Author: BBC World Service

Salmon are one of the world’s most popular fish. And - in terms of the size of the industry - they’re also the world’s most valuable. They provide crucial proteins and fatty acids to many people’s diets. But like other species of fish, their production is undergoing a historic change. Plenty of salmon is still caught from the wild, but the majority is now farmed off the coasts of countries like Norway or Chile. With global demand on the rise, listener Jodie from Australia wants to know: which is healthier, farmed salmon or wild?

CrowdScience’s Marnie Chesterton is on the case! Her first stop: a remote loch in the west of Scotland, where salmon company Mowi rears thousands of the fish in big, open-water nets. Marnie takes the chance to see for herself what salmon farming actually looks like. She then speaks to aquaculture nutritionist Stefanie Colombo, who researches the nutrient content of different types of salmon. Stefanie breaks down the health positives and negatives of each, as well as what causes some of these differences.

Crucially, farmed salmon will vary in nutrition depending on where you are in the world. Jodie, the listener who asked this week’s question, is from Australia so her fish will most likely come from Tasmania. Chemist Christian Narkowicz has been conducting chemical tests on the salmon there - he tells Marnie what he’s found.

When we ask which type of salmon is healthier, it’s also important to consider the issue of environmental health. Eilís Lawlor is an economist and the author of a report on externalities and unintended consequences of the global salmon industry. She and Marnie discuss problems of overfishing and environmental pollution.

It’s also necessary to understand where wild salmon comes from. Marissa Wilson, director of the Alaska Marine Conservation Council, explains her average day out at sea and talks about some of the consequences of industrial offshore fishing.

Finally, we ask if there’s a way to improve farmed salmon by moving it onto land? That’s Yonathan Zohar’s mission. In the basement of the Institute for Marine and Environmental Technology in Baltimore, USA, he keeps several tanks of salmon in artificial seawater, using bacteria to dispose of the waste. Is this where salmon farming is headed? Or is the future more complex?

Presenter: Marnie Chesterton Producer: Phil Sansom Production Co-ordinator: Jonathan Harris Editor: Richard Collings

(Photo: Atlantic Salmon jumping out of the water. Credit: Kevin Wells / Getty Images)

Accelerating seismic tremors are raising concerns for the thousands of people living atop a volcanic hot spot close to Naples, Italy. Volcanologist Alessandro Pino has been keeping a watchful eye on the developing situation.

We stay in Naples where, almost 2000 years ago, the eruption of Mount Vesuvius buried Pompeii, including thousands of scrolls turned to charcoal by the immense heat. This hasn’t stopped people from trying to read the scrolls, destroying hundreds in the process. Now, computer scientist Brent Seales has deployed AI and papyrologists worldwide to decipher the burnt text.

And from ancient scrolls to rainforest soundscapes, ecologist Zuzana Buřivalová has also been using AI to untangle the vast array of life heard in forests, old and new, as a tool to measure biodiversity.

Presenter: Roland Pease Producer: Ella Hubber Editor: Martin Smith Production Co-ordinator: Jana Bennett-Holesworth

(Image: A view of the fumaroles Pisciarelli in Agnano quarter of the Campi Flegrei, a volcano near Naples. Credit: Salvatore Laporta/KONTROLAB/LightRocket/Getty Images)

According to the pop icon Madonna, music makes the people come together. But can we prove that using science?

As Madonna embarks on her greatest hits world tour, the Unexpected Elements team on three continents take some of those hits and examine the science behind them.

Like a Virgin take us on an excursion into parthenogenesis, and the Komodo Dragons that can reproduce without the inconvenience of having to find a mate.

Madonna sung about travelling ‘quicker than a ray of light’, but is that actually possible? We take a very fast trip through the strange world of warp bubbles.

And we Get Into the Groove with the physicist who created a record so tiny it fits into one of the grooves of a normal record.

We also hear about the “find your ancestry” kits that have the capacity to solve so-called cold cases, identifying unknown human remains often decades old.

With the eyes of the world on events in Gaza, we discover how tech can help make sure that any reportage – video or photos – are accurate and not doctored.

All that plus your emails and WhatsApps, and a listener wonders whether fish can drown.

Presented by Marnie Chesterton, with Philistiah Mwatee and Katie Silver Produced by Ben Motley, with Alex Mansfield, Tom Bonnett, Sophie Ormiston and Margaret Sessa Hawkins