By Vernon Summerlin
Walleye and its cousin, sauger, have been on the decline for a number of years. What has happened and what is being done to assure us of future fishing for members of the perch family?
Most of the pressure on walleye comes during their spawning runs when they are easier to catch. Today there is a move among Tennessee’s anglers toward year-round sport fishing for them. They are being furnished by Tennessee Wildlife Resources Agency for stocking to take care of the growing demand. As you will read later, there are two varieties of walleye that fill niches created by the damming of the Obey and Caney Fork Rivers.
WALLEYE OF YESTERDAY
Walleye have survived and thrived for 10,000 years but after dams were constructed on Tennessee rivers their numbers plummeted. The loss of habitat and spawning areas have declined to the point stocking is required, but the stocked walleye do very well in Tennessee lakes because of the forage base.
Since the building of dams on the Tennessee River, sediment has covered the gravel spawning grounds. This loss of spawning habitat caused poor to non-existent recruitment and eventual decline in walleye populations. Water level fluctuations disrupt the life cycle of walleye also. There is better recruitment during the years we have high water.
Because of the loss of habitat and mixed gene pool, it is not likely that we will ever see the likes of the walleye caught by Mabry Harper from Old Hickory in 1960. His fish weighed 25 pounds. Let’s learn why the gene pool of the great Southern walleye has become polluted from TWRA fisheries biologist Anders Myhr.
WALLEYE IN DALE HOLLOW AND CENTER HILL LAKES
Myhr heads the Region III office and addresses the changes in the walleye population in Dale Hollow since the early 1980s.
“TWRA started a tagging project in 1984,” Myhr says, “to see where the tagged fish were eventually caught and how far they traveled from where they were released. We learned that four straight years of recruitment were missed. That means there were no significant numbers of survivors of the spawns for four years. All the fish were four to 20 years old. Some walleye in Dale Hollow are 25 years old.”
Myhr was puzzled by this four-year gap in recruitment and asked why? “In looking back four years to see what had changed in the lake,” says Myhr, “I came to suspect the introduction of the alewife. Threadfin shad die off every year due to the cold weather and it was the forage base for the fish. In 1979 we stocked alewife because it is winter hardy. More research has shown that other lakes that stocked the alewife started showing loss of recruitment of some species.
“The second thing we learned from the tagging study was that there are two distinct spawning walleye populations in Dale Hollow. Before the river was impounded, there was a natural population of walleye but after the impounding, coal mining upstream hurt those fish. To repopulate the lake, some walleye from New York were brought in, as well as from other states. These new fish stayed in the lower half of the lake and the indigenous fish stayed in the upper portion of the lake. Even in the summer time, these two populations don’t overlap much.
“We were stocking every other year,” says Myhr. “We go in and net them the year we don’t stock to see if they are surviving. They are, but we still don’t see any natural reproduction. We began stocking every year when the Normandy Hatchery came on line. TWRA is trying to maintain both populations of walleye.
“The alewife has done a wonderful job of providing a stable forage base. The lack of natural reproduction of the walleye was the one drawback but we can live with it. It may have impacted the white bass too but other lakes are having trouble with white bass reproduction now. I can’t say for sure that it’s competition with the alewife that is causing the decline in their numbers. The white bass spawns right after the walleye and their young may be in competition with the alewife too.
TWO WALLEYE NICHES
“We have tried to identify the two walleye populations genetically but we have not been able to. What I think has happened is that over the years we have put so many different strains of walleye in Dale Hollow that we have complicated the fish beyond recovery.”
Since 1964, Myhr has noticed the fish in the upper population of Dale Hollow’s walleye are twice the size of the lower lake walleye. That goes back to the theory that the southern strain of walleye was larger. The world record 25-pound walleye that came from Old Hickory Lake is believed to have been a southern walleye. Arkansas has some of that strain and TWRA imports some of them.
“I’m convinced,” says Myhr, “that we have two separate strains in Dale Hollow even if it doesn’t show up genetically. There may not be a pure genetic separation, but I still believe the upper lake walleyes are natural to the waters.”
The bass population has increased dramatically over the last 15 years that the alewives have been in the lake he adds. The alewife fits a specific niche. They only come to the surface to spawn in late April and early May. Alewives stay at the thermocline and will be 40 feet deep all summer. The walleye utilizes the alewife because they are oriented to that depth in the summer. The rainbow trout and lake trout orient below the thermocline and they work on the alewife too. The smallmouth also utilizes them. Spotted and largemouth bass utilize the threadfin shad more.
Myhr collects brood fish from both walleye populations in Dale Hollow for reproduction. He takes the fish to the hatchery where they are stimulated to spawn; the eggs are fertilized, hatched and placed in rearing ponds for no more than 30 days because of cannibalism. The ponds are drained and the small walleye are taken for stocking.
Center Hill is dependent on the spawning in the Blue Hole area of the lake and Myhr says it is the only known spawning area. “During the years of low water flow the fry die and that is fairly often on Center Hill. We are trying to establish a mid-lake spawning population here like we have in Dale Hollow. We have documented that some of our stockings have worked. We’ve found some spawning close to the dam. I feel we are successful at establishing two spawning populations in Center Hill. The mid-lake spawners provide a stop gap in case we have a complete failure in the Blue Hole region.”
Myhr admits, “We have learned a lot from this experience with walleye. We should have stuck with stocking fingerlings from our own populations rather than bringing in walleye from all over. We really messed up the genetics but at the time we didn’t know any better. We biologists make mistakes like everyone else. Now we’re trying to make the best of it.”
After Center Hill was impounded, there were a lot of big walleye caught and TWRA began stocking the lake. It has had more stockings and fish from more places than Dale Hollow has. “This cost Center Hill the size advantage. Now the average size walleye in that lake is about half the size of those in Dale Hollow”, says Myhr, “and you can expect to catch a five-pounder in Dale Hollow.”
TWRA has no crystal ball that predicts the future but they have a body of scientific data to suggest their next steps. The Normandy Hatchery is an example of seeing a need in the future being prepared. That hatchery provides anglers with walleye and sauger, and several other species.