関さば

Seki Saba is true mackerel caught by pole and line in Hayasui Seto off Saganoseki and landed at Saganoseki. Because the name depends on fish species, sea area, method, and landing place, it carries a boundary that can be traced on the map and at the port: Oita City, the Saganoseki Peninsula, Cape Sada, and the Hayasui Seto between them.

Hayasui Seto has fast current, complex seabed topography, and abundant feed. Around the Bungo Channel, water from the Seto Inland Sea and the Pacific side meets, bringing plankton into the fishing ground. Those conditions are linked to mackerel with firm flesh and good fat, the qualities that become visible when the fish is cut for sashimi.

Saganoseki fishers raise each fish by pole and line, then place the catch in live tanks on the boat for the return to port. The one-by-one method reduces the damage that can come from fish rubbing against nets, and it fits a fishing ground where fast current and uneven seabed make careful handling part of the work.

At port, cooperative staff use menkai, also called tsuragai, to judge size and weight from the water surface instead of weighing the fish one by one. Newly caught fish then spend a day in a separate new-fish tank. Ikejime and nerve removal are done by hand, fish by fish, so the flesh keeps its condition before it leaves Saganoseki.

Seki Saba is often presented as sashimi, with attention on firm bite and fat that softens in the mouth. Its main season runs from December through March, and late February is connected with a local festival for Seki Aji and Seki Saba. Behind that plate is the Oita Prefecture Fisheries Cooperative Saganoseki Branch, its member fishers, and a working community facing concrete pressures: around 400 fishers, an average age of 70, aging, and climate-related poor catches.