At least 33 people, including five children, have drowned in the Aegean Sea after their Greece-bound boat capsized off the Turkish coast.
Turkey's state-run Anadolu news agency said coastguards rescued 75 others from the sea on Saturday near the resort of Ayvacik en route to the Greek island of Lesbos.
The agency has identified the survivors as natives of Afghanistan, Syria and Burma.
The International Organisation for Migration said 218 people have died this year while trying to cross by sea from Turkey to Greece.
Turkey is hosting an estimated 2.5 million refugees from Syria.
In November, Turkey agreed to fight smuggling networks and stem the flow of migrants into Europe. In return, the EU has pledged 3 billion euros to help improve the refugees' conditions.
Saim Eskioglu, deputy governor for Turkey's Canakkale province, said the 56-foot vessel carrying more than 100 people "hit rocks soon after it left the coast and, unfortunately, it sank".
The Canakkale coast lies barely five miles north of the Greek island of Lesbos.
"We believe there are more bodies inside the boat," he told CNN-Turk television.
A private Turkish news agency, Dogan, said police have arrested a Turkish man suspected of being the smuggler who organised Saturday's disastrous sea crossing.
The International Organisation for Migration says drowning deaths are running at four times the rate of 2015, when many thousands daily sought to enter the European Union via Turkey by reaching one of more than a dozen offshore Greek islands, particularly nearby Lesbos.
Saturday's deaths take the drowning total for January above 250, whereas the agency recorded 805 drowning deaths on Turkey-Greece smuggling routes throughout 2015.
In a statement, the Turkish coastguard said it dispatched three boats, a team of divers and a helicopter after receiving calls for help.
Journalists at the scene said weather conditions on Saturday on the Turkish coast were relatively mild, with light winds and temperatures around 12C.
Joel Millman, a spokesman for the International Organisation for Migration, said the rate of deaths on Turkey-Greece human trafficking routes was "increasing at an alarming rate".
Mr Millman, speaking before Saturday's tragedy, said the rate of fatalities was running exceptionally high versus 2015. He said 55,000 had crossed by sea into Greece this month, a "very small number" versus the monthly flow in 2015.
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