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

Intern Update: Feeding, Cleaning, and Sampling

Intern update

Well we have been making our summer husbandry interns work hard the last few weeks! May 23^rd we took a road trip down to Warm Springs National Fish Hatchery to pick up 2,000 juvenile sturgeon, which is their primary job this summer. We have research and conservation projects that need field work this summer as well so there is plenty to do.  It takes everyone to keep TNACI going! 

Stephen Floyd is our full-time intern this summer. Stephen comes to us from Virginia where he just graduated from Roanoke College. He has a passion for southeastern fish and is especially intrigued by Southern Appalachian Brook Trout so he is working on an independent study of this species this summer.

Stephen cleaning sturgeon trough.

Jessica holding her first sturgeon

Jessica Hubbuch is graduate student at the University of Tennessee here in Chattanooga and is working with us as a part-time intern this summer. She is currently working on some urban stream surveys with UTC and organizes their museum of biological specimens. She is working hard this summer to help TNACI organize, label and find homes for many cool specimens that we have been saving over the years from the Aquarium. Scientists are always on the lookout for preserved specimens to use as teaching tools believe it or not!

Louise McCallie and Josh Oliver are also working with TNACI this summer. They are both volunteering their time to help us a few days each week. Louise is a 2011 graduate of GPS here in Chattanooga and just finished her freshman year at Lehigh University so we are glad to have her while she is home for the summer. Josh is finishing up his biology degree at Dalton State and is helping us out one day each week to get some fisheries experience.

Whew what a crew! We are lucky to have so much good help this summer. These guys are excited to be here and ready to work hard and learn lots!

Most of the intern work has focused on caring for our lake sturgeon babies so far.  When sturgeon are so little (many of them were 1.5 cm on May 23^rd!), they need to be fed often. The first few weeks we fed four times each day so someone had to be at work at 7am and someone had to stay each evening until 8:30. Now that they are so much bigger (up to 8.5 cm!) we have reduced that to three times per day. Regardless, each time we feed there is cleaning to do. The fish eat for an hour or two with the pumps turned off and the water calm to make it easier for them to “hunt”.  If the food sits on the bottom too long it begins to degrade, which can make the water unhealthy for the small fish, so the tanks are cleaned shortly after the fish eat.  It’s a daily cycle of feeding and cleaning... much like a human baby!

We also have to sort and measure fish so all of the individuals in each tank are approximately the same size.  This minimizes competition for food. Each week we take a series of measurements on a sub-sample of fish to keep up with how fast they are growing so that we can adjust feeding amounts and make other changes as needed. At first, all 2,000 fish were in one trough tank. Currently they have been sorted into 4 tanks and as they continue to grow they will be divided into 6 troughs. This extra space helps the fish to grow but it also increases the amount of work it takes to keep everything clean. Did I mention we clean a lot?

Measuring sturgeon

Our interns also get the chance to go in the field and help with some of our conservation projects.  Last week we went to the Conasauga River to do some surveys for Conasauga Logperch (Percina jenkinsi).  Everyone paddled kayaks down the river and snorkeled in a part of the river that we had not surveyed before.  We were assessing the habitat along this stretch of river and of course, looking for our target species. Unfortunately we didn’t find any Conasauga Logperch, but there was still a lot of aquatic wildlife to be seen so we took pictures of holiday darters, tadpoles, Mobile Logperch, turtles and insects. It was a long day but worth the effort.

Evan and Louise on the Conasauga River

River Cooter

Holiday Darter 

Musk Turtle

Later this summer we will be working at the Colvard Springs restoration site and collecting fish for the Aquarium and ongoing research projects. Stay tuned to hear more about all the work we are doing this summer at TNACI while we have all this great help! 

Start of Sturgeon Season 2012!

Well it’s that time of year again!  On May 23 Kathlina took our team of new interns down to Warm Spring National Fish Hatchery to pick up our baby sturgeon for the year, a little over 2,000 fish!  These are juvenile Lake Sturgeon (Acipenser fulvescens), a very special fish that used to be abundant in the Tennessee River.  However, due to overfishing and habitat degradation they became extirpated from Tennessee in the 1960’s.  With recent water quality improvements, TNACI has been part of a long term program dedicated to returning this fish to Tennessee waters. 

Kathlina and Carlos at Warm Springs National Fish Hatchery

Kathlina and two of our husbandry interns, Jessica and Stephen

These babies are tiny now, approximately 2-3cm (0.8-1.2 inches).  But the fish can grow to be 8 ft long and around 300 pounds!  They are also incredibly long-lived, the oldest on record being 154 years old. Your grandchildren may encounter these baby fish in the future!  Since the start of this project, around 100,000 Lake Sturgeon have been released into the Tennessee River.

The fish that we picked up today will be housed at our husbandry warehouse until they are approximately 6 months old.  In the fall we will release them into the Tennessee or Cumberland River.  Stay tuned over the summer to hear updates on our sturgeon nursery!

Lake Sturgeon Release in Nashville, Tennessee

There have been a lot of things to celebrate in April:  Easter, Earth Day, the coming of spring.  For us at the Tennessee Aquarium Conservation Institute and the Tennessee Aquarium, it was a month to celebrate milestones.  The Tennessee Aquarium celebrated its 20^th birthday and the opening of a new River Giants exhibit, and TNACI celebrated the continued success of the Lake Sturgeon Reintroduction program, one of our local river giants.  Each year we release juvenile sturgeon that are about six months old and six inches long.  Occasionally we hold fish a few months longer so that they can be released at larger sizes, which is exactly what we did this year.

Lake Sturgeon are very special fish that live in many rivers across the U.S.  They are a river giant in their own right. The largest on record are 8 ft and 310 pounds, though now sizes of 5 ft and 100 pounds are more common. They can live up to 150 years and they do not reach sexual maturity until they are in their teens. While they are not listed as federally endangered, Lake Sturgeon are considered imperiled in Tennessee.  In the 1960s, a combination of habitat degradation and overfishing caused the Lake Sturgeon to become extirpated from the Tennessee River.  After some improvements in dam discharge practices as well as benefits from the Clean Water Act in 1972, a group of agencies decided to work together to bring the Lake Sturgeon back to the Tennessee River. The Tennessee River Lake Sturgeon Working Group partners include the Tennessee Aquarium Conservation Institute, Tennessee Wildlife Resources Agency, World Wildlife Fund, Tennessee Tech University, the University of Tennessee at Knoxville, U.S. Fish and Wildlife Service, Tennessee Valley Authority, United States Geological Survey, Wisconsin Department of Natural Resources, and Conservation Fisheries, Inc.

On April 27^th, we drove up to Nashville to meet up with TWRA and a group of students from Mt. Juliet, Tennessee.  We met them at Shelby Park near Shelby Bottoms Nature Center in downtown Nashville where the Cumberland River runs through the city.  Dr. Zeb Hogan, the host of Monster Fish on the National Geographic channel was in town to help the Tennessee Aquarium open the new River Giants exhibit, so he decided to come along and help us with the release. 

Dr. Anna George and Dr. Zeb Hogan

TWRA brought thirty fish that were 2-3 years old and ranged in size from 24-30 inches.  They are still very young, and will not be old enough to spawn for at least another ten years if not longer. These fish were born at Warm Springs Hatchery in Georgia and some of them lived with the TNACI for a few months before they were taken to TWRA’s hatchery. 

Each fish has a scute, the bony plate that runs along the side and back of a sturgeon, removed that designates how old it is.  We do this so that when we catch the fish on monitoring trips, we can determine how old it is. To date, 130,000 juvenile Lake Sturgeon have been released across Tennessee.

Anna showing Zeb which scute has been removed on this fish.

Fish were removed from Springfield Hatchery's truck and carried to the water by pairs of students. 

Anna helps a student remove the sturgeon from the net that carried it from the truck to the water.

A fish swims from Zeb Hogan's hands into its new environment. 

We all had a great time!  TNACI got to drive to Nashville in style in our River Giants Volkswagen Beetle. 

The TNACI team!

The kids had a good time too.  Many took the opportunity to touch these majestic fish before letting them swim away into their new home.

  

We hope that this experience will inspire these students to be conservationists.

 

All of the students who helped us with the release.

You don’t have to be a scientist to be a conservationist. Here are some easy conservation actions you can do at home.

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 19^th.  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!

Lake sturgeon tagging

As anyone who has ever spent time near our lake sturgeon touch tank knows, sturgeon aren’t covered in scales like most fish. Instead, they have five rows of bony scutes on their back and sides which are made of a substance called ganoin. These rigid plates act as a suit of armor for the fish, especially for young sturgeon where the scutes are still sharp- the scutes wear down as the fish ages and become smaller in relation to the body size of the sturgeon.

Scientists and fisheries managers use these scutes to keep track of the age of sturgeon that we raise and reintroduce into the wild. Every fish that leaves our TNACI facility has a specific scute removed to identify the age of the fish. On odd-numbered years (i.e. 2007, 2009) we remove a lateral scute from the right side of the fish; on even years we remove lateral scutes from the left side of the fish. That way, when a scientist captures a fish from the river, he or she can run their fingers down the lateral scutes of the fish, and identify the soft spot where a scute has been removed. By counting how many scutes back from the head of the fish to where the missing scute is, the scientist can identify which year the fish was born and use this data in conjunction with length and weight measurements to judge how fast the fish has grown.

The scute removal process is inexpensive and quick, but it does not allow for identification of individual fish and over many years, it becomes increasingly difficult to tell which scute was removed because the remaining scutes will migrate together and partially fill in the gap. Next week, we will talk about another tagging method we use that allows for identification of individual fish called “PIT” tagging.



-LSF