He said the passengers included nationals from Spain, Uruguay, Peru, Russia and Indonesia.
The Falkland Islands, a British overseas territory, is coordinating the search and confirmed several crew members have been rescued. They will be taken to Stanley Hospital for assessment, it added.
However, the Falklands government did not confirm who had died in a statement and said the search would continue through the night.
On Monday, attempts were made to rescue the crew using military helicopters, but “extremely difficult weather conditions” including storms and eight-metre-high waves made the rescue impossible.
Officials said the weather made it impossible to use helicopters and they would review when another attempt to rescue the crew could be made.
An official in the northwestern region of Galicia told EFE news agency that the ship's 10 crew members, including the captain, were Spanish. Two of the Spanish nationals were scientific observers, Alvarez said.
According to ship-tracking website Marine Traffic, the Argus Georgia left Port Stanley in the Falkland Islands on Sunday night and was heading to fishing grounds.
A British Forces South Atlantic Islands (BFSAI) Atlas aircraft was able to track and report the location of the liferaft.
The Falkland Islands authorities said in a statement that the aircraft and a Voyager aircraft monitored the raft throughout the night.
Patrol boat (FPV) Lilibet and two fishing boats were also moved to the location, with the first vessel arriving on the scene to begin search operations.
The BFSAI search and rescue helicopter attempting to rescue the crew had to return to Stanley Airport to refuel. The helicopter search operation was then suspended due to worsening weather.
Argos Proines, the fishing company that owns the longliner built in 2018, declined to comment when asked by BBC News about the crew and search efforts.
