Fresno Fly Fishers For Conservation

Trout In The Classroom

Chairman: Bill Bruce

Trout in the Classroom is a program managed by the California Department of Fish and Game (DFG) which allows teachers, with a permit, to hatch trout or salmon eggs in a special aquarium incubator.  The eggs come from nearby hatcheries and the location of the classroom determines the availability of the species of salmonid to be used.  Here in Fresno the rainbow trout eggs come from the Friant hatchery and the Chinook salmon eggs come from the Snelling hatchery on the Merced River.  Some Northern California schools have the option of hatching steelhead eggs.  The special incubators needed to hatch the eggs are usually provided by sponsoring agencies such as DFG, Kings River Conservation District (KRCD), or our own Fly Fishers For Conservation.  Participating teachers must attend a workshop to become educated and to receive their permit.

The fertilized eggs are incubated at their hatchery of origin until they reach the “eyed stage”, so named because the embryo has developed to the point of having a visible eye.  At this stage the developing embryo is much less prone to mortality from movement and transfer to a new incubator.  Because salmonid eggs in the wild are buried in a nest of gravel they must be protected from light while in the classroom.  Students can watch the young fish develop for a few minutes each day.  The water in the incubator must be set at approximately 50 degrees and have a filter which pumps in air bubbles constantly.  All salmonids require water with a high amount of dissolved oxygen found only in sufficiently cold water.  One need only look at the low trout count below Friant Dam for evidence of the importance of cold water flows.  At over $500, it is the aquarium chiller which accounts for the largest expense in setting up the class aquarium.  some teachers are able to defray some of the cost by converting a small dormitory refrigerator to contain the entire 10 gallon aquarium to keep it chilled.

Hatching takes place several weeks after the arrival of the eggs at the school.  The newly hatched fish, called an alevin, has a protruding egg sac which is slowly absorbed over the course of several weeks.  The egg sac weighs the fish down and they are not able to swim freely until they “button up”or totally absorb their egg sac.  Once the “fry” are free swimming the incubator can be uncovered.  In the wild this is when the young fish are at their most vulnerable because they are out of the gravel and on their own.  Fry are fed a finely ground food provided by the hatchery.  Growth at this early stage is rapid and the teacher must plan a field trip to release the fry before they outgrow their aquarium.  Salmon and steelhead must be released in their natal stream but the rainbow trout can be stocked in the nearest acceptable river.  Most local teachers will release their fish at Lost Lake or perhaps Winton Park on the Kings River.  For students the field trip is the highlight of the whole program.  Most teachers make a day of it and use the opportunity to use the river as an outdoor classroom.

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