Most of us recognize “One fish two fish red fish blue fish” as the title of a popular children’s book by Dr. Seuss, but what does Dr. Seuss have to do with conservation?
It really isn’t that much of a stretch to link the two. Animals play prominent roles in many of Dr. Seuss’s stories, and in his book The Lorax a group of animals is pushed to near extinction as their habitat is destroyed.
This article is about lake sturgeon, a fish that was almost completely eliminated from Missouri waters because of habitat loss, pollution and overharvest. By 1910, catches of lake sturgeon were rare in Missouri.
Lake sturgeon are ancient-looking fish that feed primarily on insects, although they will sometimes eat fish and crayfish. Their mouth is a short, toothless, retractable tube that they use to suck food from the river or lake bottom. Their body is protected by numerous bony plates, each having one or more small—but sharp—raised spines.
The species is Missouri’s largest and longest-living fish. Lake sturgeon more than 100 years old and weighing more than 200 pounds are occasionally caught in several northern states and Canadian waters.
Lake sturgeon were listed as endangered in Missouri in 1974, thus protecting them from all harvest. The Department of Conservation then worked out a long-term plan that included a stocking program to help this species rebound. The first fingerlings were stocked in the mid-1980s. Lake sturgeon don’t begin reproducing until they are nearly 20 years old. After that, they only spawn every three to seven years.
As part of the long-term recovery effort, fisheries biologists have been catching and tagging fish with transmitters to track their movements and to help learn more about what habitats they prefer, what their home range is and where they will go to spawn.
Radio and ultrasonic transmitters are commonly used in fisheries work. Radio transmitters work like miniature radio stations. Each emits a different and identifiable signal. The transmitters we use are small and are powered by a C-cell battery encased in epoxy. In most cases, we have to be within a half-mile of the fish to pick up their signal.
To hear the signals, biologists use a special receiver that works just like a radio. If we want to listen for a specific fish, we simply turn the dial to its transmitter’s unique frequency.
Our receivers also include a feature that allows us to scan for all signals. The receiver stops on each fish’s frequency for several seconds, then moves on to the next one. This allows us to listen for many fish at one time.
Ultrasonic receivers emit a sound signal, rather than a radio signal. We use special listening devices placed in the water to hear these signals. All of the ultrasonic transmitters we use are on the same sound frequency, but the rhythm of the pulse is different. This allows us to listen for many fish at one time, but still allows us to identify individual fish as we get closer to them.
Rather than always referring to them by number, staff working on this project sometimes name lake sturgeon tagged with ultrasonic transmitters after characters that appear in the books of Dr. Seuss. Thing One, Thing Two, and the Lorax are just a few of the names used. Radiotagged fish are named after characters from the old Andy Griffith Show. Barney, Opie, Aunt Bea and their friends have been teaching us a lot about the lives of lake sturgeon.
Goober, a 23-pound male we caught and tagged just south of Hannibal in late March 2005, has been an especially interesting fish to follow.
After tracking him for a little over a week, he disappeared. Although we searched for him nearly every day, we didn’t find him until 10 days later. He’d moved 18 miles downriver, to the town of Louisiana. Then, for some reason, he decided to head back upstream.
Over the next six days we tracked him for another 80 miles as he made his way to Keokuk, Iowa. During that time he navigated around submerged rock dikes, through the fishing lines of shoreline anglers, and passed through three dams that break the river into large flowing pools.
This upstream movement couldn’t have been easy for Goober. During most of the year, it’s almost impossible for fish to go upstream through a dam. However, when the river is at or near flood stage, dam gates are raised. Although the water rushing through the gates is fast and turbulent, fish can dash through the gates with a burst of energy. Goober must have really wanted to go upstream to have passed through three dams.
He’s not likely to go any further upstream than Keokuk, though. The only way to move past the hydroelectric dam there is to enter a lock, a specially designed chamber that helps river boat traffic navigate around the dam. If Goober enters the lock and travels farther upstream, we might have to call for help from other states to help track him.
The initial phases of this particular project will end in 2007. We plan to continue to track our tagged fish at least until the batteries on the transmitters go dead a few years from now. Future work may include identifying habitats used by smaller fish, identifying the characteristics of chosen spawning sites and tracking fish in the Missouri and lower Mississippi rivers to see what habitats they use there.
In the meantime, the Department of Conservation will continue to stock fingerling fish to bring their numbers up. In the 22 years since stocking began, we have released almost 300,000 lake sturgeon into our big rivers. This sounds like a lot, but amounts to only one fish per acre of water. Studies from other populations have shown that it may take a minimum of three fish per acre to restore the lake sturgeon population.
Ultimately, we hope to find that our stocked fish are reproducing and that their offspring are surviving. This would allow us to discontinue stocking and should eventually allow for a limited recreational harvest.
Lake sturgeon are protected in Missouri, which means that all fish should be returned to the water unharmed immediately after being caught.
You may notice an external tag identifying the lake sturgeon as a fish marked many years ago. You might also see a wire antenna protruding from the fish’s belly, which means it is a radio-tagged fish. Do not try to remove these objects. Simply note where and when you caught the fish and approximately how long it was and contact your local Conservation office (see page 1 for a list of regional office phone numbers).
If you catch a lake sturgeon that weighs more than 20 pounds or is longer than 48 inches, record the date and location of the catch and contact your local office as soon as possible.
We expect Missouri’s lake sturgeon population to continue to recover. We are already off to a great start and are learning more about this unique species every day. With the continued support of Missouri’s citizens, we will never again have to worry about the loss of our biggest fish, and Dr. Seuss’s Lorax will remain just a story about what could happen. triangle
Would you like to learn more about Missouri’s lake sturgeon? Would you like to receive more information about Goober, Lorax, and the other sturgeon we are following? Are you a teacher interested in sturgeon lesson plans for your students?
If you answered yes to any of these questions, contact the Missouri Department of Conservation office in Hannibal at (573) 248-2530. Additional information is available about lake sturgeon on the Missouri Department of Conservation Web site.
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