Sunday, December 09, 2012

Salmon Return to the Classroom

The school year holds many things to look forward to as we trudge along; back to school dance, Labor Day weekend, cross country, NYO, Halloween, haunted house fun, thanksgiving break, basketball season, Christmas and winter break.  There is one other time of the school year that the students start asking about around September..."When are we getting the salmon?", "Are we getting salmon again this year?", "Are the salmon eggs here yet?"  Well, the eggs arrived and the 10th graders have been caring for and monitoring the eggs since their arrival in Biology class each day.  And on December 5th, we had our first alevin hatch from its cozy egg sac and squirm out into the gravel.

During the weekends I make a habit of checking the tank just to make sure things are still going well in our little 30 gallon artificial habitat, and today I noticed that the egg basket was virtually empty.  That is right, there are only about 10 eggs left that did not hatch.  As in nature, not all will survive and I had to pull about 10 stillborns out of the tank and dispose of them.  But out of approximately 500 eyed eggs, we only had a 1-2% mortality rate.  I am very pleased with the outcomes of the project thus far, to say the least.

The fish tank is going to need some more routine maintenance before Christmas break.  The hatching of the eggs produces a foamy film that is toxic to the young alevin if it isn't removed, so we will have to perform some water changes to keep maintain good water quality.  We still may have some alevin that don't mature or die for other reasons and these will need to be removed (turkey baster style.)

By the time we are ready to leave for winter break, the alevin should be at a stable state where they simply lie on the gravel bottom and gradually consume their giant yolk sacs attached to their abdomen.  When we return from break in mid-January, we should start to see some of these alevin progressing into the next stage of development, the salmon fry stage.  This is when they start venturing up into the water column and taking air from the surface to fill their swim bladders.  Then they will remain in the water column getting stronger and feeding on the fish food that students add to the tank everyday.

The project will continue until the middle of May, when we have to wrap up the project and the school year in general.  Look forward to more salmon posts to keep everyone updated on the progress of this awesome project and incredible learning experience for our students.

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