Greenpeace México oceans campaigner Alejandro Olivera onboard the Greenpeace ship Arctic Sunrise during last year's expedition to the Arctic.

In the Greenpeace oceans campaign, we talk a lot about marine reserves, the wildlife parks at sea that can help restore fish populations, improve our oceans' resilience to threats like climate change and ensure living oceans for the future. It's something we've been working on for years, including here in México. I wanted to share an example of how marine reserves can help grow fish populations and maintain local economies, but an example that will also illustrate how we must keep working to defend our oceans.

Twenty years ago, fishermen near Cabo Pulmo (the northernmost and one of the most important coral reef in the East Pacific) a few horus from Los Cabos noticed that they had to go further from the coast to catch fish and that yearly catches- and profits- were declining, so they decided to trade in their fishing nets for scuba diving gear. The local communities supported the shift from fishing to eco-tourism and the area became the best-enforced no-take (meaning fish aren’t removed from a designated area of waters) areas in the the Gulf of California, nicknamed the World’s Aquarium by Jacques Cousteau because of its unique range of marine biodiversity. (You may remember Greenpeace’s 2006 ship expedition to the Gulf of California.) The people of Cabo Pulmo still believe that showing a fish to a tourist is more profitable than fishing it out of the water.

Once the Cabo Pulmo reef area was declared off-limits to fishing, an amazing recovery began. Marine life around the reef began to flourish and the area was designated a National Park (marine reserve) by the Mexican government, declared a UNESCO World Heritage Site under UNESCO and named a wetland of international importance under the Ramsar convention. Mexican scientists recently released the results of a research project, showing that the increase in fish populations in Cabo Pulmo in the last decade is the largest increase ever measured in a marine reserve! This increase is likely due to a combination of social (strong community support for the protection of these waters and effective enforcement) and ecological factors. In a period of ten years fish “biomass” increased 463%.

A sea lion swims near Greenpeace divers displaying a banner saying "Marine Reserves Now"in the Gulf of California in November 2006 © Greenpeace / Alex Hofford

What’s even more incredible is that you can see the results of this change in Cabo Pulmo first-hand. I´ve dived in the Caribbean, in the Gulf of Mexico and in the East Pacific, and Cabo Pulmo is the most amazing diving location I’ve experienced. I´ve never seen so many large groupers on a dive, let alone all swimming together! During my last dive in Cabo Pulmo, I suddenly felt a cloud above me and when I looked up a huge school of jacks began to surround me, and we had to dive through them to reach the water’s surface. It is strange that the fish in Cabo Pulmo are so used to the presence of divers that you can get very close to them, as if they were domesticated. It was marvelous!

Unfortunately, this underwater paradise that has recovered and is now thriving is now under threat. Earlier this year, the Mexican government approved a huge coastal development project next to Cabo Pulmo marine reserve named Cabo Cortes. A Spanish development company is hoping to build a new city in this semi desert area that will have more than 27 thousand rooms, 2 golf courses and a marina that can hold 490 yachts, a resort nearly at the scale of Cancún.

Greenpeace activists hold a banner, protesting coastal property development on the coast of the Gulf of California in December 2006. © Greenpeace / Alex Hofford

Greenpeace Spain and Greenpeace Mexico have been campaigning to protect this gem in the World’s Aquarium. So far, construction of the Cabo Cortes project has not started and we will not let it happen, as the Cabo Pulmo marine reserve has brought significant economic benefits to the region. Community-managed marine reserves are a real solution and a better alternative to unsustainable coastal development, which could lead to fisheries collapse in the Gulf of California and beyond.

If we want ample fish and healthy oceans tomorrow, we need more marine reserves like the one in Cabo Pulmo today. Greenpeace is campaigning globally to change fishing practices and create a global network of marine reserves covering 40% of the world's oceans. These are necessary steps to restore our oceans - which provide food and jobs for millions - to health as the overfishing crisis continues.

Alejandro Oliveira is an oceans campaigner working in Greenpeace México’s office in México, D.F.