"I believe there is not a portion of the ground but what the trawl destroys," explained G Cormack, a fisherman from Torry, Aberdeen. "I have dragged 50 miles off Aberdeen. I have got fast there and brought up coral about 2.5ft in circumference, lumps of soft coral, and I am prepared to say that whatever is in the way of the trawler will not escape."

It is a stark description of the damage inflicted by "bottom trawling", the practice of dragging heavily weighted nets across the seafloor to sweep up fish – like cod and haddock – that thrive there. And it is all the more alarming for having been voiced almost 150 years ago. Cormack was giving evidence in 1866 to a royal commission on the impact of bottom trawling, which expanded massively in British waters from the beginning of the 19th century. Traditional fishers opposed bottom trawling, not just because they thought it damaged the seabed by ripping up coral, oyster beds and sponges, but because they believed it wiped out fish stocks. "Twenty years ago, we used to get 600 or 700 a head of fish a day," said another commission witness, B Simpson, a line-fisherman who worked off Spurn Point, Grimsby. "Now they cannot get above 20 head, or three or four score at the outside."

At the hearings, hundreds of others gave evidence, most of them damning in their views of bottom trawling, as is revealed in a recent paper by York University's Ruth Thurstan, Julie Hawkins and Callum Roberts in the journal Fish and Fisheries. The evidence was to no avail, however, for the commission decided Britain could not afford to block bottom trawling and so decreed that "unrestricted freedom of fishing should be permitted". The fishing industry lobby in Victorian times was clearly no less powerful then than it is today. These 150-year-old tales of ruined fish stocks and wrecked seabeds have a special irony for modern marine biologists and ecologists – for just as the 1866 royal commission turned its back on trying to protect the UK's marine environment, so the government today stands accused of allowing our coastal seas to be degraded to an even greater extent. Indeed, the marine devastation of the 19th century looks relatively minor compared with that of today. In the 19th century, and even in the early 20th century, bottom trawling was done by fisherman sailing 40ft wooden boats – usually owned by a single family – which dragged nets with mouths a few metres wide across the seafloor, sweeping up shoals of cod, haddock and herring. "It would have been a very tough existence," says Angela Benn, of the National Oceanography Centre, at the University of Southampton. "You were going out in all sorts of weather. It took incredible bravery and the loss of life was grim."

And it caused considerable damage to the seabed and triggered significant depletions of stocks, as the commission heard. The trouble is that these relatively modest-sized trawlers have been replaced by far, far bigger ships operated as industrial concerns by business conglomerates. They use vast, 30-tonne nets that have metal doors and chains to hold them down and are dragged across the seabed with effects that far outstrip those described by Cormack, Simpson and other 1866 commission witnesses.

"Imagine if you used a fleet of tractors to drag 30 tonnes of gear over a 150-metre wide swath of land for most days of the year," says Brian Bett, another marine researcher at the National Oceanography Centre. "You would wipe out the New Forest in a few months and the rest of the countryside not long after that. Yet that is what we are doing to the seabed round Britain. Even worse, the boats keep going over some key areas. The seafloor gets no chance to recuperate. It is tragic."

Not surprisingly, the impact on reefs, sponges and shellfish has been savage. The Firth of Forth was once home to vast beds of oysters, for example. None remains. Similarly, the Firth of Clyde once abounded with fish, shellfish, whales and porpoises. Today its seabed is barren and its fish stocks have disappeared. "Nothing worth catching is left," states Callum Roberts in his book, Ocean of Life. "The Firth of Clyde gives us a stark vision of a life without fish."

And as bottom trawling and dredging continues, such a fate awaits most other UK inshore fisheries. "Trawlers have transformed life on the seabed, converting three-dimensional, complex habitats rich in coral, sponge and sea fan to endless monotonous expanses of shifting gravel, sand and mud," adds Roberts. Nor is the damage confined to the seabed. Stocks of fish – robbed of any hiding places on the seafloor – have suffered correspondingly. Common skate, angel shark, halibut and wolfish, once plentiful, have virtually disappeared from British waters while bottom fish – which cling to the seabed – such as cod, haddock and turbot, have suffered drastic declines in numbers.

The grim scenarios described in 1866 pale by these descriptions, as Roberts makes clear. By studying the first official statistics of UK fish landings, which began in 1889, he has discovered that our fishing – which was mostly done by sailing boats without radios or echo-finders – was far, far more successful than its modern equivalent. "For every hour spent fishing today, in boats bristling with the latest fish-finding electronics, fishers land a mere 6% of what they did 120 years ago. Put another way, fishers today have to work 17 times harder to get the same catch as people did in the 19th century." And the reason for this startling state of affairs is straightforward: we have caught so much fish in our own waters over the past 150 years, there is little left for us today. Some species hover at the edge of extinction. Our seas, and the floor below them, have been stripped of their riches.

It is a dispiriting, unsettling picture and for years scientists, ecologists and others have been pressing the government for action – and appeared to have achieved success when the Marine and Coastal Access Act was passed in 2009. It laid the foundations for a national network of marine conservation zones to provide some respite for the seabed off Britain's coast. A few precious remaining populations of cod, haddock and other fish might get a chance to restore their numbers and health, it was thought. A two-year, £8m consultation exercise was set up to work out how these zones should be set up. Thousands of people with interests in our coastal regions – from fishermen to tourism experts – took part and recommended the creation of a network of 127 marine conservation zones and 65 highly protected reference areas in the seas around England. Similar plans were made for Scotland and Northern Ireland. Crucially, this network of zones would only work if enacted in their entirety, it was emphasised. The effectiveness of a patchwork cherry-picked set of zones, reduced in number, would be greatly diminished.

It had taken several years of work by thousands of people interested in saving Britain's seas to work out this detailed proposal for a marine conservation network, efforts that were then dismissed by the fisheries minister, Richard Benyon, who described the plan as the "most banal campaign running in public". The scientific evidence to back the creation of the zones and restrict fishing within them was simply absent, he claimed. There was no reason to implement the plan and curtail fishermen's jobs.

Instead, the Department for the Environment, Food and Rural Affairs (Defra) – which had originally organised the consultation – agreed only to consult on 31 of the 127 proposed zones (a number later reduced to 27), while the idea of the reference areas was dropped completely by ministers. The plan for Britain's marine network had been emasculated, although Defra later added that it might open consultations over some of the other proposed zones in future years. Not surprisingly, conservation groups and scientists were unimpressed. "These zones were the result of two years' hard work and involved thousands of stakeholders," said Lissa Batey of the Wildlife Trusts. "Scientists, conservationists and representatives of the fishing and dredging industry all took part. Proposals for zones were put forward. Some were dropped because of industry protests, others were changed. The resulting network was a consensus, and a good one." But now the plan is in tatters, a state of affairs that is described as "an absolute disgrace", says Roberts. "Many of our fisheries are on the point of collapse and our coastal waters are in a state of grievous disrepair. Yet the government has decided that it is simply not worth taking meaningful action to put right these very severe problems."

All is not completely lost, however. Although stymied over proposals for the protection zones, conservationists and biologists have recently taken an alternative approach to try to protect Britain's seas. This makes use of 107 marine Special Areas of Conservation that were set up in 1992 under the EU Habitats Directive but which were being ignored by Britain. "UK government regulators weren't doing anything about them and were allowing trawling and scallop dredging to take place," says Jean-Luc Solandt of the Marine Conservation Society. Legal challenges by a number of NGOs have now forced the government to tighten up the running of these special areas.

Fish seized at the port of Abidjan, Ivory Coast, from two Chinese ships which used 'bottom trawling' disregarding local fishing laws. Photograph: Kambou Sia/AFP/Getty Images

As a result, several have now banned bottom trawling including one major marine area in Cornwall – which introduced its ban in November. Others include marine sites near the Isles of Scilly, Devon, Dorset, Hampshire, Isle of White, Thanet in Kent, and Northumberland. "The list is not vast but we expect to be adding to it," added Solandt. "It is a start, if nothing else." This point is backed by Roberts. "There is little to be cheerful about when it comes to our marine environment, which makes recent successes with those areas protected by EU law – although limited in extent – all the more pleasing."

The real problem is one of shifting baselines, adds Roberts. The wasting of our seas and fisheries that has occurred over the last two centuries has taken place at a fairly steady rate. "One generation sees a change – in terms of loss of habitat and stocks – but does not realise similar losses were observed by the previous generation, and by the generation before that.

"A fisherman might well have been surprised by the changes he saw in the middle of the 19th century but he would be utterly horrified by the impoverished seas he would witness today. The changes have come upon us steadily – which is why we have failed to appreciate the true scale of the devastation. If it had happened over a short time, we would be much more concerned and would be taking urgent action."

Not every fish or mussel in our seas is threatened, of course. "There is still the occasional giant cod to be found in our waters and some fisheries are healthy or recovering," adds Roberts. "But overall, the position for ocean life is very worrying – particularly as our government appears to be completely unwilling to address the issue. Our seas need protection. It is as simple as that."