I started my tour of the farmed salmon life cycle at a production plant in Flakstadvåg – very much the end stage of the process where ‘smolt’ (young fish that have been through the process of ‘smoltfication’, transforming them from freshwater fish to saltwater fish) are introduced to the fresh, flowing waters on the west coast of Senja. At this stage, they’re a mere 60-100g each, but they’ll spend the next few years maturing into those four to six kilogram beasts that you’ll find in the fishmongers’.

There’s no pretending that salmon farming hasn’t faced a few negative headlines in recent years, due in part to fears around the increase in sea lice – and the subsequent warnings that pesticides used to treat the lice are polluting waters around salmon farms.

As we took a boat to see the full-grown fish circling in their pens, Jack-Robert Møller, representative of the Norwegian Seafood Council, talked through these tricky issues.

‘So we use lasers, and then of course there’s the lumpfish.’

‘Lasers? Lumpfish?’

Yes, lasers. Each pen at the production plant in Flakstadvåg is fitted with a machine that shoots currents into the water that are imperceptible to the fish but fatal to the dreaded lice. And yes, lumpfish. These are kept alongside the salmon in the same pens, where the lumpfish nibble the lice from the salmon, keeping their numbers in check. This does indeed seem like a good deal for all creatures involved (apart from the lice, of course). Each pen is draped with material around the edges so the fish can swim away to their preferred shady habitat after they’ve had their fill.

The salmon are well-fed, too. Part of the great sustainability struggle for any livestock industry needs to take into account feed – if a fish is routinely fed other creatures that could otherwise be used to feed human populations, then any claim to sustainability is on shaky ground. Norwegians have addressed this issue by developing feeds that are made of seventy percent vegetable matter, and make up the rest with fish meal and fish oil made from creatures that are not fit for human consumption, often derived from fish offal – a waste product of the industry.

Another sustainable plus for salmon production is the sheer quantity of feed salmon require compared to other livestock – every kilogram of salmon requires 1.2 kilograms of feed. Compare that with beef and pork production, which require eight kilograms and three kilograms of feed per kilo of meat respectively, and it’s obvious why people are increasingly turning to farmed salmon as a source of protein.

Then I faced the sharp end of salmon production – the packing plant. As a salmon plant novice, I suppose I expected things to be a little more, well, smelly. But the gleaming plant, with its constant flow of huge, glittering bodies, was both slightly melancholic and immensely impressive, and smelt like nothing but the sea, as all fresh fish should.

For our next stop, we ventured to Skaland in the northwest of the island, snaking around fjords and through more mountains. It is in hatcheries that the young fish are hatched and slowly conditioned in water, gradually grown until they reach the aforementioned ‘smolt’ stage and are transported via huge boats down the coast to swim in the larger pens.

Here we were guided around a series of round tanks, each containing thousands upon thousands of tiny, glittering fry at various stages of growth. It’s also where lumpfish are raised for their lice-feasting properties in later life. As well as attuning their bodies to a salt water habitat, this is where the fish are vaccinated against the most common diseases found in salmon – after all, prevention is better than cure. This is an annual task, with a huge team of Scottish experts being flown over to the plant to sedate and vaccinate each tiny fish individually.

This, of course, leads to another hot issue in salmon farming – antibiotics. The use of these drugs in any kind of livestock farming has resulted in concerns the world over from scientists warning that our growing resistance to the drugs could lead to a disaster in global health.

Norway has faced this problem head-on – while antibiotics were widespread in the early days of salmon farming, since the late 1990s, antibiotics use in Norwegian salmon farming has dropped by ninety-nine percent, all the while growing in production from 50,000 to over one million tonnes. The inoculation of fry has ensured that antibiotics are practically unnecessary in salmon farming. This is not the only means of combatting disease in farmed fish populations, however; you also need high levels of hygiene. Once the salmon are harvested from a pen, it is left for at least three months so that the natural currents can sweep up the ocean floor, leaving it fresh and new for the next generation.

All of these factors do, of course, result in fish that are not only sustainable and cause minimal damage to the environment – they taste amazing, too. Healthy and slow-grown creatures make for the best eating, with the care of Norwegian farmers really shining through in the end product.