Location and Values: The Islands and Protected Areas of the Gulf of California are located in north-western Mexico, scattered across the Sea of Cortez from the Colorado River delta in the north to the tip of the Baja California peninsula, 270 km further south. This is a serial site, comprising 244 islands and islets (clustered in eight major groups) and nine other protected areas with coastal and marine zones. It is globally important for marine conservation, and serves as a natural laboratory for the study of speciation (in much the same way as the Galapagos Islands).
A quarter of the designated area is terrestrial, forming part of the Sonoran Desert, while the rest is marine. It is an area of exceptional natural beauty, its coastal deserts and rugged islands set in the turquoise waters of the Sea of Cortez, with equally spectacular sub-marine scenery attracting divers from around the world. From a marine conservation perspective, the site is exceptional in terms of biodiversity and marine productivity, supporting 900 species of fish (10% endemic), 39% of the world’s marine mammals and a third of its marine cetaceans. Amongst these marine species, there are critically endangered species of fish (such as Black Sea Bass and Totoaba) and a tiny remnant population of the critically endangered endemic Gulf Porpoise (or Vaquita). Huge colonies of California Sea Lions, five species of dolphins and 11 species of whale are protected in the site.
The islands provide exceptional opportunities for the study of the processes of biological speciation. Some of them were connected to one another by land bridges at different times in the past (and were therefore colonized quite easily by plants and animals arriving overland from adjacent areas) while others have never been connected by land and were colonized by quite different suites of species that managed the crossing by sea or through the air. The different environmental conditions of each island have subsequently led to evolutionary changes and adaptation by the original colonizers. This has resulted, for example, in a diverse reptile fauna with 115 known species, almost half of which are endemic, in some cases even to individual islands.
Conservation Status and Prospects. According to IUCN’s Conservation Outlook Assessment (2017) the conservation status of the Islands and Protected Areas of the Gulf of California is of ‘significant concern’. The IUCN report notes that the main threat to the site’s world heritage values comes from artisanal and industrial fishing, much of which is carried out beyond the boundaries of the world heritage site. In particular, illegal gillnet fishing throughout the Upper Gulf is resulting in significant by-catch of Vaquita, a critically endangered endemic cetacean, now considered to be on the verge of extinction. It is also likely to be threatening other cetaceans, turtles, seals, sharks and fish species, including the critically endangered totoaba fish.
More generally, management of individual protected areas within this serial site is effective, but they face multiple threats from outside their boundaries. These include the impacts of over-fishing, by-catch, pollution, alien invasive species, tourism development and climate change. Pollution from agricultural, shipping and coastal developments is increasing, while mangrove habitats are badly affected by development of recreational facilities. The impacts of climate change are not yet fully understood but are likely to significantly affect corals, other calcifying organisms, and coastal wetlands, as well more general marine productivity and fish stocks.
UNEP-WCMC Site Description
IUCN Conservation Outlook
Official UNESCO Site Details