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CABI Book Chapter

Responsible fisheries in the marine ecosystem.

Book cover for Responsible fisheries in the marine ecosystem.

Description

This book addresses ecological and environmental issues associated with responsible and sustainable marine fisheries. It includes 22 chapters and has been developed from the Conference on Responsible Fisheries in the Marine Ecosystem held in Iceland in October 2001. Contents include: a global overview of marine capture fisheries; legal protection for marine ecosystems; dynamics of marine ecosystem...

Chapter 7 (Page no: 103)

The functioning of marine ecosystems: a fisheries perspective.

There is considerable evidence that environmental variability plays a major role in controlling abundance and distribution of marine populations and that fisheries alter ecosystem functioning and state. This overview documents emergent, i.e. visible to us as observers, ecosystem-level ecological patterns and addresses important questions regarding the exploitation of marine resources. Do marine ecosystems function differently from terrestrial systems? Do multiple stable states exist in marine ecosystems? Does removal of top predators in marine ecosystems result in fundamental changes in the plankton communities (top-down 'trophic cascades'), as observed in lakes? Alternatively, are marine ecosystems characterized by bottom-up control such that fishing predatory fish does not disturb community structure and function? Does heavy exploitation of forage species, such as anchovies and sardines, cause changes in the functioning of upwelling ecosystems? The key to answering these questions and exploring whether general principles apply lies in understanding the energy flow within the ecosystems. The chapter reviews different types of energy flow in marine ecosystems, i.e. bottom-up control (control by primary producers), top-down control (control by predators) and wasp-waist control (control by numerically dominant species). No general theory can yet be ascribed to the functioning of marine ecosystems. Ecological understanding and models of ecosystem functioning are provisional and subject to change, and common sense is not sufficient when studying complex dynamic systems. However, tentative and partial generalizations are proposed, namely that bottom-up control predominates; top-down control plays a role in dampening ecosystem-level fluctuations; trophic cascades seldom occur; and wasp-waist control is most probable in upwelling systems. Moreover, alternation and large-scale synchronized fluctuations in fish stocks, stability of fish communities and emergent features such as size spectra are potentially important patterns when assessing states and changes in marine ecosystems. New and meaningful indicators, derived from our current understanding of marine ecosystem functioning, can be used to assess the impact of fisheries and to promote responsible fisheries in marine ecosystems.

Other chapters from this book

Chapter: 1 (Page no: 1) Global overview of marine fisheries. Author(s): Garcia, S. M. Leiva Moreno, I. de
Chapter: 2 (Page no: 25) Obligations to protect marine ecosystems under international conventions and other legal instruments. Author(s): Aqorau, T.
Chapter: 3 (Page no: 41) Incorporating ecosystem considerations into fisheries management: large-scale industry perspectives. Author(s): Bodal, B. O.
Chapter: 4 (Page no: 47) Small-scale fisheries perspectives on an ecosystem-based approach to fisheries management. Author(s): Mathew, S.
Chapter: 5 (Page no: 65) An environmentalist's perspective on responsible fisheries: the need for holistic approaches. Author(s): Agardy, T.
Chapter: 6 (Page no: 87) Ecological geography as a framework for a transition toward responsible fishing. Author(s): Pauly, D. Watson, R. Christensen, V.
Chapter: 8 (Page no: 125) Food webs in the ocean: who eats whom and how much? Author(s): Trites, A. W.
Chapter: 9 (Page no: 143) Regional assessments of prey consumption and competition by marine cetaceans in the world. Author(s): Tamura, T.
Chapter: 10 (Page no: 171) Multi-species and ecosystem models in a management context. Author(s): Stefansson, G.
Chapter: 11 (Page no: 189) Multiple uses of marine ecosystems. Author(s): Rosenberg, A. A.
Chapter: 12 (Page no: 197) Impacts of fishing gear on marine benthic habitats. Author(s): Kaiser, M. J. Collie, J. S. Hall, S. J. Jennings, S. Poiner, I. R.
Chapter: 13 (Page no: 219) The magnitude and impact of by-catch mortality by fishing gear. Author(s): Cook, R.
Chapter: 14 (Page no: 235) The effects of fishing on species and genetic diversity. Author(s): Kenchington, E. L.
Chapter: 15 (Page no: 255) The effects of fishing on non-target species and ecosystem structure and function. Author(s): Gislason, H.
Chapter: 16 (Page no: 275) Anthropogenically induced changes in the environment: effect on fisheries. Author(s): Richardson, K.
Chapter: 17 (Page no: 291) The performance of fisheries management systems and the ecosystem challenge. Author(s): Sutinen, J. G. Soboil, M.
Chapter: 18 (Page no: 311) The role of harvest control laws, risk and uncertainty and the precautionary approach in ecosystem-based management. Author(s): Butterworth, D. S. Punt, A. E.
Chapter: 19 (Page no: 321) Modifying fishing gear to achieve ecosystem objectives. Author(s): Valdemarsen, J. W. Suuronen, P.
Chapter: 20 (Page no: 343) Incorporating ecosystem objectives into management of sustainable marine fisheries, including 'best practice' reference points and use of marine protected areas. Author(s): Sainsbury, K. Sumaila, U. R.
Chapter: 21 (Page no: 363) Governance for responsible fisheries: an ecosystem approach. Author(s): Sissenwine, M. P. Mace, P. M.
Chapter: 22 (Page no: 393) Towards ecosystem-based fisheries management. Author(s): Sinclair, M. Valdimarsson, G.

Chapter details