilities being small-scale and scattered. Plans were initially made to develop new land and consolidate processing facilities, but delays in construction hindered progress. Additionally, difficulties in expanding to reclaimed land arose due to poor fishing conditions and declining prices. Consequently, the plan was revised to attract land-based aquaculture facilities instead. This initiative allowed for the collection of facility usage fees and created new employment opportunities on the island.