This is the award commemorative paper of “Weather Routing for a Fishing Vessel on the Route between Fishing Port and Fish Ground” printed in 2018. We have researched and developed the high-resolution weather routing system for fishing vessels since 2014. Weather routing is one of the methods to find minimum time route or minimum fuel consumption route by using weather information. We renewed the weather routing system of merchant ships for fishing vessels by applying a detailed grid size of weather information and a short interval of calculation. In this paper, we introduce the possibility to apply the weather routing to an actual fishing vessel, a skipjack pole and line fishing vessel and present that weather routing can influence safe navigation, energy efficiency and fishing trip planning in helping to decide a departure time for fishing grounds.

Red tides are major problems for fish aquaculture as they can cause massive mortality. To prevent fishery losses due to red tides, this study simulated the movement of red tide plankton around a fish cage using particle-based computational fluid dynamics (CFD). A scale model of a fish cage with a net height of 0.95 m and diameter of 1.0 m was used. A fish cage with a tarp in the surface zone was also studied in terms of whether it prevented the red tide from entering the cage.

The flow velocity inside the fish cage without the tarp was slightly lower, while the tarp drastically decreased the velocity inside the fish cage. Based on the simulated transport of the red tide, the inflow ratio (number particles entering the fish cage/all particles) was calculated. The inflow ratio of the fish cage without the tarp was about 100%, and was lower in the fish cage with the tarp. A tarp length three times the red tide depth was required to reduce the inflow ratio to 20%.

Using the proposed simulation, we can estimate the transport of red tide plankton and determine the effects of the red tide on aquaculture. The simulation could help fish cage designers. We believe that our method will contribute to efficient fish aquaculture.

This study performed a simultaneous towing operation by using a neuston net and a manta net with a flowmeter at the net mouth and compared the ability of each net for collecting microplastics (MPs) floating in the sea surface. The mouth of the neuston net immersed to a deeper layer and thus filtered more water, compared to the manta net. Thus, this study calculated the swept area by multiplying the distance estimated from the flowmeter and the width of the net mouth, and then expressed the concentration of MPs as the number of collected MPs per swept area, instead of the number per filtered water volume. The concentration estimated from the collected MPs by shape and size were almost equal between the two nets, and thus the results of MPs collected by the two nets are comparable. The towing distance by GPS position differed from the distance estimated from the flowmeter, depending not only on the flow direction against the ship heading during net towing, but also on net clogging by phytoplankton etc. Utilization of a flowmeter is therefore strongly recommended to assess the area swept by the net.

The bladder moon snail, Glossaulax didyma, is a carnivore and predator of bivalves, especially the commercially important asari clam, Ruditapes philippinarum. However, little information is available on natural predators against this naticid gastropod. We found small shells similar in appearance to bladder moon snail larvae, from the feces of pen shells, Atrina lischkeana, collected in Isahaya Bay on Kyushyu Island in western Japan. Ingestion of the snail larvae by pen shell has not been reported previously. To clarify if A. lischkeana can ingest the larvae of G. didyma, the larvae were experimentally fed to pen shell. Dead but incompletely digested G. didyma larvae were found in the feces of A. lischkeana after 1 day, showing that the pen shells can ingest the snail larvae, which may be potentially controlling the population of this predatory gastropod.

This paper presented the outline of the 2020 JSFE autumn symposium “Marine plastic issues and measures in fishing industries” held on 4 December 2021. At the symposium, there were four sessions with ten presentations: two presentations on the current state and future policies for marine plastic debris and fishing-related waste; two presentations on beach, floating, and benthic marine debris derived from fisheries; three presentations on case studies and future challenges for collecting marine debris by fisheries; three presentations on technical developments for reducing and recycling plastic waste derived from fishing industries. After the sessions, we had a general discussion about future policies for collecting marine debris by fisheries and challenges of technical development for reducing and recycling plastic waste derived from fishing industries.

Japan has been actively promoting international contributions to measures against marine plastic pollution, such as advocating “Osaka Blue Ocean Vision” at the G20 Osaka Summit in 2019. We are also proceeding variety of actions in Japan based on the national action plan to tackle marine plastic litter and resource circulation strategy for plastics formulated in 2019, and regarding fishery-related efforts, we have revised the fishery waste treatment guidelines and been carrying out activities to take ashore marine litter with fishermen’s cooperation. These efforts will be outlined in this article.

Marine plastic litter affects not only the environment and marine ecosystems, but also fisheries, such as contamination concern for fish catches. There are several measures made by the Fisheries Agency, for example, 1) public announcement of “Guidelines for Promotion of Systematic Disposal of Fisheries Waste” in order to promote well-planned disposal of used fishing gear; 2) development of fishing gear made of environmentally friendly materials and recycling technologies for fishing gear; and 3) promotion of fisher’s activities to bring back marine litter, etc.

Plastic marine debris is a major problem in beach marine litter issue. Most parts of fishing gear and nets are made of plastic, and it is well known that synthetic fiber ropes and fishing nets occasionally entangle and damage living organisms. It is also a big problem that plastic fishing gear deteriorates into small fragments, so called “microplastics” during use, during drifting after abandoned, and after being washed ashore. In addition, it is quite difficult to collect the abandoned fishing nets and ropes which intricately get entangled and entangled with rocks on the beach. There is an urgent need to manage used fishing gear thoroughly and to strengthen measures to prevent loss of fishing gear.

In coastal areas, the distribution density of plastic bags, plastic bottles, food packaging materials, etc., which are derived from daily life, tends to be higher in the sea areas closer to urban areas where the population density is high. On the other hand, in the offshore area, the density of foamed styrol and other uncategorized plastics was high. The average distribution density of microplastics in the offshore area were higher than that in the coastal area. The proportion of plastic products was high in the benthic litters with as floating litters, but the proportion of fishing gear including fishing nets in the benthic litters was higher than that in the floating litters. This tendency was strong in the sea areas where the fisheries and aquacultures were active.

Fishermen have a responsibility to conserve marine environment from a viewpoint of their making a living with the oceans. This paper presented marine environmental conservation activities carried out by fishermen in Munakata city, Fukuoka Prefecture: collection of benthic and floating marine debris as government-funded projects focusing on the multifunctionality of the fisheries and fishing community; and fishermen’s voluntary activity of marine debris collection during their daily fishing operation. The General Incorporated Association SeaSonS supported the collection of coastal marine debris conducted by fishermen who stopped going out fishing due to stormy weather. Analytical findings of the debris collected in this activity was also presented. In the future, in order to maintain the cooperative activities of more fishermen to collect marine debris, it is necessary to create some support system that leads to the fisherman’s income as a profitable business.

Fisheries related organizations in Hachinohe City have declared to take three actions towards Goal 14 of SDGs. One of the three actions is promotion of trawl fisher’s activity for collecting benthic marine litter toward target 14.1 (prevent and significantly reduce marine pollution including marine debris). Through the activity, it was found that fishers regarded anything other than marketable catch as marine litter, and that types of marine litter varied, depending on fishing methods. In addition, many processes performed by fishers were required to collect marine litter, and there were several factors disturbing fisher’s activity in each process, such as fisher’s feeling tedious and concern about danger in the process. Fishers play an important role in the collection of marine litter, and thus some support system as well as compensation for processing costs is necessary to promote fishers’ activity of marine litter collection.

Interviews were held with local governments and fishermen in seven areas (Kaga City, Kanazawa City, Tokyo Bay, Awaji Island, Munakata City, Yatsushiro Sea, and Aoshima Island) cooperating in the “Demonstration project: Collection of benthic debris in cooperation with fishermen” to understand the status of benthic debris and their impact. A questionnaire survey on the “motivation for starting litter collection” and “expected effects” was distributed across municipalities and fishermen in 21 prefectures and demonstration areas where benthic debris collection activities are being conducted with subsidies from the Ministry of the Environment. The interviews with the local governments and the questionnaire surveys revealed some challenges. In the future, it is necessary to organize and analyze the obtained results in more detail and include the results in the preparation of the “Manual for the Collection of Marine Debris in Cooperation with Fishermen and Municipalities (tentative name)”.

We, Refinverse, Inc., has pursued business in polyamide fishnets recycling since we established Ichinomiya Plant in 2019. Currently, we collect annual amount of about 300MT of used fishnets in cooperation with various stakeholders such as fishermen, fishnet maker, industrial waste disposer. The collected used-fishnet was firstly washed in our original process and then processed into pellets by melt extrusion. The recycled polyamide materials are mainly used for injection molding and reborn as automotive parts, construction parts, and agricultural machine parts etc. Nowadays, many fashion brands are very interested in the fishnet recycled fiber, and so we are developing the polyamide fiber made from used fishnet. We expect that the use of fishnet recycled materials expand with technological development and its application to various products as well as increase in the collection of used fishnets.

Marine plastic litter as well as CO₂ emissions that cause global warming are both urgent problem that must be solved to prevent a global environmental and ecological disaster. Modern fishing gear is made predominantly of petroleum-based plastics, which are one of the main sources of marine plastic litter. There are concerns about the impact of microplastics as well as abandoned, lost, or otherwise discarded fishing gear (so-called “ghost gear”) on ecosystems worldwide. In addition, rising sea temperatures in Japanese coastal waters caused by global warming are leading to fluctuations and declines in fishery resources. Fishery materials made of petroleum-based plastics are known to emit CO₂ during production and incineration. In this paper, we describe the current state of recycling fishery materials as well as the development of biodegradable plastic for use in fishery materials, which could be an effective solution for reducing marine plastic litter and CO₂ emissions.

The Eco Mark program, which the Japan Environment Association undertakes, is managed in accordance with ISO 14024. Certification criteria for every product category have taken the environmental burden at each the life stage (resource extraction, manufacture, distribution, use, recycling, disposal) of products into consideration. Eco Mark covers wide range of categories in terms of resource circulation for plastics since its start 30 years ago. Eco Mark launched the first ever Type I Ecolabel criteria “Products made from Recycled “Marine Plastic Litter” in Feb 2021.