Book Reviews

The Ecology, Exploitation, and Conservation of River Turtles Don Moll and Edward O. Moll Oxford University Press, New York, USA, 2004, 420 pp., 93 ﬁgures. ISBN 0-19-510229-0; £19.99 (hardback: boards).

Don and Edward Moll’s book examines the status of the world’s river turtles, defined as those primarily occupying lotic (flowing water) habitats, and their roles in ecosystems and in human cultures. As the authors point out, these are some of the least-known vertebrates, generally ignored by both herpetologists and aquatic biologists. About 65% of all chelonian species at least sometimes occupy rivers, and 35% fall within the strict definition used. River turtles are diverse, including 10 of the 13 living turtle families, only excluding the terrestrial Testudinidae and the marine Cheloniidae and Dermochelyidae. Information on the distribution and conservation status of the approximately 39 genera and 104 species involved is tabulated early on, together with their common names. The latter are used extensively in the book, and sometimes annoy Ð repeated use of long names such as “the giant South American river turtle” calls out for condensing to “P. expansa”, for example Ð and river turtle names are often long in English. Werner (2004) noted the drawbacks of common names extending to 4 or 5 words, but had not come across the Madagascan big-headed side-neck turtle! Chapters 2 and 3 (Diversity, adaptations and roles in the ecosystem; Communities and habitats) cover the basic ecology of river turtles, including a table of convergent characteristics. Size is perhaps the most important variable in river turtle ecology: only large species enter midstream in large rivers, while small species are restricted to tributaries or the marginal shallows. Large species are similar ecologically to sea turtles, indeed pre-adapted to this niche, and several use sea beaches for nesting or enter the sea to feed. Indeed, Pelochelys and Trionyx are now more common than sea turtles in Turkish shrimp trawl bycatch. Many species show striking colours and sexual dichromatism, some examples being illustrated in four colour plates. Common reproductive characteristics include large clutches of small eggs, short incubation periods, multiple clutching and communal nesting, perhaps a response to a variable and unpredictable environment. Most river turtles are opportunistic omnivores, though there is a trend to herbivory in large species and in the tropics.

Abundant species may provide significant ecosystem services Ð Murray River turtles have been estimated scavenge 180,000 tonnes per year, and Indian species were formerly reared to help clear half-burnt corpses from the Ganges. Applied herpetologists will be most interested in the remaining four chapters, which make up more than half of the book. Traditional exploitation methods are described in Chapter 4. There is a long history, indeed pre-history, of human utilization of river turtles, with remains in middens dating back 20,000 years. Many techniques were graphically described by the early explorer-naturalists, and a wide variety remain in use today. These include diving; wading and feeling; hooked poles; arrows, harpoons and spears; netting and trapping; hook and line; capture on land while basking or nesting. There appears to have been convergent development of efficient techniques such as hooked poles (still in use to catch hibernating alligator snapping turtles), pegging lances with a detachable spike and cord, and multiple- hook trotlines. Some methods have been adapted for scientific study of river turtles. Chapter 5 reviews turtle exploitation, past and present, region-by-region. 16 turtle species (not all riverine) have been used commercially for food in the USA (most of which were tasted by Archie Carr); Chelydra serpentina and Apalone spinifera are the most important today. In most states the catch is regulated by licenses, catch limits and seasons, but these are often not based on biological considerations. Exploitation is greater in the tropics and subtropics, where river turtles can be staple foods. The Asian turtle trade in particular is described, largely based on the 1999 symposium presentations (van Dijk et al., 2000), in its appalling scale. 13,000 tonnes of live turtles are shipped to China from other parts of Asia annually. This trade shows the classic pattern of unsustainable utilization, with a shift to less preferred species and size classes, and an expanding catchment area. Turtles in Vietman and Bangladesh, then India, Myanmar, Laos, and Cambodia, and now Indonesia have all been sucked into the Chinese turtle consumer’s ravenous maw. Each chapter begins with a descriptive profile, and some sections also make use of case studies. For example, that on the trade from Bangladesh highlights the lack of effective protection received by most tropical river turtles. Indian and peacock softshell turtles were exported, though both species were legally protected from capture, killing, or trade. Turtles were exported under aliases, sometimes as species not occurring in Bangladesh, or as the non-existent “Trionyx certilsfionus”. River turtles also have other uses besides meat. Podocnemis expansa has long been a dietary staple in the Amazon basin, kept in corrals of a few hundred turtles per village, from the dry to the wet season. Known as “river cattle”, turtle oil was more important than meat or eggs in commercial trade, being used for cooking and lamp oil. Bates (1863) describes the practice and extent of the trade, with export of oil from about half a million adult females annually from the upper Amazon. Turtle populations were decreasing by the 1850s apex of the commerce in oil, and were only saved by the advent of kerosene and vegetable oil. The Asian turtle trade is based on medicinal use as much as meat, in so far as these uses can be separated, one individual often contributing to both. More favourable interactions between river