I think that you can go a few different routes here.
You can take a Gaelic name (Scottish or Irish), or you can use a name that refers to seals. It depends on what kind of tone you want for your writing. A seal-reference is a bit on the nose, but a Gaelic name would be more serious, and perhaps blend in with your other characters, if they are also Irish/Scottish.
If you go to Wikipedia, you will find some names of families that are supposed to be descended of selkies or mermaids, as well as place names. You could take those names and make them into your main character’s name.
“There is also the tradition that the Conneely clan of [name_f]Connemara[/name_f] was descended from seals, and it was taboo for them to kill the animals lest it bring ill luck. And since “conneely” became a moniker of the animal, many changed their surname to [name_u]Connelly[/name_u].[44][45] It is also mentioned in this connection that there is a Roaninish (Rón-inis, “seal island”) off [name_u]Donegal[/name_u], outside Gweebarra [name_u]Bay[/name_u].[46]” (from Wikipedia).
Here, I see some name potential already: [name_u]Connie[/name_u], Conmar, straight up [name_f]Connemara[/name_f]. [name_f]Roana[/name_f] is also an option.
"In the Faroe Islands there are two versions of the story of the ‘seal wife’. A young farmer from the town of Mikladalur on Kalsoy island goes to the beach to watch the selkies dance. He hides the skin of a beautiful selkie maid so she cannot go back to sea, and forces her to marry him. " (Wikipedia on Faroese legends of the selkie).
Here you can use Mikla or Kalsey.
The name Murchadh means “sea warrior”. Not exactly a pretty name, and male too. But you can mess with it and make it pretty. Murchaha. Marchad. You will probably need help from a Gaelic speaker, which I am not, so take my creations here with a large bag of salt.
Dùghlas means “black water”. Dughlasa, Daghlas, Dughleesa… You get my point.