Sturgeon pre-release measurements by Charlotte V.

On October 7, we took a trip to TNACI with the intention of observing trout spawning. When we arrived, the head of the program told us that the spawning could not take place due to the maturation of the fish. So after we put all the trout back into their tank, one person netted ten sturgeon from each tank, while another would measure each one in millimeters, someone else would measure the fish in grams, and the last person would record all of the data. There are six sturgeon tanks, and the fish are separated into each tank by size. In some tanks there was an average of 200 millimeter fish, while in others there was an average of 90 millimeters. The bigger fish tended to weigh around 20-30 grams, and the smaller fish leaned more towards the 8-12 gram range. The TNACI employees informed us that the smaller fish, because they are the same age as the bigger sturgeon, will also be released tomorrow, even though they might have a lower survival rate.

While we were gathering data about each sturgeon, Shawna Mitchell (Science coordinator @TNACI) taught us about the anatomy of the sturgeon. The sturgeon is a pretty weird looking bottom feeder, native to the Tennessee River. A sturgeon’s mouth lends itself to being a bottom feeder by being on the underside of its body, and being flat, so that it can swim along the river’s bottom picking up different things to eat such as mollusks and other crustaceans.

Another body part that’s important to a sturgeon’s survival is its barbels. The barbels are the things that hang down from its nose that move through the river silt detecting food for the sturgeon to eat. One cool adaptation that the sturgeon has is its ‘glowing’ eyes. They are small and are perched on top of the sturgeon’s head. Because sturgeon live at the bottom of the river where it’s dark, they have to be able to absorb all the light that they can and be able to reflect it so they can see. Their eyes do this for them and enable them to see predators, as well as food that might be swimming around.  

Water quality at TNACI - by Larkin B.

Today we went back to TNACI and learned how to test the sturgeon tank water to see if there is any chlorine in it. This type of testing is not normally used when testing in the field, because there is typically not any chlorine in the rivers. Tap water is used in the tanks at TNACI, so the water must be checked and treated. 

 There are 4 tanks we tested, each one is tested to make sure certain chemicals are not building up and creating a toxic environment the fish could not live in. To do this we learned how to test the pH, nitrate, and ammonia levels. 

If the water below pH of 6 or above 8.5 the water in the tank must be changed, because it is a harmful environment for the fish. 

The ammonia in the tank should be as close to zero as possible and this varies with temperature and pH. These parameters were tested using an spectophototometer and ionized water was used as the control. 

On our way out, the TNACI interns explained to us how the invasive mosquito fish is being measured as part of a study of its impacts on the barrens topminnow.