Field Guide for Sharks of the Genus Carcharhinus

Foreword When I first saw the illustrations of sharks by Dietmar Weber many years ago, during a meeting of the German Elasmobranch Society, I was completely baffled how someone can depict a shark so realistically and with such clarity in detail. The pictures, which are scientific absolutely correct portrayed, really screamed at one's face, use me for a shark identification book! Since then, his pictures have illustrated conservation reports, calendars, posters, conference banners and now, for the first time, they have found their way into a field guide. But these are not only pictures of sharks; they are complete tables with featured details of specific body parts, sometimes juvenile specimens, rows of teeth and other highlighted characteristics that help the reader to identify the species. Marine biologist Matthias Voigt has collected over several years all the nitty-gritty data on species of the genus of Carcharhinus. He has visited many museums, took pictures, contacted scientist around the world to send him information and photos to sum it up into one big picture of this genus. This book describes 33 species of a group of sharks that are very hard to identify due to their similar appearance. Together with a wealth of information on biology, life history and distribution, the identification key leads the reader to the species information. Almost all sharks of the genus Carcharhinus are coastal to pelagic sharks that occur in the tropical fisheries world-wide as targeted catch or by-catch. Their fins are primary goals for the fin market in Asia. Correct identification of these similar looking species is essential to establish species-specific management plans and for reported landing data. May this book by this help to actively support the conservation of these magnificent creatures of the sea. Heike Zidowitz Chair of the German Elasmobranch Society Preface The appearance of a new field guide identifying all recent species of sharks in the renowned genus Carcharhinus arouses various expectations among hobbyists and divers as much as it does for ichthyologists and paleontologists and probably also for commercial fishermen and conservationists. In me, it awakens memories of long-standing interests, and it makes me happy that the authors asked me to publish this guidebook in my publishing house. In 1973, I was a young student of biology and paleontology searching the literature to compare the teeth of fossil sharks. It was then that "The genus Carcharhinus (Carcharhinidae)" by Bass, D'Aubray and Kistnasamy appeared in the series, "Sharks of the East Coast of Southern Africa" published in the "Investigational Reports" in Durban, South Africa. Their illustrations of the seventeen species occurring in the region were the best pictures of modern Carcharhinus teeth) available at that time. In 1979/1980 I was in Wellington, New Zealand as a doctoral student. My supervisor there, Professor J. A. F Garrick, worked on his monograph of the genus Carcharhinus, which was published in 1982, as "Sharks of the genus Carcharhinus". Traditionally - following Bigelow & Schroeder 1948 and Bass, D'Aubrey & Kistnasamy 1973 - the emphasis of the work was to compare as much morphometric data as possible. But Garrick saw the great importance of a more detailed investigation of the tooth morphology: "If one takes an overview of shark systematics in general, the best single feature that could be cited for determining similarities and differences between taxa at all levels, but perhaps predominantly at the generic level, is the shape of the teeth." (Garrick 1982, p. 20). I was fascinated by the detailed drawings of the teeth. Garrick recognized the great variability of the teeth within a species, and therefore he illustrated the tooth rows of both a male and a female specimen of the species, C. brachyurus and C. dussumieri, showing a pronounced sexual dimorphism. Unfortunately, drawings and/or photographs of Carcharhinus teeth in more recent publications, e. g. in the FAO Species Catalogue "Sharks of the World" by Compagno 1984, in "Sharks of the order Carcharhiniformes" Compagno 1988, Last & Stevens 1994 and 2009, "Field Guide to the Sharks of the World" Compagno, Dando & Fowler 2005, and Naylor & Marcus 1994, were in many cases too much "idealized" and less suitable for identification. The Illustration of the whole animals varied from simple black-and-white contour drawings to more realistic and sometimes highly artistic colored drawings, e. g. in Last & Stevens 1994 and 2009. Nowadays, all species of Carcharhinus could be differentiated by using DNA analysis in the laboratory. But how could this work in the field? How does one identify the shark seen while diving or visiting an aquarium or caught by rod or net or found in the fish market? For such determination, one needs meaningful, colored illustrations and a key to the most important characters, above all those of the teeth. Some expect to find all information in the Internet but anyone who is experienced knows that what he will find there is not satisfying. If one looks for taxonomic publications about sharks in the genus Carcharhinus, one must read the scientific literature. This kind of literature, however, is not accessible to everybody, and sometimes not easy to understand. Over the last three decades, researchers have learned much about the physiology of sharks, their taxonomy, however, has remained where it was more than 30 years ago. When the two authors of this book, Matthias Voigt and Dietmar Weber asked me to publish their book, I needed little persuasion to agree to the project. At last, here were two, enthusiastic, young marine biologists, who would continue the tradition of earlier scientific descriptions of sharks and would supplement it with very high quality illustrations that would result in a field guide useful for everyone. They combine the necessary experience with the insight that makes the sober, morphometric data accessible even for the layman and allows the identification of all presently known, recent species of Carcharhinus. Dietmar Weber's illustrations of sharks are as realistic as one could wish. The digitally remastered photographs of the teeth follow the tradition of Bass et al. 1973, and Garrick 1982, but show this time substantially more details. Especially for teeth of the holotypes, the illustrations shown here could not be any better. I connect this field guide with the hope that further volumes may follow. It is a substantial step towards a comprehensive representation of all species of sharks. As a paleontologist, I would like to see even more of the variations that show up in the heterodonty of young and adult individuals and in the differences of males and females. Hopefully, this field guide will contribute to improved recognition and better understanding of these animals, hunted and endangered by humans, so that they may finally be protected before they become extinct. Fritz Pfeil Munich 2011