I've unlocked and purchased the Depth Charges mastery for my skiff, but there is no option to use them. From what I've been told by my guildmates, I should have a skill for it on my skill bar but it's not present: the only skills I have are the three different speed settings, Toggle Anchor and Angler's Sense.
Included links to screenshots showing that I do have the mastery unlocked but no skill for it
https://imgur.com/wSfPtqG
https://imgur.com/JxsLsoF