Vaquita – Last Chance for the Desert Porpoise

The Gulf of California, also called the Sea of Cortez, is a thousand mile long strip of ocean wedged between the mainland of Northwestern Mexico and Baja California. Scorching desert surrounds the Gulf.

Towering cactuses stand like sentinels above sparse, scrubby vegetation. This is the last place on earth you would expect to see a porpoise, but the desolation surrounding the gulf belies the productivity beneath the sea surface. Seasonal winds and a thirty-foot tidal range dredge up cool, nutrient rich waters that support an enormously productive marine food chain.

The Gulf is one of Earth’s most diverse and exquisite marine habitats, playing host to a diversity of resident and seasonal cetaceans. It is home to the world’s largest animal, the enormous blue whale. Populations of fin, sei and sperm whales also plow its depths, pods of common dolphins are regularly seen in schools of thousands and multitudes of breeding seabirds crowd together on cactus studded islets.

Interestingly, the vaquita restricts itself to the tiniest portion of the shallow, turbid northern gulf. In fact, its range is the smallest of any cetacean on Earth. Although once endemic to most of the Gulf of California, it is now believed to survive only in the small area between San Felipe, Rocas Consag and the tidal mouth of the Colorado River.

The northern Gulf of California is not only home to the vaquita but also is to approximately 100,000 people who live around its margins.

The northern gulf is a relatively shallow inland sea with a very high tidal range (~8 m). Tidal mixing brings nutrients to the surface waters, making the waters of the northern gulf some of the most productive of any ocean (Álvarez-Borrego and Lara-Lara 1991). The high productivity of the waters resulted in a great abundance of fisheries resources, some of which are now depleted by overfishing. The initial development of the three major settlements in this area (Puerto Peñasco, San Felipe, and El Golfo de Santa Clara) was intimately linked to the commercial fisheries that developed there.

Commercial fishing originally developed in the 1920 to exploit large populations of totoaba. Early fishing methods included handlines, spears, and dynamite. In many cases, only the swim bladder was harvested for sale to Chinese markets. By the 1940s, totoaba fishing was primarily by gillnets, and most of the catch was exported to the United States. Totoaba catches reached a maximum of 2,000 tons per year in the late 1930s and early 1940s (Cisneros-Mata et al. 1995), but the species continued to decline under heavy fishing pressure and is currently listed as endangered. A total ban on the fishing for totoaba did not occur until 1975 (Flanagan and Hendrickson 1976).

As the totoaba resources declined in the late 1940s, trawling for shrimp (Penaeus spp.) overtook gillnetting for totoaba in economic importance. Shrimp trawling was primarily carried out from Puerto Peñasco because it was the only fishing village with a harbor deep enough for trawlers. Other gillnet fisheries developed for sharks, rays, curvina golfina (Cynoscion othonopterus), chano (Micropoganias megalops), and other species using small outboard-powered boats called pangas.

Panga fishermen in San Felipe and Santa Clara discovered that they could compete with the shrimp trawlers by entangling shrimp in gillnets called chinchorro de línea. Gillnetting and trawling for shrimp are now the most important fisheries in the upper gulf. The relative importance of fishing to the area has, however, declined considerably in the past two
decades.

Tourism has greatly surpassed fishing in economic importance in Puerto Peñasco and San Felipe. El Golfo de Santa Clara remains primarily a fishing village, but there is optimism that access by a new paved road may provide increased opportunities for tourism and associated development.

Although there has been a shift from fishing to a tourism-based economy in the region, the Gulf of California remains the raison d’être for both. Given that the economy of the region is so closely tied to the Gulf of California and given that the region is the only habitat of two endangered, endemic species (vaquita and totoaba), the health of this ecosystem is critical. Fortunately, primary production remains high and pollutant concentrations remain low, because of tidally driven upwelling that brings clean, nutrient rich deep water to the surface waters and the lack of river input of pollutants.

The principle human-caused perturbation to the northern gulf ecosystem has been overfishing and the reductions in flow from the Colorado River to near zero levels. Overfishing has driven long-lived species such as totoaba, sharks, and groupers to commercial extinction in the northern gulf ecosystem.

Reduction in flow from the Colorado River has likely made conditions even worse for totoaba and for another estuarine-breeding fish, curvina golfina. However, the reduction of river input is not thought to have adversely affected the vaquita (Rojas-Bracho and Taylor 1999).