Lake Mendota sightings-monster or sturgeon?

Lake Mendota is in Wisconsin and is 82 feet deep .It is said to be the home of a lake monster which also has been reported in the neighbouring lake Monona.
Sightings began in the 1860s, by a Mr W.J. Park and his wife who were boating near Governor's Island on Lake Mendota.. The couple were in a small boat when, they came across what appeared to be a log or piece of driftwood. When Park raised his oar to tap the log, the water suddenly boiled up and the "log" dove under the water.
"That this was a monster of some sort, we have no doubt," wrote Park. "And we were not too long in deciding that retreat was the better part of valor and we resolved to say nothing about the matter." He and his wife came forward in 1892 after other reports.

This report on Oct. 17 in 1892, by a group of 12 young men who said saw a 35-foot-long creature in the lake, prompted Park to come forward. The same year a young man reported encountering the creature in the Yahara River, which links Mendota and Monona lakes. He said it looked like a log, except that it swam and dove and it had tried to overturn his boat.
On Aug. 22, 1899, Barney Reynolds reported seeing a creature in the lake near the landing for the Bernard Boat Yard.

In 1917, a man fishing for perch off Picnic Point saw "a large snake-like head, with large jaws and blazing eyes, emerge from the deep water not more than 100 feet away." The man was paralyzed with fear at first but then ran away, leaving his pole and catch basket behind.

There appear to have been no recent sightings but then I found this:

In 1917, a University of Wisconsin student walking on the north shore of Picnic Point found a large, thick object that resembled a fish scale. He could not identify it, nor could a UW professor who examined it. It was described as an unusual scale, "of large size, thick and very tough," The State Historical Society records that one anonymous professor, originally from New England, believed the scale belonged to a "sea serpent."
Then this was found:
According to the society, dredging on the same lake in the 1890s revealed some "huge vertebrae" belonging to a long-dead, unknown creature. Unfortunately I was unable to uncover any more information on this.

Older native legends make reference to "wak tcexi", long-tailed beasts that supposedly lived off the eastern shore of the lake. It should also be noted that in Lake Mendota, they have captured sturgeons that were twenty five feet in length.

So could the scales been from a huge Sturgeon? It would have been thought the academics would have recognised the scales of a sturgeon. It is an interesting tale and it will be interesting to see if any more sightings turn up.