IV.10 Spatial Dynamics of Marine Fisheries [Image Plates follow page 509]
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IV.10 Spatial Dynamics of Marine Fisheries Daniel Pauly and Reg Watson OUTLINE 1. Introduction 2. Geography of fisheries’ productivity 3. ‘‘Fishing down’’ as a major feature of contemporary fisheries 4. Mapping fisheries’ interactions 5. Conclusions Key features of the evolution of marine fisheries from their near-coastal antecedents to their present existence as industrialized , high-sea ventures are recalled along with some of the elements that led, in the early 1980s, to the emergence of the United Nations Convention on the Law of the Sea and to exclusive economic zones being granted to maritime countries. The world’s marine fisheries’ catches peaked in the late 1980s, as newly exploited areas ceased to compensate for the collapsing stocks of traditional fishing grounds. It is demonstrated that the expansion that until then had masked these collapses was southward (from northern temperate and boreal fishing grounds toward subtropical and tropical areas and onto the Southern Hemisphere), into deeper waters, and toward species previously not exploited and generally lower in the food webs, this last process being known as ‘‘fishing down marine food webs.’’ We examine these trends in some detail for shelves, where most of the world catches are taken, ‘‘transition areas ’’ (fronts, upwellings, seamounts), and oceanic waters, each characterized by a different productivity regime, determined mainly by the mechanism that lifts deep, nutrientrich waters into the illuminated surface layers. Overcoming these trends will involve a rethinking of the resource allocation that is underlying current exploitation patterns, which presently treat the fishing industry as quasiowner of marine resources that are, in reality, public property. Other allocation issues involve the relationship between small-scale and large-scale fisheries and the wisdom of subsidizing fisheries . To fully understand the scale of these problems, however , maps of fisheries’ withdrawals and other indicators of the ecosystem impacts of fisheries are essential, as they, more than any other form of presentation, can communicate complex phenomena at various scales to the public and decision makers. GLOSSARY bloom. A population outbreak of microscopic algae (phytoplankton) that remains within a defined part of the water column. demersal. Organism that lives on or near the bottom of and/or feeding on benthic (bottom) organisms. EEZ (exclusive economic zone). Area up to 200 nautical miles off the coast of maritime countries as declared under 1982 United Nations Convention of the Law of the Sea. Within their EEZs, coastal states have the right to explore and exploit, and the responsibility to conserve and manage, the living and nonliving resources. extirpation. The process whereby an animal or plant species is rendered extinct in a particular area or country while it survives in others. When a species consists of several populations, the extirpation of the last population is equivalent to the global extinction of that species. fishing down the marine food webs. The process wherein the fisheries within a given marine ecosystem, having depleted the large predatory fish on top of the food web, turn to increasingly smaller species, finally ending up with previously spurned small fish and invertebrates. This process is now well established in many parts of the world. fish meal. Fish and fish-processing offal that is dried, often after cooking and pressing (for fatty fish), and ground to give a dry, easily stored product that is a valuable ingredient of animal feeding stuffs. In Peru, fish meal is made mainly of anchovies; in northern Europe, mainly capelin, sand eel, mackerel , and Norway pout are used for fish meal production . In Japan, the principal species are sauries, mackerels, and sardines, and in the United States menhaden. gyre. Major cyclonic surface current systems in the oceans, roughly corresponding to the unproductive, highly stratified areas of the oceans that are most remote from the continents. IUU. Illegal, unreported, and unregulated fishing. longline. Line of considerable length, bearing numerous baited hooks, that is much used in tuna fisheries. The line is set for varying periods up to several hours at various depths or on the seafloor, depending on the target species. Longlines, which are usually supported by floats, may be 150 km long and have several thousand hooks. neritic. Inhabiting the shallow pelagic zone over the continental shelf, i.e., waters less than 200 m deep, and deeper waters in areas of coastal submarine slopes. pelagic. Living and feeding in the open sea, i.e., associated with the surface or middle depths of a body of water but not in association with the bottom. purse seine. A fishing net used to encircle...


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