Conservationists will head to Westminster today to present a 250,000-name petition calling for greater government protection of the UK's marine life.

The signatures, written on silver 'scales' and attached to a 'petition fish', will be presented to environment minister Richard Benyon at a parliamentary reception hosted by the Wildlife Trusts.

The Norfolk Wildlife Trust (NWT), which collected about 10,000 of the names, will be among the organisations hoping to highlight the risks which they believe will result from failing to designate important habitats as Marine Conservation Zones (MCZs).

The 127 sites initially recommended by stakeholder groups for the MCZ project include the Cromer Shoal Chalk Reef, which runs for 30km along the north Norfolk coast and is now thought to be the longest in Europe.

Recent underwater surveys have shown the reef to be a rich biodiversity hotspot which is home to a species of sponge that was previously unknown to science.

But the NWT was 'very disappointed' when the site was not listed among the 31 which Defra proposed for designation in December.

Brendan Joyce, chief executive of the NWT, said he hoped today's event would convince the government to designate these 31 sites as soon as possible – and set a clear timetable for the rest, including Cromer Shoal.

'Whilst the government treads water, wildlife-rich areas in our seas continue to suffer degradation,,' he said. 'MCZs should protect the species and habitats found within them from the most damaging and degrading of activities whilst mostly allowing sustainable activity to continue.

'The network was designed to ensure that we don't end up with isolated and vulnerable sites and to ensure that the wide range of marine habitats found in UK seas are protected. Failure to designate all but a very small proportion of sites recommended by these stakeholders will mean that we lack the ecologically coherent network that our seas so badly need to recover.'

The Westminster event coincides with the publication of a new poll, commissioned by The Wildlife Trusts, which outlines public support for protecting threatened sea life.

Another new report published today, also commissioned by The Wildlife Trusts, highlights the benefits to society and the economy if the MCZ network is adopted.