The Taiwanese "trout", the landlocked brook masu salmon, spends its life in the upper reaches of the Tachia river in western Taiwan. This protected species is a relic of Taiwan's most recent ice-age, when the Taiwan Strait became a land bridge as ocean water was transformed into polar glaciers, which cut off the migratory paths. 

Since this salmonid needs a low temperature to survive and reproduce, it only lives in several sections of the streams high up in the mountains that are only a few kilometres in length. A study has found that the equal temperature isotherm which defines the habitat of the salmonid has moved 1.6 kilometers upstream in one decade due to global warming.

How many fish survive? it's difficult to know, but perhaps only about 1600.

Source: Wei-Chun Tseng and Chi-Chung Chen
Dept of Applied Economics, National Chung Hsing University, Taichung 40246, Taiwan
Available online 3 August 2007. Journal: Ecological Economics.