As a former Marine and Fisheries Minister, I have followed the painstaking process of designating Marine Conservation Zones (MCZs) with great interest. The long overdue announcement last week that 27 MCZs would be designated in English Seas was hailed by the Government as a seminal moment for our marine environment.

Yet, in reality, four years since Labour passed the landmark Marine & Coastal Access Act, these first 27 sites are 100 shy of the original network of 127 MCZs; a network proposed following two years of extensive consultation with stakeholders, costing the taxpayer £8m. We are still a long way from our international commitment to delivering a full ecologically coherent network of Marine Protected Areas.

The Government cannot ignore the growing and diverse calls for the swift delivery of this full network. The Commons Science & Technology Select Committee’s Marine Science Inquiry reported that the process was “floundering badly” – a point echoed by no less than 85 eminent marine scientists in a letter to the Prime Minister in April urging the Government to re-affirm it’s commitment to a full network. Following a public rally on Parliament in February, more than 350,000 members of the public signed a petition in support of MCZs delivered to No. 10 Downing Street in June 2013. The Sea Users Development Group – the representative body for key marine sectors including aggregates, ports, renewables, oil and gas, and the Crown Estate – issued a statement alongside eNGOs calling for the swift designation of a full ecologically coherent network. Designating this network is not only vital to stemming the alarming decline in marine biodiversity, but in providing clarity for businesses on where they can develop with less risk of impacting on protected habitats and species. It is not only the public support for this network that is overwhelming, but both the scientific and economic imperative.

What of future designations? Given the attritional progress to date, do we seriously believe that this Government will have the ambition within the promised future tranches to deliver a truly effective network? It is baffling that Defra continues to state that the scale of its ambition will be defined by “what is affordable” – we should not be designating MCZs in spite of the need to revive growth, but because of this need. The seafloor habitats that these sites will protect are not just the bedrock of the ecosystems they support, but are the foundations of the vast array of goods and services provided by our seas. Just last week, the publication of Defra’s Sea Angling 2012 study showed that recreational sea fishing contributed £2.1bn (almost three times that of commercial fishing) to the economy, and supported more than 23,600 jobs. We must also dispel the scaremongering from some quarters that MCZs will be wholesale no-take zones; MCZs will only prevent activities that damage seafloor habitats, likely affording low impact fishing methods such as potting and static gear the opportunity to flourish at sustainable levels. The fishing industry constitutes many practices. However, the damaging and indiscriminate methods of scallop dredging and heavy towed gear are not universally acceptable. The full network of MCZs, even when added to existing MPAs, would still only place less than 25% of our seas in sustainably managed areas. Put another way, over three quarters of our seas would still be open to potentially more damaging practices. Is suggesting that one quarter of our seas be managed in a truly sustainable manner really such a lofty ambition?

There remains an enormous disparity between our attempts to manage the terrestrial and marine environments sustainably – 87% of the number of Special Areas of Conservation in the UK are on land. Delivery of a full network of MCZs that ensures the full wealth of species and habitats that grace our seas are managed sustainably is a historic opportunity that should not be squandered.