Located just a couple miles apart, Big Green Lake and Lake Puckaway couldn't be more different. Big Green, which covers 7,325 acres, is our state's deepest lake, with a maximum depth of 237 feet. Puckaway, at 5,500 acres, is one of our shallowest big lakes, with a maximum depth of only 7 or 8 feet.

Big Green is clear, cold and slow to warm up in spring. It has what biologists call a "two-story" fishery: lake trout and ciscoes in the deeper water, and walleyes, pike, bass and panfish in the shallower water. Weed growth is limited to the shallow bays and shoreline areas.

Puckaway is a wide spot in the Fox River, which enters the lake at its west end and exits at the east end. Warm, dark and fertile, Puckaway is highly productive. It supports good numbers of largemouths, northern pike, walleyes and panfish.

Carp are present in both lakes. On Puckaway, they were so numerous that they destroyed most of the aquatic vegetation and roiled the water, making life difficult for other fish species. A carp-control program was started there in 1979 when the lake was poisoned and restocked with game fish. On Big Green, carp destroyed vegetation in some shallow bays, most notably the Spring Creek inlet at the lake's east end, which was historically a walleye spawning area. Commercial fishermen are contracted to remove carp from both lakes, and barriers have been installed at both ends of Big Green to keep carp out of sensitive areas.

The outlet of Big Green is the Puchyan River, which enters the Fox well downstream of Puckaway. Department of Natural Resources fisheries biologist Dave Bartz of Montello says walleyes may have moved from one lake to the other historically, but he believes dams prevent any mixing of the two populations today. Genetic studies have confirmed that these are two distinct populations. Because of this, and because the lakes are so different, each requires a different management approach.

Al Walker and Joel Baranowski from the Green Lake Chapter of Walleyes For Tomorrow check a fyke-net catch. (Photo by the Wisconsin DNR)

MANAGING BIG GREEN
"Big Green has always been a low-density walleye lake," said Bartz. Typical of deep, cold lakes with a two-story fishery and a ciscoe population, it produces big fish, but not great numbers of them."

Bartz says walleyes once ran up Silver Creek and spawned near Ripon, but today most walleyes spawn in the lake, which can be problematic.

"A deep lake like Big Green has wide temperature fluctuations in spring," Bartz said. "Under ideal conditions, walleye eggs hatch in seven to 10 days. If an onshore wind blows cold water into an area where walleyes have spawned, the eggs may sit on the lake bottom for three weeks or more before they hatch."

The longer incubation period can subject the eggs to greater dangers, such as predation and smothering by filamentous algae, which has covered rocks in shoreline areas in recent years. Once they hatch, the tiny fry have to contend with white bass, ciscoes, rock bass and other fish that have no trouble finding them in the clear water. As a result, Bartz said, natural reproduction is low and fry survival rates are poor.

Despite the low walleye densities, walleye fishing is popular on Big Green, although the lake has a reputation of being tough to fish. Local anglers have pushed for walleye stocking on Big Green since the early 1990s. Because this is a unique population, Bartz did not want to bring in fish from anywhere else. "We told them the only way to do it was to use the Green Lake fish as brood stock," he said.

And so the Green Lake Chapter of Walleyes For Tomorrow (WFT) stepped in to help manage walleyes there. Since 1999, the chapter has netted spawning walleyes each spring, raised up to 7.5 million fry per year in a portable hatchery and released them in the lake. In 2000, they also raised and released about 12,000 fingerlings. Bartz documented an increase in walleye numbers in 2002, but was unable to do so during spring and fall electrofishing surveys in 2003 or 2004.

The WFT chapter, under the leadership of Al Walker and Joel Baranowski, wants to keep raising fry, but Bartz would rather see them put more effort into raising fingerlings, which have a much better survival rate.