NA BDO Patchnotes 01/02/2017
Now you can obtain "Bottle with a Note" by spearfishing.
There is a chance of obtaining a treasure map upon opening a Bottle with a Note.
Right-click the treasure map to receive a treasure hunting quest.
Based on the quest content, figure out the location of the treasure and dig it up.
Hand over the treasure to Marzana in Ibellab Oasis to receive Sealed Golden Treasure Chest as a reward.
Use a Gold Key to open the Sealed Golden Treasure Chest.

I got ONE from fishing here:
https://bdocodex.com/th/theme/3440/
I don't know why...

Is it still Obtainable with fishing in Kama?

Edit 28.10: I have one from the Point from "Spielkind" - Atanis Pond/Atanisteich
So, Still Catchable there!

Still obtainable. Just caught AFK fishing on season in Duvencrune with Coelacanth event.