Three reservoirs used this year; care taken not to spread aquatic nuisance species
PRATT — It's walleye egg-taking time for the Kansas Department of Wildlife and Parks (KDWP), and fisheries biologists will harvest walleye eggs from three reservoirs this month. Walleye egg-taking will begin on March 18 at Cedar Bluff Reservoir, March 22 at Hillsdale Reservoir, and March 28 at Milford Reservoir. Nets will be placed to catch spawning females that provide eggs for the department's walleye and saugeye hatching programs. Fall test netting revealed large populations of big walleye in these three lakes.

With recent infestations of zebra mussels, white perch, and other aquatic nuisance species (ANS) in several Kansas reservoirs, special care will be taken to prevent the spread of these potentially-destructive species. All sperm and egg collection will take place on each lake and the fish returned to that lake immediately. Eggs will be fertilized at the lake, as well, so no fish will be moved.

On March 16, KDWP biologists began catching male sauger and milking them for milt (sperm) for the saugeye hatching program. Milt is preserved in vials that are taken to Milford Reservoir to fertilize walleye eggs. Before this fertilization takes place, however, the walleye barge will be taken off the lake and into a parking lot to complete fertilization. This will prevent any sauger milt from dripping off the barge and into the reservoir.

Biologists will work for the next few weeks collecting and fertilizing eggs, transporting them to KDWP's hatcheries at Farlington, Milford, and Pratt, and eventually stocking fish throughout the state. Some fry are stocked in hatchery ponds to be raised to fingerling size and stocked later in the summer. Others are stocked directly into lakes as fry.

In addition to walleye, the Milford Hatchery will produce the saugeye — a walleye/sauger hybrid. Saugeye grow faster and larger than sauger and are thought to be more adaptable to high flow-through reservoirs than the walleye. To prevent production of fertile saugeye that have the potential to breed with walleye already in a lake — and potentially diluting that walleye population's genetics — a "triploid induction" process will be used on some of the saugeye produced. Triploid induction is a technique that allows genetic manipulation of a chromosome number to create a potentially faster-growing, but sterile, saugeye.

KDWP's statewide harvest goal for 2010 is 103 million eggs, with a production goal of 80 million walleye, 15 million saugeye, and eight million sauger. Because fewer than 5 percent of eggs hatch in the wild, artificial spawning and hatching is used to increase egg survival rates as much as 40-50 percent. When hatchery-bound eggs reach their destination, biologists monitor incubation closely. Water flows are checked to ensure constant but controlled movement. Water temperatures and oxygen content are also routinely checked. Dead eggs rise to the top of the jars and are siphoned off each day. At 60 degrees, hatching generally occurs on the eighth or ninth day of incubation. As the fry break out of their egg cases, they are carried upward by the water into large circular holding tanks where they are held for two to four days. Then they are ready for stocking.

All this activity may not be high-profile, but it means more fish in the frying pan for Kansas anglers. In fact, the hatching process makes Kansas walleye fishing possible. As waters warm and days grow longer in late March and early April, many anglers take their cue from fisheries biologists. Walleye spawning in shallow, rocky areas — usually rip-rap along the face of dams — provide anglers the opportunity to take some very large fish.
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