When the trout turned to alevin, we visited the learning commons and observed and journaled about them. On February 17, we noticed that our alevin were starting to turn into fry. The yolk sacs were so small that you could barely see them. At least five of the alevin had already turned to fry, and we are beginning to see their rainbow colours but ALL of the trout need to be fry to be released from their nursery basket into the main fish tank. They will be ready to be released when 75% of the fry start to "swim up". This means they are ready to feed. We still have a lot to learn about our rainbow trout. For instance, some of us are still wondering why we have to squeeze the fish to get the eggs and milt out?
Here is a poem we read (written by Ms. Keet's mom): Oncorhynchus mykiss In a riffle, in a redd Tiny alevin went to bed They dreamed of rivers cold and blue Of swimming fast like fishes do. Then one day when they were bigger About the size of your index finger They developed markings on their sides The little alevins were becoming frys! They’d flex their spineless fins and flutter (the pelvic, adipose and caudal). Above the zooplankton on which they fed Before, exhausted they returned to bed. And as the frys increased in size They started eating worms and flies Until at last they were fully grown And set off to explore alone Some chose a stream some chose a lake Some thought the ocean would be really great Until the day they had the urge To return to the headwaters in a mighty surge Oncorhynchus mykiss, a rainbow trout of glory I’m glad I had this chance, to tell your family story So keep on swimming forward, keep on swimming true It’s always such a pleasure just simply watching you. Peggy Ann Schroter
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The eggs that were going to survive have all changed to Alevin now. Other eggs were either unfertilized or needed to be removed as they had a white fungus.
The alevin don't move a lot unless their nursery basket is wiggled. they don't have a need to move as they have a yolk sac that provides all their nourishment. It looks somewhat like a front facing backpack. The keen eyes of out little scientists noticed what appears to be a conjoined twin. they found four eyes peeking from one egg! Hopefully, those trout we have that are now alevin are healthy and continue to flourish and turn to fry. Our eyed eggs were picked up from the Bow habitat Station on January 25, 2018. We were given 65 eyed eggs. As of Feb 1, 2018, 5 eggs have been removed from the tank as they had turned white (see above photo caption). The Alberta hatcheries say that they typically have a mortality rate of 20% - and this is in an environment where everything is very controlled.
Thus far, our results are pretty typical. An ATU is an Accumulated Thermal Unit. It is determined by adding daily temperatures together. The ATUs on February 1st are 320 ATU. We are told we can expect our eggs to hatch into alevin between 300 - 350 ATUs. Any day now! On October 4th, the Grade 3 students went to the Bow Habitat Station to learn about Rainbow Trout. We explored the aquariums, the Discovery Centre, learned about Alberta's fish, and cast our fishing lines into the Bow Habitat Station's "Kid Can Catch" Pond.
This was an exciting opportunity to learn about the rainbow trout's life cycle and to visit the place where we will ultimately release the fish we raise this year. In fact, some of the fish circling our lines were raised and released by last year's Grade 3 students. Of note? The fish hatchery is closed to the public and will officially close on November 1st. This is in order to update their water treatment facilities which are from 1973. Yay! Something older than me finally. The hatchery is expected to remain closed for one year. Our eyed eggs we collect from the Bow Habitat Station in late January will likely come from the Cold Lake hatchery. |