Hokkaido Set-net Fishery (Japan)

Abstract

Through vertical integration with local industries, the large-scale set-net fishery in Todohokke, Hokkaido, which is a multispecies fishery (supported by high species diversity), has demonstrated the ability to adapt to changes in fish species composition that climate change has induced in fish landings. This fishery catches both groundfish and migratory fish at the confluence of multiple ocean currents with a fixed net at the designated fishing ground. This fishery has a passive nature and is immobile, which makes it difficult to adapt to changes in catch species over time and space, such as by adopting altered fishing strategies and fishing locations (high place attachments, immobility). Changes in sea surface temperatures and ocean heat wave effects, which are thought to be caused by climate change effects, have significantly altered the species composition of landing and changed the main landing species. Throughout its history, the local seafood industry and the landings of this fishery have shaped vertical integration. With the transition of the main landing species, the local fishing industry is able to create economic value in the fish market for new main landing species (flexible/agile infrastructure, resilience mindset). Therefore, the fishery was evaluated as being resilient to the change in fish species caused by climate change, not through the fishery alone, but by vertically integrating the fishery with the local seafood industries that require this fishery’s landing for their economic activities.

Executive Summary

The Japanese coasts are dominated by multispecies fisheries due to the significant influence that the local marine environment has on the abundance and species composition of fish available. Four distinct seasons and multiple large-scale ocean currents characterize the Japanese coastal waters, which play a substantial role in shaping the coastal environment. Fish abundance and distribution are significantly impacted by changes in the frequency and intensity of the coastal environment and the marine ecosystem structure. Due to this unique coastal environment, coastal communities in Japan have developed multispecies fisheries that catch and exploit various fish species year-round, all of which are largely distributed for and consumed as Japanese cuisine.

Japan’s large-scale, set-net fishery is the most important fishing sector amongst its coastal fisheries. This fishery involves a unique Japanese fishing method that targets diverse fish species that shift with the ever-changing coastal marine environment. The large-scale, set-net method was designed to guide pelagic and demersal fish into nets (International Center for Living Aquatic Resources Management 1980). Through this process, the set-net gears are fixed at a designated location during a certain fishing period. As a designated fishing area, the prefecture government grants set-net fishing rights to fishers (Makino 2011). The fishery is characterized by a completely passive approach with no fish chasing or landings of multiple species.

Todohokke, located in South Hokkaido, Japan, is known for its large-scale, set-net fishery, whose structure extends over 2~4 km. For more than 100 years, it has been sustained as a traditional fishery that catches more than 100 fish species commercially. They are blessed with abundant fishing grounds due to the nutrient-rich waters produced by the two ocean currents that meet there. A cold ocean current, the Oyashio Ocean Current of the North Pacific, flows southwestward along the coast of eastern Hokkaido before meeting a warm ocean current, which splits off from the Tsushima Warm Current, which flows northward across the Sea of Japan. As a result, large-scale, set-net fisheries in Todohokke catch both fish migrating through the Tsugaru Strait and from the North Pacific Ocean.

It may also be fair to argue that various currents flowing along Japan’s coastline, including Kuroshio, Oyashio, Tsushima Currents, and Liman Currents, affect the various pelagic fish species that migrate along the coast.

The fishery is characterized by these two features.

• High species diversity (ecological)
• No mobility (social-economic)

Climate change has led to a pronounced shift in the composition of fish species landing in this fishery in recent years. In large-scale, set-net fisheries, the nets are fixed to a specific fishing ground. As a consequence, changes in the migration patterns and distribution of fish species have a direct impact on this fishery’s landings. The catch of Japanese common squid, Todarodes pacificus, the most important species caught for the local processing industry, has declined sharply since 2015, while the catch of yellowtail, Seriola quinquerasiate, has increased since 2010, indicating a species shift. Squid landings have declined because of changes in spawning habitat and migration patterns associated with climate change (Sakurai et al. 2002), while yellowtail catches have risen significantly because of ocean heatwaves that occurred between 2010 and 2016 as a result of a warm water eddy caused by the Kuroshio Current which prevented the Oyashio Current from moving southward (Miyama et al. 2021).

The large-scale, set-net fishery in Todohokke is resilient in the social-economic dimension to changes in species diversity caused by climate impacts. As squid landings decrease, ex-vessel prices (i.e., sales price upon landing) increase, complementing the decrease in squid landings as a percentage of total income. Meanwhile, the local fish market develops an appropriate ex-vessel price for yellowtail, so that the ex-vessel price does not decline with a sudden increase in yellowtail landings, as the main catch shifts to yellowtail. As a result of this mechanism, even if the landings of the main fish species changes, total income does not significantly decrease.

This fishery is resilient to changes in species diversity in their landings as a result of climate change because a flexible market system is vertically linked to local industries. Vertically integrated local industries allow unit prices to adapt to changes in species composition with agility and flexibility. As a result, the annual landing value of the Todohokke set-net fishery is relatively stable and resilient to changes in the species composition of their landings.

Attributes that characterize this flexible market system and that may have had a positive impact on resilience are summarized below.

• High flexible and agile infrastructure (social-economic)
• High resilience mindset (social-economic)
• High place attachment (social-economic)