Anglers in the county may flourish this year, thanks to warm weather during the winter.

Monday, April 01, 2002

Anglers in the county may flourish this year, thanks to warm weather during the winter.

The oxygen level of Albert Lea Lake during the ice season was unusually high. The Minnesota Department of Natural Resources and Freeborn County Environmental Services anticipate the conditions will result in a higher fish survival rate.

According to a survey by the DNR, the saturated oxygen level of the lake was between nine and 11 milligrams per liter this winter – a high oxygen level for the season.

DNR Area Fisheries Supervisor Jim Wagner attributes the figure to a shorter period that the lake was covered with ice during this winter season.

&uot;If the level falls below three, game fish cannot survive. If it becomes less than one, that causes a total fish kill,&uot; Wagner explained. &uot;This year, the overall fish survival rate must be high.&uot;

Much of the ice, which had started covering the lake in mid-December, has already disappeared.

The ice prevents oxygen intake from the water surface. Further, it blocks sunlight and deactivates the photosynthesis of aquatic plants.

Andy Henschel, County Environmental Services Watershed Field Technician, points out the shorter ice cover period also means more possibility for small game fish to avoid being caught by predators.

The average depth of the lake is only 3.5 feet. During the ice period, all fish tend to gather at the lower reaches of the channel, which has a depth of more than 10 feet.

Lacking in mobility, small game fish become easy prey for bigger fish, Henschel said.

A DNR survey shows a dramatic decrease in the proportion of rough fish: 80.7 percent in 1984 dropped to 36 percent in 2000. In that period, the game fish population went up slowly from 0.9 percent to 1.5 percent.

Among rough fish, carp are labeled by the DNR as the number-one enemy for water quality.

Their bottom-rooting activity destroys stands of aquatic vegetation and increases water turbidity, which makes the lake less suitable for more desirable pan and game fish.

The county has been initiating efforts to nurture game fish and improve the water quality of Albert Lea Lake.

This winter, the environmental services placed an aeration system in the middle of the lake to supply oxygen and make open water.

The Lake Committee serving the county will come up with an improvement proposal this spring. The plan will most likey include a replacement of the old Albert Lea Lake dam, dredging of bottom sediments, and temporary drawdowns of water levels.