Just go to eldrich zone on crystal isles and look for big bubbles that have some black clams/oysters inside of them, put your angler fish inside the bubble, harvest, and enjoy the best black pearls harvester in the entire game, super easy, rank up for people to see this.

On the new map, Lost Island- there is a sunken ship in the very bottom left corner. I mean, tucked almost right in the corner, where the barriers meet. If you go inside the sunken ship, to the bottom of it, you will find clams full of only black pearls. The devs have a sense of humor, I'll give them that!

On Fjordur, the only way to obtain Black Pearls without going underwater is through, one, the Magmasaur den at the volcano in a cave inside the Fire Wyvern den, or two, from taming Gachas found in Asgard. Hope this helps anyone playing on the new map.

Abberation,

Along the forbidden koolaid (down by drakes)at bottom. Can harvest 6k + in one lap around. Make sure you have a dino with a lot of weight to get out or at least the dino retrieval pad. Suggest s-dire bear if you are using the dino retriever.

I just found that when I command otters to attack fish in rivers, the highest rate of harvesting black pearls is from salmon, followed by piranha and coleacant.I had a team of 3 otters that slaughtered a total of ~30 fish and harvested 27 black pearls. Big profit...

"This is for only mobile players. Just tame a otter and turn on his/her victim item collection from the corner side of your device and give his/her agreesion to attack target and whistle it to follow you. Then go to small fishes and punch them and wait for some time. Keep warned that your otter's have to kill and hervest that not you. If the otter kill and hervst the fish then it will give you black Pearl. But it has only 35.78% chance to give you black Pearl.This is the tip to get black Pearl safely without any damage. Jay hind

Just become Jack Sparrow and summon Calypso

On the island map, this is such a pain to collect. Takes ages

first tame an ichthy then go to rag about 75,23 more black pearls then you can carry on the sea floor and not to dangerous just keep an eye out for megs

Pain in the ass to find on mobile