Wednesday, April 4, 2012

Spring Lake Sturgeon Sampling 2012

With 9 boats and about 40 crew people we hit the water hard in search of Lake Sturgeon during the week of March 19th.  And wow what a week! TNACI sent five people up to assist TWRA, USFWS and UTK with the effort. We, the Tennessee River Lake Sturgeon Working Group, are sampling at various times of the year to learn more about their movement patterns and wild behavior and we were hoping to catch the sturgeon running up stream as the temperatures began to warm. 

Each morning, the Tennessee River Lake Sturgeon Working Group planned where each boat would set trot lines for the day.

We were surprised with an unusually warm spring and even our sampling week provided days in the mid 80’s! The weather made for an incredibly pleasant week on the water, unlike the rain, ice and cold that we experienced in November. But… the fishing was not nearly as successful. Approximately 80 trot lines were set out each day, all baited with carp and buffalo (the fish not the bovine) throughout the upper Tennessee drainage: Ft. Loudon Reservoir, Watts Bar, Melton Hill, Tellico, Chickamauga, Hiwassee, Douglas, Cherokee, etc. By Thursday morning we had managed to catch hundreds of catfish, 2 hellbenders, a few crappie, drum, buffalo and 4 Lake Sturgeon!

GIS Intern Evan Collins with a large Blue Catfish.
Media Intern Jacob Henson and Sustainability Coordinator Ashford Rosenberg pulling in a trot line.

Conservation Intern Sarah Candler with a small Flathead Catfish.

One of these prize catches was actually collected by a team of TWRA staff that was surveying for sauger below Watts Bar Dam. They were pretty surprised to get a Lake Sturgeon as by-catch but of course we were thrilled to take it off their hands. That individual was a 2003 year class fish and measured 41” long so was quite the catch.

Conservation Associate Kathlina Alford with a Lake Sturgeon

Later Thursday evening a team from UTK and TWRA were able to collect four more Lake Sturgeon with dip nets in an air boat! Of course we were glad they could double our sample size but we were all jealous of that experience and hopefully we can recreate that technique next spring. In shallow clear water Lake Sturgeon are easily identified and after dark they are stunned by the lights from a boat so can be scooped up with a dip net. This could prove to be a less labor intensive and less stressful sampling method for this species in the future.

Last November we were able to catch 30, but this spring the numbers were way down with the grand total only being eight. Wild Lake Sturgeon experience their annual spawning run each spring as the water warms up so we are anxious for signs that the released fish in Tennessee will begin spawning in the next few years. 

Each Lake Sturgeon that we catch is scanned for a PIT tag which has a unique identification number. This, along with missing scutes, tells us the age of the fish. If a tag is not found, we inject one under the skin. Weights, measurements and fin tissue for genetic analysis are also taken for each Lake Sturgeon we catch. Through this process we are learning more about how this fish behaves in our warm southern waters and we are able to monitor the success of the reintroduction program for this species.
Measuring a Lake Sturgeon
On a similar note, the Lake Sturgeon in Wisconsin have begun their spawning activity several weeks earlier than expected, so a team from USFWS left this week to go up and collect eggs for the Tennessee River reintroduction program this year. Each year they collect around 90,000 eggs to bring back to Warm Springs National Fish Hatchery where they are hatched and grown for about one month before they are disturbed to the various grow-out facilities, including TNACI. We are anxious to get our 2012 juveniles very soon!

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