When Spanish rescuers reached the boat drifting off the Canary Islands after days lost at sea, the scene was shocking: they found seven bodies and dozens of survivors, three of whom would later die.

The boat had set off from Dakhla in Western Sahara with 62 North Africans on board, but the attempt to reach the islands cost 10 people their lives.

For Salvamento Maritimo lifeboat crews working one of the most dangerous migrant routes to Europe, such scenes are common as increasing numbers leave the African coast in small wooden boats in the hope of reaching the Spanish archipelago off the northwestern coast of Morocco.

"There's been very bad weather over the past 10 days so any boat that has set sail is probably in danger," says Manuel Capa, a crew member with Salvamento, Spain's civilian coastguard service.

'In this world of seafarers, we're supposed to be tough, strong men but it's about having a heart,' says Manuel Capa 'In this world of seafarers, we're supposed to be tough, strong men but it's about having a heart,' says Manuel Capa Photo: AFP / LLUIS GENE

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"On the boat, the cook doesn't usually come on deck, but we were so overwhelmed that we had to use him. We were just exhausted getting them out, people were dead and we just didn't have the strength," he told AFP.

"At moments like that, you get a rush of adrenaline and you do what you have to do, but then there are moments when you think back to the trauma and suffering of these people.. and it's hard to understand," he said, breaking down in tears.

"The problem is the migration policies that are causing this type of journey and people's deaths."

Last month, 70 boats reached the Canary Islands carrying 3,038 people, government figures show.

More than 20,000 people have reached Spain's Canary Islands this year, the vast majority rescued by Salvamento Maritimo lifeboats More than 20,000 people have reached Spain's Canary Islands this year, the vast majority rescued by Salvamento Maritimo lifeboats Photo: AFP / LLUIS GENE

Two nights later, more frontline workers, among them medics and translators, gather at Gran Canaria's Arguineguin port as the Guardamar Polimnia offloads dozens more shattered survivors draped in red blankets, who are handed face masks as they stumble off the boat, their legs barely functioning after nine days lost at sea.

This time two people died, their bodies carried off in white plastic shrouds.

"It is a very hard crossing, one of the most dangerous of the migratory routes," says Paula Atochero, a nurse who has worked triage at Arguineguin for the past year.

Satellite map of the Canary Islands and the African coast Satellite map of the Canary Islands and the African coast Photo: AFP / Gillian HANDYSIDE

"Most of those who arrive have severe hypothermia that... can cause your vital organs to stop functioning. In other cases, there is also severe dehydration because when they have no food or water, they start drinking seawater which has a high concentration of salts."

Others suffer from "patera foot", a muscle inflammation that prevents blood flow, or compartment syndrome, which can cause septicaemia and needs treating in intensive care.

"These are serious pathologies and if left untreated they can lead to amputations, intensive care and, of course, death," she said.

Atochero was one of the two medics seen trying desperately trying to save a Malian toddler at the harbour in March. Although they managed to revive her, she eventually died after five days in intensive care.

"We've had many traumatic experiences at Arguineguin, there is no rescue without trauma so when these things happen, it shakes you up because you do what you can to save a person's life and often fail in the attempt."

For those working on the front line, repeated exposure to such suffering has an emotional cost with Capa saying one of his colleagues who jumped into the migrant boat to help the survivors out and found the bodies "just collapsed".

Last year, Salvamento Maritimo invested in a 24-hour helpline with access to therapists who provide "guidelines and tools to help you cope" in the event of a traumatic rescue.

"In this world of seafarers, we're supposed to be tough, strong men and many people don't want to publicly show what they're feeling so shedding a tear is seen as cowardly. But it isn't, it's about having a heart and feelings," he said.

In an address to the Canary Islands regional parliament last month, Ismael Furio, Salvamento Maritimo's main rep from the CGT trade union warned that the biggest problem was "the lack of resources within its rescue crews", describing the situation as "pretty extreme".

Of the 12 boats stationed in the Canary Islands, most have a three-man crew, meaning only one sailor is on deck to haul often dozens of survivors off their rickety boats.

Even so, Salvamento crews in the Canary Islands had saved thousands of people in the first 10 months of the year, he said, saying just three boats had rescued nearly 7,000 people.

"This is no longer a union issue.. we have not come here to ask for more money or more reinforcements. We have come to say that if there is only one person on board our boats, we can only rescue on in two people," he warned.

"If Salvamento Maritimo's work is sidelined, it will be a serious mistake that will end up costing very many people's lives."