4 results
Foreword
- Edited by Andrea Belgrano, Charles W. Fowler
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- Book:
- Ecosystem Based Management for Marine Fisheries
- Published online:
- 17 February 2011
- Print publication:
- 03 February 2011, pp xiii-xvi
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Summary
The necessity of an ecosystem approach (EA) to fishery management has been gaining worldwide recognition in recent years. This concept provides an attractive alternative to viewing fisheries mainly as a profit-oriented economic enterprise, especially given a growing dissatisfaction with a long, mixed, and in some cases dismal record of resource overfishing, depletion, and collapse. Though it is intuitively appealing, the EA concept has been rather difficult to define formally. Yet, something called “an ecosystem approach” is now being attempted in many different fisheries systems – collectively characterized with as much variety as common ground. There are yet more proposals for how to implement an EA waiting to be put into practice. The diverse collection of examples in this book provides an overview of EA both in current practice and future potential, and may contribute a subjective sense of what EA actually is, whether or not we attempt a definition.
Part of the difficulty in defining EA is that it reflects a set (or sets) of values, and human values notoriously elude formal definition. Such plausible concepts as “ecosystem health” are value-based, and it may be a false assumption that they can be measured and defined objectively. However, once the subjective terms of reference for EA have been established, some degree of conditional objectivity may become possible.
Man is the only creature that frequently takes action based on an abstract, imagined, and even probabilistic future.
15 - Synthesis and perspective
- Edited by Dave Checkley, Scripps Institution of Oceanography, University of California, San Diego, Jürgen Alheit, Yoshioki Oozeki, Claude Roy
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- Book:
- Climate Change and Small Pelagic Fish
- Published online:
- 08 January 2010
- Print publication:
- 20 August 2009, pp 344-351
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Summary
Summary
The Small Pelagic Fish and Climate Change (SPACC) program was created to facilitate research on the dynamics of populations of small pelagic fish, including anchovy and sardine. These populations exhibit large variations in size, extent, and production on the scale of decades. At times, anchovy and sardine alternate in abundance. Collectively, small pelagic fish often occupy a central role in the food web they occur in, often described as a wasp-waist ecosystem. Humans are an integral part of those ecosystems. Variability of populations of small pelagic fish is believed to be due primarily to variations in climate and fishing, but the mechanisms of these relations remain unknown in most cases. It is also uncertain whether these ecosystems alternate between states, e.g. regimes, and whether inherent variability may limit our ability to predict their future states. The fisheries for populations of small pelagic fish are increasingly global in nature. While the global catch of small pelagic fish constitutes approximately one quarter of the world fish catch and has been relatively constant during the past several decades, the catch of individual taxa and stocks varies much more. The management of these fisheries will be challenged by increasing demand for human consumption and mariculture in light of their finite and variable production, importance within the ecosystem, and unprecedented climate change, and will depend on both science and governance. We recommend continued, global research on climate change effects on small pelagic fish, and its periodic assessment for use by decision makers.
12 - Mechanisms of low-frequency fluctuations in sardine and anchovy populations
- Edited by Dave Checkley, Scripps Institution of Oceanography, University of California, San Diego, Jürgen Alheit, Yoshioki Oozeki, Claude Roy
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- Book:
- Climate Change and Small Pelagic Fish
- Published online:
- 08 January 2010
- Print publication:
- 20 August 2009, pp 285-299
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Summary
Summary
The hypothesized mechanisms reviewed in this chapter have been selected as having potential for generating low frequency variability in sardine (Sardinops spp.) and anchovy (Engraulis spp.) populations such as those experienced in the California Current, Humboldt Current, and the Benguela and Kuroshio Current systems. No generally accepted theory yet exists. An initial framework for such a theory is proposed, in which sardine productivity is linked to low frequency variability in boundary current flows, which is also related to the characteristic sea surface temperature anomalies associated with sardine productivity in these systems. During periods of weaker flow, planktonic sardine larvae are able to gain swimming capacity before being flushed from the system, allowing sardines to inhabit the main body of the boundary current. During periods of stronger flows, successful sardine reproduction is restricted to coastal waters, and productivity is relatively low. Anchovies are always restricted to coastal waters, and are more influenced by upwelling and coastal productivity; these characteristics tend to be correlated with boundary current fluctuations, giving rise to a tendency (but not requirement) of sardine and anchovy alternations. The Japanese system lacks coastal upwelling, but the cold, nutrient-rich Oyashio Current provides an analogous function.
A wide variety of mechanisms can be added to this framework as appropriate to individual systems. Physical processes include patterns of boundary current flow, including current meandering and formation of cyclonic eddies. A latitudinal shift in the source water coming from the North Pacific has been identified in the California Current, and contributes to the characteristic temperature and nutrient anomalies.
2 - A short scientific history of the fisheries
- Edited by Dave Checkley, Scripps Institution of Oceanography, University of California, San Diego, Jürgen Alheit, Yoshioki Oozeki, Claude Roy
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- Book:
- Climate Change and Small Pelagic Fish
- Published online:
- 08 January 2010
- Print publication:
- 20 August 2009, pp 6-11
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Summary
Summary
This chapter briefly summarizes the history of scientific understanding of the fluctuations of small pelagic fishes and fisheries. The classical quantitative models underlying modern fishery analysis and management were developed in the 1950s and 1960s. Although California and Japan had previously experienced collapses of major fisheries for small pelagics in the 1940s and 1950s, it was the collapse of the “scientifically managed” Peruvian anchoveta fishery in the early 1970s that drew worldwide attention to the problem of collapsing small pelagic fisheries. The inability of the anchoveta to regain its former levels of productivity cast doubt on the classical equilibrium fishery models. In the late twentieth century, substantial progress was made toward understanding the environmental influences on these fishes. Some of the major environmental influences (which often may not be specifically identified) fluctuate at interdecadal time scales, giving rise to prolonged periods of high and low fish productivity, abrupt transitions including collapses, global teleconnections and phase relationships. These so-called “regimes” have recently become a major topic of research in fishery science. Despite scientific progress in understanding many facets of these fisheries and their fluctuations, there still is no accepted theory of the fishery–oceanographic dynamics of small pelagic fishes that links their commonly shared properties and that provides the predictive capability needed for ecosystem-based management.
Introduction
This history of small pelagic fisheries focuses specifically on the development of a scientific understanding of their dynamics, especially regarding their problematic fluctuations in abundance. Fréon et al. (2005) describe several distinct historical periods in the study of pelagic fish stocks, a system that is adopted for this review.