BARCELONA, Spain — The number of migrants and asylum-seekers who reached Europe in 2020 is the lowest it has been in the past decade, according to a report released Friday by the United Nations migration agency. But deaths and disappearances on sea routes remain alarmingly high with only a small fraction of bodies recovered and victims identified. 

Of the 93,000 people who entered Europe irregularly last year, roughly 92% did so via the Western, Central and Eastern Mediterranean Sea, as well as through the Atlantic Ocean off West Africa to Spain's Canary Islands, often on unseaworthy boats. 

Arrivals in the Canaries, considered part of the Schengen area, increased by 750% last year. The numbers had already picked up before the pandemic following tougher border controls and interceptions on the Mediterranean by North African countries, but COVID-19 seems to have "acted as a multiplier of existing factors motivating migration on this route," the report said.

It added that many migrants previously worked in sectors such as fishing and agriculture that have suffered greatly from the economic consequences of the pandemic. 

The sea routes are lethal. The International Organization for Migration's Missing Migrants Project has confirmed the death or disappearances of nearly 2,300 people last year. This number is higher than in 2019 when 2,095 victims were recorded and slightly lower than in 2018 which had 2,344. 

The Central Mediterranean north of Libya saw 984 people perish in 2020. Meanwhile, on the Atlantic route to the Canaries at least 849 victims were recorded — more than four times as many as in any previous year, according to the report, "Maritime Migration to Europe: Focus on the Overseas Route to the Canary Islands." 

Another 300 deaths have already been documented so far this year, the report said. 

The organization admits its data is incomplete.  So-called "invisible shipwrecks," when entire boats disappear and leave no survivors, are especially concerning.

Not included in the report's death toll for last year are nine cases of invisible shipwrecks reported in the Atlantic and Mediterranean last year with hundreds of additional potential victims, according to IOM data requested by the AP. 

"Such cases are extremely difficult to detect, let alone verify, and are yet another indication that the true number of deaths on maritime routes to Europe is far higher than indicated by the available data," the report said. 

The Associated Press has most recently come across an example of uncounted deaths after interviewing two survivors who reached the Canary Islands last November. According to them more than 20 people on their boat did not survive the two-week odyssey.

The group of approximately 180 people had departed the town of Joal-Fadiouth in Senegal but ran out of food, water and fuel after the eighth day. 

"It was horrible," said Babacar Mboup, a former fisherman who was among them. "I saw people dying by my side." Their bodies were thrown overboard after they passed away, one by one. 

Finally, a Spanish rescue helicopter found their boat drifting 33 miles from the island of El Hierro. When rescuers reached the 158 survivors, only one body remained on the boat. Fearing backlash, those alive did not tell authorities that another 20 people were in the ocean. And so only one death was recorded.

Mboup says he didn't know most of those who died but had alerted the family of one of the deceased whom he did know. His name was Lamine, and he was 28 years old.