Officials say at least 54 crew members on a fishing trawler that sank in the icy waters of the Western Pacific Ocean have died. Rescuers continued to search for 15 more in freezing conditions on Thursday. (Reuters)

MOSCOW — Scores are dead after a fishing trawler sank overnight in the sea of Okhotsk off the eastern Russian peninsula of Kamchatka, about 150 miles south of the city of Magadan.

Russian news outlets reported at that at least 56 members of the 132-person crew were found dead by midday Thursday, while the country’s emergency services ministry counted 63 sailors saved by fishing boats in the area responding to the search and rescue operation.

Officials did not swiftly explain why the vessel sank, though Russia’s Investigative Committee surmised in a statement Thursday morning that “the most likely reason” was “a possible collision with an obstacle.” The committee also noted that there was damage to the ship in the area of its engine room.

But the head of Russia’s Emergency Situations Ministry insisted Thursday that law enforcement agencies were exploring at least 10 theories as to what caused the vessel Dalniy Vostok -- Russian for “Far East” -- to flood and sink, according to Russian reports. The Investigative Committee has also opened a criminal investigation to examine questions of negligence or violation of safety procedures.

The deputy director of Russia’s Federal Fisheries Agency, Vasily Sokolov, told reporters that the vessel had not been overloaded with the catch, according to Russian reports. He also confirmed that the trawler had lifted a heavy dragnet on board.

But other officials have suggested that lifting that trawl was what ultimately brought the ship down. Sergey Khabarov, deputy chairman of the Kamchatka region, told the Russian state news service TASS that the ship tried to raise the approximately 100-ton dragnet without enough fuel in its tanks to counter the weight, lost its balance in the process and sank within 15 minutes in rough seas.

The ship never sent out an SOS signal, according to Russian state news outlets.

The 132-person crew was made up of 78 Russians and 54 citizens of other countries, according to Russia’s Investigative Committee: 42 Burmese citizens, five from of Vanuatu, four Ukrainians and three Latvians.

Twenty-six fishing boats participated in the rescue operation, the Investigative committee said.

Officials quoted in Russian reports said most of those rescued were seriously injured and were awaiting evacuation Thursday.