Black cod, which is also known as sablefish, is found in the Northern Pacific Ocean in an arc extending from California to Japan but mostly around Alaska and the Aleutian Islands. It is no relation of the cod on sale in every fish and chip shop.

Black cod's USP is its high oil content - about 20 times the level in Atlantic cod. Whereas most fish use an air bladder to regulate their depth, the black cod uses oils in its muscle. These oils gives it a rich velvety mouthfeel worth £40 a serving in a fancy restaurant.

REACHING THE BRINK

The black cod fisheries of Alaska and Canada are a fascinating 30 year morality tale of over-fishing, the grasping of the problem, hamfisted efforts to solve it and ultimately, success.

Although black cod was nothing special in the USA and Canada until recently, Japan had always considered "gindara" a top drawer fish. In the years when fishermen were free to drop their nets up to 3 miles off any coast, Japanese boats would make the trip across the Pacific to scoop up the black cod. It was a useful supplement to their own more modest supplies. Local fishermen were not offended - to them, black cod was hardly worth the trouble of landing it.

But by the late 1960s national fishing limits had reached 12 miles from any nation's shore and were on their way to 200 miles. As the Japanese fishermen sailed for home, the Japanese fish merchants caught the first plane to Vancouver. The conversation probably went something like this.

"Hi, our boats used to catch the black cod from here."

"Yes and you were welcome to it."

"So, what happens to it now?"

"We don't go looking for it. But if we catch it, we probably land it."

"And how much do you land?"

"The whole fleet probably lands about 700 tonnes a year."

"Well, we'd like to buy all 700 tonnes."

"Is that right? And what you thinking of paying for it?

"How about twice what you get at the moment?"

"Well, how about that? Say, you wouldn't be wanting any more than 700 tonnes would you?"

"Well, in fact, we'd like about 10,000 tonnes."

"Hmmm. Well we might see what we can do for you."

British Columbia's official statistics show that Canada's black cod catch rose from 720 metric tonnes worth 60 cents/kg in 1972 to 4,200 tonnes worth $2.80/kg by 1985. Both figures continued to expand. The same happened in Alaska, on a larger scale.

DISASTER AVERTED

Everyone realised these catches were unsustainable, so in 1981 the Canadian authorities set a quota - just a single figure across the whole fleet, reviewed annually. Licences were handed out to 48 vessels. Each year, black cod fishing ceased (in theory) from the day the quota was reached.

This began to protect the stocks, but the resulting fishing practices were a nightmare: every vessel caught fish as fast as possible to ensure it didn't lose out to rivals. In 1981, the quota was caught in 250 days. In 1989 it took 14 days. And that was when a workable system was finally settled upon The maximum catch was divided between the 48 boats. They could catch it when they liked. No stupid rushing; everyone has time to take care of their catch. As the landings are spread over a year not a fortnight, the pricing is firmer.

The maximum catch is reviewed annually to maintain stocks. It is lowered as often as it is lifted. In 2016, the 48 Canadian vessels landed 2,700 tonnes worth $11 per kg. Alaska operates a similar regime.

The fisheries end of the US Department of Commerce seeded a project to attempt black cod farming in 2012. An ambitious fish farmer, Global Blue, began to try commercialising this work. They released this video in 2017 their product began to reach the market in 2018. The Fsh Society bought our first farmed black cod in 2019 The video from Global Blue gives a picture of the farming setup.

WHAT'S IN IT?

The following table shows the levels of key nutrients in black cod, alongside those for Atlantic cod.