Taiwan salmon or salmon in Taiwan? Celebrating the 100th anniversary of the discovery of Formosa landlocked salmon

Abstract

Formosa landlocked salmon (FLS), Oncorhynchus formosanus, is a Critically Endangered species (IUCN Red List, Kottelat 1996) native to Taiwan and only remaining in a small mountain stream, Chichiawan Stream in Shei-Pa National Park (Yan 2000). The species is at a critical crossroads; it is facing a variety of threats including small population numbers, fragmented habitat due to damming, invasive species, and climate change. It is thought that FLS originally migrated south from the Sea of Japan when ocean waters were cooler than they are today (Numachi et al. 1990; Gwo et al. 2008; Gwo 2019a). They inhabited one river system, the Tachia River, and became landlocked when sea level rose. It is now relegated to small populations between flood and erosion control dams. Conservation strategies will depend on how the authorities answer the question posed in the title of this paper; do they want to conserve FLS as a distinct taxonomic entity with the likelihood that it will go extinct given its limited genetic variability, or should they perform genetic rescue, thereby bringing in new genetic material from a different species/subspecies to increase genetic variability but risking the unique status of FLS?