UNCERTAIN, Texas — Deep beneath the surface of Texas’ only naturally formed lake there used to swim a massive, open-mouthed dinosaur-era fish with a long snout and prized caviar. Now, decades after the paddlefish was almost completely wiped out, it’s coming back to Caddo Lake.

This time, the fish will be closely tracked by scientists, researchers and students in 20 schools as part of a broad collaboration between private, state and federal agencies attempting to revitalize a long-damaged ecosystem by changing the water releases from a nearby dam. Scientists believe if the paddlefish survive it will be a sign the ecosystem is recovering.