DNR: Walleye egg take a success despite squeeze of late ice-out
This spring’s late ice-out meant a shorter window of time for the Minnesota DNR to take walleye eggs for annual fish stocking. But despite a two-week late start, the agency collected enough eggs to meet stocking goals.
This year’s 10 egg-take operations met their goal of collecting 4,100 quarts of eggs, the DNR said in a release Thursday, May 10. With each quart containing an estimated 120,000 eggs, that’s about 492 million walleye eggs and is comparable to the average taken in past years.
The DNR oversees the largest walleye hatchery operation in the United States, and stocks 1,050 managed lakes on a rotating schedule that is prescribed by individual lake management plans.
After taking eggs and fertilizing them with walleye milt, the eggs are taken to hatcheries where they take about three weeks to hatch in specialized jars. Two-thirds of the fry are stocked directly into lakes within a few days of hatching. Roughly one-third of the fry hatched each year by the DNR are kept in rearing ponds throughout the summer and are stocked as fingerlings in the fall. It takes 3 to 4 years for a walleye to reach keeper size in Minnesota – about 14 to 15 inches.
A vast majority of the walleye caught by Minnesota anglers come from waters where the fish reproduce naturally – about 260 larger walleye lakes and in large rivers. But because of stocking, walleye can be found in an additional 1,050 Minnesota lakes spread throughout the state. This year’s walleye fishing season opens Saturday, May 12.
In this season of egg-take operations, Cut Foot Sioux near Deer River and Pike River near Tower experienced large numbers of fish in the traps after the first day and both operations were able to meet their goals in three days instead of the normal 6 to 8 days.
Spawning is a naturally stressful activity for fish. Egg take operations are staffed 24 hours a day so dissolved oxygen levels in the water and crowding can be monitored to minimize fish losses.
Fish spawning is triggered by day length and water temperature. The Pike River site has dark water that warms more quickly when the sun shines. Once the ice went out, water temperatures rose and the fish responded very quickly.
This year’s late ice-out could offer a silver lining for future fish numbers and anglers. Later ice-outs followed by consistently rising daily temperatures can be beneficial to developing a strong year class of walleyes. Consistently warming temperatures help create a surge in the zooplankton that provide an important food source for newly hatched fish.