Seven Afghan migrants, including three children, died after their boat sank late on Monday off Turkey's northwest province of Çanakkale.
The boat was carrying 20 people when it sank, the Turkish coastguard said in a statement, adding that 12 other Afghan migrants and an Iranian national had been rescued by fishing boats and search and rescue teams.
The Turkish Coast Guard took the survivors to safety while the Iranian was detained on suspicion of being a human trafficker.
Security forces intercepted another 31 illegal migrants in Ayvacık on Tuesday before they arrived on the shore to board a boat to Lesbos island.