A second group of deported migrants has arrived by ferry in Turkey from Greece as part of an EU deal to reduce the numbers reaching Europe.
The boat carrying 45 Pakistanis left Mytilene on Lesbos for the short journey to the Turkish port of Dikili.
Three demonstrators who dived into the harbour were fished out by coastguards.
Some 200 mainly Pakistanis were deported on Monday under an EU deal with Turkey, the main transit route for undocumented migrants.
However, the returns process was interrupted as asylum applications surged in Greece.
Under the EU deal with Turkey, migrants who have arrived illegally in Greece since 20 March are expected to be sent back to Turkey if they do not apply for asylum or if their claim is rejected.
And for each Syrian migrant returned to Turkey, the EU is due to take in another Syrian who has made a legitimate request.
Each deportee was accompanied by a guard from the EU's border agency, Frontex, with a doctor and interpreters also aboard.
"Nobody indicated to our escorts last-minute that they would like to apply for international protection," Frontex spokesperson Ewa Moncure told reporters in Greece.
A second group of 95 deportees, from the Greek islands of Samos and Kos, was also due to be ferried to Dikili on Friday, after first being brought to Lesbos.
Of those being returned to Turkey on Friday, the non-Syrians will be taken to deportation centres while any Syrians will be taken to refugee camps to take the place of Syrian refugees who will be directly resettled in the EU.
'Their dream was over' - Sophie Long, BBC News, Lesbos
The first group of migrants arrived at Mytilene Port at dawn in four buses. They disembarked quietly and walked slowly and calmly between two lines of policemen.
After the confusion of the past days, wondering what would happen to them as they waited in an over-crowded detention centre, at that moment there was clarity and only one way to go - onto the boat in front of them. And they knew where it would take them.
Later, another group who'd been collected from Kos and Samos by ferry walked silently down the gangway of one boat accompanied by a Greek police officer and back up the gangway of another, accompanied by an officer from Frontex, the EU border agency. Some were covered with blankets. Many held a small bag of belongings. All were held securely by the arm.
This second group had come from all over the world. From India, Morocco, Pakistan and the Palestinian Territories. There were also four Iraqis, among them a woman, the only one to board the boat. Today they were all heading in one direction, back to Turkey. Their dream of a better life in Europe was over.
'Shame on you'
The small group of protesters in Mytilene chanted "EU - shame on you".
One million migrants and refugees have entered the EU by boat from Turkey to Greece since early last year.
The returns arrangement has alarmed rights groups, who say Turkey is not a safe country for migrants.
Citizens of Pakistan make up the fourth-biggest group of undocumented migrants arriving in Greece this year, after Syrians, Afghans and Iraqis.
In the first three months of the year, 5,317 Pakistanis entered the country. Some of them are reported to have started a hunger strike at Moria camp on Lesbos.
"We risked our lives to come here, we don't want to go back to Turkey because they are going to send us back to Pakistan," one man, who called himself Ali, told AFP news agency.
"We don't want to apply for asylum in Greece, we want to go to Germany."
Some 11,000 migrants remain camped at Greece's border with Macedonia, prevented from heading northwards to other EU states.
Migrant arrivals in Greece by sea from Turkey have dropped sharply, from a couple of thousand per day early last month to the hundreds this month, data from the International Organization for Migration show.
There is concern in Italy that migrants deterred from trying to reach Greece might try to enter the EU from North Africa instead, using the sea route from Libya to Italy.
Of migrant arrivals by sea recorded this year to 7 April, 19,322 came to Italy, compared with 152,461 entering Greece.
"We are concerned because it's predictable that this summer, maybe hundreds of thousands of people maybe will arrive from Syria and African countries through Italy going to Europe," Giorgia De Acutis of the Italian Red Cross told Reuters news agency.
What next for the deportees
- Upon disembarkation in Turkey, they are given medical checks, and are registered and fingerprinted
- They are then bussed to "reception and removal" centres, possibly in the north-western town of Kirklareli, near the Bulgarian border
- The Turkish authorities apply to their home countries and they are deported
Sources: international news agencies, Turkish media
A note on terminology: The BBC uses the term migrant to refer to all people on the move who have yet to complete the legal process of claiming asylum. This group includes people fleeing war-torn countries such as Syria, who are likely to be granted refugee status, as well as people who are seeking jobs and better lives, who governments are likely to rule are economic migrants.