A ship in South Korea sank on Monday with 62 people onboard. Authorities say over 50 fishermen are still missing.

The vessel was catching pollock in the western Bering Sea when it encountered high waves. The ship went under near the Russian border.

South Korean officials say the ship began to list in the storm, and the high waves caused the storage areas to flood. The poor weather and water conditions also delayed the rescue effort, a South Korean Ministry of Fisheries and Oceans official told the Associated Press under condition of anonymity. Four shipping boats are assisting the search.

Seven passengers were rescued, and one body was recovered on Monday. A Foreign Ministry official reported Tuesday that the death toll is expected to rise because no other passengers have been found in the freezing water. South Korean Prime Minister Chung Hong-won told the Cabinet that the Russian government will assist in the rescue effort.

The 2,000-pound ship was owned by Sajo Industries, a fishery and seafood production company. Representative Kim Kang-ho said the vessel was 36 years old, and had left Busan, South Korea, on July 10. Pollock is considered a winter delicacy in the country.

An anonymous Sajo official reported that the sunken vessel had eight lifeboats, and the seven survivors and one deceased fisherman had used them to escape. The official also said that the boat's captain issued an escape order.

Artur Rets, chief of the Russian port Petropavlovsk-Kamchatsky, told the RIA Novosti news agency that the rescued fishermen are doing well, and will return to South Korea when the weather improves.

On April 16, a sunken South Korean ferry caused the deaths of nearly 300 people. Prosecutors held the senior crew members primarily responsible for the deaths of 292 passengers and crew, and the presumed deaths of nine unrecovered persons.