Oncorhynchus formosanus
CR

Oncorhynchus formosanus

Unknown

Photo: Wikimedia Commons (CC) via https://en.wikipedia.org/wiki/Oncorhynchus_masou_formosanus

Overview

A detailed profile for this species is sourced from the IUCN Red List of Threatened Species as assessments become available.

The Formosan landlocked salmon faces severe threats from habitat degradation in Taiwan's high-altitude streams, where rising water temperatures due to climate change exceed the species' thermal tolerance. Dam construction and water diversions have fragmented its already limited range in the Dajia River system, while agricultural runoff and sedimentation degrade water quality in remaining habitats. The species' restriction to cold mountain streams above 1,500 meters elevation makes it particularly vulnerable to warming temperatures.

Threat summary

Habitat

Endemic to cold, high-altitude mountain streams in Taiwan's Central Mountain Range, primarily in the upper Dajia River watershed above 1,500 meters elevation. Requires pristine, well-oxygenated waters with temperatures below 20°C and rocky substrates for spawning.

FRESHWATER· major

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Frequently asked questions

Why is Oncorhynchus formosanus classified as Critically Endangered?
Oncorhynchus formosanus is classified as Critically Endangered — facing an extremely high risk of extinction in the wild — because population sizes are very small, declining sharply, or restricted to a tiny range. The Formosan landlocked salmon faces severe threats from habitat degradation in Taiwan's high-altitude streams, where rising water temperatures due to climate change exceed the species' thermal tolerance. Dam construction and water diversions have fragmented its already limited range in the Dajia River system, while agricultural runoff and sedimentation degrade water quality in remaining habitats. The species' restriction to cold mountain streams above 1,500 meters elevation makes it particularly vulnerable to warming temperatures.
Where does Oncorhynchus formosanus live?
Oncorhynchus formosanus occurs in across multiple regions. Country-level distribution data is sourced from the IUCN Red List and cross-referenced with GBIF occurrences.
What are the main threats to Oncorhynchus formosanus?
The main threats to Oncorhynchus formosanus are ai-1, ai-2, ai-3, and ai-4. The full IUCN-classified threat record for this species is detailed on the species page.

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