OSHKOSH, Wis. (WFRV) We're getting an exclusive look at the dangers out on Lake Winnebago.  Several massive spots of open water haven't frozen over.

Don Herman knows ice -- and he isn't seeing much of it out on the lake.  "This is probably only the 3rd time I've see this in 39 years."  The Oshkosh-area ice expert took us out to a spot on the lake, where "the open water is about 100 foot wide and 300 yards long."

50 degree temperatures earlier this week kept several areas from freezing over.  Strong winds also played a role.  Ice in the lake is about 14 inches thick.  But some spots have only recently hardened and are 7 inches thick.  These areas are now covered in snow making it difficult for fishermen to tell were the stable ice ends and the thinner ice begins.  Herman says falling temperatures could help add a few more inches.

There's also concern that there will be many more people out on the ice beginning next week with the start of sturgeon spearing.  "A week from Saturday," Herman reminds us.  "They are going to start cutting in.  I tell everyone, on the west shore, you need to go out with four-wheelers."  On Friday, Herman says two pick-up trucks fell through the ice in Shawano Lake.  It's another reminder to use extreme caution.

Last year, Lake Winnebago saw a full, 16 day sturgeon spearing season.  According to the DNR, 566 sturgeons were harvested throughout the state.