by Eric Niiler
San Diego Union Tribune, Wednesday, June 17, 1998
SAN FELIPE, Mexico -- Flying 600 feet above the broad Colorado River delta, Silvia Manzanilla scans the coffee-colored water below with high-powered binoculars.
Her quarry -- the vaquita, or "little cow" -- is the Gulf of California's rarest marine mammal, a small porpoise of which experts believe fewer than 300 still exist, with more than 30 killed yearly in illegal nets set for totoaba, a kind of giant sea bass.
So it is with some optimism that Manzanilla, a biologist at Mexico's National Autonomous University (UNAM), has discovered vaquita feeding in the channels of the delta, an area flushed by tremendous tidal surges and an occasional slug of fresh water that sneaks past the dams and agricultural canals hundreds of miles upstream in the United States.
With this discovery comes the possibility that more of these animals exist than previously thought, and evidence that what little fresh water from the Colorado River reaches the gulf nourishes an entire marine food chain.
"Dorsal fins," Manzanilla says over the airplane intercom as pilot Sandy Lanham banks the single-engine Cessna into a tight downward spiral. Looking again, Manzanilla identifies the animals as bottle-nosed dolphins. "They're not vaquita," she says. "But this is a good sign."
Lanham's maneuver drops the plane to 300 feet, pushing passengers against the cramped cabin walls (and forcing one to reach for an airsick bag). Through the open side window, the four occupants watch a feeding frenzy in progress.
The dolphins swirl around a school of fish, dazing them with powerful strokes of their tails. Sleek gray-white bodies splash above the river's surface, teeth snapping at their prey.
The flight turns south and the water changes from the delta's muddy brown to the shimmering deep blue of the upper gulf. Over the next three hours, Manzanilla and the others will spot a trove of marine life, but no sign of the vaquita.
About 25 miles east of San Felipe near a solitary rock pinnacle jutting from the water, the surface is roiled by several hundred common dolphins voraciously feeding on giant masses of krill, a shrimplike crustacean that forms thick underwater mats. The dolphins are joined by individual humpback, fin and sei whales who strain the nutritious krill mats through their giant baleen filters.
Others, too, are attracted by the smorgasbord at sea: a lone bull shark, several individual sea lions and groups of bat rays, their yellow-brown diamond-shaped bodies gliding just below the surface as they feed on microscopic plankton.
A few miles away, fishermen in small open panga boats set drift nets between floating buoys. Intended for sharks, these nets catch everything in their path, including marine mammals.
The gulf waters north of San Felipe are part of the Gulf of California Biosphere Reserve. Fishing is restricted in the delta region, but that hasn't troubled fishermen, who operate with little government oversight.
"Trawlers have devastated the area. The gill nets are catching juvenile and young" vaquita, said Manzanilla, a determined woman with sandy brown hair and flashing blue eyes. "Any expectation of vaquita coming to an age to reproduce is hindered by fishing activity. At the same time, the government of Mexico has not at all set rules and regulations to have this area controlled."
The former president of Mexico, Carlos Salinas de Gortari, declared the upper gulf to be a protected biosphere reserve in 1993 during the crucial weeks before the U.S. Congressional debate on the North American Free Trade Agreement.
While the declaration brought attention to the region, and may have won votes from environmental supporters in Congress, it hasn't been backed supporters in Congress, it hasn't been backed up with government action, critics say.
The biosphere's full-time manager, operating out of the town of Puerto Penasco, has a small panga, but cannot patrol the vast area at night when much of the illegal fishing is done by shrimpers and fish trawlers. The situation is made worse by the presence of dangerous narcotraficantes, who smuggle drugs through the delta region disguised as fishing boats.
The Mexican government has come under fire in recent years for failing to stop overfishing and illegal fishing throughout the entire Gulf of California. Many of the gulf's commercial species -- corvina, yellowtail, shark, marlin, scallops, snapper, halibut, grouper, lobster and sea cucumber -- have declined in recent years although few definitive scientific assessments exist.
In the biosphere reserve, enforcement of fishing regulations is split between Mexico's Institute of Ecology and the Environmental Attorney General.
"It's a very bureaucratic system," said Exequiel Ezcurra, a former Mexican environmental official who helped create the biosphere reserve in the Salinas administration.
"When we started seven years ago, it was a no man's land and a catastrophe," said Ezcurra, now director of the Center for Biodiversity of the Californias at the San Diego Museum of Natural History. "The traffic of boats is lower than it used to be. It has improved, but it's not the way we would have liked it to be."
In a hopeful signal from the government, nine fishermen were arrested earlier this year for illegal fishing of corvina, a popular commercial fish whose numbers are declining.
But getting information about the decline of the vaquita is more difficult. Fishermen no longer like to cooperate with biologists because they fear penalties.
The vaquita, also known as the Gulf of California harbor porpoise, is on the list of endangered species in both Mexico and the United States. Scientists do not have good historical data on the vaquita population.
Discovered just 40 years ago, the animal is extremely reclusive and hard to find. Only a handful of population surveys have been attempted over the years, researchers say, with mixed results.
This modestly sized marine mammal feeds on small fish and squid and grows to about 4 feet at adulthood. Unlike dolphins, vaquita usually remain in small groups of no more than three individuals.
Their biggest threat is getting caught and drowning in gill nets set for totoaba, a large grouper-like fish sold as sea bass. Catching totoaba is now forbidden because it has been nearly fished to extinction, but fishermen continue to seek it, inadvertently killing vaquita in the process.
"Enforcement is the key," said Carlos Navarro, a biologist and editor for the Intercultural Center for the Study of Deserts and Oceans, a conservation group based in Puerto Penasco and Lukeville, Ariz. "If one fishing boat goes out, the rest will follow."
Navarro has seen fishermen rescue a vaquita beached in shallow water. He also has picked up carcasses of dead vaquita in municipal dumps of fishing villages. Building the fishermen's trust is the first step to getting across the value of the reserve and of protecting the vaquita.
"Most fishermen have not seen a vaquita, they truly believe it's a myth," said Navarro. "They don't trust biologists."
Flying across the upper Gulf and the Colorado delta region, it's easy to see how the two ecosystems are linked. For countless years, the Colorado River flowed unimpeded from its headwaters in the Rocky Mountains through the Grand Canyon and Arizona desert before finally emptying into a broad delta at the Gulf of California.
This confluence of silt-laden fresh water and nutrient-laden sea water created a rich habitat. Groves of cottonwood and willow hid bobcat, coyote, deer and the great jaguar, dubbed by the locals "el tigre."
Quail, geese, cranes and untold species of shorebirds crowded the estuary. After a three-week canoe trip through the area in 1922, naturalist Aldo Leopold described the scene in an essay entitled "The Green Lagoons":
"On the map, the delta was bisected by the river, but in fact the river was nowhere and everywhere, for he (the river) could not decide which of a hundred green lagoons offered the most pleasant and least speedy path to the gulf. ... For the last word in procrastination, go travel with a river reluctant to lose his freedom in the sea."
Beginning with the construction of the Hoover Dam in 1936, water to the gulf from the Colorado has been slowed and cut to a near-trickle. The siphoned river supports California's massive agricultural industry and slakes the thirst of millions living in such places as Las Vegas, Phoenix, Los Angeles and San Diego.
Today, water reaches the gulf only when dams release excess storm flows. The delta -- an area the size of Rhode Island -- has largely become a barren salt flat.
Getting the river's users to release water downstream for environmental reasons has proven to be nearly impossible. Seven U.S. states continually battle for water rights, while Mexico, which receives only 10 percent of the flow, wants water for growing agriculture and municipal drinking water in Tijuana and Mexicali.
As a result, the fate of the vaquita -- and several endangered bird species that live in the delta region, as well -- is uncertain. One environmental group, based in Tucson, has filed a notice of intent to sue the U.S. Bureau of Reclamation, the agency which regulates the flow of the Colorado River.
The group alleges the lack of water flow violates the U.S. Endangered Species Act.
The law "clearly requires federal agencies to protect these species regardless of international borders," said David Hogan, a spokesman for the Southwest Center for Biological Diversity in Tucson. "We're finally seeing with data what we've known for years, freshwater from the Colorado River is essential for the Gulf of California ecosystem."
During the 1982-83 El Nino, for example, water flowed through the region for the first time in decades and re-created a 50,000-acre wetland known as Cienega de Santa Clara. Flows also picked up during the flooding of the Gila River in the early 1990s and during this year's El Nino.
During 1994 and 1995, Manzanilla videotaped large groups of vaquita feeding in the delta during low tide, something no other scientists had seen before. She made 13 separate sightings of vaquita.
She also saw vaquita feeding alongside bottle-nosed dolphins, indicating that the region is important to both animals, and that fresh water makes the delta a good place to feed.
Rain and fish
But other scientists remain skeptical.
"Silvia is the only one who thinks they go to the estuary," said Jay Barlow, a biologist at the National Marine Fisheries Service's regional office in La Jolla.
Barlow believes there may be less than 300 individual vaquita remaining, according to a 1993 ship survey. He doubts the connection between fresh water from the Colorado and the level of fish and other marine organisms in the upper Gulf.
"Vaquita eat whatever fish are abundant," he said. "It will do fine as long as it has some fish available."
But other studies support Manzanilla's theory that a large area of the vaquita's habitat may have been overlooked.
Edward Glenn, a University of Arizona biologist, has found that shrimp harvests by fishermen in the upper gulf increase dramatically when the Colorado River flows.
"Even modest flows of 2 to 5 percent of the river can double the catch," Glenn said.
Young shrimp and fish breed in the delta and hide from larger fish who need to stay in saltwater. Only dolphins and the vaquita can stand the changing salinity, according Glenn, and would likely venture into the estuary to feed.
"Nobody has looked (for the vaquita) there before," he said.
During a series of flights in May, Manzanilla and Navarro made only two sightings of vaquita: one swimming north of San Felipe, and the carcasses of a vaquita and a dolphin, the latter with its tail cut off.
She plans to continue her research flights this summer and fall, looking for clues whether the vaquita is taking advantage of water from El Nino-year runoff.
"There has been a sub-estimate and the population may be larger," she said.
While other scientists may dispute her thesis, Manzanilla and her critics both agree that the vaquita remains in peril from fishing in the upper Gulf. "We're very concerned about the species," Barlow of NMFS said. "If nothing is done, the vaquita won't be around in 10 or 20 years."