The net breakage and predation are a severely damage to the manila clam, Ruditapes philippinarum, farming using the net bags in the Shigetomi tidal flat, located in the northern part of Kagoshima Bay. This study aimed to estimate the cause of net bag breakage by monitoring with interval cameras. The cameras were placed on the seafloor approximately 1 m away from the net bags to record at 5-second intervals from installation until sunset. The images were used to analyze the behavior of the species that approached the net bags. Fish behavior was divided into appearing, contacting, pecking, and pulling the net bag. Blackhead seabream, Acanthopagrus schlegelii, and yellowfin seabream, Acanthopagrus latus appeared, contacted, pecked, pulled at the net bags. There were some tears in the nets bag that were observed to be pecked and pulled by Acanthopagrus sp., and the tears of about 5–10 cm in length were enough large for the mouth of Acanthopagrus sp.to pass through. Shells were observed outside the net bags after Acanthopagrus sp. pecked the net bag. From these results, we estimated that Acanthopagrus sp. broke the net bag and prey on manila clams by removing them from the net bags.

Compared with other vessels, small vessels such as fishing boats undergo significant disturbance even under relatively small wave heights. Particularly, for small fishing boats, if a large-angle roll occurs while a fisherman is working on the deck of a parked boat, he may falling into the sea, even if capsizing does not occur. Therefore, understanding the predictability of the time-series data of ship roll motions in waves is important when investigating seaworthiness. Ueno et al. showed that the prediction method of Farmer and Sidorowich is effective for the time-series data of ship roll motion in the waves of the narrow-band response of a resonance system, which is stochastic data, and that it is superior to predictions using the conventional linear autoregressive model. In stochastic data such as the time-series data of the narrow-band response of a resonance system, because the number of neighborhood vectors changes as time progresses, the calculation may become unstable. Therefore, Ueno and Fan used a method that maintains the number of neighborhood vectors. In this study, we analyzed the number of neighborhood vectors and the prediction accuracy. It was confirmed that the optimum number of neighborhood vectors exists.

Snow crab Chionoecetes opilio catches in the western part of Sea of Japan reached their peak in the 1970s. Since then, the catch has been continuously declining to the present, and fishermen have eagerly desired the recovery of its stocks. Therefore, the national government has developed 25 protected areas by 2020 to contribute to the recovery of its stocks.

We attempted to verify the effectiveness of the protected areas by conducting surveys of population density of snow crab using crab cage trap. Survey sea areas were Tajima Protected Area 2 (T-2A), Akasaki Protected Area 2 (A-2A), and Hamada Protected Area 1 (H-1A). Tajima Protected Area 2 was found to be effective in protecting over 12th instar males and mature females. Akasaki Protected Area 2 and Hamada Protected Area 1 were also effective in protecting mature females. These protective effects are thought to be due to the water depth of the protected areas. In addition, most of the snow crabs captured were individuals with a carapace width of 60 mm or more. This result suggested that catching characteristics of crab cage trap were strongly influence.

This study concerning high-density polyethylene fishing net disposal elucidated the parameters of reclaimed oil from discarded fishing nets, with marine diesel oil and marine gas oil as a reference for comparison, and then assessed its suitability for the operation of the high-speed diesel engines in fishing vessels. From the result of the property analyses, the reclaimed oil was a flammable liquid including the ingredient of gasoline, kerosene, and marine gas oil, the flash point was 1 degree Celsius, thus it is necessary to mix it with mixing marine gas oil or marine diesel oil to use as fishing vessel fuel oil, the filter-plugging temperature was 1 degree Celsius, thus indicating the need to consider the possibility of filter blockage in cold regions. On the other hand, from the result of the engine test, the reclaimed oil showed no problem as the fuel oil in high-speed diesel engine. The reclaimed oil and the marine gas oil showed no differences in fuel consumption adjusted for calorific value and exhaust gas temperature, and NOx, SOx, CO, and CO₂ content in exhaust-gas with the reclaimed oil decreased in comparison with them in marine gas oil and marine diesel oil.

This paper describes the 30-year history of activities of the Japanese Society of Fisheries Engineering. Specifically, it outlines the chronological order of the Society’s activities in three phases: from the time of its establishment to 2000, from 2000 to 2010, and after 2010. At the end of this paper, the following appendix table is provided: 1) major events of the society (in chronological order), 2) names of past presidents and vice presidents, 3) list of society awards (awards of Japanese Society of Fisheries Engineering Society, best paper awards, encouragement awards, excellent technology awards, special awards, and student excellence awards), and 4) number of memberships.

Thirty years have passed since the Japanese Society of Fisheries Engineering was established in 1991. From the viewpoint of the Planning Committee, we summarized the contents of three representative society activities that have been conducted so far: 1) holding of annual meeting, 2) holding of symposiums, and 3) activities of research group, and presented future prospects.

The Japanese Society of Fisheries Engineering (hereafter referred to as the Society) is described in the Sea Grant Project of MIT and the Fisheries Engineering Laboratory of Hokkaido University regarding the fisheries engineering that represents the Society, but it does not necessarily show the current state. When the Society was established, it developed in a way that was different from the aspirations of Prof. Makoto Nakamura, who was the chairman at the time of the establishment of the Society. Currently, fisheries engineering including advanced marine environmental engineering, design of fishing villages and harbors, fishing boats, fishing production system, and measuring instruments is progressing in the main fields. Recently, however, the number of members has decreased, and the number of research presentations has also decreased. Now is the time to review people, goods, and money, and for example, to host international conferences and move in the direction of internationalization.

This is a summary report of the Japanese Society of Fisheries Engineers Spring Symposium 2022, 30th Anniversary Commemorative Roundtable Discussion, “The Road Ahead for Fisheries Engineering.” Before the roundtable discussion, the following were reported: 1) the current activities of the Society from its inception to the present; 2) trends in the number of papers by research field at scientific meetings; 3) trends in the number of symposia by research field; and 4) the origin of the Society, its characteristics, and proposed activities for the revitalization of the Society. In the roundtable discussion, the participants first introduced the trends of research and development in their respective fields of expertise. Then, there was a lively discussion on the direction of research and development that the fisheries engineering field should take toward the realization of the Sustainable Development Goals (SDGs) and carbon neutrality, as well as on technological issues that should be developed in the future. Finally, opinions were exchanged on the direction of the society’s activities.