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4 - Variability from scales in marine sediments and other historical records
- 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 45-63
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- Chapter
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Summary
Summary
Records of variability in populations of small pelagic fishes exist from a variety of historical sources that precede industrial fishing catch records. We review the historical records of artisanal fisheries, archeological remains, and fish remains from marine sediments. Fish scale deposition rates from ocean sediments offer the most quantitative records with little bias from anthropogenic factors. As quantitative estimates from fish scale deposition rates and their comparison with other records depend on chronostratigraphies, we discuss chronological development in detail, as well as the preservation and significance of fish scale flux. The different historical records indicate considerable variability in small pelagics prior to industrial fishing. However, the historical records provide little support for paradigms of ecosystem variability based on industrial catch records, such as synchronous worldwide fluctuations in abundance of small pelagic from different boundary currents or alternations of sardines and anchovies within a given boundary current. Rather, a variety of different modes of variability in small pelagics is consistent with paleoceanographic evidence for many different climate states and modes of variability.
Introduction
Some of the best evidence of long-term variability in marine populations comes from different records of pelagic fishes. There is evidence from industrial catch records of many decades in length, artisanal catch records, historical observations, archeological remains, and fossil remains in marine sediments. Small pelagics reflect many aspects of climate change effects on fisheries, since their recruitment and population size are sensitive to environment conditions. However, understanding variability in population size of small pelagics is intertwined with understanding their migrations (presumably in search of ideal environmental conditions).
3 - Habitats
- Edited by Dave Checkley, Scripps Institution of Oceanography, University of California, San Diego, Jürgen Alheit, Yoshioki Oozeki, Claude Roy
-
- Book:
- Climate Change and Small Pelagic Fish
- Published online:
- 08 January 2010
- Print publication:
- 20 August 2009, pp 12-44
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- Chapter
- Export citation
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Summary
Summary
The habitats of populations of small, pelagic fish, especially anchovy and sardine, in the Benguela, California, Humboldt, and Kuroshio-Oyashio current systems, and in the NE Atlantic, are described and discussed in regard to future climate change. These stocks have been the primary concern of the Small Pelagic Fish and Climate Change (SPACC) program of International GLOBEC. Each of these regions and stocks has a unique set of climate and ocean conditions and their variability. However, they also share common characteristics. Spawning and development occurs within broad ranges of temperature (12–26 °C) and salinity (<30–36) and in regions of high plankton production, associated with either upwelling or freshwater. Often, sardine are more oceanic and anchovy more coastal, often associated with wind-driven upwelling and rivers. Sardine tend to make longer migrations between spawning and feeding regions than do anchovy. The habitat of most populations of small, pelagic fish expands when the population size is large and contracts when it is small, often into refugia. Climate change may affect populations of small, pelagic fish by causing poleward shifts in distribution due to warming, some of which have already occurred. Other potential effects are due to changes in winds, hydrology, currents, stratification, acidification, and phenology.
Introduction
Small, pelagic fish, especially anchovy and sardine, abound in many, productive regions of the world ocean. Their habitats include areas with coastal and oceanic upwelling and freshwater influence and can be characterized by both geography (properties of the coast and bottom) and hydrography (properties of the water). The effects of climate change, be it of natural or anthropogenic origin, on populations of small, pelagic fish, are mediated by their habitats.