By: ITV News correspondent Juliet Bremner

Sitting in a dark cramped room across the table from Elsa Guerreiro there was an all pervading sense of sadness.

We didn’t speak the same language but we didn’t need to, her large eyes spoke only of grief and loss.

Elsa Guerreiro lost her husband Amandio in November 2015. Credit: On Assignment

Last November her husband Amandio had been swept off the rocks at the place they call "the end of the world."

He was just 47 years old and his death has left Elsa bringing up their two teenage daughters alone. She struggles financially and emotionally.

As her story unfolds I have a growing feeling that this is a death that could so easily have been avoided.

The message Elsa is desperate to spread and the reason she is prepared to speak to me so soon after her husband’s death is that fishing for crustaceans known as percebes or goose barnacles is dangerous.

Amandio was one of a handful men to die last year as they collected the delicacy.

Percebes or goose barnacles are in high demand in Spain and Portugal. Credit: On Assignment

The percebes are ugly looking creatures that resemble a bird’s foot and cling to the rocks along the rugged coast of South West Portugal.

We call them Goose Barnacles - not that the British eat many of them.

But in Spain and Portugal there is huge appetite.

They only flourish in very specific conditions; Galicia at one end of the Iberian Peninsula and at Sagres where we spent several days - the far tip of Portugal where it spills into the Atlantic.

The scarcity and popularity of these barnacles means they are much prized - gold nuggets delivered from and nourished by the sea.

On Assignment's Juliet Bremner handles the precious goose barnacles. Credit: On Assignment

"Gold" is the word the head of the professional catchers collective Paulo Barata kept using when he was speaking to me.

Paulo boasts of how the cliffs from which they now gather the barnacles used to have real gold seams running beneath them, now replaced by this seafood variety that helps make him and his family feel rich.

When the barnacles are scarce, and at their most difficult to catch, they sell for around 35 euros a kilo.

Paulo is one of just 80 families to have a much prized licence to harvest the barnacles. These families inherit the right to harvest them and they guard it fiercely.

They claim that only they know how to respect the barnacles, which means ensuring nothing is caught during some autumn months to allow the percebes to breed and regenerate.

They argue passionately against newcomers being allowed to obtain additional licences.

Paulo Barata is one of many men risking their lives harvesting barnacles. Credit: On Assignment

But it means that the odds are hugely stacked against Amandio and other amateurs like him. The temptation is huge at a time when Portugal is still mired in a recession after the financial crash of 2008. Amandio was a construction worker but had been unemployed for 3 years.

Up to two kilograms of percebes can be legally caught by those without licences for personal consumption.

Although Elsa insists that her husband was only attempting to feed his family, the police reports show that much bigger bags of the lucrative percebes were strapped to Amandio's waist when they pulled his body from the waves.

Let me be clear, this is a dangerous pastime for all those who attempt it.

Our team watched the professional fishermen from Vila do Bispo wading out to the rocks at low tide, strapped to each other and repeatedly pummelled by the pounding waves as they brought in their catch.

But we also saw amateurs or illegal fisherman for whom it is far more perilous.

They are attempting to avoid the coastguard who strictly enforce the limited licences, they tend to work in the most exposed locations, without the best equipment and most dangerously they are often alone without anyone to raise the alarm.

Paulo and his fellow fishermen dominate the harvesting of barnacles. Credit: On Assignment

It is of course possible that this coast could support more than 80 professional fishing licences. It might mean that amateurs wouldn’t have to take such extreme risks.

And working on the principle of supply and demand it should also lower the price. With more men catching the percebes there would be more available to sell to fishmongers and restaurants.

But that is also the reason I suspect that no more licences will be granted.

While the undoubtedly powerful Paulo, supported by his fellow fisherman, claim they ensure that the life-cycle of the "gold" from this part of Portugal's sea is protected, and that only properly trained fisherman expose themselves to the risks; this ultimately means the high price they fetch is preserved exclusively for them.