Lake Sturgeon Sampling 2012

TNACI loves November, and not just for the Thanksgiving holiday.  November is the month for Lake Sturgeon monitoring!  For one week TNACI and its partners in the Lake Sturgeon reintroduction project (University of Tennessee, US Fish and Wildlife, TWRA, and TVA) intensely sample the upper Tennessee River in an effort to capture sturgeon that have been released there over the last 14 years.

We actually kicked off our week of sturgeon in New Orleans at the Southeastern Fishes Council meeting where scientists from all over the Southeastern U.S. convened to share their research.  TNACI talked to this group about the Lake Sturgeon project and how far it has come in the last decade.  After catching only 5 Lake Sturgeon over 10 years, the working group enlisted the help of commercial fishermen in November 2011.  This resulted in 34 sturgeon caught over the sampling week!  They ranged from the 1999-2010 year class and the largest was 44 inches and 18 pounds.  The scientists at SFC were excited to hear about the beginning of recovery of Lake Sturgeon in the Tennessee River, and TNACI was eager to hit the water and see what happened this year.

The day after we got back from New Orleans, we met with the Lake Sturgeon team near Knoxville to begin baiting hooks and determining where to sample.  Each day’s schedule was basically the same: 

1. Pull trotlines in the morning

Kathilna pulling in lines with TWRA

2.  Re-bait

Evan baiting trotlines

Ashford chopping bait

 3.  Setting trotlines in the evening

TWRA putting out trotlines

Trotlining is a very labor-intensive fishing method, as lines must be coiled carefully within the box to ensure the lines go out without getting caught on themselves. 

Ashford coiling

Look at those beautiful coils!

Trotlining gone wrong

It was a cold week, with air temperatures in the 30’s most mornings.  The first evening we set trotlines in the rain! Thankfully, this effort in bad weather was not wasted as the team caught 17 sturgeon the first day!

Kathlina with a Lake Sturgeon

Every Sturgeon was measured and weighed.

Dave Matthews from TVA with a Lake Sturgeon

Measuring a Lake Sturgeon

We also scanned each fish for a Passive Integrative Transponder (PIT) tag.  PIT tags are basically like the microchips that are commonly used in pets.  Each tag has a unique number that can be used to identify an individual.  If the fish did not have a PIT tag, we injected one so that we can monitor recapture and movement.  

Injecting a PIT tag

Scanning for a PIT tag

We also checked to see which scutes were missing to determine the age of the fish. 

Scutes 5 & 6 appear to be missing from this fish

TVA began collecting data on the type of bottom where we were catching sturgeon by collecting sediment with a PONAR grab dredge.  The sediment composition through the sampling area did not seem to change much, as it was mostly composed of clay and some silt.

Depositing sediement

Putting out the PONAR grab dredge

Mostly clay and silt sediment from Fort Loudoun Reservoir

It was a successful week, with 52 Lake Sturgeon caught by Friday.  The biggest was nine years old, 49 inches and 17 pounds.  This is the most we have ever caught in a single sampling week and is almost double last year’s catch.  While this is a promising sign, it is still too soon to determine if this will be a self sustaining population.  Lake Sturgeon do not reproduce until they are in their teens, and the oldest fish in the Tennessee River right now are 14 years old.  We are also not sure how much dams are affecting the movement of the fish.  Some have been caught as far downstream as Kentucky Lake, but it is still yet to be seen if the dams and reservoirs will affect reproduction and recruitment.  We hope that one day there will be a healthy recreational fishery for this special animal.  But remember, it is still illegal to keep a Lake Sturgeon, so if you catch one, please release it and report it to TWRA; you will receive a certificate of appreciation.

   

Bernie with a Lake Sturgeon

TNACI Awarded Grant for a New Conservation Program

For the last 14 years, the Tennessee Aquarium Conservation Institute and its partners have been working diligently to rear Lake Sturgeon in captivity and reintroduce them into the Tennessee River.  For the last three years, we have worked with Conservation Fisheries Incorporated to breed endangered Conasauga Logperch in captivity and augment their populations in Tennessee and Georgia.  This year, TNACI was awarded a grant from the National Fish and Wildlife Foundation to create a new propagation program.

Photo of a Southern Appalachian Brook Trout in its natural environment.  Photograph by Dave Herasimtschuk. 

Southern Appalachian Brook Trout  (SABT) in Tennessee and North Carolina are distinct from the Brook Trout found elsewhere in the United States because they have been geographically isolated from their northern relatives for thousands of years.  They are under threat from habitat degradation and invasive species introduction.  Historically, they lived in cool, fast flowing streams in the southern Appalachian Mountains. Logging and agricultural practices, however, have decimated Appalachian forests, which in turn harm the waters where brook trout live.  When surrounding forests are lost from creeks, water temperature rises, oxygen levels drop, and siltation from erosion increases, all resulting in streams that can no longer support brook trout.  In addition, introduced populations of rainbow trout, brown trout, and even northern brook trout compete with native SABT for the most high quality habitat.  In the Southeast, only 3% of historic watersheds support SABT populations.  

Conservation measures for this fish have been underway over the last few years at other hatcheries in the Southeast.  However, we at TNACI are attempting to take a different approach.  In general, trout hatcheries (and hatcheries for other fish) operate on flow-through systems.  When TNACI was located in Cohutta, GA, our Lake Sturgeon were in a flow-though system.  While this is energy efficient and has the potential for housing large numbers of fish, disease transfer and escapees can be a problem.  This grant will help TNACI develop techniques for rearing SABT in recirculating systems that drastically reduce disease transfer and escape concerns.

With assistance from our partners (Tennessee Wildlife Resources Agency, the U.S. Fish and Wildlife Service, and the U.S. Forest Service) we have collected 50 Brook Trout for brood stock.  This is a beautiful fish, especially during the fall when they spawn.  All year, the fish have red spots along their sides, and their pectoral, pelvic and anal fins are red with a white leading edge.  But when spawning season arrives, the red coloring becomes much more pronounced.  

SABT in July

SABT in October

We have already stripped some of our SABT of their gametes (eggs and sperm).  It is a delicate process that involved gently squeezing the trout.  Once fish were stripped, 1% saline was added to the eggs and sperm and the solution stirred with a turkey feather.  The turkey feather is an old tradition that has been used for decades in fish hatcheries.  Now that the eggs have been fertilized they are being held at TNACI until they hatch, which takes about two weeks.  We should have babies (larval SABT) very soon!

Stripping a SABT and taking a fin clipping

Fertilized trout eggs