Shrinking Mekong megafish underlines risks to the river, study finds

The megafish of the Mekong River are shrinking, a new study has found. In the most comprehensive analysis of species size in Southeast Asia’s Lower Mekong Basin, researchers have tracked a generational shrinkage among the river’s iconic gargantuan fish, which are among the largest freshwater fish in the world. The size decline in the Mekong is a troubling trend for the ecosystem on which more than 65 million people across six countries depend. It also mirrors shrinkages of other megafauna in river basins around the world. “At its core, the analysis shows that the Mekong River’s biggest, slowest-to-mature fish species, and especially those at highest risk of extinction, are the ones shrinking fastest,” Zeb Hogan, a co-author of the study and biologist at the University of Nevada, Reno, said