I'm going to expand a bit on idea for a wharf.

You get Techology "Migration". It determine how much villagers can be on a raft at once and how much skills the newcomers will have on arrival.

Level One: You can send up to 2 villagers away.
Newcomers will arrive with little to no skills (Untrained).

Level Two: You can send up to 4 villagers away.
Newcomers will arrive with some skills (Trainee).

Level Three: You can send up to 6 villagers away.
Newcomers will arrive with plenty of skills (Adept).

If you send the villagers away, you'll need to pay Tech points for raft and rebuild it again.

You need to pay additional Tech points if you "recruit" some new villagers.