A review by the Irish Sea Network has found 36% of the sea is designated as some form of Marine Protected Area.
Just 5% of this has full management in place, with less than 0.01% fully protected.
The Irish Sea Network is made up of the six wildlife trusts from the region.
This includes Northern Ireland, Scotland, Wales, England and the Isle of Man along with the Sustainable Water Network in the Republic of Ireland.
Each have their own policies, laws and positions on the marine environment.
“There’s a lot of demand on our Irish Sea at the moment, lots of renewables, off-shore wind and so on, and that’s going to increase the pressure on this special sea,” said Annika Clements, from Ulster Wildlife.
“Working in silos is the big problem. So we’ve got to talk to each other and develop a regional approach to managing the sea.”
There are many key species in the Irish Sea, from sharks and shellfish to seabirds, and some are critically endangered.
The review says important habitats and species have been diminished by decades of human activity; native oyster beds are scarce, landings of important fish such as cod have plummeted, and sightings of harbour porpoise have declined.
With six nations having an interest, developing a strategy is a complex challenge.
“The Irish Sea is a really important regional sea, both ecologically and socio-economically,” said Georgia de Jong Cleyndert, from the North West Wildlife Trusts.