Dentry: Egg harvest exceeds expectations
April 20, 2005
A long, drawn-out spawning season kept biologists on edge wondering if they would meet their goal of 75 million walleye eggs this year, but the wearisome work paid off in spades.
Gill nets Division of Wildlife biologists set in four Front Range reservoirs from mid-March through last week finally produced nearly 90 million eggs.
After being fertilized and hatched in the safe environment of state hatcheries at Wray and Pueblo, most of the tiny walleyes (and saugeyes) will be stocked in eastern plains reservoirs in the next few days.
"We surpassed our expectations, but it was difficult," said Northeast Region senior biologist Greg Ger-lich. "There was some differential hatching, especially from Cherry Creek and Chatfield. It just drifted along."
Fearing a shortage of eggs from those two key brood reservoirs, and from Pueblo Reservoir, the Cherry Creek spawn-taking crew packed their nets off to Carter Lake, west of Berthoud, for the first time. There they were pleasantly surprised.
"Colorado Walleye Federation volunteers were very helpful this year, particularly at Carter," Ger-lich said. "We got almost 5 million eggs from Carter."
But Carter Reservoir delivered some troubling clues about post-drought challenges the division faces to fine-tune the forage/predator balance in some Front Range and northeastern plains reservoirs. "Carter has the largest males I've ever seen, but they're really skinny," Gerlich said. He said the slim walleyes point to a "forage issue."
Gerlich said baitfish are scarce in Carter, so its walleyes feed on young, stocked kokanee salmon when they can. Smaller walleyes fatten on crayfish. But when they reach 18-20 inches and need a fish diet, they have to work hard to eat.
"The larger fish are running low on groceries," Gerlich said. To address the problem, he is considering stocking spot-tail shiners or some other baitfish there. The grocery shortage also applies at nearby Horsetooth Reservoir, where biologist Ken Kehmeier has been probing the benefits of stocking shiners.
The food shortage is even worse out east, where the forage base comprises gizzard shad.
Gerlich speculates that drastic water level fluctuations caused by drought have disrupted shad spawning success. For whatever reason, the baitfish aren't as plentiful.
In hopes of fixing the shad deficit, Gerlich and Kehmeier plan to net adult shad elsewhere and stock them in the plains reservoirs in the next couple weeks before the shad spawning season. Hopefully, the shad will spawn and their progeny will prevent disaster.
Such behind-the-scenes efforts of fisheries workers ultimately are even more important to Colorado angling than high-profile walleye, trout and other stocking operations.
CATCHABLE HORDES: For several weeks, the Division of Wildlife has been ladling trout into waters around the state. This year's haul will include 3.6 million catchable-sized rainbow trout.
"Catchable" trout are stocked mainly in lakes and reservoirs to fuel "put-and-take" fisheries. Destinations include many small, urban ponds that can't support trout in summer. Check the stocking report in today's Colorado Fishing Report.
Following last year's innovative approach, the division also plans to stock 12- to 14-inch channel catfish in warmer Front Range waters. About 4,000 of the larger catfish were stocked last year. The species grows fast in warm water.
State hatcheries also plan to stock 14.4 million "subcatchable" trout for "put-and-grow" trout fisheries this year. Most of the trout are stocked in streams where natural reproduction needs a boost because of heavy fishing pressure.
In the long term, anglers at low elevations also will benefit from 46.8 million fry and fingerlings of warm-water species that are scheduled to be stocked this year. The division says the warm-water component will be 7.8 million shy of normal because of lingering low-water problems at some plains reservoirs.