Boats taking the would-be refugees across the Aegean Sea towards Greece sank in bad weather, according to Dogan, a Turkish news agency.
Ten bodies were found on the shore near the resort of Ayvalik, Dogan reported.
In a separate incident, seven bodies were found off the resort of Dikili, just to the south.
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Turkish coastguards were dispatched to search for any possible survivors, and eight people were rescued from the sea.
There was no immediate information on the nationalities of those involved.
Other reports put the toll at 21, including three children.
A two-year-old boy who drowned on Sunday became the first known refugee casualty of 2016.
Nearly 850,000 migrants and refugees crossed into Greece last year, most paying smuggling gangs to ferry them over from Turkey in fragile boats.