The speedboat came alongside and the Melanesian men aboard offered gifts of fruit and jars of jam and preserves.

"And they gave us five big sugar-bags full of fish," he said.

"They were good, big fish, of all kinds. Some were fresh, but others had obviously been in the sun for a while.

"We told them there was no way we could possibly use all those fish. There were just two of us, with no real place to store or keep them. They just shrugged and told us to tip them overboard. That's what they would have done with them anyway, they said.

"They told us that his was just a small fraction of one day's by-catch. That they were only interested in tuna and to them, everything else was rubbish. It was all killed, all dumped. They just trawled that reef day and night and stripped it of every living thing."

Macfadyen felt sick to his heart. That was one fishing boat among countless more working unseen beyond the horizon, many of them doing exactly the same thing.