三方五湖と鳥浜貝塚：縄文人の湖Jomon People of Mikata Five Lakes

Today, I am at Mikata Five Lakes (Mikata Goko) in Fukui Prefecture. Mikata Five Lakes refers to a group of five lakes—Lake Mikata, Lake Suigetsu, Lake Suga, Lake Hiruga, and Lake Kugushi—formed along Wakasa Bay facing the Sea of Japan, surrounded by gentle hills and mountains. Renowned for their serene and beautiful landscape as a prominent part of Wakasa Bay Quasi-National Park, these lakes were designated as a Ramsar Convention wetland site in 2005 due to their outstanding natural environment. A distinctive feature of Mikata Five Lakes is that each lake varies greatly in depth and salinity, ranging from freshwater to brackish and seawater, creating a rich variety of ecosystems with unique species of fish and aquatic life inhabiting each individual lake.

In particular, Lake Mikata is a freshwater environment famous for its traditional winter fishing method called tataki-ami fishing, conducted using a unique, elongated boat. Because Lake Mikata alone is freshwater, it is also renowned as a major eel-producing area. When walking from the station to the lakeside village, although today’s intense heat left the streets completely deserted, I observed a row of restaurants specializing in eel dishes. However, what fascinates me most about this area is its unique nature as a historical indicator. Among various historical sites, the Torihama Shell Mound, considered one of the most significant Jomon archaeological sites, particularly drew my attention.

Torihama Shell Mound is a wetland archaeological site located in a lowland approximately at sea level near the confluence of the Hasu River and Takase River, flowing into Lake Mikata, one of the Mikata Five Lakes. It dates from the Incipient to Early Jomon Period (approximately 13,000 to 5,500 years ago) and has gained recognition as an invaluable site for understanding the overall picture of the Jomon Period due to its extensive scale and well-preserved organic remains. Since its discovery in 1962, archaeological excavations spanning over a quarter-century have yielded numerous groundbreaking discoveries, significantly transforming previous perceptions of Jomon people.

Thanks to the wetland conditions, the site exceptionally preserved organic materials such as wood, grasses, and seeds—usually decomposed and lost—with over 250,000 such artifacts discovered, making it unparalleled in Japan. This abundance of well-preserved organic remains has allowed researchers to comprehensively reconstruct the livelihoods, environment, and culture of the Jomon Period.

Moreover, it has become apparent that climatic shifts during the Jomon Period led to migration of settlements in response to warming and cooling phases, suggesting that the area should be examined from a regional perspective, not limited to Torihama alone. Particularly transformative was the discovery of numerous dugout canoes from the Jomon Period in the southern area of Lake Mikata. Two cedar dugout canoes were found at Torihama Shell Mound, and an additional nine were discovered at the nearby Yuri Site, totaling eleven canoes. The manufacturing dates of these canoes vary significantly—from approximately 6,300 to 2,700 years ago—suggesting that Torihama-Yuri served as a harbor-like gateway to the lake.

However, unlike today, Lake Mikata during the Jomon Period extended farther southeast. Although no visible traces remain, archaeologists collectively refer to this ancient expanse as Old Lake Mikata (Ko-Mikata-ko). The Jomon people who inhabited Torihama and Yuri Sites lived adjacent to this ancient lake inlet (and were part of kinship groups migrating with climate changes). Notably, the discovered dugout canoes strongly resemble the elongated boats currently used in Lake Mikata’s fishing, suggesting continuity of traditional boat-building methods since the Jomon era.

Interestingly, analysis reveals that from the Late Jomon Period onward, these dugout canoes evolved into forms specifically designed for lake fishing. Astonishingly, evidence shows that as early as the Early Jomon Period, when local people grew tired of lake fishing, they ventured from Lake Mikata through Lake Suigetsu, Lake Suga, and Lake Kugushi, eventually reaching Wakasa Bay to engage in deep-sea fishing. Indeed, their diet was remarkably abundant, as remains of tuna, dolphins, and whales frequently found at the shell mounds indicate. This discovery overturns the previous notion that Jomon people lacked the technology to venture far offshore, clearly demonstrating that they were already adept at capturing challenging fish like tuna. Thus, it can be said that the Japanese fondness for tuna began during the Jomon Period.

Moreover, the advanced seafaring skills of these Jomon people played a significant role beyond fishing, facilitating the exchange of resources and information across regions. For example, obsidian—highly valued by Jomon people—primarily came from around Suwa in Nagano Prefecture but was also sourced from areas such as Yamagata on the Sea of Japan coast in Tohoku and Oki Islands. Similarly, sanukite was transported from Mount Nijo (Nijozan) in Osaka, and pyroxene andesite arrived from the Noto Peninsula. Even today, surveying a map of Japan reveals Wakasa as an important intersection point along the Sea of Japan, connecting eastern and western Japan during the Jomon Period. Furthermore, traveling deeper inland from Lake Mikata, one reaches the vast Lake Biwa to the south, evoking thoughts of later historical migrations towards Yamato (southern Nara Prefecture), a region that later became Japan’s political center.

This connection is not merely a product of my imagination. Just about thirty minutes east by train from Mikata Five Lakes is the city of Tsuruga, a place rich with ancient traditions. Coincidentally, having booked a hotel there, I was surprised upon leaving Tsuruga Station to encounter a statue of Tsunuga Arashito (都怒我阿羅斯等), a prince from Gaya, an ancient kingdom across the sea on the Korean Peninsula. In fact, the name Tsuruga itself originates from Tsunuga Arashito, who is said to have first called the area “Tsunuga (角鹿)” upon his arrival. This area indeed has many legends of people who came across the sea and may have served as a key gateway towards Yamato. Observations from the train journey through Wakasa reinforce this impression, as widespread rice cultivation, evident in lush, green paddy fields, remains prominent here today.

Historically, extensive rice farming around Mikata Five Lakes began around the 12th century, greatly influenced by the development of manorial estates (shoen, 荘園) as aristocratic and religious institutions expanded their domains. This influence was profound, and records indicate that intensified manor development around Mikata Five Lakes during the Kamakura Period resulted in rice paddies accounting for 72.8% of agriculture near Lake Mikata. Conversely, Lake Suigetsu lacked suitable flatlands for rice cultivation, which remains the case today.

Critically, although Japan is often perceived as the final destination or the easternmost point of migration due to its location and migrant traditions, the Jomon people at this site overturned this fixed idea. Central to this historical upheaval is a certain form of art discovered at Torihama Shell Mound. While I observed this today, I will detail it further tomorrow.

Yet, today, no one is outside. Walking through the village, I encountered vast fields and houses but met no one on the streets, as though autonomous vehicles traversed an abandoned world. While this region strongly preserves aspects of 20th-century Japan, the low population density gives the surreal impression of traveling back to the sparsely populated Jomon Period.

Having spent the entire day walking beneath the cloudless summer sky, seeking shelter near the empty lakeshore proved difficult. Interestingly, a partial reconstruction of a Jomon settlement offered respite from the sun inside a pit dwelling (竪穴住居). I never imagined avoiding the heat within such a dwelling, but beneath its thick, thatched roof supported by wooden beams, it was pleasantly dark and significantly cooler than outside. Perhaps the Jomon people, much like us today, devised ways to comfortably endure climate change. Whether the thick layers of thatch were specifically designed for protection from solar damage is uncertain, but this technology eventually spread throughout Japan, becoming a quintessential rural landscape.

With no one outside, I felt as though I had the Jomon settlement entirely to myself. Resting within the pit dwelling and experiencing this unreal atmosphere, I pondered deeply, while feeling the Wakasa breeze, how the Jomon people—Japan’s ultimate survivors—endured and overcame climate extremes and natural disasters far harsher than ours.