Friday, June 25, 2010

Growing fish

June is a busy month at TNACI. Each year in early June we receive thousands of lake sturgeon fry from Warm Springs National Fish Hatchery to grow out for release into the Tennessee and Cumberland Rivers. Together with our partner hatcheries all across the Southeast, we have already released over 90,000 fish back into Tennessee waters. Each year we are able to reintroduce larger and larger numbers of fish. Our fish arrived from Warm Springs with an average weight of 0.082 grams and a total length of 28.5 mm. As of last week, the fish have reached an average weight of 0.27 grams. This may not seem like much, but this 0.19 gram increase is an increase of over 235% in size!

Not all our fish grow at the same rate though. Some fish are doubling in size every two weeks while others seem to barely grow at all at first. This keeps us busy grading (sorting) fish into tanks with other like-sized individuals. We try to keep fish with others of similar size so that we can efficiently offer them the right sized foods and to prevent the bullying of smaller fry by larger ones. As the fish get bigger, we are able to offer them larger and more nutritious feeds. Depending on their size, each tank (there are five right now, but we’ll eventually have eight or more) is fed a different combination of newly hatched brine shrimp, chopped frozen bloodworms, frozen Cyclop-eeze, and a commercially made fish feed in pellet form.

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