Jiro Ono, 89, widely considered the world's greatest sushi chef, has some dire news for aficionados of raw fish: The delicacy's best days may be behind us. 

"The future is so bad," the owner of the three Michelin star-rated restaurant Sukiyabashi Jiro, who was the subject of the 2011 documentary "Jiro Dreams of Sushi," told CQ in December. "Even now I can't get the ingredients that I really want. I have a negative view of the future. It is getting harder to find fish of a decent quality."

The reason is overfishing, particularly of the endangered bluefin tuna, a sushi staple. With 90 percent of the world's fisheries deemed either maxed out or overexploited, we may be, as one conservationist put it, in the era of "peak wild fish." 

Whether the ocean apocalypse that Ono foresees comes to pass will depend on conservation efforts and international accords with spotty records of preventing overfishing. Yet fish aren't about to disappear from stores or restaurant menus. There just may be fewer wild fish hunted and hauled out of the seas. Farmed fish will pick up the slack.

As the oceanographer Jacques Cousteau said:

“We must plant the sea and herd its animals using the sea as farmers instead of hunter. That is what civilization is all about -- farming replacing hunting.”

By some measures, this transformation is well under way: almost as much fish is produced via aquaculture as is caught at sea, according to a recent report by the UN's Food and Agriculture Organization. For certain species of fish and seafood, almost all that is consumed is farm-raised. For example, about 90 percent of all shrimp eaten in the U.S. is farmed, as is almost all European sea bass, some times sold in the U.S. as branzino.

David Fuller's view

I think the remarkable Jack Cousteau summarised the problem perfectly in those two brief sentences above. 

The long-term solution is certainly not in more efficient fishing, which only has the capacity to increase yield temporarily before wiping out remaining supplies of wild fish. 

I am a regular consumer of farmed salmon, which cannot compare with the wild variety for flavour when used as sushi.  However, I have certainly developed a taste for it when lightly steamed, and recommend it.