A Review of the Discovery, Research, and Conservation of the Formosan Landlocked Salmon (Oncorhynchus masou formosanus) in Taiwan

A Review of the Discovery, Research, and Conservation of the Formosan Landlocked Salmon (Oncorhynchus masou formosanus) in Taiwan

First documented in Taiwan in 1919 as Salmo formosanus, the Formosan landlocked salmon (Oncorhynchus masou formosanus) holds the distinction of being one of the southernmost subspecies of Masu salmon (Oncorhynchus masou), and one of the most tropically distributed salmonids along with the Mexican golden trout and Mexican rainbow trout. Its morphology, ecology, and genetics have since been studied extensively, with particular focus on how factors like check dams impact its distribution. However, a sharp decline in wild numbers prompted the Taiwanese government to list the salmon as endangered under the Act on Wildlife Conservation in 1989. This critical designation led to a major conservation initiative: the establishment of an artificial propagation program within Shei-Pa National Park. The restoration team quickly found success, achieving complete artificial propagation by 2004, and establishing a sustainable breeding program using captive-bred fish. Starting in 2006, the release of artificially propagated fingerlings marked the beginning of a decades-long restoration effort. The results have been remarkable. Over 30 years (1994–2024), the population has exploded from an estimated 200 individuals in 1992 to a high of 18,630 in 2023, finishing at 16,897 in 2024. Habitats have similarly expanded, growing from a single stream to a total of nine major river basins. While the wild population is now considered stable, ongoing efforts are dedicated to identifying additional suitable habitats to fully reintroduce the Formosan landlocked salmon to its historical ranges.