MEXICO CITY — The shallow-water reefs at Cabo Pulmo, in Mexico’s Sea of Cortez, are a national treasure, a marine reserve with a remarkable back story about how a once-abused environment can rebound.

The protected waters are now packed with fish.

A Spanish real estate developer was planning to build a mega-resort the size of Cancun on the barren Baja coast right at the edge of the marine reserve — which drove Mexican and international preservationists at Greenpeace and the World Wildlife Fund nuts.

Greenpeace activists protest in front of the National Palace in Mexico City on June 4. The activists were demonstrating against plans to build a resort in Cabo Pulmo on the Baja California Peninsula. (Eduardo Verdugo/AP)

On Friday, Mexican President Felipe Calderon, himself a scuba diver, announced that the government was pulling the permits and canceling the project.

This is a big deal in fish circles.

The proposed Cabo Cortes resort, at the southern tip of Mexico’s Baja California state, may have included five-star hotels, time-share condos, a shopping mall, an airport, golf courses and a major marina — all just a short boat ride from the reef and in a place as dry as a bone, where many locals opposed the development.

Instead, Calderon says, the government will help the nearby former fishing village of Cabo Pulmo improve its services in a small-scale, sustainable way. The village now has a couple of fish joints and three dive shops, some sandy roads and a few rustic inns, most without AC. The town runs on solar power, just enough to keep the beer cold.

What is remarkable about the reef is that just a few years ago it was almost fished out. As The Washington Post reported last year, researchers say that the biomass of fish in the no-take marine reserve increased by an unprecedented 463 percent in just 10 years, offering hope that, if just left alone for a little while, the planet’s depleted seas can rebound.

On an empty spit of shadeless sand a few miles north of Mexico’s Cabo Pulmo marine reserve, a Spanish development conglomerate had planned a mega-resort, appalling environmentalists. Friday, Mexican President Felipe Calderon announced the project was canceled. View a photo gallery from last year.

“The move by President Calderon to stop an ill-conceived mega development project that would have devastated valuable Mexican coastal resources is good news for the marine life and local communities that depend on them,” said Amanda Maxwell, Latin America project director at the Natural Resources Defense Council, in a statement.

No word from Hansa Urbana, the Spanish developer, on the decision.

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