A French appeals court on Friday upheld prison sentences of between four and eight years for four Somali men found guilty of seizing a French sailing boat in the Gulf of Aden in 2008 and holding its two passengers hostage.
A fifth man was acquitted.
A Paris court had earlier also acquitted one defendant and sentenced five others to prison terms of between four and eight years in the trial of the original six suspects.
The prosecution on Wednesday asked for prison terms of up to 10 years.
The pirates, today aged 22 to 36, seized the Carre d’As and its two passengers, French couple Jean-Yves et Bernadette Delanne, on September 2, 2008.
The two were held for two weeks on the boat before they were freed unharmed by a French navy commando and the pirates captured.
One pirate was killed in the rescue operation.
The kidnappers had asked for a two-million-dollar ransom but it was never paid.