The Gulf of California: Biodiversity and Conservation

5. Fishes of the Gulf of California

CHAPTER 5 Fishes of the Gulf of California philip a. hastings, lloyd t. findley, and albert m. van der heiden Summary The Gulf of California has a rich history of exploration and scienti fic discovery, and its fishes have been an important part of that history . The first major oceanographic expeditions collecting fishes in the Gulf were conducted by the U.S. Fish Commission steamer Albatross between 1889 and 1911. The ship’s naturalist, C. H. Gilbert, described 168 Gulf fish species as new to science over his career. Numerous other reseachers from around the world contributed to our current knowledge of the systematics of Gulf fishes. To date, over 900 species of fishes have been recorded from Gulf waters, and trends in species descriptions indicate that other new species remain to be identified, described, and named. The Gulf owes its faunal diversity, in part, to its location at the juncture of the tropical and temperate regions of the eastern Pacific Ocean. The Gulf fish fauna is dominated by tropical species (87 percent of Gulf fishes also occur south of the Gulf ), but it also includes a significant number of species known from temperate areas (31 percent of Gulf fishes also occur north of the Gulf, in the temperate waters of coastal North America). Nearly 10 percent of Gulf fish species are endemic: found nowhere else in the world. This includes a diverse array of species with varied phylogenetic and geographic affinities. The northern Gulf includes several endemic species historically associated with the Colorado River estuary, and these are of obvious special concern to conservation biologists. The diversity of fishes increases as one moves southward in the Gulf, with nearly twice as many species known from the southern Gulf as from the northern Gulf. The clear and often calm waters of the Gulf of California, together with its striking biodiversity, have made it an ideal setting for the study of Fishes / 97 the biology, ecology, and behavior of fishes. This microcosm of the larger eastern Pacific and world oceans provides unlimited opportunities for studying and understanding the processes of evolution and ecology in the marine realm. Conservation of this incomparable region and its biotic resources will ensure the continued heritage of this remarkable region for future generations. Introduction Fishes play a prominent role in the ecology, evolution, and economics of the Gulf of California (Sea of Cortez). Fishing activities led to early establishment of several towns surrounding the Gulf, especially in its northern region (Munro Palacio 1994; Bahre et al. 2000), and fishes and fisheries products continue to contribute significantly to the economy of northwestern Mexico (see Cisneros-Mata, chapter 6 in this volume). The abundance and diversity of Gulf fishes, together with the Gulf’s often calm waters, support a thriving tourist industry and continue to lure numerous biologists from around the world. Herein we review some of the history of ichthyology in the Gulf of California, provide an overview of the diversity of Gulf fishes, and briefly review past studies on the ecology and evolution of Gulf fishes. A Brief History of Gulf of California Systematic Ichthyology By the early 1800s, nearly 50 widespread fish species that would eventually be recorded from Gulf waters had been named—based mostly on specimens collected in other parts of the world. These included several well-known species such as dorado or dolphinfish, Coryphaena hippurus Linnaeus , and the white shark, Carcharodon carcharias (Linnaeus). By the mid1800s , this number had risen to nearly 140 species, but it was not until the latter half of that century that the bulk of species now known from Gulf waters were described (fig. 5.1). This upsurge resulted from extensive collections of fishes from other areas of the Pacific, especially the coast of Central America, that were studied by zoologists from around the Western world. European scientists studying Gulf fishes included Albert Günther of the 98 / hastings, findley, and van der heiden British Museum, who described 60 species of fishes from the region (e.g., Günther 1864; see fig. 5.2), and Franz Steindachner of the Natural History Museum, Vienna, who described 31 species of Gulf-occurring fishes (e.g., Steindachner 1877). However, many of these newly collected specimens fell into the hands of North American scientists: Samuel Garman of Harvard ’s Museum of Comparative Zoology, who described 36 species of Gulf fishes (e...