Turning the tide is easy. Tides are after all very predictable; just wait for the right moment before pushing the water back. When it comes to re-directing a current it is far more difficult – it takes climate change to shift the Gulf Stream.

What is happening to the world's fisheries, at the local, regional, or global scale appears to be more like a one-way current than a tide with ups and downs (Pauly et al., 2003). Strong enforcement of effort restrictions may bring a relief in the parts of the world where strong governance is in place (Worm et al., 2009), while most of the world's marine ecosystems continue to be overexploited. We are gradually eroding many of the ecosystems on which our food supply from the oceans relies, even if we may not notice it as individuals (Pauly, 1995). What can we do to curb the direction of widespread degradation? It is a daunting task to embark on – one where we cannot explicitly express how we will go about solving the problem. We do, however, have an idea of, and experience with, techniques and materials we can use to deliver a small contribution toward the solution.

What is clear is that if we as scientists are to make such contributions we must speak up and seek to be heard (Baron, this volume). We must convey the best available scientific information to decision and policymakers (Reichert, this volume).

The need to move from a sectoral to an ecosystem approach in the management of fisheries has become compelling in recent years. Many elements of ecosystem-based management (EBM) of fisheries have been identified but implementing them has proven to be elusive. Management of the oceans' fisheries on an ecosystem basis entails ecosystem-based management of the oceans themselves and, given the diversity of fisheries and marine ecosystems, there is no single recipe toward this end. In this book, we present a broad collection of the elements and some of the recipes for ecosystem-based management. We believe it is one of the first books to deal with this approach to management of the oceans.

This book was inspired by a founding father of research on ecosystem-based management, Daniel Pauly. When he was awarded the 13th International Cosmos Prize late in 2005, Amanda Vincent and Villy Christensen obtained support from the University of British Columbia (UBC) – where Pauly was Director of the Fisheries Centre – for a symposium to honor him for receiving the Cosmos Prize and to be held at the Fisheries Centre on the occasion of his 60th birthday, May 2, 2006. With UBC's generous support, we were able to invite a number of prominent scientists and policymakers with whom Pauly has worked during his career to give presentations at the one-day symposium, which was titled, “Thinking Big: A Global Look at Fisheries Science.”

INTRODUCTION

Fishing affects all levels of biological organization, from individuals to populations, affecting their demographic and genetic characteristics, as well as communities and ecosystems, (e.g., Hutchings, 2000; Law, 2000; Jackson et al., 2001; Daskalov, 2002; Pauly et al., 2002). Among the many effects of fishing, those referring to the marine ecosystem (i.e., trophic structure and energy flow within the ecosystem) have received particular attention in recent years.

This attention is in part because of the pioneering work of Pauly et al. (1998a). These authors used the world fisheries catch statistics (published annually by the Food and Agriculture Organization of the United Nations, FAO) and the trophic level (TL; Froese, this volume) of all species or groups of species contributing to the catches and showed that the mean trophic level of the catches had declined significantly, by about 0.5 TL, over a 50-year period. This decline was observed for global marine catches as well as for the majority of the different FAO subareas of the Atlantic, Indian, and Pacific Oceans, and the Mediterranean and Black Seas. This process, which, as will be shown here, has had a strong impact on fisheries science, is now known as “fishing down marine food webs” (FDFW). In fact, FDFW gave “flesh and bones” to something that many fisheries scientists intuitively had in their minds, while formal descriptions were few (Christensen, 1996).

FDFW was very enthusiastically received by the media (Baron, this volume) as well as by a large part of the scientific community.

INTRODUCTION

We are moving toward ecosystem-based management of fisheries, and it is clear that ecosystem modeling is an important tool for evaluating scenarios and trade-offs as part of such a move. This chapter evaluates the extent of ecosystem modeling as an active research field, the potential usefulness of the models for fisheries management, and actual use of ecosystem models in fisheries management. In addition we present some recommendations for how the move toward ecosystem-based management can be supported through an adaptive environmental assessment and management process.

It is important at the outset to be careful about what it means to “use” a model in fisheries management. At one extreme, imagine taking model predictions at face value and applying them blindly in setting reference points and regulations; some managers seem to hope for or expect such models to appear, presumably as absolution or excuse for not making thoughtful choices in the face of uncertainty. No fisheries model, whether a highly “precise” single-species assessment or a crude ecosystem biomass flow scheme, will ever be reliable enough to use in such an uncritical way, if for no other reason than unpredictability in environmental conditions. At the opposite extreme, we can certainly use even very simple trophic interaction calculations to screen qualitative policy options and answer very basic questions raised in management settings (e.g., could predation rates by some particular predator that fishers do not like be high enough to ever justify a culling policy?).

Fisheries have always been important to humanity. In the last century we have, however, witnessed how industrialization of fisheries leads to widespread overexploitation of fish populations. Our general reaction has been to strengthen the call for fisheries management, even if opinions of what this requires differ.

The idea of managing at the ecosystem level has been around for years (McIntosh, 1985), and numerous international agreements make it clear that this is the way forward for management for fisheries as well as for many other resources, such as forestry. Yet, there is considerable uncertainty in the minds of most scientists, environmentalists, managers, and policymakers, of what the term actually implies. Many definitions have been put forward, and we are slowly and gradually getting a clearer picture of what is involved in implementing ecosystem-based management of fisheries.

Pikitch et al. (2004) stated that approaches to ecosystem-based management of fisheries should avoid degradation of ecosystems while minimizing the risk of irreversible change therein, consider how to obtain and maintain long-term socioeconomic benefits, and in the process gain an understanding of the likely consequences of human actions. Clearly, area-based management has to be an integral part of ecosystem management, and it must be carried out so as to balance conflicting trade-offs and ensure long-term economic and social sustainability. Implementing ecosystem-based management requires going beyond traditional management and business-as-usual, and this is, in essence, what has dictated the content selection for this book.