Choshichi Yachi Shell Mound

Chōshichiyachi Shell Mound: A Window into Jōmon Fishing Culture

Tucked within the Kikyōno Industrial Park in Hachinohe City, Aomori Prefecture, the Chōshichiyachi Shell Mound (長七谷地貝塚) is one of northern Japan's most significant archaeological sites from the Initial Jōmon period. Dating back approximately 8,000 years to around 6,000 BCE, this National Historic Site preserves the remnants of a coastal settlement whose inhabitants developed a remarkably advanced fishing culture at the dawn of Japan's prehistoric era. Designated as a related asset of the UNESCO World Heritage "Jomon Prehistoric Sites in Northern Japan," Chōshichiyachi offers a rare glimpse into how ancient communities adapted to dramatic environmental changes and thrived along the shores of a now-vanished bay.

The Ancient Oirase Bay: A Lost Landscape

To understand the significance of Chōshichiyachi, one must imagine a landscape vastly different from today. Around 8,000 years ago, the earth was experiencing a period of significant warming known as the Jōmon Transgression, when sea levels rose approximately three meters higher than present levels and temperatures were about two degrees Celsius warmer. As the ocean advanced inland along the Gonohe River valley, a large, shallow inlet called the Ancient Oirase Bay (古奥入瀬湾) formed in what is now the lowland area surrounding the river.

The Chōshichiyachi settlement was established on a low hilltop at an elevation of 10 to 20 meters, overlooking this bay's extensive tidal flats. Behind the settlement, deciduous broadleaf forests of oak and beech spread across the hills, providing the community with a rich variety of both marine and terrestrial resources. This ideal location — where ocean met forest — enabled the inhabitants to develop a diverse and sustainable way of life that would endure for generations.

Why It Was Designated a National Historic Site

The Chōshichiyachi Shell Mound was designated a National Historic Site on May 25, 1981, with approximately 30,000 square meters placed under protection. The site holds exceptional value for several reasons.

First, it is one of the oldest known shell mound sites in northern Japan, predating the famous Sannai-Maruyama Site by more than 2,000 years. The shell mound was formed during the peak of the Jōmon Transgression, when sea levels reached their highest point, making it an invaluable record of environmental conditions during this critical period.

Second, the site provides extraordinary evidence of early maritime adaptation. The discovery of sophisticated bone and antler fishing tools — including combination fishhooks, open-socketed detachable harpoon heads (known as the Chōshichiyachi-type harpoon), and sewing needles — demonstrates that these early Jōmon people had already developed advanced offshore fishing techniques at a remarkably early stage of the period.

Third, the shell mound serves as a natural time capsule preserving detailed information about the ancient environment. The remains of approximately 30 species of shellfish and 20 species of fish, along with bird and mammal bones, provide scientists with an extraordinarily detailed picture of the ecosystem that sustained these early communities.

Highlights and Discoveries

Connection to the UNESCO World Heritage Jomon Sites

The Chōshichiyachi Shell Mound holds the distinction of being a related asset (関連資産) of the UNESCO World Heritage "Jomon Prehistoric Sites in Northern Japan," which was inscribed on the World Heritage List in July 2021. While it is not one of the 17 core component sites, its role in illustrating early Jōmon maritime adaptation and coastal settlement patterns makes it an important part of the broader narrative of Jōmon culture in northern Japan.

Hachinohe City is also home to the Korekawa Site, one of the 17 core World Heritage component sites, which dates from the Final Jōmon period (approximately 1,000 BCE to 300 BCE). Together, these two sites span nearly the entire arc of Jōmon civilization in the Hachinohe region — from the earliest coastal fishing communities at Chōshichiyachi to the highly refined artistic culture of the late Jōmon at Korekawa.

Visiting the Site and Hachinohe City Museum

The Chōshichiyachi Shell Mound site itself is preserved as a green open space within the Kikyōno Industrial Park area. The site is open to the public at all times without prior reservation, though there are no facilities or parking directly on site. The archaeological remains have been backfilled for preservation, so the surface appears as a peaceful grassy area. An explanatory signboard provides basic information about the site's history and significance.

To fully appreciate the discoveries from Chōshichiyachi, a visit to the Hachinohe City Museum is essential. Located within the grounds of the historic Nejo Castle Site, the museum displays a cross-section peel specimen of the shell layers, Akamidō-type pottery, bone fishhooks and harpoon heads, and other artifacts excavated from the site. The museum's archaeology exhibition hall places these finds within the broader context of Hachinohe's rich prehistoric heritage.

The Hachinohe City Museum is open from 9:00 AM to 5:00 PM (last entry at 4:30 PM) and is closed on Mondays (except the first Monday of the month and national holidays), the day following national holidays (except weekends), and during the year-end and New Year period (December 27 to January 4). General admission is 250 yen for adults, 150 yen for high school and university students, and free for elementary and junior high school students. A combination ticket with the Nejo Castle historic park is also available.

Nearby Attractions

A visit to the Chōshichiyachi Shell Mound can easily be combined with other cultural and natural attractions in the Hachinohe area.

• Nejo Castle Site (根城跡) — A National Historic Site and one of Japan's Top 100 Castles, this medieval fortress built in 1334 has been carefully reconstructed to show life during the Nanbokuchō period. It is adjacent to the Hachinohe City Museum.
• Korekawa Jomon Museum (是川縄文館) — This museum showcases artifacts from the Korekawa Site, a UNESCO World Heritage component site. Highlights include exquisite lacquerware, the famous Gasshō Dogū (praying clay figurine), and elaborately decorated Late and Final Jōmon pottery.
• Kabushima Shrine (蕪嶋神社) — A dramatic cliff-top shrine overlooking the Pacific Ocean, famous for its colony of approximately 40,000 black-tailed gulls, designated a national natural monument.
• Tanesashi Coast (種差海岸) — A designated National Scenic Beauty featuring dramatic rocky coastlines, natural grass lawns extending to the ocean's edge, and a scenic walking trail stretching over 12 kilometers.
• Hasshoku Center (八食センター) — A massive market hall offering the freshest seafood, local specialties, and grilled-at-your-table dining, perfect for experiencing Hachinohe's thriving fishing port culture.