Korea's only native salmon run once filled this river. Genetics show the population was distinct from Japanese stocks, making their near-extinction the loss of a unique evolutionary lineage.
A distinct genetic heritage
The Chum salmon (Oncorhynchus keta) returning to the Namdaecheon River represent a unique and isolated branch of the species. Genetic analyses using mitochondrial DNA and microsatellite markers confirm that Korean chum salmon are a distinct population. They possess a lower genetic diversity compared to larger populations in Japan, Russia, and North America, but this has made their contribution to the overall species-level gene pool evolutionarily significant. This population marks the southernmost limit of the species' geographic distribution, having migrated through the waters off Russia and Alaska to reach the Korean Peninsula.
The life of a Namdaecheon salmon begins in the river's gravel beds. After hatching, the young fry spend only a few days or weeks in freshwater before migrating downstream to the ocean. They then spend three to five years maturing in the North Pacific, undertaking a migration that can cover nearly 20,000 kilometers. As adults, they are driven by a powerful homing instinct to return to the exact stream where they were born to spawn and then die, completing their life cycle. This philopatry, or natal homing, is what has kept the Namdaecheon population genetically isolated over millennia.
A population in peril
Historically, the Namdaecheon River supported a large salmon run, with over 70% of all salmon returning to Korea choosing this river. However, populations have seen a sharp decline over the last half-century. The reasons are multifaceted and common to salmon populations globally. Dam construction alters river flows and blocks migration routes. Logging and development along riverbanks increase water temperatures by removing shade and introduce silt that can smother eggs in the gravel redds. Water pollution and the effects of climate change, which warms both rivers and oceans, further stress the fish.
In response to the declining numbers, extensive restoration efforts are underway. The Yangyang Inland Fisheries Research Institute is central, operating hatchery programs that release millions of salmon fry into the river each year. More recently, Yangyang County has invested 28.2 billion KRW to construct Korea's first dedicated natural salmon spawning ground, set for completion in 2026. This 58,152-square-meter facility aims to create optimal, naturalistic conditions for salmon to spawn, potentially increasing survival rates from less than 10% in the wild. The facility will also feature an underground observation center for ecological tourism and education.
💡Fun Facts
The Yangyang Salmon Festival, started in 1996, is held every autumn, typically in late October, to celebrate the salmon's return.
Male chum salmon returning to spawn develop dramatic changes in appearance, including large, canine-like fangs and bold, calico-like stripes of red and black.
Chum salmon are the most widely distributed of all Pacific salmon, found from Korea and Japan across to Siberia and North America, as far south as Oregon.
A pharmaceutical company in Korea extracts DNA from the milt of returning Namdaecheon salmon to produce medical and cosmetic products.
The river is a natural, public space and is always accessible. The best time to potentially view the salmon run is from late October to November. The annual Yangyang Salmon Festival takes place during this period.
Admission
Access to the river is free. The Yangyang Salmon Festival has free admission, though some hands-on activities, like salmon catching, require a participation fee.
Accessibility
The area along the Namdaecheon riverbanks, especially around the festival grounds, is generally flat and accessible.