It was good news when scientists in Puerto Peñasco, a fishing and tourism hub in Baja California, found proof for the first time of the rapid “reseeding” effects of marine reserves —- how a no-fishing zone can replenish fish stocks by exporting babies beyond its boundaries.
The Puerto Peñasco divers were worried about the declining stocks of snails and scallops, the bread and butter of their trade. So, beginning in 2001, they worked closely with researchers to design, set up and monitor three de facto marine reserves where fishing was banned. The no-fishing zones extended along 11 miles of rocky coast and around San Jorge Island, 20 miles offshore in the northeastern Gulf.
Within a year, there were big increases in the abundance of juvenile rock scallops and black murex snails both inside and outside the reserve boundaries. The bigger and older the shellfish got inside the reserve, the more larvae, or babies, they produced, and the more they drifted with the current, quickly reseeding the depleted areas where fishing was allowed.
The reserves extended over 30 percent of the fishing grounds, but the local cooperative of about 22 divers could see that it was beneficial. They volunteered their time to count scallops and snails underwater. They kept an eye on each other, too, taking occasional trips to the island to see if anyone was cheating.
During the first two years of the reserves, there were only 13 violations of the fishing ban out of 2,000 local diving trips from Puerto Peñasco. Nobody wanted to risk being ostracized. News of the thriving shellfish stocks spread along the coast. The Mexican government recognized the divers with a Presidential Conservation Award.
“Things were going so well,” said Richard Cudney-Bueno, who helped design the Puerto Peñasco reserves as an adjunct biology professor at the University of Arizona School of Natural Resources and a researcher at the University of California, Santa Cruz Institute of Marine Sciences.
And then the roving bandits came.
They arrived in a handful of boats from 200 miles away, and they started poaching in the reserves that had been maintained based on trust at San Jorge Island. There was nothing the locals could do. The Mexican government had never formally recognized the fishing ban, and nobody had a legal right to throw out the newcomers.
The locals weren’t going to stand by and let others reap the benefits of their investment at San Jorge. So, they joined in the poaching, and it spread from the island to the coastal reserves in a free-for-all.
Within a month, the local populations of scallops and snails plummeted by half as the divers took in big hauls, driving down the market price. By the end of two months, the shellfish stocks had dropped to pre-closure levels.
“The whole thing got wiped out due to disruption of the social structure that had supported it,” said Peter Raimondi, a University of California, Santa Cruz biologist who collaborated on the study. “Scientifically, it was really interesting, but for the people who experienced it on the ground, it was terrible.”
How Reserves Work
The establishment of marine reserves is typically controversial and fraught with conflict. Environmentalists seek the conservation benefits of “underwater parks,” but the fishermen don’t see what’s in it for them. Where’s the proof, they want to know, that reserves can actually replenish stocks elsewhere?
In their groundbreaking study of the Puerto Peñasco reserves, published this year on the PLoS ONE blog, Cudney-Bueno, Raimondi, William Shaw of the University of Arizona and their colleagues in Mexico, describe how they were able to predict and then confirm the rapid effects of the dispersal of fish larvae outside the reserves.
By tracking local currents in the Gulf of California and calculating how far the wandering larvae would travel, the scientists pinpointed exactly where the larvae, now grown to little scallops, would eventually attach to the rocky ocean bottom. They predicted, correctly, that it would be about a 10-day trip for the floating larvae to locations between 12 and 30 miles away.
The divers counted young shellfish in the “reseeding” locations and inside the reserves both before and two years after the fishing ban went into effect. The scientists found that the density of juvenile rock scallops increased more than 40 percent inside the reserves and more than 20 percent in fishing areas outside the reserve boundaries. The density of black murex snails in fishing areas increased threefold.
Robert Warner, an evolutionary ecologist who helped design a 318-square-mile network of marine reserves around California’s Channel Islands, the largest such network off the continental United States, called the Puerto Peñasco study “an important contribution to the marine reserve literature.”
“It shows a rapid increase in juvenile settlement in areas downstream from reserves, after only two years,” Warner said.
As previously reported by Miller-McCune, local fishermen were engaged in the monitoring efforts at the Channel Islands, just as they were at Puerto Peñasco.
But there the similarity ends. The Channel Islands marine reserves are vigorously enforced by the National Park Service, National Marine Sanctuary, US Coast Guard and California Department of Fish and Game. These agencies patrol the reserve network by air, by sea and on land. The park alone spends about $350,000 per year on enforcement.
As many as 200 fishermen get verbal or written warnings or citations every year at the Channel Islands, park officials said. In addition, the patrols stop more than 1,000 boats yearly to hand out educational materials and deter them from fishing in the reserves.
A Happy Ending
Belatedly, the Mexican government is giving Puerto Peñasco some support.
In a before-and-after study published on the PLoS ONE blog this year, Cudney-Bueno tells how the government in 2006 finally gave the diving cooperative exclusive rights to harvest rock scallop in their fishing grounds. Such formal Mexican fishing “concessions” are rare, and Puerto Peñasco’s was the first in the Gulf of California.
Today, the shellfish stocks are building back up and the diving cooperative is working with researchers to design a management plan, backed by the government, that will include permanent seasonal closures and no-fishing zones for rock scallop and quotas in areas where fishing is allowed. It will give them even more of a buffer than they had before, Cudney-Bueno said.
“It’s just crucial to have control over the fishing grounds,” he said. “The divers know that leaving a place untouched for some time will only lead to an increase in resources. People really can manage their own regions, but if you don’t have the umbrella backup, it’s very hard to control.”
The Mexican government does not have the resources to regularly patrol reserves in the Gulf. But next time, if the bandits come, the Puerto Peñasco divers can legally call on the local port authority to deal with them.
The story of Puerto Peñasco’s success, failure and success has given a boost to fishery protection elsewhere in the northern Gulf, with funding from the David and Lucile Packard Foundation. In Bahía de los Angeles and Bahía de Kino as well as Puerto Peñasco, fishermen are working with researchers to protect not only scallops and snails, but also stocks of crabs, lobsters, sea cucumber and groupers.
“The pie has been sliced in too many pieces in the Gulf,” Cudney-Bueno said. “Some communities are really taking things into their own hands. There’s a sacrifice in establishing reserves, absolutely. But there’s so much belief in the resilience of the system.”