A government adviser is trying to allay concerns about restrictions imposed by planned marine conservation zones (MCZs) around the Welsh coast.
The Welsh government will create three or four MCZs by 2014 from a list of 10 potential sites identified by experts.
Campaigners say the zones will destroy fishing and tourist industries in the Llyn Peninsula and Anglesey.
But Dr David Parker says “normal recreational activities” will not suffer and fish stocks will improve.
Dr Parker, chief scientist with the Countryside Council for Wales, said activities, including swimming and diving, will still be allowed within the proposed “highly protected” zones.
But such zones will put a stop to both commercial and recreational fishing as well as other “damaging” activities such as dredging and renewable energy projects.
Boats would be allowed to sail through the zones but not anchor in them, as that would damage the sea bed, said Dr Park who is advising the Welsh government on the science of the proposals.
Ministers are consulting on sites, with some local people worried that a marine reserve on their doorstep would damage the local economy by putting fishermen out of business and deterring tourists.
Dr Parker told BBC Radio Wales’ Eye on Wales programme that those with concerns should look at the global experience of MCZs, as 61 countries already have similar marine reserves.
He said evidence showed they could combine “tremendous non-destructive public use” with environmental benefits.
“You get more fish, you get more biomass, you get fish that have greater reproductive success. These effects can spill over into the surrounding marine environment.”
Dr Parker also believes that the planned adoption of up to four of the 10 proposed sites will help scientists to understand and manage seas better.
“We don’t have any information about what the Welsh marine environment would look like without human intervention,” he said.
“We need to understand much better how to manage the marine environment in a sustainable way – so we can have all the human activities such as fisheries and recreational in a sustainable way.”
It’s only appropriate to look at limiting damaging activity in a small number of areas