Conservation biology—that combination of biology, economics, and policy trying to stem the loss of bio-diversity—has focused mainly on terrestrial problems and issues. Perhaps this is inevitable, since we are a terrestrial species, and perhaps even appropriate, since the impact of humans has been greater on the land than in the sea. But the sea covers 70 percent of our planet's area, and 95 percent of the volume where life occurs, so a treatment from a marine perspective is overdue. Marine Conservation Biology: The Science of Maintaining the Sea's Biodiversity, edited by Elliott Norse and Larry Crowder, delivers. The 25 chapters by 43 authors, with a foreword by conservation biology pioneer Michael Soulé, cover a wide range of topics: population biology, species invasions, fisheries management, habitat destruction, pollution, marine reserves, restoration efforts, and legal and ethical issues.

Why a separate book on marine conservation biology? In the first two chapters, editors Norse and Crowder point out that conservation challenges in the sea differ in fundamental ways from those on the land. The ranges, fecundity, and vagility of organisms are different. Legal and management structures are different. Economic incentives are different. And, most fundamentally, the attitudes of people are different.

Part 1, “Marine Populations: The Basics,”covers topics that set the stage for the rest of the book. Stephen Palumbi and Dennis Hedgecock note that high fecundity and wide larval dispersal have implications for the design of marine reserves, and also for the probability and speed of recovery after population reductions. Don Levitan and Tamara McGovern review the Allee effect in the sea, the tipping point that makes recovery from small population sizes especially difficult. Ransom Myers and Andrea Ottensmeyer discuss extinction risk. Because species in the sea are harder to observe and monitor, it is likely that many marine species extinctions are unrecorded “silent extinctions.”Julia Parrish illustrates how knowledge of behavior can contribute to effective conservation actions. This introductory section could have been strengthened by a chapter on changes in the sea from a long-term perspective. Marine conservation efforts are handicapped by the difficulty of conceiving what pristine ecosystems really were like. Worse, each generation of marine biologists takes an increasingly degraded state as the goal for restoration (the “sliding baselines” syndrome).

Part 2 is entitled “Threats to Marine Biological Diversity.” The editors introduce this section by listing five main threats to marine diversity: overexploitation, physical alteration, pollution, alien species, and climate change. Pollution and alien species are covered in chapters by Nancy Rabalais (nutrient overenrichment), James Carlton and Gregory Ruiz (invasions), Kiho Kim and colleagues (diseases), and Denise Breitburg and Gerhardt Riedel (multiple stressors). Overexploitation and physical alteration are covered in part 3. Curiously, however, there is no chapter on the fifth threat, climate change. Global warming is mentioned only briefly as an extinction threat, mainly in relation to coral reef bleaching.

In part 3, “The Greatest Threat: Fisheries,” we get to the heart of the matter. The problem is not simply that we catch too many fish. Richard Law and Kevin Stokes document how fishing alters the size, age, and genetic structure of exploited populations, usually selecting for greater rates of reproduction at the expense of growth and survival. Les Watling compares bottom trawling to forest clear-cutting and oil exploration: Although the destructive effects of trawling are often more widespread and longer lasting, the general public is far less aware of them. Fisheries also catch animals that are not the target of the fishery (bycatch). This incidental catch is often the main threat to long-lived marine animals such as turtles, seabirds, dolphins, and whales. Selina Heppell and colleagues discuss how the life histories of long-lived species, including targeted species such as sharks, make them highly vulnerable to the effects of fishing.

The title of the chapter by Dave Preikshot and Daniel Pauly poses the central question: “Global Fisheries and Marine Conservation: Is Coexistence Possible?” They contend that fisheries management fails to meet broader conservation goals because of two “pathologies”: a focus on single species instead of whole ecosystems, and the traditional view that the fishing industry is the sole legitimate user, in effect the owner, of marine living resources. The final chapter of part 3 seems to illustrate the point. Ray Hilborn refers to unharvested fish as “surplus,” is sanguine about ecosystem changes as a result of fishing, and defends the single-stock approach to fisheries management. As I read the chapter, the core philosophical issue became clear. By current standards, well-managed fisheries, such as the ones Hilborn describes, reduce the target species (often a top predator) to about 30 percent of its natural (unfished) abundance. The target species is in no danger of extinction, and let us assume that bycatch of other species is not an issue. Under these conditions, is the 70 percent reduction of a top predator acceptable? If not, what level is compatible with maintaining a healthy ecosystem? Calling for a sustainable level of fishing is not sufficient because, as Hilborn points out, fishing can be sustainable at different levels. Sustainable overfishing is not an oxymoron.

Part 4, “Place-based Management of Marine Ecosystems,” has four chapters on how marine reserves contribute to conservation goals. Reserves are defined as areas with the highest level of protection. (The term “sanctuary” seems to have been captured by the US Marine Sanctuary Program, which, paradoxically, allows fishing). Marine reserves hold great promise as effective tools for fisheries management (Joshua Sladek Nowlis and Alan Friedlander) and as a means of restoring habitats and populations already damaged by fishing (Callum Roberts). Because many (but, importantly, not all) marine organisms have a planktonic larval dispersal stage, meta-population aspects of marine reserves are important (Romuald Lipcius et al.). In the open sea, the concept of “place” is literally more fluid, so reserves might be defined on the basis of oceanographic features, such as fronts or isotherms, rather than fixed coordinates (Elliott Norse et al.).

The book appropriately concludes with part 5,“Human Dimensions.”James Acheson provides an illuminating cross-cultural perspective on the circumstances that lead to successful fisheries management. Alison Rieser and colleagues discuss the legal framework for marine conservation, but limit their excellent discussion mainly to US laws—so many marine conservation problems are inter- and extranational that a broader coverage of legal issues would have been useful. Robert Richmond offers a measured review of the benefits and limits of marine restoration efforts, and cautions against the hubris of assuming that we can restore whole ecosystems. He emphasizes that restoration efforts, while valuable, should not be used as an excuse for further degradation. Dorinda Dallmeyer's chapter on the development of a sea ethic is reflective. Louis Botsford and Ana Parma, in a chapter on uncertainty, describe how the ratchet effect leads to overfishing: Because of constant economic and social pressure for higher catches, fishing rates increase during times of high abundance but do not decrease during times of low abundance. Botsford and Parma make the important point that decisions under multi-species or ecosystem management will have greater uncertainty than under single-species management. The corollary (not developed in the book—unfortunately, given current enthusiasm for ecosystem management) is that unless we change how we deal with uncertainty and associated burden-of-proof concepts, ecosystem approaches to management could work against marine biodiversity and conservation goals, rather than support them. The final chapter by Norse eloquently argues that we can no longer afford a frontier mentality toward the sea. The sea should be zoned according to its uses, just as on land. There is a thoughtful discussion of the pros and cons of individual fishing quotas, co-management, and marine reserves, and how these could fit into a larger system of ocean zoning.

Overall, the tone of Marine Conservation Biology is hopeful; many chapters either suggest solutions or give positive examples of overcoming problems. As in many multiauthored books, chapters vary in style, coverage, and assumed background. All chapters are well referenced, however, and there is both a subject index and a species index. Either for reference or teaching, this book will be valuable to anyone interested in marine conservation biology.