Top Predators in Marine Ecosystems. Their Role in Monitoring and Management . Boyd, I., S.Wanless, and C. J.Camphuysen , editors . 2006 . Cambridge University Press , New York , NY . Conservation Biology 12 . 392 (xiv + 378) pp . $130.00 (hardcover). ISBN 0–521-84773–7. $70.00 (paperback). ISBN 0–521-61256-X .
I will start with a recommendation—buy this volume for a long plane ride. Read it, recommend it to others, and then donate it to your library. It is a great resource. Stemming from a Zoological Society of London symposium held in April 2004, it more than meets the goal stated on the jacket cover as: “[t]his book investigates the theory that the population and behavioral dynamics at the upper end of the marine food chains can be used to assist with management.” It covers a much larger range of perspectives than that, including a substantial number of chapters devoted to ecosystem-based approaches and, as represented in the subtitle, attempts to address the role of top predators in both monitoring and management programs. Fishery-related and food-web interactions are a component of the concerns at all levels.
The contents include 24 chapters—too many to review as individual components. The authorship includes 56 contributors, most of which represent European institutions. It has a bias for coverage of high-latitude systems that are, of course, both among the most intensively fished and extensively studied. The taxonomic foci include birds, mammals, and fishes representing a geographic range of ecosystems from the high Arctic to Antarctica. Seabirds are well represented as subjects for study. The book includes an adequate index and, with minor exception, a diversity of legible figures and tables. It also has lots of boxes that emphasize specific messages—that is a mechanical summary of the components. In fact, the major positive and generally instructive attribute of this volume is its range of epistemological views.
Represented herein are arguments from empiricists asserting that an ecosystem perspective can only be developed by continuing expansion of data-collection efforts. In some cases this is accompanied by value-laden statements to the effect that if some creature or process is in the ecosystem, it must be important and fully understood if proper management is to proceed for the benefits of ecosystem goods and services. That is the most strident view and is writ large in the call for marine reserves. Another example is the tenet that knowing the “primacy of physics” is essential to understanding and management of marine ecosystems. On the other hand, some chapters (also authored by empiricists) actually pose their arguments as testable hypotheses, use the existing data accordingly, and reach valid conclusions in support of and/or contrary to the basic assertions that “more data are required.”
In my view fisheries are among the most powerful forces of ecological change. We know that fisheries are constantly changing. We know that fishery effects can include complex compensatory responses in food webs. Clearly, more data would be valuable, but we also have to recognize that the management process will not wait for each and every scientist to be fully satisfied with the existing information. The U.S. National Academy of Sciences addressed these issues in a recent report (National Research Council. 2006. Dynamic changes in marine ecosystems: fishing, food webs, and future options. National Academy of Sciences, Ocean Studies Board, Washington, D.C.).
Chapters based on theoretical approaches are several and varied. Those range from detailed attention to the mechanistic accounting for components in predator–prey interactions to larger-scale assessment of behavior by predators in an unpredictably variable environment. Modeling approaches include individual-basic energetics, prey-switching behavior, direct and indirect effects of fisheries, and the larger economic consequences brought to play in taking a systems approach where fisheries are involved.
My favorite chapters include the analysis of increases in North Atlantic fulmar populations (Thompson, chapter 12). This one includes consideration of paleoecological evidence and alternative drivers of more recent change due to the subsidies (discards) of fishery effects. Another favorite (Croxall, chapter 11) draws from experience in using predators of krill off South Georgia Island in the Antarctic and develops a strong rationale for dealing with the scale and scope appropriate to effective monitoring. And a third is the “multiple hypotheses” approach developed by Wolf et al. (chapter 19) in analyzing the possible causes of the decline of Steller sea lions in western Alaska. This is the ecological detective at work. In this case, there are 10 candidate causes. The core question has been, is it food? So far, food looks like the best answer. But there are strong hints that harbor seals and killer whales are among the participating suspects.
The title will attract many kinds of readers. Some may react to the fact that the volume is among the Conservation Biology series from Cambridge. A first thumbing through of the contents suggests that conservation-laden rhetoric may dominate. This is wrong. The book offers a much more comprehensive range of approaches and some truly outstanding examples of both inductive and deductive logic. It is a great read, and it will educate you with a diversity of fascinating examples and stimulate your thinking about how people express alternative views of scientific endeavor. Buy it and make lots of notes in the margins as you read. Schedule this one for a discussion by your colleagues and students. I predict that will be lively and instructive.