@Enmos
Yes, probably a whale bone
The next question is how it got there (The lake is relatively high up in the hills, 150 -200 metres).
Washed there by near end ice age floods...
Have they determined its age yet ?
Hum,
I don't know.
I suspect it dates from the last ice age; perhaps when the land was lower and it got stranded, or a massive tidal wave could have deposited it there.