In 1993, as a result of public and scientific outcry about its fate, the Mexican government created the Upper Gulf of California and Colorado River Delta Biosphere Reserve [see map]. Within the reserve, gill nets are prohibited. At the time, the reserve was thought to include most of the vaquita’s marine habitat, but after two shipboard surveys, in 1993 and 1997, it became clear that as much as half of the population was actually living south of the reserve boundary. Consequently, in December 2005 the Mexican government designated a vaquita refuge, which overlaps part of the biosphere reserve and includes an area where some 80 percent of recent vaquita sightings have been made.
In spite of the good intentions reflected by the creation of those protected areas, harmful fishing practices have continued virtually unchecked. A 2006 review concluded that there has been little or no change either inside or outside the biosphere reserve since its creation. When we visited the vaquita refuge in March 2006, we found unattended gill nets set right in the middle of it. One of us (Rojas-Bracho) recently launched a series of aerial surveys, which will provide a far better appraisal of fishing activity throughout the region than has so far been possible. But because the boundaries of the reserve and the refuge are not marked, and because there is little enforcement of the no-gill-netting rule, poor results seem all but inevitable.
Fishermen, armed with nets, are the main reason for the vaquita’s decline—just as they are for the mortality of marine mammals everywhere else in the world. Of the six porpoise species, for instance, the two that live in open oceans—and thus have the least exposure to gill nets—are faring much better than their shallow-water relatives. Populations of Dall’s porpoise (Phocoenoides dalli) in the North Pacific and the spectacled porpoise (Phocoena dioptrica) in the Southern Ocean are in relatively good shape.
For the rest, the story is quite the contrary. On the Yangtze River in China, an endemic population of finless porpoise (Neophocoena phocoenoides), the world’s only freshwater porpoise population, is in steep decline. The causes? Unmanaged fishing and rampant development on the river. The marine populations of finless porpoise are somewhat better off, depending on how much fishing is done in their home waters. The message is clear: if there’s a net in the water, a porpoise will find it.
And then there’s the baiji (Lipotes vexillifer), a dolphin that lived only in the Yangtze River. In the fall of 2006 one of us (Pitman) took part in a search for the last baiji. For the past twenty to thirty years the baiji had been recognized as the world’s most critically endangered cetacean, because of its high rate of accidental drownings in fishing gear. In a six-week survey, the searchers failed to find a single individual—and in the end, were forced to conclude that the baiji, after more than 20 million years swimming in the Yangtze, was probably extinct.
There are troubling similarities between the baiji and the vaquita, the next cetacean in line for extinction. Historically, both species occupied small, insular ranges surrounded by fishing communities. They both faced the same threat to survival: nets. Both species, like all cetaceans, were slow to mature and had long intervals between births, so even if the threats to their survival had been removed, their reduced populations would have recovered very slowly. Both had been at risk of extinction for some time. “Protective measures” were put in place for both: reserves were created and laws were crafted that made harmful fishing practices illegal in protected areas. But the reserves existed largely in name only, and enforcement was unsuccessful.
All that remains of the baiji are lessons. Extinction is real. Unmanaged fishing practices have the potential not just to reduce populations of aquatic mammals, but to catch and kill every last member of a species. And extinction can happen quickly, right before our eyes. A scientific paper published a few months before the Yangtze River survey concluded that the baiji would be extinct in twenty years if protective measures were not stepped up. But the last baiji had probably already died before that article was written.