Waterworks: Fish Population Assessments

COUNTING FISH ON OUR LAKE

In May and June this year Aitkin DNR Fisheries did an assessment of the fish population on our lake. On a Tuesday evening, May 26th, about 9 p.m., my neighbor noticed a boat crew out on the lake with bright lights, towing a raft near her shore, with some unusual equipment. Next morning we talked it over, and I called Rick Bruesewitz, Fisheries Supervisor, to learn what was going on at Nord Lake. It had been about one hour of “standard electrofishing” for Largemouth Bass, with his fisheries crew cruising near shore, around the perimeter of the lake.
This is what I learned about electrofishing. Using electrical probes, a charge is introduced in the water that attracts and then stuns the bass temporarily. The crew scoops up the unconscious fish and puts them in a towed tank for examination, before releasing them unharmed. The fish are measured and weighed, and a few scales are removed to estimate the fish’s age.
I also learned that this was only the beginning of a periodic population assessment of the fish in our lake. Two years ago Rick had presented an historical summary of the Nord Lake Fishery at our annual lake association meeting, dating from 1960. There would soon be a sampling of all species around the lake. He agreed to let us know in advance when the trap nets and gill nets would be placed in the lake, so that we could notice them and avoid getting tangled up with the floats and nets.

TRAP NETS AND GILL NETS

On the week of June 22-26, the three-man fisheries crew returned to set and lift nets around the lake, leaving each net in place for a few days. The trap nets are set near shore, with a float and a trap out in the water and the weighted net bottom attached onshore. The gill nets are deployed out in deep water, between two buoys a short distance apart. Lead-weighted lines hold the base of the gill nets on the lake bottom. During the week boat traffic was light, and we put out the word to residents to steer clear of these orange floats.

PRELIMINARY RESULTS

Of course, we will not disclose here exactly what was learned. The details of all Aitkin Area fishery population assessments can be viewed at the DNR office next to Southgate on Highway 169. However, a number of Largemouth Bass were collected and released, and the lengths and average weight are in a preliminary report.
There were nine trap net sets and nine gill net sets, during the week. The significant species observed included: Black Crappie, Bluegill, Dogfish, Hybrid Sunfish, Largemouth Bass, Northern Pike, Pumpkinseed, Walleye, and Yellow Bullhead.
Copies of these catches were shared with lake association members at our annual picnic last Saturday. To find out more about fish surveys - when they are scheduled and to learn about the populations on your lake of interest - just call DNR Fisheries at 927-3751.

Water Treatments

On July 1st the Aitkin Independent Age weekly newspaper ran my previous posting in its Outdoors Section, as the "Waterworks" column, published every First Wednesday over the last 11 years. A portion of the piece is included here -

MODERN WATER TREATMENT

Suburban developers buy off and take over natural open space to clear cut and bulldoze forest, farm fields, and wetlands to house the thousands who flock to the Cities for better paying jobs and for their cultural amenities. The rainfall on these made-over suburban communities runs downhill into ponds, streams, wetlands, rivers, and lakes. The roofs, asphalt driveways, patios, and chemical lawns all add their ingredients into our once beautiful waters. To escape their routine of commuting, working, and schooling, the suburban families search out a “lake place” for summer weekends. They bring their horticultural habits with them, as well as memories of winter vacations on the saltwater beaches in the Gulf of Mexico.

These Minnesota lake properties used to be the province of resort owners who offered weekly rentals with housekeeping cabins, a fishing boat, and a swimming beach.
Most of them have gone the way of the family farm, with only a few large Ruttgers or Craguns left, and quite a few RV campgrounds around the settled lakes. But a large number of northbound folks decide to buy land. Pull up a house trailer and someday maybe build a cabin or retirement home. They may find vacant resort property with cabins that can be remodeled and enlarged. Everyone wants his own dock and sand beach. In this way the shoreline on many lakes is altered, and the lake water changes from clear and transparent to not-so-clear as before. (end of excerpt)

This brings us to the Fourth of July 2009. Our lake was filled with floating algae yesterday morning on a no-wind glassy surface. The shallows in front of our dock are filling slowly, year by year, with more emergent aquatic vegetation.

Some of the shoreland residents use chemical fertilizers and herbicides to groom their lawns that reach down slope to the water's edge. Heavy rains flush these components into the lake, which takes up excess nutrients of phosphate and nitrogen. This process hastens the lake's eutrophication - the filling of a fresh water basin with more and more plant growth. What once was a clear lake becomes, over time, a green vegetation-choked wetland marsh.

Water planners in Aitkin County are providing lake stewardship guidebooks to newcomers, educational pieces in the newspaper, and briefings for lake associations, all containing information about "best practices" for taking care of the lakes and rivers we enjoy.

The lakeside image of a grassy fairway to a broad sand beach, as the ideal, is fixed in many minds. But it has nothing to do with healthy lakes in Northern Minnesota, and in fact, can lead to their decline.

My message for everyone who comes up to our lakes is this: Stop mowing or clearing any lawn or vegetation within at least 15 feet of the shore. Let the seeds in this ground sprout and grow to restore a natural filter for the shoreland runoff. It's as simple as that. A cleared narrow path about 10 feet wide is all you need for access to boating and swimming at your dock. Install no more dock structure than necessary to float your watercraft.

This is one very important way that you can help improve the quality of the lake water.