About 164,000 years ago, people living in a South African coastal cave discovered the joy of seafood. Discarded marine snail shells deeply buried in the muck of human habitation represent the first evidence of seafood dinners. From then on, the increasing presence and richness of archaeological remains, and historical evidence, testify to our deepening love affair with seafood.

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We soon developed the wits, skill and technological armoury necessary to capture fish and shellfish. Cave trash in East Timor shows that we could catch sharks and tuna over 40,000 years ago. North African mosaics depict us 2,000 years ago catching fish from boats with cast nets, drift nets, hook and line and even amphora-shaped octopus traps.

But it wasn’t until the late 19th century, when steam engines were added to boats, that the era of industrial fishing began. Thereafter, fishing intensified swiftly and spread across the world’s seas and oceans, going further offshore and reaching deeper.

In the aftermath of the second world war there was great optimism that the oceans would feed humanity forever. Books were published with titles such as The Inexhaustible Sea, and the newly constituted Food and Agriculture Organisation of the United Nations – FAO for short – began to collect statistics on how many fish we landed. Every year from 1950, their figures logged the growing might of the world’s fishing fleets in the relentless growth of the heap of fish and shellfish taken from the sea.

Problems began to emerge with fishing in the 1960s and 70s as the productivity of many stocks faltered and some fisheries collapsed, as did that for North Sea herring. The toll of fishing rose into the 1990s with more stock collapses, with Canadian cod the biggest crash.

But optimists could take heart at least from the FAO data: although catches had levelled off, they were not falling. With hindsight, and the benefit of a study published this week by Daniel Pauly and Dirk Zeller of Canada’s University of British Columbia, we now see that we placed too much faith in FAO.

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The study shows in stark detail that FAO figures do not report lots of the fish we catch: fish taken by small-scale and subsistence fishers, especially in developing countries, recreational catches, and catches thrown away at sea because they either have low value or boats have no quota for them. In reality, we take 50% more fish than we thought – a staggering total of about 130m tonnes a year all told.

That levelling off in landings was an illusion too. “Peak fish” came in 1996, since when landings have declined by over 1m tonnes every year (despite our holding on to more of the fish we once threw over the side).

Statistics are only as good as the data on which they are based, but these figures represent a huge improvement on FAO numbers. They are calculated from hundreds of country-by-country analyses that painstakingly reconstructed landings year by year back to 1950. We can be confident in the picture they paint. At the global scale, fisheries are in trouble. And while some countries are working hard to make their industries sustainable, such as the US and New Zealand, most are in deepening crisis.

Seafood is immensely important. An estimated 1 billion people depend on it as their main source of animal protein, and demand will only rise as the world population soars. But just when we need it most, the reliability of seafood is in doubt. It is particularly worrying that industrial fleets from places such as the EU, China, Taiwan and Japan, having depleted their own stocks, are now overfishing the waters of developing countries to which they have bought access. Their plunder – the take is large and reckless enough to justify the word – jeopardises the livelihoods of countless people. In west Africa, falling fish availability in markets has led to increased hunting of bushmeat, bringing people into greater contact with diseases carried by wildlife, perhaps even Ebola.

We can’t go on this way for much longer. Recognising you have a problem is the first step on the road to recovery, and these new figures leave us in no doubt of the urgency of fixing overfishing. In a nutshell, we have to fish less, waste less and devise ways to capture what we want more selectively and with less collateral damage. We must also protect more by putting places off limits to fishing so that the seas can continue to thrive and provide in our fast-changing world.