I'm on a fishing boat in the Maldives, riding a rough sea and dodging tuna as these glistening, slippery rockets of muscle are hauled up and tossed onto the deck by a line of 10 or 12 frenetic fishermen.
With shouts and grunts these fishermen expertly and swiftly hook the fish on board, one by one, while live bait is thrown into the water to create a feeding frenzy and entice the tuna to bite at anything that moves.
This is the Maldivian way of fishing and only tuna is being caught here -- sustainable fishing at its best. They are using a traditional pole and line method, unchanged for generations, with no overfishing and no by-catch.
"We only catch tuna, nothing else, because our lines are specially made for tuna, so it is not possible for any shark or dolphin to get injured or killed," master fisherman Ali Saaed, 45, says with pride.
UK retailers such as Sainsbury's, M&S and Waitrose, and brands such as Fish 4 Ever and Reel Fish, have for several years sourced their tuna from Maldivian fishers, because of its lack of by-catch.
And I'm here in the Maldives on the Greenpeace flagship Rainbow Warrior to witness how this fishing method offers part of a solution to end the overfishing and ecological crisis in the wider Indian Ocean region.
I've crossed the Indian Ocean from Mauritius, where local artisanal fishermen complain about the declining catch, blaming the European purse seining fleets using Fish Aggregation Devices (FADs), and Asian long liners for emptying their territorial waters of marine life.
"The catch is going down. Year after year, it is going down. I have made an estimate that in the next 10 years, maybe there will be no fish left," says Mohamedally Lallmahomed, secretary of the Fishermen Syndicate of Mauritius, an association of local artisanal fishermen.
This reality in Mauritius is a familiar story across the globe as local fishermen's livelihoods, and the prosperity of their families and communities, are being threatened by indiscriminate industrial fishing that creates by-catch and is intensive in catching juvenile tuna.
But an alternative exists in the Maldives, where locally-owned, smaller-sized pole and line boats fish just 10-20 miles beyond the coral reef edge. And unlike Mauritius, there is clear air of confidence in the future of the Maldivian fishery.
The extra jobs created by pole and line tuna entails a modest premium to be paid by retailers. Sainsbury's, M&S, and Waitrose have absorbed these costs for sustainably-minded consumers, who, through their buying power, are bringing greater wealth to island communities across the Maldives.
Saeed inherited his first fishing boat from his father at the age of 20. That was 25 years ago and he now employs 26 fishermen from the island of Hulhumeedhoo, home to 4,000 and where fishing remains the community's lifeblood.
One of those employees, Ahmed Zahir Lainofaruge, 36, has spent nine years on Saeed's boat and dreams of becoming a master fisherman with a boat of his own.
"Pole and line fishing ensures that the fish will remain here. It is sustainable. If they use a net, then all the fish is gone and there is no fish to catch the next day," he says.
And returning to port from the day's fishing with Saeed and his crew, I see how the village gathers to welcome the return of the boats, lingering for a while, talking in the shade of palm trees, exchanging the catch and cleaning the boat.
They depart shortly after on mopeds, bikes and by foot, returning to their homes, with each of them clutching their share of the day's catch.
This is sustainability and fairness at work.