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The vaquita’s home is a truly unique area of marine habitat in the Northern Gulf of California. The area is unique for a number of reasons. Situated at the delta of the Colorado River, for the last five million years this massive river system has been dumping sediment into the Northern Gulf, creating a shallow basin filled with warm, murky water.
An aerial view of the Colorado River Delta. Photo by Sean Bogle.
Before dams were built along the Colorado River there was a huge amount of variation in the flow of water into the Gulf of California. Peak flows in the summer reached more than 100,000 cubic feet per second, sending a huge amount of sediment into the gulf, while low flows in the winter months often dropped below 2,500 cubic feet per second, a mere trickle. The sediments carried by the Colorado River created a vast delta system composed of the massive amounts of sediment that have accumulated over the past five million years. It was these geologic forces that shaped both the marine and terrestrial ecosystems of the region.
The land surrounding the Colorado River delta and Northern Gulf is a vast desert, punctuated by the long spindly branches of the ocotillo, and an occasional giant Cardón cactus (a close relative of the Saguaro cactus). There are vast stretches of salt flats, sand dunes, and numerous dry rocky peaks along the coastline. To the west of this desert landscape lies the Sierra de San Pedro Martir mountain range, its highest peaks reaching above 10,000 feet elevation. These mountains are home to desert bighorn sheep, and another iconic endangered species, the California condor.
A Turkey Vulture, close relative of the California condor, perched atop a giant Cardón cactus along the coast of the Northern Gulf of California. Photo by Sean Bogle.
Today, the Colorado River often runs dry before reaching the Gulf of California. Although this has undeniably altered the ecosystems or the Northern Gulf in a dramatic way, it does not seem to have had a significant impact on the vaquita. Early vaquita researchers thought that the species might actually utilize the delta, and survey efforts in the 1990s were conducted in the northernmost reaches of the Gulf. Today, due largely to the acoustic monitoring program, we have a better understanding of the vaquita’s range, and we know that they rarely venture up into the river delta.
Remote acoustic detectors positioned throughout the vaquita’s range show us that the species spends most of its time along the Western coast of the Northern Gulf – very close to the small town of San Felipe. Here, despite the dramatically decreased flow from the Colorado River, the water remains warm and extremely cloudy. Tides in the Northern Gulf are some of the most dramatic in the world, with a sea level change of up to 27 feet from highest to lowest levels. The tides create strong currents, which constantly kick up all the accumulated sediment along the seafloor. Visibility underwater can sometimes be as low as two to three feet.
Long-beaked Common Dolphin is barely visible in the murky waters of the Northern Gulf of California.
The Northern Gulf of California is also quite shallow as a result of millions of years of accumulation of sediment, allowing the water temperature to rise significantly during the hot summer months. In August when air temperatures are commonly well above 100 degrees, the water temperature can approach 90 degrees.
It is all of these factors that create the unique marine ecosystem that the vaquita calls home. There is a high level of endemism in the Northern Gulf because of how distinct the marine environment is – 10% of the region’s fish species are endemic, including the totoaba, the Cortez stingray and many others – 84 endemic fish species in total. The vaquita, however, is the only endemic marine mammal found in the area.
For a long time it was commonly believed that the decrease in flow from the Colorado River was the cause behind the vaquita’s dramatic decline, but research conducted in the 1990s disproved this theory. Despite the changes that have occurred in the Northern Gulf in modern times, the vaquita appears to have no problem finding food and reproducing. If it weren’t for the use of gillnets in the region, the population would almost certainly be doing just fine.
Much of the water that once flowed into the Northern Gulf of California is now diverted for agriculture. Photo by Sean Bogle.
So although the marine environment has certainly experienced changes, it is the changes that have occurred on land that have had a dramatic impact on the vaquita population. While many historians would begin the human history of the Northern Gulf region at the moment when the modern towns of San Felipe and Puerto Peñasco were founded, there have been people living in the region for long before these communities were established in the 1920s. Today, the only remnant of the pre-Columbian human population is the Cocopah Tribe, a very small indigenous community located along the Colorado River delta.
An examination of the pre-Columbian human history of the region is interesting because it shows us that a large human population coexisted with the vaquita for an extended period of time. While there are currently only about 1,000 members of the Cocopah tribe, in 1605 Spanish missionaries estimated that there were 6,000-7,000 Cocopah people living in the region. Recent archeological evidence shows us however, that in most areas of the Americas, 90-95% of the human population was wiped out by Old World disease within the first few generations after initial contact with Europeans. By 1605 when Spanish missionaries made their population estimate, this impact had likely already been felt, meaning that the human population of this region may have been somewhere between 60,000 and 120,000 people in pre-Columbian times – comparable to the current population of the area.
But were these ancestors of the Cocopah aware of the vaquita’s presence? Did this pre-European human population have any impact, positive or negative, on the vaquita population? These are extremely difficult, if not impossible, questions to answer. But one thing is clear – there has been a human presence on the landscape in the Northern Gulf of California for many thousands of years, but not until modern times has the vaquita faced the threat of extinction.
After declines in the Native American population in the Northern Gulf, there was a long period of time with an extremely low human footprint on the land. From the late 1500s through the early 1900s the area was very sparsely populated. This began to change in the 1920s, when people began to move into the area to exploit the region’s fisheries. There has been steady growth of the human population since then, with the town of San Felipe expanding to become home to more than 20,000 people, and Puerto Peñasco on the opposite side of the Gulf growing to over 60,000 residents. A third small town in the very northernmost corner of the Gulf, El Golfo de Santa Clara, is home to just under 4,000 people.
San Felipe, Mexico.
It is the presence of these human neighbors and their chosen fishing practices that have altered the marine ecosystem to the detriment of the vaquita.
It could be argued however that the people living in the Northern Gulf of California are not solely to blame for the gillnet use that is the cause of the vaquita’s decline. The fishery responsible for the most dramatic negative impact on the vaquita is the illegal fishery for the totoaba, a large fish species that is also endemic to the region. The totoaba is fished with gillnets because of the demand for its swim bladder in China.
So although the vaquita is found only in this small pocket of unique marine habitat in north-western Mexico, it is the demand for the swim bladder of the totoaba in China that is driving its extinction.