About 1,000 tiny fry hatched by Leesa Lyles’ class at Warren Road Elementary School were placed into the canal last June in special cages built by science teacher Carl Hammond-Beyer and his students at Davidson Fine Arts Magnet School.
During the warmest months of July and August, oxygen levels occasionally fell below the standards for trout, but water temperatures remained in the acceptable range.
However, as the fish grew inside their submerged drum cages, things got crowded and some died.
“Space was a limiting factor, and once they got to a certain size, they also started eating each other,” Hammond-Beyer said.
During the most recent count, about 50 to 60 of the trout remained alive, and had grown from 1.5 to 2 inches in June to more than 6 inches.
The occasional drops in oxygen levels coincided with extended heavy rains during the summer, he said.
Lyles said students hope to repeat the experiment this fall and may hatch brown trout next time because they are more tolerant to temperature and oxygen level changes.
“If we get browns, we feel they might do a little better,” she said. “There has been a big learning curve during this whole process.”
Also under way will be efforts to redesign the underwater cages for the fish, with hopes of finding a way to avoid overcrowding as the fry grow into larger fish.
Hammond-Beyer and his students were awarded a $500 “innovation grant” from Georgia Tech that will be used to build better cages.
In the meantime, he said, students plan to release the surviving rainbows into the canal later this fall to let them fend for themselves.
The eventual objective, Hammond-Beyer said, is to collect data to prove to the Georgia Department of Natural Resources that the canal could support trout sufficiently to allow a recreational fishery.