'Evidence-based protection' means that we must only conserve what we can show is already there.
It is nearly ten years since Turning the Tide: Addressing the Impact of Fisheries on the Marine Environment was presented to Parliament.
Over 500 closely argued pages, the report's authors (the government's own scientific advisers) concluded that 30% of UK waters needed full protection if the aim was to "protect the resource in the long term rather than protect economic gain in the short term."
This document set in motion the process which led to the Marine Act of 2009, resulting in turn, last month, in the creation of the first Marine Conservation Zones.
The Stennis Ledges in Lyme Bay are one of those 'MCZ's and the announcement was warmly welcomed by Dave Sales: "It's fantastic news for the small boats", he told me.
A lobster fisherman for over 50 years and chairman of the West Bay Fishermen's Association, he points to the map on his kitchen table: "We're fortunate here in that we're ahead of the game. We had 60 square miles protected by the Statutory Instrument in 2008, then another thirty with the SAC. Now the MCZ extends the protected area right across to Portland."
Lyme Bay has indeed fared better than most. When researchers, civil servants, fisheries representatives and NGOs gathered in London a week after the announcement, not many were so upbeat.
A television series, books, a petition which attracted half a million signatures - all of these formed part of the long campaign to hold the government to its commitments under the Marine Act.
Back in 2004, Turning the Tide sounded a cautionary note: "Scientific advice can carry little weight when there are high short-term political, social and economic costs when moving towards sustainability ... it will require high-level commitment to overcome these obstacles." So? Has the commitment finally materialised? Is that what the MCZs mean?
Scroll forward to 2013 and here is the Fisheries Minister George Eustice: "Over 500 marine protected areas already exist around the UK", he enthuses, to which the MCZs are a thrilling addition.
On the government's website, through a fog of dubious grammar, the terms are more or less clear:
"Activities, for example fishing, will only be regulated if they cause harm to wildlife or damaging habitats that are being conserved in the MCZ."
Hmmm. Ten years ago a Marine Protected Area meant an area "dedicated to the protection of biological diversity ... managed through legal or other effective means." It meant protection for "entire ecosystems". Were there really 500 such areas around the UK even before 21st November? The claim is a startling one, on which the minister did not feel the need to expand.
'Evidence-based protection' means that we must only conserve what we can show is already there.
He felt no such need because what we have here is a case of semantic slippage. Marine Protected Areas in the original sense do exist, in places like Lyme Bay, and where they exist most people welcome them. But in too many other cases and places they have protected very little.
"Legal or other effective means" have not yet, in the real world, presented any obstacle to the rogue scallop dredgers from Scotland and the Isle of Man. The creation of "ecologically coherent networks" mattered ten years ago too, as did areas in which there would be no fishing.
Of the 127 sites recommended by the Wildlife Trusts, just 27 have been designated and not one of them includes a no take zone. More sites will be created in two further tranches but 27 sites sounds very much as if we are exactly 100 sites short. It sounds as if scientific advice has indeed carried less weight than it might have.
Not everyone at the London gathering saw it this way. Joan Edwards, of the Wildlife Trusts Living Seas programme - a committed and long term campaigner on the issue - saw a hopeful sign in the government's openness to further designations. She felt the new minister's willingness to talk again about "ecologically coherent networks" was significant, particularly as the government approaches a difficult election.
Jean-Luc Solandt of the Marine Conservation Society saw this as an occasion to re-examine attitudes: "As ecologists we see the ecology, but we need to see the food and fertiliser which others see too." We know enough, now, to see that 'protecting' a habitat doesn't just mean different things to different people - it means different things in different places as well.
In Lyme Bay as in Port Erin or Lamlash Bay or off Lundy, lobsters and scallops recover within 5-10 years of closing an area to dredgers. Seagrass beds also return, sometimes. Once you destroy maerl or chalk reefs, they're gone.
In each case such knowledge ought to be informing our attitudes. He conceded, though, that at present "we have the remnants, the bits and pieces - these will never deliver the eco-services everybody needs."
Only protection of broad-scale habitats can deliver those and here we come to the radioactive core of this question: the drift toward protecting 'features' rather than whole sites.
Earlier legislation required officials to state what features would be protected by any given designation. The term meant sometimes a geological feature or habitat, sometimes a particular organism, but was clearly only one part of what justified protecting the larger site.
'Features' have now been fastened upon by fishing industry lobbyists as a general-purpose escape clause. One such group is the bizarrely named Marine Protected Areas Fishing Coalition. Its very name is an excellent example of the semantic slippage I've referred to. It is funded by, and operates as a tool of, the industrial fishing fleet.
Specifically it acts as a kind of dredge which is towed back and forth over the public discussion, knocking flat anything sensible which it encounters. The website states quite openly that its purpose is to make "the strongest case possible for maintaining open access to fishing-grounds."
Its spokespersons claim to speak for a victimised minority. It is certainly a minority: one wonders how many members of the general public would offer their signatures in support of its activities. Not many victimised minorities - outside the banking sector perhaps - enjoy such influence over government.
So still-existing 'features' are now what the whole process begins with: these must be identified and their protection must be justified. Birds and cetaceans don't count. The industrial fishing fleet is not required to justify the harm it does to marine habitats.
The burden of evidence is, rather, on those seeking to protect such habitats, who must justify everything. It is not clear, even within the new MCZs, how much protection is being afforded to what does not qualify as a 'feature'.
So for example, the Stennis Ledges MCZ, in Lyme Bay, protects Chesil Beach and the Ledges themselves, or rather the native oysters and sea fans which are found on them. The exact status of the coarse and fine sands in between these features is uncertain, though they play host to large aggregations of spider crabs and cuttlefish every year.
The scallop dredgers meanwhile argue, entirely straight-faced, that as members of a victimised minority they should be readmitted to the areas between 'features'.
This naturally gives rise to much confusion and was of course intended to do just that. The legislation is there, but, with the help of bodies like the MPA Fishing Coalition, government interprets it in such a way that it yields an absolute minimum of real protection.
When the situation is explained to marine conservationists from Australia, New Zealand or the United States, they shake their heads in disbelief: "They think Monty Python was a comedy", one speaker put it. "I have to explain it was a documentary."
This humour is fact very much in line with the present government's downgrading of conservation in pursuit of 'blue growth' at sea. In practise this means maximising profit over all other considerations - and a peculiarly myopic version of profit, at that.
The same Marine Act called for the development of Marine Plans, the first of which, for the east coast, has just been published. The Wildlife Trusts and others have expressed concern at the absence of serious engagement with the impact of industrial fishing in the North Sea.
One of the best answers to 'features-led protection' in the interests of victimised minorities comes, again, from Lyme Bay. Five years ago, after the first closure of 60 square miles, Emma Sheehan of the University of Plymouth carried out a video survey of the state of the sea-bed, a survey which has continued since.
Her work confirms what few would ever have doubted. Ross corals are up by 385%, branching sponges by 414%, pink sea fans by 636% - all of which means extra nursery areas and structures for larval settlement. How about those for growth figures? Lobster fishermen are noticing the increased numbers of young animals they are finding in their pots (and returning). Exact figures on the catch per fishing effort are expected soon.
All this can be measured and shown to the public. And the figures above are actually for the pebbly sand between the reefs. In other words, left alone for five years what emerges at surprising speed is that reef-associated species will spread far beyond the places where they "ought to be".
What better illustration could there be of the folly of what the fishing industry refers to as "evidence-based" protection? They mean that we must only conserve what we can show is already there.
Or what is left, rather. A visitor to the Isle of Man in 1836 wrote that the seaweed "may be seen waving to and fro at great depth, so extraordinary is the clearness of the water; a perfect submarine forest." Was that how the Irish Sea looked to you, last time you crossed from Holyhead?
Callum Roberts reviewed the evidence for what its waters looked like when they were fished with hook and line and static nets, filtered by vast oyster-beds, when they were home to angel sharks, halibut, abundant turbot and even lophelia coral.
The oyster-beds were dredged later in the 19th century by sailing boats then steam-trawlers. Diesel-powered vessels were next, then monofilament nets, and sonar. At every stage, technological advance allowed a brief leap in profit, at the expense of the small boats and the marine habitat.
Reduced now to a 'fishery of last resort', the same prawn trawling which has prevented the recovery of cod on the Grand Banks continues in the Irish Sea, alongside the dredging which is wrecking the sea-bed's integrity.
Can we learn to regulate the use of our technologies? Thirty years ago the arrival of spring-loaded dredges brought the Lyme Bay reefs within range of the scallopers - in other words a technical advance. Today, the dredges are banned and the sea-bed's recovery is surveyed using drop-down video.
All dredgers are legally required to fit Inshore Vessel Monitoring Systems while tracking devices which use mobile phone networks rather than satellite are being suggested for the smaller boats. Perhaps, here and there, we are finally learning to put our technologies to sensible use.
But the wider marine habitat which we have been mistreating all this time, altered now also by eutrophication and the effects of climate change, is more vulnerable than ever to invasive species. The longer we wait for more ambitious protection, the worse it will get.
Melville somewhere calls the sea "an old, old sight and yet somehow so young" and I suppose we all know what he means. At this point it can carry on renewing itself, and us. But only if we let it.
Horatio Morpurgo is a journalist and campaigner. He lives about a mile away from Lyme Bay and was involved in the successful local campaign to exclude the scallop dredgers from Lyme Bay and establish a Marine Protected Area.
Horatio's book Drake's Graffiti (Erewhon, 2010) situates Marine Protected Areas in the longer story of the West Country's relationship with the sea.
This article also draws on the Managing UK's Marine Natural Resources conference held at SOAS on 28 November 2013.
Photograph: Colin Munro Photography.