1. If DNR funding permits, three samples should be collected from a particular lake on a minimum of three dates between June and September (for a total of at least nine samples: three samples on three dates). Otherwise a total of three samples per lake may be acceptable.
- Ideally, samples should be collected every three weeks beginning the first week of June during non-profile water sampling weeks.
2. On each sampling date, veliger samples should be collected from different locations in a lake using a 0.5 meter diameter, 54 micron mesh plankton net.
- Lower the net 2 meters into the water in the deepest part of the lake and pull it up vertically.
- Care should be taken to pull the net up slowly enough so that no pressure wave is created on the surface of the water.
- If you are creating a pressure wave, you are under-sampling the water column. Slow down.
3. When multiple lakes are sampled on the same day from different lake systems (i.e. Lake Mendota to Fish Lake), the net should be disinfected with vinegar between each sampling location; this will eliminate cross contamination of samples and reduce the risk of transporting veligers from lake to lake.
- Use a spray bottle of vinegar to spray the entire net, especially the inside.
4. Sampled should be preserved as soon as possible with ethanol (4 parts 95% ethanol, 1 part sample).
- Add a pinch baking soda to the sample for acidic lakes (not Madison Lakes).
- Store samples in a 250-ml plastic bottle or a pint size mason jar.
- Take samples to the DNR South Central Headquarters on S. Fish Hatchery Road.
- Include a copy of the lake maps marking where the samples were taken from.
- DNR will box and ship.