Tonga's acting solicitor general, Sione Sisifa, says the crown conceded a sentencing appeal in the Princess Ashika case, because the sentence was harsher than that others handed down.
John Jonesse headed the Shipping Corporation of Polynesia, which operated the ferry whose 2009 sinking caused the deaths of 74 people.
He was convicted on eight charges and sentenced to five years jail but successfully appealed the length of the sentence last Friday.
The Court of Appeal reduced his sentence to three and a half years, with the last three years suspended, and since Jonesse had already served six months he walked free.
Sione Sisifa says the New Zealander dropped his appeal against conviction.
"TONGA APPEAL TP 18"
We conceded the appeal against sentence on the grounds that Jonesse would withdraw his appeal against convictions. Jonesse's sentences were far more serious of that of the captain and first mate and in our opinion his sentence should be parallel to those of the captain and first mate.
The Court of Appeal also reduced the length of the suspended sentences of the captain and first mate but that hasn't affected their prison terms.