Thursday, December 5, 2013

The next generation of Clearwater Chinook

The next generation of Chinook are on their way!!!!

In August we spawned adult Chinook. Their progeny have been quietly incubating in the dark, cold heath stacks here at Dworshak Fish Hatchery. Dark? Cold? I know, it doesn't sound all that pleasant, but if you are a salmon egg a nice 37 degree heath tray is a wonderful place to call home. You have oxygen rich water flowing around you at just the right volume, light is limited so eggs can develop properly, and there are NO PREDATORS! Easy living.

Our egg sorters count and separate live and dead eggs. 

After our initial egg counting, called enumeration, we hand pick any dead eggs from the incubation trays. This job is labor intensive, but it keeps fungus growth down and our eggs and rearing environment healthy. In a few short years, these tiny embryos will grow to be 10-20 pound adults.

Jeff is removing dead eggs from a heath tray. There are 5000 eggs in each tray! This year we have about 2.15 million Chinook eggs in incubation at Dworshak. The eggs are incubated in 37 degree water (F). It is chilly in the incubation room!

A tray full of healthy eggs is a beautiful sight!!!

Twins! The center egg has two embryos inside. They are probably conjoined at the yolk sack, and unfortunately they will not survive. The egg on the left is a healthy embryo. The egg on the right is an embryo that is not forming correctly; notice how tiny the eye spots are. The top egg is dead.

With good rearing and a little luck most of these tiny eggs will be released as smolts in the spring of 2015. After that they will have to fend for themselves, but some, hopefully many, will return as adults and we will start the process again. 

Photos and Text by Angela Feldmann


  1. Thank you for sharing this fascinating information! About how many eggs will survive, develop, and be released in 2015?

  2. Our goal is to release at least 1.5 million smolts and 300,000 parr. The parr will be released in August, 2014. We see about a 90% survival from eyed egg to smolt.