Triploid hybrid crappie may hold the solution for small waters
Mississippi’s large reservoirs provide great crappie fishing opportunities. Unfortunately, it’s a different story in ponds and small impoundments where crappie populations either become overabundant and chronically produce small, slow-growing fish or cycle between a few years of good crappie fishing followed by several years of abundant but small fish. For this reason, managers recommend that crappie should not be stocked into waters smaller than several hundred acres.
A non-reproducing crappie would prevent the all-too-common problem of overpopulation and, therefore, be a useful tool for small impoundment management.
The Magnolia crappie is that tool.
The Magnolia crappie is a hybrid between female white crappie and male blackstripe crappie. The blackstripe crappie is a true-breeding strain of black crappie that can be recognized by a prominent dark stripe on the back and top of its head from the dorsal fin to the snout. The blackstripe crappie occurs naturally in low numbers in several Mississippi reservoirs.
What is significant about the Magnolia crappie is that it is genetically sterile and, therefore, cannot reproduce. Sterility results from the fact that this fish has three sets of chromosomes, a condition call triploidy. Natural, reproducing crappie have two sets of chromosomes, a condition called diploidy.
The non-reproducing triploid crappie is the result of research initially conducted at the University of Mississippi and now continued by Justin Wilkens and his staff at the MDWFP North Mississippi Fish Hatchery near Enid Lake.
The triploid condition is created by subjecting the fertilized eggs from the white crappie-blackstripe crappie cross to high pressure for 2 minutes beginning at exactly five minutes after fertilization. The high pressure — 7,000 to 7,500 psi — disrupts the normal division of the chromosomes such that the developing egg retains an extra set of chromosomes.
The triploid hybrid crappie develops, grows and functions like a normal, diploid crappie. The fish might develop eggs and sperm, but the extra set of chromosomes interferes with the normal cellular process that produces eggs and sperm, so the sex products are not viable.
The North Mississippi Fish Hatchery is expecting to stock about 50,000 Magnolia crappie into lakes throughout Mississippi this fall. The fish will be about 4 inches long at stocking.
The following lakes are scheduled for stocking: Lake Charlie Capps, Lake Claude Bennett, Deer Creek, Holmes County State Park Lake, Lake Jeff Davis, Leroy Percy State Park Lake, Lake Mike Connor, Olive Branch Lake, Prentiss Walker Lake, RecCon Lake, Roosevelt State Park Lake and Simpson County Lake.
The goal of the Magnolia crappie project is 100 percent triploid offspring. Wilkens and his hatchery crew have been continually trying different procedures to reach that goal.
“So far, it has been a trade-off between high survival and high percentage of triploids,” Wilkens confided. “Two years ago we used 7,000 to 7,500 psi pressure and got 95 percent triploid fish, but survival was low.
“Last year, we lowered the pressure treatment to 6,000 psi. Survival was much better, but only 48 percent of the fish were triploids.”
Wilkens went back to 7,000 psi pressure treatment this year and expects a high percentage of triploids. By the time you read this, Wilkens will know how successful he was.
The 5 percent of fertile fish remains a problem, and the Magnolia crappie is not yet perfected for use in small ponds. Wilkens and MDWFP management biologists are not concerned about 5 percent of fertile fish right now because the fish are stocked into lakes with existing diploid crappie populations and strong bass populations that are expected to crop the little reproduction that may occur.
Funded by angler-generated Sportfish Restoration Funds, the North Mississippi Fish Hatchery is continuing to improve the production of Magnolia Crappie.
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