If Earth’s rapidly depleting stocks of fish are ever able to recover, scientists have warned that a full third of the planet’s oceans must be closed to all commercial fishing. According to many conservation groups, this type of action could “set the clock back 200 years” and almost completely reverse the current extreme decline in fish populations. Once the populations have returned to natural level, then new regulations and responsible fisheries management could revitalize this massive industry.

According to Callum Roberts, Professor of Marine Conservation at the University of York, “20 to 40% of the sea should be protected.” The Marine Conservation Society and the Royal Society for the Protection of Birds all support the idea of a 30% closure. “What we would see is a flourishing of life,” Roberts says. “In 20 years, we could get to a point where a lot of species are in a far more productive state.”

The European Commission has set forth a proposal for a reduction in fishing ship fleet size and a massive cut in current fishing levels, but Roberts believes these will not work without the inception of Marine Protected Areas or MPAs. “Just cutting fishing effort is not enough,” says Roberts, “If we are ever going to have sustainable fisheries, MPA networks are an essential, indispensable part of any rational management package.” As an example of the desperation of this situation, consider this figure: In the North Sea, 93% of cod are fished before they have had a chance to breed.