This week’s guest blogger is John Farndon, with his second guest post. Having studied earth sciences at Cambridge University, John has written more than 300 books on science and nature including How the Earth Works, The Wildlife Atlas, The Practical Encyclopedia of Rocks and Minerals, and the forthcoming The Atlas of Oceans.

Last week, I saw in the news that the EU has pledged to change the clause in the Common Fisheries Policy which effectively forces fishermen to throw millions of dead fish back into the sea.

As it stands, fishing boats can only land particular numbers of particular fish. So any fish hauled up in the nets surplus to quota is simply chucked overboard, already dead. In the whitefish industry, up to half the catch is discarded. With flatfish, over 70 per cent of the catch goes overboard. The waste is appalling. As a policy designed to protect threatened fish populations, it clearly doesn’t work.

Thanks in part to public pressure stirred up by TV chef Hugh Fearnley-Whittingstall, EU fishery officials are now looking at how best to alter the system. One suggestion is that fishing boats are required to land all their catch and count any extra fish as part of the quota, regardless of species or size. So boats have to stop fishing as soon as they catch a certain tonnage, even if only a small proportion is the fish they want. The UK is trying this tactic out in the North Sea at the moment.

This is good, and yet it is just the tip of the iceberg, or rather the tiddler in the shoal. The fishing industry has created a global crisis in the oceans, the scale of which is only just beginning to dawn.

The dreadful wastefulness of bycatch (unwanted fish caught up in the nets) is just part of the picture, as I discovered when writing my forthcoming book Atlas of Oceans (Yale UP and A & C Black). Each year a staggering 30 million tonnes of unwanted fish are dumped in the sea, including dolphins, whales, turtles as well as countless smaller sea creatures. Yet the wastefulness of bycatch, shocking though it is, is just part and parcel of the way the world’s fishing industry is now scooping marine life from the oceans like there was no tomorrow.

In the 1950s, the annual fish catch around the world was 20 million tonnes. Now, thanks to industrial fishing boats that can haul fish from the sea at an awesome rate, it is over four times that much at 80 million tonnes. The annual take has declined slightly in recent years – not because there has been much let up in the relentless pursuit of wild fish, but because fish are becoming so scarce they are harder to find even with modern location techniques.

Fishing quotas have been in place for decades but have not prevented many populations of once abundant fish being fished out. Northern cod, North Sea mackerel, Antarctica’s marbled rock cod, bluefin tuna and many other populations have all but gone. Ninety per cent of large predatory fish such as tuna, sharks and billfish have been removed over the last century. Notoriously, the

In 2006, Boris Worm, a marine ecologist at Dalhousie University in Halifax, Nova Scotia, Canada, presented a study which projected that overfishing was proceeding at such a breakneck speed that the oceans would be entirely fished out of edible fish by 2048. Some experts argued that Worm was overstating the problem, and one of his critics, Ray Hilborn, joined him on a new study, completed in 2009. Even this new study suggested that 63 per cent of fish populations were being fished at such unsustainable levels that they will inevitably collapsed unless there is some change.

By themselves, EU quotas quickly become irrelevant. As fish populations in the inshore waters of the developed countries are fished out, so the boats move on to exploit the inshore waters of developing countries, or out into the deep, where species only recently discovered are already under threat of extinction. Commercial fisheries have also been ‘fishing down food webs’ which means that once they have fished out big fish, they move on to smaller fish and will eventually be catching jellyfish and plankton.

Nonetheless, there are grounds for hope. There are places where fish stocks are managed properly, and where there is only a limited amount of illegal fishing. There fish stocks do seem to show signs of sustainability and even recovery in some cases. Out of 10 regions in North America, northern Europe and Oceania that Worm and Hilborn’s team looked at closely, five showed signs of improvement, with diminishing rates of exploitation in recent years.

In other words, political and government action can make a difference, and more importantly so can consumer pressure and choice to alter fishing practices. The biggest choice the consumer can make, though, is to remember that every morsel of wild food is precious. Jellyfish stew, anyone?