what am i

I live in the cold , fresh water of rivers.

I am one of the rarest , warm blooded animals in the world.

I sadly shall come to extinction in roughly 50 years.

I live in the old , fungi covered dams in China.

There are about 40-70 other left of my breed.

My relatives live in the massive , blue ocean.

I breath the soft , clean air.

WHAT AM I ?

 Comment what you think i am.