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Salmonids in the Virtual Classroom


A Partnership Between TCSOS and the California Department of Fish & Wildlife

The video above is a live stream from the salmonid aquarium located in the Tuolumne County Superintendent of Schools office. Best viewed using Chrome or Safari web browsers.


When will they hatch?

The salmon eggs were added to our aquarium on Wednesday, January 6th and the anticipated hatch date is sometime in January.  Have your students check-in daily to watch for changes as the eggs, grow, hatch, become alevin, and then “button up” and become fry.  Live streaming will be available until the fry are released into the Stanislaus River sometime in early March 2021.

Hatch Worksheet

Use this worksheet and the information below to estimate the date when the salmon eggs will hatch.

Date eggs were fertilized = December 14, 2020
Date eggs were delivered = January 6, 2021
Total Thermal Units (T.U.) at hatchery = 460
Average water temperature of aquarium  = 50º F
Total Thermal Units (T.U.) required for hatching = 840

That’s a lot of eggs!

Salmon Eggs By the Numbers

Chinook Salmon lay an average of 5,400 eggs. Coming in a close second are steelhead with 4,900 eggs, and the other species ranging from 1,000+ to 3,000+ eggs.

Average Eggs Laid Per Spawning Fish


Average Survival Rate

Photo & Video Resources

Featured Video

California’s Central Valley Chinook Salmon

Featured Video

Salmon Life Cycle Song
“I Will Survive”

Amazing Life

The Lifecycle of a Salmon



The cycle begins in freshwater, when a redd, or a female’s nest of eggs, is fertilized. These eggs remain in the gravel throughout the winter, and the embryos develop. 



In the spring, the eggs hatch, and alevins emerge. These are tiny fish with the yolk sac of the egg attached to their bellies. Alevins stay close to the redd for a few months. 



Fry swim to the surface of the water, fill up their swim bladders with oxygen, and begin to feed.  Chinook fry usually spend less than 5 months in freshwater



Eventually, environmental cues cause fry to begin their migration downstream towards the oceans. At this time, smolting begins, and scales grow as they turn a silvery color.


Adult Salmon

While some salmon remain in coastal water, others migrate northward to feedings grounds. Chinook salmon may spend up to eight years in the ocean.


Spawning Salmon

Upon reaching natal streams, females build nests, or redds. These little depressions in the gravel are made by the female by turning on her side and using her tail to dislodge stones or pebbles. Males fight with other males for spawning rights with a female. The dominant male will court the female and upon spawning, they release eggs and milt simultaneously. The eggs will settle into the gravel, and the female will cover the eggs with loose gravel and move upstream in order to prepare another redd. Eventually, both the males and females die, supplying the river habitat with nutrients and the seeds of the next generation that will someday return to continue the cycle.

Learn More

The Salmonids in the Virtual Classroom and the Classroom Aquarium Education Program are just a few of the educational outreach programs provided by the California Department of Fish & Wildlife.

California’s Environmental Principles and Concepts

California’s Environmental Principles and Concepts (EP&Cs) highlight the deep relationship between humans and the natural world.

Tricia Dunlap

TCSOS STEM Coordinator

Gail Davis

Salmonids in the Classroom Program Coordinator