The boat was carrying 42 Afghan migrants – including 12 children and seven women – and a Turkish captain, the Hurriyet news website reported. It was believed to have been heading for Bulgaria or Romania, but it was unclear where it set to sea.
Turkey is one of the main departure points for migrants aiming for the EU, but most travel across the Aegean to Greece.
The boats are often makeshift dinghies, usually overcrowded, with the migrants paying thousands of dollars to smugglers in Turkey.
Two months ago another group of migrants – mostly Syrians and Afghans – was rescued by the Turkish coastguard off the northern coast reportedly heading for the EU.
“The wind is making our task very difficult. The boat is a very small one. But they were carrying 40 people in it. We are seeing bodies of children floating in the sea,” rescuer Ali Saruhan told Hurriyet Daily News.
Seven coastguard vessels and a helicopter were conducting the search in the Black Sea, some 3 miles north of the Bosphorus, the coastguard said in a statement.
A fisherman who helped retrieve the bodies told Hurriyet that all were without life jackets. He said that babies were among the dead.
The official Anatolia news agency said that rescuers were alerted to the sinking by fishermen and arrived at the scene of the accident to find the vessel semi-submerged.
Correspondents say that it is not clear what caused the boat to sink, although overcrowding, bad weather conditions, the poor condition of the vessel or even a collision with another boat were all possibilities.
Since the start of the civil war in Syria, thousands of migrants have been trying to reach the EU by making the treacherous sea journey from the western and southern Turkish coast.
Tens of thousands of migrants have also attempted to cross the Greek and Bulgarian borders by land, Hurriyet says.
0YNBG3GpH6gImage source: Wikimedia Commons President-elect Donald Trump celebrated his election victory at the Ultimate Fighting…
Millions of voters across the US chose to return Donald Trump to the White House…
Donald Trump declares victory in the US election as he addresses jubilant supporters in Florida.…
Stocks around the world are rising as Donald Trump appears to be on the cusp…
Donald Trump has won Pennsylvania, North Carolina and Georgia and taken a lead over Kamala…
Quincy Jones, the celebrated musician and producer who worked with Michael Jackson, Frank Sinatra, Ray…