LONDON (Thomson Reuters Foundation) - A record 7,495 refugee and migrant deaths were recorded worldwide last year - almost a third higher than in 2015 - with the vast majority perishing in the Mediterranean Sea, the International Organization for Migration (IOM) said on Friday.

The preliminary 2016 toll, which is likely to rise as more data comes in, pushed the number of fatalities for the last three years to 18,501, or almost 20 deaths a day, IOM said.

“These data ... are simply shocking. And we don’t believe we are anywhere near counting all of the victims,” IOM Director General William Lacy Swing said in a statement.

“We are past the time for counting. We must act to make migration legal, safe and secure for all.”

The 2016 total of 7,495 deaths compares with 5,740 last year and 5,267 in 2014.

IOM, which has collated data on migrant deaths for its Missing Migrants Project since 2013, said the increase was largely due to better research methods.

However, some migrant routes also grew more deadly, particularly the Mediterranean crossing between North Africa and Europe, where nearly 4,600 people perished in 2016.

IOM said reports of deaths often came from migrants themselves who increasingly chronicled their journeys on social media.

IOM spokesman Joel Millman said the agency had developed good tools for tracking migrants through social media in Latin America, but that some other parts of the world were “almost invisible to us”.

Routes used by Iraqis, Pakistanis and Afghans crossing Iran and Turkey may be much deadlier than data suggests, he told a media briefing in Geneva.

The Horn of Africa, Bay of Bengal and corridor linking Ethiopia and South Africa are other regions where the picture is far from complete.

“These are very robust migrant corridors and extremely dangerous ... but we just don’t have the tools in place to track them,” Millman said.

“It’s likely we won’t ever get a true, final number for all these tragedies,” he added. “We hope for the day when these numbers begin dropping. But that may not come for a while, yet.”

Millman also highlighted two unexpected regions for migrant deaths in 2016, including among the growing number of Cubans crossing Colombia and Panama’s Darien Gap.

A sudden movement of thousands of Haitians leaving Brazil has also seen reports of migrant deaths in Chile, Ecuador, Mexico and Central America - something that was rare in the past, he said.

Many Haitians headed to Brazil following their country’s devastating 2010 earthquake, but are now leaving for other destinations following a slump in the economy and the end of the Olympics.