Intense management' aids fingerling stocks
St. Paul State DNR officials say a combination of pond-reared walleye fingerlings, those purchased from private vendors, and yearlings strained from the ponds this spring will enable the department to surpass its fingerling stocking goals this year.
Roy Johannes, DNR Fisheries program consultant, said fingerling stocking, along with the stocking of about 14,000 pounds of yearlings this spring, should easily surpass the goal of 130,000 pounds of fish, perhaps nearing 150,000 pounds.
"We're closing in on the quota," he said this week.
Earlier this year, DNR biologists collected yearlings, or carryover fish, that eluded nets during last year's fingerling stocking and didn't succumb to winterkill this past winter.
"It's the second year we've done that," Johannes said. "We're intentionally trying to manage our rearing waters better."
The benefits of doing so are twofold: yearlings are stocked in the spring, and there are fewer predators to prey on the fry that are put in the ponds. All told, the yearling collection will be about 10 percent of this year's fingerling quota.
"We've looked at doing it in the past, but never had the time," or the money, Johannes said. Extra money has been made available through the Accelerated Walleye Program, which took effect in 2000.
Collecting carryover fish in the spring is no easy task, according to Johannes.
"You must (monitor) the water temperature closely," he said. "Fish make a run (toward shore) at ice-out, but when it gets warmer, they move offshore, so you've only got a short window when the fish are available."
The DNR currently has about 340 rearing ponds for walleyes, equally about 20,300 acres of water. Just a few years ago, rearing capacity was in the 15,000- to 16,000-acre range, Johannes said.
Still, to ensure quotas are met, the DNR purchases walleye fingerlings from private vendors. Johannes said the state Legislature made available about $500,000 for such purchases.
This year, about 20,000 pounds of fingerlings will be bought from fish-rearers. The cost per pound of fingerlings varies but was between $14 and $18 per pound, according to Johannes. Vendors are given seven geographic areas of the state on which to bid. The bid depends largely on how far fingerlings will need to be transported. Last year, he said, about 7,500 pounds of fingerlings were purchased from private vendors.
Johannes said another positive from this year's DNR fingerling crop was the size of the fish there were about 18 fingerlings per pound. Usually there are several more fish per pound. An early spring and good growth rates probably contributed to this, Johannes said.
Typically, a base quota for fingerling stocking needs is determined in the spring. Following fall surveys, "contingency" requests are made for lakes whose fry stocks didn't perform as hoped.
But, Johannes said, "Our goal is to consistently hit the 130,000 mark."
Last fall, the mark wasn't reached. Because of poor winterkill the previous winter, and subsequent predation on fry, only 97,000 pounds of fingerlings were stocked. However, in 2001, there were about 160,000 pounds of walleyes stocked in the fall.
The winterkill improved somewhat during the 2002-03 winter, Johannes said. And given a "normal" winter, this could be a good year for winterkill, which removes potential predators that didn't make it into lakes this fall. Lower water levels could decrease the amount of water flowing into ponds. The flow oxygenates the water, lessening the chance for winterkill in the shallow ponds.
Johannes said a DNR study continues in which officials use reverse-aeration to deoxygenize rearing ponds.