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Notes from July 14th, 2023, meeting of the Six-County Lakes and Rivers Meeting

Lakeside Center, Nicolet College Rhinelander, WI


9:00 Welcome/Updates: Eric Olsen, Director, UW-Extension Lakes

9:10 Wisconsin Policy Picture: Mike Engleson, Ex. Dir. Wisconsin Lakes Association

9:30: Zebra Mussels and Spiny Water Flea, Dr. Gretchen Gerrish, Director, UW Center for Limnology, Trout Lake Station

10:00: Loons and Lead Poisoning, Mark Naniot, Director of Rehabilitation, Wild Instincts, Rhinelander.

10:30 Break

10:45: Panel Discussion: Who Ya Gonna Call?

Great panel: 2 zoning directors, a sheriff’s deputy and 2 DNR wardens.


Summary Notes

Note – some of these results have been augmented by R. Garrett

9:10 session – no helpful information

9:30 session – helpful and full of scary info. Zebra mussels.  Wisconsin is infested with Zebra mussels in many counties.  Here is info from the web on the distribution identification of Zebras:


Zebra Mussels

The material on the next page shows the distribution of the Zebras in the state; they exist in many Wisconsin counties.  We must do all in our power to keep them out of our lakes. 

Note the language to the left of the map:

Female zebra mussels can produce up to 1 million eggs per year. The larval, veligers, hatch in 3 to 5 days and develop byssal threads (strong, rootlike protein structures) soon afterwards, which allow them to attach tightly to surfaces. Veligers can spend up to a month free-floating in the water column before finding suitable habitat to attach onto using their byssal threads. The free-floating larval stage combined with the large number of offspring zebra mussels can produce allows them to quickly spread.


Spiny Water Flea. 

From DNR document:

  • Spiny and fishhook water fleas are predators – they eat smaller zooplankton (planktonic animals), including Daphnia. This puts them in direct competition with juvenile fish for food.
  • Young fish have trouble eating these water fleas due to their long, spiny tails.
  • The spiny and fishhook water fleas produce rapidly through parthenogenesis, commonly known as asexual reproduction, which means that no males are required, and populations can explode.

Dr. Gerrish said a single flea produces 10 offspring every 2 weeks. She says a single invader can produce 1 million offspring in 10 weeks. Here is the distribution of this major pest:

The spiny water flea was first identified in North American in 1984 in Lake Huron. Native to Russia’s Lake Ladoga, adjacent to the Baltic Sea, it arrived in the Midwest in the early 1980s after ships from European ports discharged ballast water into the St. Laurence River.

In the quarter-century since, the aquatic hitchhikers have spread by the “billions” across all the Great Lakes. The creatures have begun to invade “our most pristine lakes,” the smaller inland waters of the Midwest and Canada.

Fleas are in Trout, Plum, Ike Walton, Stormy and Star Lake.

How do we prevent these terrible invasives from reaching our lakes?

  1. Avoid movement water between lakes.
  2. Don’t move sediments between lakes.
  3. Wash and scrub boats, ropes, fishing gear, etc. for boats operating near infested areas.
  4. Let boats dry for 5 days between lakes.
  5. Don’t dump bait buckets into new water.
  6. Gut fish on land and do not throw internals into new water.

Dr. Gerrish invited us all to attend the Trout Lake Station open house on Aug. 4th from 1-5 PM.


Mark Naniot painted a sad picture of the effect of lead poisoning on loons. Lead is killing many loons each year – even a small bb from a shotgun shell can kill a loon in a few days. Since my notes were not particularly good, I have gone to the web for information.


How do loons ingest lead fishing tackle?

The majority of loons and grebes that die from ingested lead tackle acquire it as a result of fishing activity (e.g., ingesting a fish that has broken a line and has ingested or attached tackle, or mistaking lead weights for the small stones that they normally ingest to aid in digestion.


How does lead tackle kill?

Once ingested, the lead tackle goes into the gizzard. The acid and grinding action of the gizzard erodes the lead, which then passes into the bloodstream and organs and poisons the loon or grebe. Even a single small lead split shot sinker is fatal, which will die within 2-4 weeks of ingesting a piece of lead fishing tackle.

While some might assume that ingestion of fishhooks might cause loons to die, in fact only a small number of loons and grebes die from injuries resulting from swallowing hooks. Loons and grebes have evolved to swallow spiny fish (like sticklebacks), so they are able to deal with fishhooks. In the vast majority of loons and grebes, the hooks (either hooks on jigs or separate hooks) are very rapidly broken down in the gizzard.

Once ingested lead tackle, can the bird be saved?

It’s rare. Usually, loons do not display symptoms until lead is already at toxic levels in their bloodstream. At that point, the only option is to humanely euthanize the bird.

What types and sizes of lead tackle do loons ingest? 

Loons ingest both lead fishing sinkers and jigs. A sinker is attached to a fishing line to sink it, while a jig is a hook with a lead weight molded around it. Loons have ingested jigs weighing more than 4 oz and sinkers weighing more than 2.5 oz.

The acid and grinding action of the gizzard erodes lead sinkers and jigs, so hooks, weed guards, and other components of this tackle may no longer be present when it is removed from dead loons. Loons’ ingestion of lead jigs with and without attachments like weedguards has been documented, and neither these nor a painted coating will protect loons from lead poisoning.

If an eagle consumes the flesh of a contaminated loon, they can die as well.

Panel Discussion

The panel discussion was effective, but it is difficult to focus on specific topics because the discussions were fairly long. One point was made by the DNR wardens – the DNR is suffering from low staffing levels. One person’s area od responsibility were far too large to be effective.

Overall, the sessions were very effective and point out areas of focus for the Board – do a better job of screening boats to prevent the contamination of our lakes and lobby for lead free fishing gear and lead-free shot.  


Dick Garrett/Mary Taylor