Populations of Hucho taimen have declined across Russia, Mongolia, and China, and large adults are now rare in many historical reaches due to overfishing, habitat degradation, water-quality pressures, and dam effects. The species is one of 325 candidates for international protection under consideration at the Convention on Migratory Species' COP15, Campo Grande, Brazil, March 23-29. Credit: Zeb Hogan Some of the longest and most essential animal migrations on Earth take place beneath the