"This was a Herculean task that no one else has ever attempted.While the results necessarily remain uncertain, they undoubtedly represent our most complete picture yet of the global state of fish catches." Worm said the world's fisheries were being over-exploited but that some stocks were being sustainably managed: "Where such measures have been taken, we find that both fish and fishermen are more likely to persist into the future." Global fish catches rose from the 1950s to 1996 as fishing fleets expanded and discovered new fish stocks to exploit.
Prof Callum Roberts, at the University of York in the UK and not part of Pauly's team, said: "We can see more clearly now, for example, the immense value of fish to poor people in developing countries," he said.
"We can see how industrial fisheries from developing countries are robbing these people of livelihoods and food.
But after 1996, few undiscovered fisheries were left and catches started to decline.
The decline since 1996 has largely been in fish caught by industrial fleets and to a lesser extent a cut in the number of unwanted fish discarded at sea.
Seabirds continually mistake plastic for fish eggs, devouring large amounts.
Plastic in animals' stomachs not only release deadly toxins, but can also lead to slow starvation by obstructing the animals' bowels.
We know how to fix this problem but whether we do it or not depends on conditions that are difficult." A 2015 study showed nearly 500 Chinese fishing vessels operating off west Africa, with scores of cases of illegal fishing, according to Greenpeace.
Illegal and pirate fishing take place in many parts of the world.
"The fact that we catch far more than we thought is, if you like, a more positive thing," he said.