"Collect Lake Sponge" quest never appears for Rhamph in freshwater. Bug, or intentional?

Rhamph never gets the "Collect Lake Sponge" quest in freshwater in-land such as in Young Grove, or Triad Falls. I am assuming this is a bug and not intentional purely because rhamph is able to quest in the ocean. If it can quest in the ocean where the water is much deeper, then it should easily be able to quest in lakes for the lake sponge quest where the water is much shallower, hence I think rhamph never getting this quest at all is a bug. If this isn't a bug and is a (somewhat questionable) design decision, then sorry for this post.