No more people have been pulled from the water since last weekend, when 14 survivors and two bodies were found.
The ferry MV Matui was travelling between the islands of Santo and Ambae with 53 people on board when it sank on September 11, a deputy commissioner of Vanuatu's Maritime Safety Authority, Lloyd M Fikiasi, told The Associated Press.
The sinking was not reported for a full day, officials said this week, and the number of people on board was unclear for several days.
Some earlier registered as missing were found not to have travelled on the boat, Fikiasi said.
While two bodies were recovered last weekend, the search at sea ended Thursday with 37 still missing.
The authority this week laid criminal complaints with the police about the owners of Tui Shipping, the company's management and the ferry's master, for breaches of maritime law, local news outlets reported.
Vanuatu's Daily Post reported that the vessel was not authorised to carry passengers and that the company was warned about overloading of personnel and cargo by inspectors the day before the sinking.
"This loss appears to be the result of strong winds and marine warnings not being heeded, and possibly of negligence including overloading of the vessel," Prime Minister Jotham Napat said on Sunday.
The country's meteorological service issued a marine warning for strong winds and high seas on the day the ferry sailed.
Napat on Friday visited survivors and bereaved families on Santo and Ambae, where he called for calm and pledged an independent investigation into the sinking.
He earlier said he had cancelled a scheduled visit to the UN General Assembly in New York to deal with the disaster.
A national memorial service would be held September 27, Napat said.
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