Based on the heavy concentration of sardines in the eastern sea, sardine (jeongeori) fishing became a full-fledged industy from the mid-1920s.

Sardine fishin became a leading Korean fishery activity with such effective development of fishery techniques and ntroduction of new techniques that in 1937, the sardine haul reached nearly 1.4 million tons.

This was a world record for the haul of a single fish species in a single fishing ground, and the fishery developed into a higher value-added industry, called the sardine “industry.”

Notably, the fish oil obtained during sadine processing supplied the greatest part of war industry oil, including fuel oil for ships, so the focus shifted to production of fish oil.

One sardine fish oil pocessing plant in the port of Cheongin handled from 5,000–6,000 to as much as 10,000 tons or more of fish oil ondaily basis.

As resources dwindled after the 1940s, the industry declined, but the sardine industry marked the beginning of modern fisheries, incorporating the latest fishing methods utilizing modern scientific technology.