Moving Outside: Spring Chinook Finally See the Light of Day

Chinook eggs and alevin

The 2012 brood of Dworshak Spring Chinook salmon have been nestled in the security and darkness of incubation trays since spawning, way back in August. In those trays eggs developed into alevin and alevin grew into fry. Fry are notoriously hungry critters, as most animal babies are. They have used up the nourishment contained in their yolk sac, have developed a working digestive system and are ready to put it to use! 

In hatchery speak we call these hungry little fry “swim-up fry” because as these fish are ready start feeding they are also ready to start swimming freely. In order to control their buoyancy (ability to move up and down in the water) they must first fill a little balloon like organ called the swim bladder. When the fish are put into raceways the first thing you see them do is “swim up” to the surface and take gulps of air to fill their swim bladder.