Skip to contentSoapboxEcosystemsLike flyways for birds, we need to map swimways for fishKnowing the largely unseen migration routes of freshwater fish is key to protecting species Fishers and officials carefully tag a Mekong giant catfish before it is released back into Cambodia's Mekong River in December 2024. The critically endangered species is among many fishes that migrate through one of the world's most threatened river systems.Zeb Hogan/USAID Wonders of the MekongBy Stefan Lovgren30 seconds agoFor almost a century, migratory flyways have been a cornerstone of bird conservation. Knowing where these aerial highways are helps protect habitats and monitor species through carefully mapped routes that connect breeding, feeding and resting grounds.But birds arent the only kinds of animals taking vast treks. Freshwater fish do, too.Unlike birds, whose flight paths are visible to the naked eye, these fish migrations remain hidden beneath the surfaces of rivers. This invisibility has left them largely overlooked, even as migratory freshwater fish populations worldwide have plummeted by more than 80 percent since 1970. Habitat fragmentation, overfishing and pollution have taken a devastating toll on species essential to aquatic ecosystems and human livelihoods.