How large can be adult Leviathans?

[Lord Korag.8439]

All Leviathans seen in-game are Adolescent Leviathans, meaning they are young and therefore still growing. Most of the bones also seem to be about the size of the adolescents.

Is there any clue about how large can adult fully grown specimens be?
If I recall correctly, in the book Sea of Sorrows is a Leviathan called The Maw. However, it was described more like a fifty-foot long sea snake, so I wonder how closely related it was to the Adolescent Leviathans, if at all.