Fish success story in Baja, Mexico, but development looms

The fish population in an undersea park near the southern tip of Mexico’s Baja peninsula has been booming.

Fish populations in Parque Nacional Cabo Pulmo (Cabo Pulmo National Park) grew more than 460 percent from 1999 to 2009, according to a 10-year analysis published in the Public Library of Science (PLoS) ONE journal this week (August 12, 2011). The recovery shows that even small reserves can allow fish populations in the Gulf of California to recover, according to the authors.

But, according to an August 12, 2011 story in Nature News, the area is under threat from the development of a resort aiming to house thousands of tourists and a marina just a few kilometers to the north. The researchers are now working to compile environmental data, such as the direction of prevailing ocean currents, in an effort to quantify the probable impact of the resort and petition against its development.

The ocean in and around the park was previously depleted by fishing. But citizens living around Cabo Pulmo established the park in 1995 and have strictly enforced its no-take restrictions.

The researchers from Scripps Institution of Oceanography at UC San Diego now consider Cabo Pulmo – tucked away in Baja California Sur – to be the most robust marine reserve in the world. The percentage recovery there isn’t unprecedented – one recent study found an average of 446% in 55 marine protected areas, according to the Nature News story. But the researchers told Nature News that the density of fish living on the park’s reef is the best they have seen anywhere on record.

National Geographic Explorer-in-Residence Enric Sala, who started the study in 1999, said:

We could have never dreamt of such an extraordinary recovery of marine life at Cabo Pulmo. In 1999 there were only medium-sized fishes, but ten years later it’s full of large parrotfish, groupers, snappers and even sharks.

The most striking result of the paper, the authors say, is that fish communities at a depleted site can recover up to a level comparable to remote, pristine sites that have never been fished by humans.

Octavio Aburto-Oropeza, lead author of the study, said:

The study’s results are surprising in several ways. A biomass increase of 463 percent in a reserve as large as Cabo Pulmo (71 square kilometers) represents tons of new fish produced every year. No other marine reserve in the world has shown such a fish recovery.

The paper notes that factors such as the protection of spawning areas for large predators have been key to the reserve’s robustness. Most importantly, local enforcement, led by the determined action of a few families, has been a major factor in the park’s success. Boat captains, dive masters and other locals work to enforce the park’s regulations and share surveillance, fauna protection and ocean cleanliness efforts.

Strictly enforced marine reserves have been proven to help reduce local poverty and increase economic benefits, the researchers say. Cabo Pulmo’s marine life recovery has spawned eco-tourism businesses, including coral reef diving and kayaking, making it a model for areas depleted by fishing in the Gulf of California and elsewhere.

Co-author Brad Erisman said:

The reefs are full of hard corals and sea fans, creating an amazing habitat for lobsters, octopuses, rays and small fish. During some seasons thousands of mobula rays congregate inside the park and swim above the reef in a magnificent way.

The scientists have been combining efforts to monitor the Gulf of California’s rocky reefs every year for more than a decade, sampling more than 30 islands and peninsula locations along Baja California, stretching from Puerto Refugio on the northern tip of Angel de la Guarda to Cabo San Lucas and Cabo Pulmo south of the Bahia de La Paz.

During the ten years of the study, the researchers found that Cabo Pulmo’s fish species richness blossomed into a biodiversity “hot spot.” Animals such as tiger sharks, bull sharks and black tip reef sharks increased significantly. Scientists continue to find evidence that such top predators keep coral reefs healthy. Other large fish at Cabo Pulmo include gulf groupers, dog snappers and leopard groupers.

Co-author Exequiel Ezcurra said the area was not in very good health during the 1990s but the community was enthusiastic about its recovery:

If you visit [Cabo Pulmo] now, you cannot believe the change that has taken place. And all of it has occurred thanks to the determination of a community of coastal villagers that decided to take care of their place and to be at the helm of their own destiny.

Aburto-Oropeza added:

Few policymakers around the world are aware that fish size and abundance can increase inside marine reserves to extraordinary levels within a decade after protection is established; fewer still know that these increases often translate into economic benefits for coastal communities.

Bottom line: A ten-year study of Mexico’s Parque Nacional Cabo Pulmo (Cabo Pulmo National Park) shows that fish populations increased by 460 percent, largely due to the community’s effort in protecting the area. Results of the study appear in the Public Library of Science (PLoS) ONE journal on August 12, 2011. The area is under threat from the development of a resort aiming to house thousands of tourists and a marina just a few kilometers to the north. The researchers are now working to compile environmental data in an effort to quantify the probable impact of the resort and petition against its development.

Read more at Scripps Institution of Oceanography

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