1. Trang chủ
  2. » Kỹ Thuật - Công Nghệ

Encyclopedia of Global Resources part 49 pps

10 98 0

Đang tải... (xem toàn văn)

THÔNG TIN TÀI LIỆU

Thông tin cơ bản

Định dạng
Số trang 10
Dung lượng 91,99 KB

Nội dung

Chaparral-Dominated Lands The chaparral of temperate coastal climates, such as that in Southern California, ignites easily and is likely to burn from surface fires every ten to fifteen years. In fact, without fire, chaparral fields, which also support manzanita, scrub oak, and coyote brush, become choked, and many nonsprouting shrubs die. Light fires every twenty to thirty years are therefore neces- sary to species survival. Unburned for longer than that, the fields accumulate so much dead debris that the chances for a tremendously destructive fire soar. Forest Fires Great diversity in tree types and, accordingly, fire fre- quency and intensity, exists among evergreen and de- ciduous forests. Forests can fall prey to all types of fire; crown and high-intensity spotting fires are most com- mon in Douglas fir-dominated areas, while mature stands of pure juniper are nearly impossible to burn. In general, fire helps maintain the dominance of pines by preventing hardwoods, which burn more readily(withtheexceptionofsomeoakspecies),from invading. Several pine and spruce species, most nota- bly ponderosa pine, require fire-cleared soil to germi- nate seeds. Wildfire intervals range from five to ten years for ponderosa pines and up to five hundred years for redwoods. Beginning in the 1960’s, government land manag- ers used controlled burns and unopposed wildfires to clear away underbrush and dead trees in public for- ests. However, since such fires destroy public timber resources and sometimes, out of control, ravage pri- vate lands and human residential areas, the practice has been controversial, especially after the devastat- ing Yellowstone National Park fire of 1988. The political as well as economic infeasibility of con- trolling overgrowth may have contributed to South- ern California’s “Station Fire” of 2009, which ravaged roughly two hundred square miles of the Angeles Na- tional Forest and adjacent residential interface areas (an area the size of San Francisco) during the largest forest fire in the history of Los Angeles County. The region, normally prone to fires driven by Santa Ana winds, instead underwent a fuel-driven fire that threat- ened lives and destroyed approximately one hundred homes as well as vast areas of wildlife habitat. Australia experienced similar massive fires during this period. Such events, while part of a natural cycle, pose im - mediate threats not only to ecological and other natu - ral resources but also to human infrastructure when development has encroached on the areas subject to burning. Combined with evidence of global warming and concomitant trends toward droughts and longer or unbroken “fire seasons,” such fires can beexpected to increase the strain on economic and human re- sources. Roger Smith Further Reading Carle, David. Introduction to Fire in California. Berkeley: University of California Press, 2008. DeBano, Leonard F., Daniel G. Neary, and Peter F. Ffolliott. Fire’s Effects on Ecosystems. New York: J. Wiley, 1998. Pyne, Stephen J. Awful Splendour: A Fire History of Can- ada. Vancouver: University of British Columbia Press, 2007. _______. Fire in America: A Cultural History of Wildland and Rural Fire. 1982. Reprint. Princeton, N.J.: Princeton University Press, 1988. _______. World Fire: The Culture of Fire on Earth. New York: Holt, 1995. Quintiere, James G. Fundamentals of Fire Phenomena. Chichester, England: John Wiley, 2006. Rossotti, Hazel. Fire. New York: Oxford University Press, 1993. Wein, Ross W., and David A. MacLean, eds. The Role of Fire in Northern Circumpolar Ecosystems. New York: Published on behalf of the Scientific Committee on Problems of the Environment of the Interna- tional Council ofScientificUnionsbyWiley,1983. Whelan, Robert J. The Ecology of Fire. New York: Cam- bridge University Press, 1995. Wright, Henry A., and Arthur W. Bailey. Fire Ecology: United States and Southern Canada. New York: Wiley, 1982. Web Sites Canadian Forest Service, Natural Resources Canada Canadian Wildland Fire Information System http://cwfis.cfs.nrcan.gc.ca/en_CA/index U.S. Geological Survey Natural Hazards: Wildfires http://www.usgs.gov/hazards/wildfires See also: Erosion and erosion control; Forest fires; Forest management; Forestry; Grasslands; Range - land; Slash-and-burn agriculture. 428 • Fires Global Resources Fish and Wildlife Service, U.S. Category: Government and resources Date: Established 1940 The U.S. Fish and Wildlife Service, a part of the U.S. Department of the Interior, is the primary federal agency charged with protecting the nation’s fish, wild- life, and associated habitats. Background The U.S. Fish and Wildlife Service (FWS) grew out of two agencies: the Bureau of Fisheries (1871) in the Department of Commerce and the Bureau of Biologi- cal Survey (1885) in the Department of Agriculture. Each held specific duties designed to protect the country’s fishing, game hunting, and other natural re- sources. Under Presidential Reorganization Plan 111, Franklin D. Roosevelt consolidated the agencies and created the FWS in 1940. Impact on Resource Use Under the Fish and Wildlife Act of 1956, the Fish and Wildlife Service was given legislative status and di- vided into two divisions: the Bureau of Commercial Fisheries and the Bureau of Sport Fisheries and Wild- life. The latter eventually took over the agency when the commercial division moved into the Department of Commerce in 1970. The FWS is a bureau of the De- partment of the Interior. It seeks to enforce legisla- tion pertaining to wildlife and to protect associated natural resources. A director, under the umbrella of the secretary of the interior, is in charge of the nearly nine thousand employees of the FWS. To fulfill its duties, the FWS developed a three- pronged approach: conservation, research, and en- forcement. Conservation relates to the 38 million hectares in more than seven hundred areas of the Na- tional Wildlife Refuge System that fall under FWS ju- risdiction. In addition, the FWS maintains the Na- tional Fish Hatcheries System and provides support to state and local agencies seeking federal funding or intervention. Its research activities involve a na- tional network of field agents and biologists who work to protect wildlife and its surroundings. FWS policy maintains that the protection of habitat through con- servation and research is essential to the survival of animals. Its mission includes particular attention to endangered species. The agency’s approach to enforcement has evolved through the years. In addition to its central adminis- trative office it has eight regional offices and almost seven hundred field offices. Through its regional of- fices and hundreds of field stations, the FWS has in- creased the numbers of animal species under its care. From regulating migratory bird hunting and issuing duck-hunting licenses to setting limits on fish catches and enforcing the protection of threatened wildlife, the FWS has greatly expanded its role over its history. Eventually “wildlife” came to represent a traditional definition of animal life as well as fresh and anadro- mous fish, certain marine mammals, and identified endangered species. In the late twentieth century, as national policy extended to include a more conser- vational and environmental approach, the FWS re- sponded with improved regulation of wetlands and the wildlife refuge system. Legislative support brought increased research into the water, air, and plant life of wildlife habitats. In addition to preservation, one of the most important tasks of the FWS is education in wildlife and conservation, particularly geared to the youth of the United States. The FWS features numer- ous programs addressing issues of wildlife. The FWS has a law enforcement division aiming to stop crimes against wildlife and those committed on its lands. The FWS also has the world’s only forensics laboratory devoted to solving and preventing crimes against wild- life. The 38-million-hectare National Wildlife Refuge System is the only collectionoffederal lands managed exclusively for the benefit of wildlife. This beautiful ecosystem includes diverse water, land, and forest habitats. About 750,000 hectares of wetlands, essen- tial to the health and welfare of wildlife and humans, are included in this total. More than thirty-nine mil- lion tourists visit the National Wildlife Refuge System annually. Despite the importance of this system, the FWS managed these habitats for decades without an organic law. “Organic law” means a fundamental constitution or law that outlines the basic principles of government.Without an organic law, the FWS over- saw the National Wildlife Refuge System by means of piecemeal legislation and regulation. Congress passed numerous important pieces of legislation af- fecting FWS throughout the second half of the twenti- eth century. For example, the Federal Aid in Sport Fish Restoration Act (Dingell-Johnson Act), enacted in 1950, established a program to improve the fishery resources of the nation. The National Wildlife Refuge Global Resources Fish and Wildlife Service, U.S. • 429 System Administration Act, enacted in1966,served to protect the refuge areas from damaging uses. The En- dangered Species Act, enacted in 1973, entrusted FWS with responsibility over many endangered spe- cies. The Alaska National Interest Lands Conserva- tion Act, enacted in 1980, greatly expanded the Na- tional Wildlife Refuge System, adding more than 21 million hectares of land. A watershed moment for the FWS came in 1997 with the passage of perhaps the most important legis- lation in its history. The National Wildlife Refuge Sys- tem Improvement Act of 1997 was a major legislative scheme affecting federal use and oversight of wildlife lands. Congress passed the act as Public Law 105-57. President Bill Clinton signed the act on October 9, 1997. The National Wildlife Refuge System Improve- ment Act provided the organic law for the FWS. In other words, all of the actions of the FWS should fol- low from this act. It represents a comprehensive set of legislation that mandates the responsibilities and ac- tions of the FWS as it relates to the National Wildlife Refuge System. The act is divided into ten parts, cover- ing such topics as hunting, trapping, and fishing; con- cerns relating to live wildlife and fish; the sale, pur- chase, and transport of wild animals; and licensing, enforcement, penalties, and regulations. Perhaps most important, the act gave a strong mission statement to guide the Department of the Interior and the FWS. This mission statement emphasizes the mandate to protect wildlife and maintain the diversity, health, and outstanding qualities of the habitats. The act re- quired a new process todetermine which recreational activities are appropriate in the refuges. The act also recognized that traditional activities such as fishing, hunting, and wildlife observation are appropriate public uses of the National Wildlife Refuge System, as long as they do not harm the environment. Finally, the National Wildlife Refuge System Improvement Act required the FWS to devise a comprehensive plan to conserve all of the refuges under its management. The FWS received $280 million under the Ameri- can Recovery and Reinvestment Act of 2009 to com- plete projects that enhance the wildlife habitats while providing jobs and stimulating the economy. This measure harked back to the days of the Civilian Con- servation Corps (CCC). The CCC (1933-1942) was created as a project of the New Deal, both to provide jobs in a time of economic crisis and to develop and conserve natural resources in the United States. In late 2009, the FWS releasedastrategicplantohelpthe wildlife and habitats under its management to survive the impact of global climate change. In its efforts to conserve, research, and protect through enforcement, the FWS often faces opposi- tion from business interests and conservation groups. The logging industry, for example, has criticized cer- tain protective measures, claiming that they place more importance on animals than humans. Conser- vation groups, on the other hand, have criticized the FWS for allowing controlled predatory animal reduc- tions on federal refuge land. In all such instances, the FWS finds itself faced with balancing national policy with wildlife interests. The FWS provides a vital link between the U.S. gov- ernment, U.S. citizens, and the natural world. The FWS prides itself on managing the largest and most impressive wildlife habitat in the world. Through its protective as well as investigative functions, the FWS works to maintain a strong level of biodiversity in the United States. Jennifer Davis, updated by Howard Bromberg Further Reading Bean, Michael. The Evolution of National Wildlife Law. 3d ed. Westport, Conn.: Praeger, 1997. Fischman, Robert. TheNational Wildlife Refuges:Coordi- nating A Conservation System Through Law. Washing- ton, D.C.: Island Press, 2003. Freyfogle, Eric, and Dale Goble. Wildlife Law: A Primer. Washington, D.C.: Island Press, 2009. See also: Conservation; Department of the Interior, U.S.; Endangered species; Endangered Species Act; Fisheries; Wetlands; Wildlife. Fisheries Categories: Plant and animal resources; environment, conservation, and resource management Fisheries, places where fish or other aquatic foods are caught or taken, provide an important source of pro- tein. Fishing technologies range in scope from simple hook-and-line fishing in small ponds to industrial op- erations that use huge nets stretching behind seagoing trawlers. Many experts believe overfishing has placed fisheries throughout the world in danger of ecosystem collapse. 430 • Fisheries Global Resources Background Oceans cover nearly 71 percent of the Earth and con- tain 86.5 percent of the Earth’s water (510 million cu- bic kilometers). Freshwater areas cover an additional 1 percent of theEarth. Most life existsin ecosystems at or below the surface of water.Aquatic ecosystems have a distinct advantage over land-based ecosystems be- cause their life-formsarenotlimitedbyalackof water. Nutrient-rich areas of the ocean are green with lush plant growth, and can produce more food than culti- vated farmland. Even polar ocean areas with pack ice most of the year are rich with algae growing in open areas and inside ice. Furthermore, “blue-water deserts”—ocean regions with low nutrient levels— produce more biomass (total weightof plants and ani- mals) per unit of surface than land deserts. Food resources from water include finned fish, shellfish, crustaceans (such as shrimp, krill, and lob- ster), cephalopods, some marine mammals and rep- tiles, and plants. Water plants should be included in a discussion of fisheries because they are the ultimate source of food for animals that are fished and because some mixture of plants and animals are often har- vested. World fisheries and aquaculture supply more than 145 million metric tons of high-protein food each year, which is more than beef, pork, or poultry. Globally, fishing is a $92-billion-a-year industry di- rectly employing nearly 38 million people and indi- rectly employing an additional 162 million people. (Subsistence fishers in tropical areas are probably undercounted in numbers but estimates suggest about nineteen million fishers; financial measures are hard to apply.) In the United States, commercial fishing annually harvests roughly 3.65 billion kilograms of fish and shellfish worth more than $4 billion. In the United States alone, the secondary market and con- sumption value of seafood have an annual value of more than $195 billion. Oceanic Plant Life Sunlight drives photosynthesis, by which plants sup- ply almost all food on Earth, either directly or indi- rectly, through the animal life feeding on them. Be- cause the top several hundred meters of ocean water absorb virtually all sunlight hitting it, these upper- most waters contain the oceans’ supporting photo- synthetic plants. Below the oceans’ illuminated zone, animal life becomes progressively scarcer, and ani - mals feed on living and dead matter drifting down to them. Biologically productive areas ofoceans occur mostly in coastal regions, where minerals and nutrients are washed from land and where currents and winds dredge nutrient-rich sediments from the near-shore ocean floor. Similarly, nutrients from the deep ocean can be brought to coastal regions by differing ocean temperatures meeting to form convergent zones, re- sulting in upwelling—warm water rising to the surface and bringing with it conditions favorable for plant and animal life. Less than 1 percent of ocean areas are occupied by coastal ecosystems, yet these areas are twenty times more productive than the open ocean. Near-shore waters are home to mangrove swamps, salt marshes and tidal wetlands, coral reefs, and estuaries. Between 95 and 98 percent of commercial fishery spe- cies spend their early lives in fertile estuary ecosys- tems. Coral reefs harbor more plant and animal phyla than any other ecosystem; and tidal wetlands are the rearing grounds for vast numbers of crustaceans and mollusks. These near-shore waters are the primary ar- eas for marine life, and three-quarters of the world’s fish harvest occurs within 9 kilometers of continental shorelines. A number of freshwater and near-shore plants are similar to land plants, including species such as eel- grass, turtle grass, and kelp, beds of which are often called ocean forests. Many near-shore plants, such as nori in Japan, are eaten directly. Others are harvested for use as food additives. For instance, giant kelp (or bull kelp) off the west coast of North America is har- vested by clipping barges (which could be described as floating lawnmowers) for agar and alginate, used for stabilizing ice cream and beer foam. Semiaquatic plants such as mangrove trees, cat- tails, and other swamp plants also have a tremendous effect on fisheries. Many fish spawn and spend their early lives around these types of plants. The areas where they are found are sometimes considered waste- land, but they are actually crucial to many fished spe- cies, including shrimp. In fact, river estuaries, man- grove swamps, and salt marshes produce more organic material per unitareathananyotherareas onEarth. Away from shallow water, most oceanic plants are drifting algae barely large enough to be seen without magnification. In freshwater and near-shore waters, algae may comprise a large or small part of the ecosys- tem. In the deep ocean, phytoplankton (from the Greek words for “plant” and “wanderer”) is one of the only food supplies for many marine animals. Al - though individually small, phytoplankton numbers Global Resources Fisheries • 431 are so great that they represent most of the vegetable mass in the oceans: an estimated new growth of 18 bil- lion metric tons per year. Phytoplankton eaten by tiny animals, such as zooplankton, are food for small schooling fish, such as sardines, pilchard, herring, capelin, and anchovy. In turn, these fish are eaten by higher predators in the food chain, such as cod and mackerel, which are eaten by “top predators,” such as tuna, sharks, and porpoises. In each stage from phyto- plankton to top predators, about 90 percent of the food content is lost. Fishery Locations The richest fisheries have traditionally been along continental shelves. Continental shelves are gently sloping regions transitioning between the continents and the deep ocean. Continental shelves represent only 8 percent of the ocean expanse. Roughly 16 per- cent of the ocean expanse is continental slopes with gradients about ten times steeper than the gently slop- ing shelves. Continental slopes drop off 500 to 3,000 meters into the ocean depths. Along these continen- tal slopes, nutrient-rich upwelling occurs. Where the continental shelves are broad, major fisheries exist— or did exist before they were damaged by human ac- tivities. Three-quarters of all marine organisms spend at least a portion of their lives along a continental shelf. Major shelf fisheriesinclude the waters around Ice- land, the Patagonian shelf (extending to the Falkland Islands), the Sea of Okhotsk, the shelf around Alaska, island chains and coastal waters from Indonesia throughJapan,thePersianGulf,andtheGrand Banks east of North America. Major shelf fisheries that were important but have declined because of overfishing and pollution include the North Sea, the Baltic Sea, the Black Sea, Chesapeake Bay, and many areas in the Mediterranean. Coral reefs, which have some similarities to land ecosystems, are actually colonies of tiny animals that contain algae within their bodies. Reefs are areas of high productivity. The algae provide oxygen and food to the coral, while waste matter and carbon dioxide from the coral are nutrients to the algae. This symbio- sis allows reef ecosystems to be as productive as near- shore waters, even though nutrient levels are typically lower for reefs in tropical waters. However, this symbi- osis also makes reefs vulnerable to excessive fertiliza - tion from pollutants, particularly phosphates from fertilizers and detergents. Reefs are also highly sensi - tive to changes in turbidity, saline variation, and water temperature. Corals actually rebuild their environment to sur- vive, and, in the process, create a more productive fishery. Like shellfish, corals grow their own calcium- carbonate living environment, in which living layers build atop the remains of older generations. The coral reefs grow with many gaps and fissures, allowing water to flow continually to the live corals. These gaps provide hiding places and nests for many small and juvenile creatures, many of which help defend the corals frompredators.Becauseofcorals,theislandsof Polynesia have many small but rich fisheries. The Great Barrier Reef on the north side of Australia is enriched by corals and has the added advantage of a broad shelf area. Other natural areas of high productivity are cre- ated where deep water rises to the surface in an upwelling. Exceptionally cold meltwater from Antarc- tica is heavier than the bottom water, so bottom water is pushed toward the surface. Consequently, one of the largest areas of high biomass is along the conti- nental slopes of the Antarctic. Another area of upwelling exists west of Peru, where a current from the north meets a current from the south, and the combined current flows west. The resulting gap is filled by an upwelling that supports anchovy production. Periodically, an increase in warmer water (the El Niño current) weakens this upwelling, causing a drastic fall in plankton, and hence anchovy, production. A “crash” of this fishery in the early 1970’s, a result of an El Niño, was made worse by overfishing. Similar current-induced up- welling occurs along the Moroccan and Namibian coasts. Waters off Alaska have upwelling and large shelf areas, making them especially fertile. Most of the deep ocean away from land is abyssal plain or “blue-water desert” with low productivity; this is especially true near the equator. These waters have sufficient nitrates and phosphates to support higher levels of marine life but lack trace amounts of iron, a mineral vital for phytoplankton survival. Existing Fisheries The evolution of fisheries has involved both the avail- ability of fish and the public’s taste in seafood. Top predators, such as tuna, are prized for their taste, but schooling fishes that feed on zooplankton are har - vested in the greatest tonnage. Another factor in the evolution of fisheries is that species tend to decline as 432 • Fisheries Global Resources they are overfished, so new species must be fished. The schooling fish that generally represent the high- est tonnage of fish caught are a cheap source of pro- tein. As such, roughly 25 percent of the fin catch is processed into fishmeal for livestock, and an addi- tional 50 percent of fishmeal is consumed by aqua- culture. Also, 70 percent of all fish oil is consumed by aquaculture. Invertebrates are much lower in ton- nage than finned fish, but they make up a significant percentage of the value of the fisheries trade. They include prized crustacean species such as lobster,king crab, and shrimp. They also include shellfish such as clams, abalone, and scallops. Krill are small zooplankton crustaceans similar to shrimp. Krill are the primary food for baleen whales, which strain water for their tiny prey. Some limited krill fishing has been done to provide fishmeal. (Ithas been noted that people may be slow to accept krill in their diets on a significant scale because cooked krill look similar to maggots.) The largest krill population is in waters around Antarctica, where the krill popula- tion is estimated at 600 million metric tons. Further estimations indicate that a sustainable yield for krill would be one-tenth of this total. These same Antarctic waters also support a large population of whales, which survive on krill. Any overharvesting of krill would have an adverse effect on whales. The northern polar region has the largest single-species fishery in the world—pollock, which thrive in the Bering Sea near Alaska. The world’s largest remaining cod fish- ery is in the Barents Sea of northern Europe. The Barents Sea fishery is threatened by pollution, min- eral exploration, busy shipping lanes, overfishing, and illegal fishing. Unsustainable commercial fishing practices, in combination with an illegal catch esti- mated at 90 million metric tons per year, are pushing the Barents Sea cod fishery toward collapse. Fishing Technologies Fishing can be done with hooks, traps, or nets; all three of these fishing methods are used bysubsistence fishers and small fishing operations. For large-scale, industrial fishing operations, nets are the most practi- cal and efficient tools. Large fishing operations radi- cally changed fishing and the world’s fisheries in the twentieth century. Although some mechanized fishing was done in the nineteenth century, commercial fishing produc - tion was only around 2.5 million metric tons at the be - ginning of the twentieth century and had reached 18 million metric tons at the beginning of the 1950’s. Then a combination of insecticides, newly introduced medicines, and better hygiene reduced disease, allow- ing a rapid growth in human population, which cre- ated a growing market for food. At the same time, better transportation allowed rapid shipment of pre- mium catches, so lobsters, for instance, would never again be considered food for poor people along the coast. The greater fish market was met by investments in technology. First came large boats, followed by so- nar navigation equipment, spotter aircraft, and nylon nets, which are nearly invisible to fish andaremorere- sistant to rotting than natural fibers. More important, large factory ships allow processing of thecatch at sea. A factory ship need not steam back to port frequently, but can stay out fishing until its hold is full. Factory ships also allow profitable fishing farther from shore, which is important because these ships often deplete nearby fisheries. In one hour a factory ship can har- vest as much fish as a sixteenth century fishing boat took in a season. There are three major categories of nets: trawl nets, purse seines, and drift nets. Trawl nets are coni- cal nets dragged across the bottom with the big, open- end first, funneling fish into the closed point of the cone. Purse seines are nets held as vertical walls by floats at the top and weights at the bottom until the wall can surround an area of the water and thebottom can be pulled together. In the 1970’s and 1980’s, com- mercial fishing fleets began using large drift nets, many as long as 50 kilometers. These massive nets “vacuumed” or “swept” vast swaths of ocean, collect- ing everything in their range. Though the nets were intended for cod, tuna, and squid harvest, their use resulted in massive “bycatches” of nontarget species, including sharks, dolphins, whales, and sea turtles. Such large drift nets were banned foruse outside a na- tion’s 370-kilometer exclusive economic zone (EEZ), within which a country has exclusive control of all ma- rine resources. Forty percent of the world’s oceans are under control of individual nations claiming EEZs, but nets as large as 2 kilometers are still in use on the open ocean. Large, high-tech operations (plus smaller but nev- ertheless highly capitalized operations) directly em- ploy more than one million people worldwide and take about two-thirds of the world’s harvest. Some nineteen million subsistence fishers and small opera - tions take the balance. The small operators are often poor, but they spend much less per unit catch and use Global Resources Fisheries • 433 most of what they catch. This contrasts with industrial fishing operations, which tend to specialize in a single species. As a result there are often “unwanted” catches referred to as “bycatch.” Bycatch can be fish that are too young, nontarget species, or over-quota. However, bycatch fish are usually dead from being netted and dropped in a hold, sitting forminutesor hours during the sorting process. The bycatch is discarded back into the sea and equates to more than 20 million met- ric tons per year. This dead and dumped bycatch af- fects fish populations present and future. The Death of Traditional Fishing By the early twenty-first century, fishing had become a troubled industry, its many successes having led to a string of related fishery collapses. The basic problem with fishing as it evolved in the latter twentieth cen - turywas that it was a hunter-gatherer operation rather than an agricultural one: Fishers do not nurture and protect schools of fish as farmers protect herds of cat- tle. This fact alone limits productivity. For instance, there is little investment in habitat for fish, such as in maintaining wetlands for juveniles of many species or clear rivers and estuaries for salmon and other river- spawning fish. Worse, fisheries management according to the hunter-gatherer dynamic is based on the idea that the fish are common property, with each fishing opera- tion competing with the others for the fish. Any fish- ers who hold back in catching fish to save breeding stock for the future lose catch to other fishers willing to take the fish. In 1976, Garrett Hardin applied the term “the tragedy of the commons” to the problem of overfishing. The term has also been applied to the 434 • Fisheries Global Resources Data from U.S. National Oceanic and Atmospheric Administration, National Marine Fisheries Service, , 2007. Source: Fisheries of the United States 7.4 1.7 5.7 2004200320022001200019951990 0 2005 2006 2 4 6 8 10 7.5 1.3 6.2 7.9 1.2 6.7 8.2 1.3 6.9 8.7 1.4 7.3 9.0 1.2 7.8 9.3 1.3 8.0 9.3 1.1 8.2 9.5 1.1 8.4 Human food Industrial use Total U.S. Domestic Fisheries Catch Totals (billions of kilograms, live weight) grazing of cattle; however, cattle can at least be counted, but fish populations are more likely to be gauged by catch. Thus, fishers using advanced equip- ment to catch the dwindling numbers of fish can cre- ate the illusion of a stable population. An entire fish species may ultimately be fished to near extinction, and the fishery may collapse, but the worst offenders will be the most profitable until the disaster occurs. Furthermore, many fishing practices have dire ef- fects on other species. More powerful boats and trawl nets equipped with “rock-hoppers” and better con- trols can drag rough-bottom areas with less danger of snagging the nets. Trawlers can work rough areas that fishers have avoided before and can fish steadily deeper-hunting bottom fish (such as cod, flounder, eels, and turbot). However, the sea bottom is also hab- itat for the young of many species and has food for many others. In a manner similar to coral reefs, the bottom ecosystem functions best when old shells, worm tunnels, and sponges and other attached or- ganisms provide a complex environment where juve- nile animals can hide from predators. A one-metric- ton boom dragging across the bottom kills attached animals, compacts the sedimentso that worms cannot burrow well, silts some animals to death, and gener- ally grinds the area down to wasteland. Years later, the lost production on the bottom manifests itself as miss- ing adults elsewhere. Finally, the areas closest to land, which are usually the richest fisheries, are subject to poisoning by pol- lutants. The Chesapeake Bay produces only a fraction of the life that early settlers found there. The Black Sea, naturally darkened by anaerobic decomposition (rotting without oxygen), is blacker because of fertil- izer runoff and toxic contaminants. In 1991, three thousand people in Peru died from cholera linked to sewage-contaminated seafood. Many human excesses were overmatched by the vastness of the oceans until the late twentieth century. By the mid-1990’s, production exceeded the estimated 90-million-metric-ton sustainable yield of a wild ocean; by 2002, the yield had dropped to 63 million metric tons. The best fishing grounds have moved progres- sively farther from the ports of the fishing fleets, so production increases are largely confined to the last frontiers in the Indian Ocean. Virtually every fishing region of the world is overexploited or under pres- sure. In the 1990’s, the Grand Banks (east of Canada) began collapsing noticeably. In 1992, the Canadian government halted cod fishing in Canadian waters because there were virtually no cod of spawning age. Human-induced climate change will surely and seri- ously affect ocean fisheries and commercial fishing. As warming and cooling surface waters disrupt cur- rents and phytoplankton populations, additional fresh water entering the marine habitat from melt-ice will alter regional salinity; increases in water depths will inundate estuaries and tidal zones, altering breeding and rearing habitats; and deepening coastal waters will drop coral reefs below thevital photic zone, stress- ing their ability to survive. Nonetheless, production has been maintained by various subsidies for bigger and more sophisticated boats going farther and fishing deeper to catch dwin- dling fish stocks. Many subsidies are given to fishing fleets simply to help cover the cost of fuel to run the boats and processing operations. It is estimated that a cumulative worldwide annual investment of around $34 billion in subsidies is helping to deplete theglobal fishery, with the subsidies accounting for 20 percent of the value of the annual commercial harvest. Japan provides the largest annual subsidies to fishers (about $2 billion). The result of such subsidized fishing is that one-half of all major fish stocks are close to their capable limit, with another 15 percent identified as overfished. The delayed crisis in the marine fishery, when it ar- rives, will probably be painful for the world’s fishing fleets. Nations are increasingly limiting fishing by for- eign boats so they can rebuild production. Mean- while, unregulated waters are being overfished. At some point the collapse of the Grand Banks fishery will be repeated in a number of areas. The continued large investment and subsidies of large fishing fleets have increased marine harvests for decades, but in most regions fish harvests have exceeded estimated sustainable yields. Fish stocks have collapsed in many regions of the globe and many fishing businesses have gone bankrupt. High-gain commercial fishing has devastated some of the most traditionally productive fisheries. To meet demands for fishmeal and table fish, fish not previously sought are being harvested at unsustainable rates. By the late 1990’s, the U.S. gov- ernment had reported that for three hundred species of harvested fish for which data were available, one hundred were being fished beyond sustainable yields. When fish stocks reach critical levels of depletion and unsustainability, many nations put fishing bans into effect. In 1992, along the Georges Bank, stock levels Global Resources Fisheries • 435 of haddock, cod, and flounder became so low their harvest was banned. In 2003, Pacific coast rockfish be- came so endangered an emergency ban on all bottom fishing was enacted. In 2008, Pacific salmon stocks had become so low a ban on their commercial harvest was put into place. The loss of viable fisheries has also resulted in armed conflict between nations. As fish stocks de- crease from overfishing, territorial waters have be- come aggressively monitored to stop other nations from harvesting within those zones. During the late 1950’s and mid-1970’s, Britain, Iceland, and several other European countries with commercial fishing fleets engaged in what has been called “the cod wars.” Because Iceland is highly dependent on fish exports, it extended its territorial waters to protect its regional fish harvests; to ensure its extended boundaries, Ice- land patrolled the waters with naval gunboats. Great Britain did not recognize Iceland’s territorial waters claims and sent its own naval warships to support the British fishing fleets venturing into the disputed waters. These “cod wars” were the impe- tus for the United Nations Convention on the Law of the Sea (UNCLOS), which, in 1982, established global territorial wa- ters limits and the extent of EEZs. During the mid-1990’s, a similar fishing conflict between the United States and Canada resulted in “the salmon war.” While no naval fleets were involved in “the salmon war,” back-and-forth retaliatory fishing quotas and retaliatory unlimited harvest practices resulted in an intense diplo- matic battle and, eventually, a Canadian fishing-boat blockade of an American ferry in Prince Rupert harbor. In 1999, the two governments signed a treaty to coordinate management of the Pacific salmon fishery. Regulation, Aquaculture, and Mariculture The mechanized hunting by unsuper- vised fishing fleets is as inherently prob- lematic as the whaling and buffalo hunt- ing of the nineteenth century that drove these hunted species to commercial ex- tinction. Eventually these fleets will have to be replaced by regulated fishing and organized mariculture in which marine- water-living plants and animals are bred, protected, and cultured. As with agriculture on land, this shift will increase production many times. Regulated or rationalized fishing is simply manag- ing ordinary fishing so the catch is sustainable. Regard- ing the taking of freshwater fish, states sell limited numbers of licenses and limit fishing catches. Similar limitations are increasingly set within the EEZ. Con- trolled harvesting has allowed the Norwegianstomain- tain fish production at sustainable yields. It should have allowed the United States and Canadian govern- ments to maintain a smaller sustainable yield than they have attempted. Ultimately, treaties must apply to international waters in addition to domestic waters. Along with the controlling of production, fish hab- itats must be protected or repaired. British Columbia invested in reducing silt runoff from logging, and the reward was a rebound in salmon production. Treating some of the world’s presently untreated sewage would have important health benefits for people as well as for fisheries. Suggestions have been made that fishing 436 • Fisheries Global Resources U.S. Aquaculture Production, 2006 Thousands of Pounds Metric Tons Thousands of Dollars Finfish Baitfish — — 38,018 Catfish 566,131 256,795 498,820 Salmon 20,726 9,401 37,439 Striped bass 11,925 5,409 30,063 Tilapia 18,738 8,500 32,263 Trout 61,534 27,912 67,745 Shellfish Clams 12,564 5,699 72,783 Crawfish 80,000 36,288 96,000 Mussels 962 436 4,990 Oysters 13,711 6,219 92,602 Shrimp 8,037 3,646 18,684 Miscellaneous — — 254,738 Totals 794,328 360,305 1,244,145 Source: Data from the National Oceanic and Atmospheric Administration, National Marine Fisheries Association. Note: Miscellaneous includes ornamental and tropical fish, alligators, algae, aquatic plants, eels, scallops, crabs, and others. rentals or production taxes be used to support con - trols and habitat improvement. They would also help reduce the excess capacity in the industry. Aquaculture is culturing fish and plants in fresh water. It has been practiced for centuries in Asia. In rice culture, small fish can be raised in the paddies during the water-covered stage and caught when the paddies are drained. Hatcheries have long been used throughout the world to increase the numbers of sport fish or commercially fished species (although stocking has risks of reducing genetic diversity, and hence the viability of the wild stocks). From hatcher- ies, it was a short step to fish farming of salmon, trout, catfish, carp, tilapia, and shrimp. Fish farming is a fast- growing source of production, having profits of more than $1 billion dollars per year in the United States. There is some commercial production of freshwa- ter algae, such as spirulina, which was eaten by the an- cient Aztecs and is still harvested and eaten around Lake Chad in Africa. As with plankton, the produc- tion per unit of area is greater than any land plant. Water hyacinths (water lily) and certain other water plants could also beused for livestock forage and even for human food. Once again, culturing of the plants could be combined with water animal production. Aquaculture, too, has risks and costs. Fish-pond wastes can pollute neighboring waters, and, as with stocking, a risk exists of weakening the species by re- ducing genetic diversity. Another risk is that econom- ics would naturally drive fish farmers toward high con- centrations of animals, thus increasing the risk of disease. Antibiotics can be used, but routine antibi- otic use can create antibiotic-resistant microbes. There are also probable environmental costs; for example, shrimp farmers in undeveloped countries have often destroyed mangrove swamps to make their farms, thus destroying wild stocks of shrimp and other spe- cies that start life in the mangrove swamps. The loss of the mangroves also makes shorelines susceptible to devastating erosion from storms. Mariculture is essentially agriculture in the ocean. Once again, Asian countries have pioneered many processes. Some edible plants are cultured on nets. Shellfish such as oysters are grown on ropes sus- pended from rafts. Because they do not touch thebot- tom, these shellfish are safer from starfish and other bottom-dwelling predators. A few commercial opera- tions in the West are pioneering fish cages in the open ocean, where vast distances allow nearly unlimited clean-water input and waste disposal. Australia has several successful open-ocean operations for the rear - ing of tuna. More speculative proposals for the future include vast networks of cables and nettingthatwould provide holdfast points for near-shore plants such as kelp. Beds of plants, in turn, would provide food and habi- tat for sea animals. Such marine plantations could be fertilized by chemicals or perhaps by artificial upwellings connected with oceanic power stations. While aquaculture and mariculture help provide fish and seafood, the fish-feedrequiredfor this type of operation to be successful puts pressure on wild fish- eries. It requires almost 1 kilogram of fishmeal de- rived from wild fish to produce one-half kilogram of farmed salmon. In 2001, fish farming required one- third of the world’s production of fishmeal. Estimates indicated that this proportion was approaching one- half in 2010. Roger V. Carlson, updated by Randall L. Milstein Further Reading Charles, Anthony T. Sustainable Fishery Systems. Mal- den, Mass.: Blackwell Science, 2001. Clarke, Arthur C. The Challenge of the Sea. Illustrated by Alex Schomburg. New York: Holt, Rinehart and Winston, 1960. Clover, Charles. The End of the Line: How Overfishing Is Changing the World and What We Eat. London: Ebury, 2004. Earle, Sylvia Alice. Sea Change: A Message of the Oceans. New York: Putnam, 1995. Ellis, Richard. The Empty Ocean: Plundering the World’s Marine Life. Washington, D.C.: Island Press/ Shearwater Books, 2003. Kura, Yumkio, Carmen Revenga, Eriko Hoshino, and Greg Mock. Fishing for Answers: Making Sense of the Global Fish Crisis. Washington, D.C.: World Re- sources Institute, 2004. Pew Oceans Commission. America’s Living Oceans— Charting a Course for Sea Change: A Report to the Na- tion—Recommendations for a New Ocean Policy. Arlington, Va.: Pew Oceans Commission, 2003. Rogers, Raymond A. The Oceans Are Emptying: Fish Wars and Sustainability. New York: Black Rose Books, 1995. Stickney, Robert R. Aquaculture: An Introductory Text. Cambridge, Mass.: CABI, 2005. United Nations Food and Agriculture Organization, Fisheries Department. The State of World Fisheries and Aquaculture, 2008. Rome: Author, 2009. Global Resources Fisheries • 437 . agriculture. 428 • Fires Global Resources Fish and Wildlife Service, U.S. Category: Government and resources Date: Established 1940 The U.S. Fish and Wildlife Service, a part of the U.S. Department of the Interior,. Wildlife Service (FWS) grew out of two agencies: the Bureau of Fisheries (1871) in the Department of Commerce and the Bureau of Biologi- cal Survey (1885) in the Department of Agriculture. Each held. the Department of Commerce in 1970. The FWS is a bureau of the De- partment of the Interior. It seeks to enforce legisla- tion pertaining to wildlife and to protect associated natural resources.

Ngày đăng: 04/07/2014, 01:20