Lake Hamana eel

The name Hamanako unagi is anchored in the Hamanako area, defined here as Hamamatsu and Kosai. It refers to mature Japanese eel, Anguilla japonica, raised by cooperative members, with more than half of the rearing days spent beside this lake. English names include Lake Hamanako Unagi and Lake Hamanako Japanese Eel, but the center stays the same: Lake Hamanako, cooperative producers, and Japanese eel. The cooperative network also lists 27 producers, giving the name a visible community of ponds and people.

Lake Hamanako is a brackish lake where fresh water and sea water mix, and shirasu eel gather around the lake and the mouth of the Tenryu River. Around the ponds, producers have used groundwater from the Mikatahara plateau and springs near the lake, while sandy lowlands made pond building practical. The mild average temperature of about 15 degrees Celsius adds another concrete condition behind the work: water, lowland soil, and weather all meet at the pond edge.

In the Edo-period image Tokaido Gojusan Zue by Utagawa Hiroshige, skewered eel kabayaki appears at Arai-juku, tying eel eating to the old road beside Lake Hamanako. The lake is considered a birthplace of eel aquaculture, and the modern turn came in the Meiji period: Hattori Kurajiro saw Lake Hamanako from a train window during an 1897 aquaculture survey trip to Aichi, and pond culture succeeded around Maisaka in 1900. In 1949, the Hamanako Aquaculture Cooperative gave the member ponds a shared regional name.

Once shirasu eel enter the ponds, feed changes with growth; daily feeding may use kneaded feed or pellets. Shizuoka eel farming places pond care, equipment, and water-quality management in the same working routine, with rearing described as taking roughly six months to two years. Around Hamanako, the cooperative account also points to outdoor ponds in summer and houses in winter, so the path from juvenile eel to mature eel moves with water temperature, feed, and the condition of the pond.

Deshico, introduced in 2024, is a named line inside Hamanako unagi and should stay separate from the wider family. Its boundary includes cooperative-member farms, rearing in the Hamanako area from fry until the eel leaves the pond, approved feed, and two quality checks. The line also makes pond work unusually visible: refreshed pond soil, water-quality and bacteria balance, oxygen levels, and temperature management. Notes of thick flesh, tenderness, and rich fat belong to Deshico itself.

Hamanako and Shizuoka eel can be handled live, or prepared as shirayaki and kabayaki. Those forms show how a pond-raised Japanese eel enters the table without turning the regional name into a single dish. The Edo-period custom of eating eel on Doyo no Ushi no Hi gave summer a strong eel association, and Hamanako unagi is still easiest to understand through live eel, white-grilled shirayaki, sauced kabayaki, and that seasonal habit.

Continuity for Hamanako unagi also appears in parent-eel release work. After repeated poor shirasu eel catches, Japanese eel was designated endangered by IUCN, and the Lake Hamanako parent-eel release council has continued buying and releasing silver-stage parent eels since the Heisei 25 fiscal year. Participants include the aquaculture cooperative, fishery cooperative, eel-cuisine group, sales association, Shizuoka Prefecture, Hamamatsu, and Kosai, placing pond producers, fishers, and local water departments in the same lake work.