Fisheries are areas where fish are caught. Fisheries supply a large fraction of the world's food, but are under severe stress today from over fishing. Climate change may add to the stress on ocean fisheries by changing the planktonic food web that is the basis of the marine food chain. Changes in fisheries are associated with damage to coral reefs by water heating and ocean acidification, and other means.
Fish populations are also shifting to different ranges because of warming water, with resulting changes in marine ecology and fishery populations. Climate warming affects freshwater fisheries by reducing dissolved oxygen, increasing stratification (layering of deep water), and shifting the patterns of rainfall that supply lakes and rivers with water.
Historical Background and Scientific Foundations
Humans have harvested fish for thousands of years. However, not enough fish could be harvested to injure large fish populations until the twentieth century, when mechanized ships in large fleets began to ply the seas. Most fish are captured at sea: in 2005, 7.6% of all fish were caught in freshwater, 9.5% were raised on freshwater fish farms (aquacultured), 7.1% were aquacultured at sea, and 75.7% were captured wild at sea. Sixty-nine percent of the total fisheries output was used for human consumption, the remainder for other purposes (for example, pet food). Fish provide 2.6 billion people with 20% or more of their dietary protein. About 15% of the world animal protein supply is from fish.
The world wild-fish catch increased 4.5-fold from 1950 (19 million metric tons) to 2000 (90 million metric tons). However, the global catch leveled off in the early 2000s and has declined slightly since, probably passing its all-time historic peak. There are few fish stocks that are not already being intensively exploited, and many fish populations are declining. Some fishing fleets are subsidized by governments, which encourage over fishing, and in most fisheries there is either a struggle to fill catch quotas before others do or to simply catch every fish possible.
Such practices lead to what fisheries experts call “the race for fish.” The race for fish is causing fish abundance to decline in many fisheries, with consequent structural changes to ecosystems, loss of jobs, and the breakdown of fishing communities. Aquaculture can also stress wild fisheries, as the food supplied to captive fish (e.g., shrimp) often consists of small, wild fish caught in indiscriminate fine-meshed driftnets that reduce populations of commercially valuable species by harvesting their young along with adults of small, noncommercial species.
Fish populations fluctuate over decadal time scales (10 or more years), in some cases centennial time scales; fish populations in areas that are geographically separated often vary at the same time, showing the influence of climate. Freshwater fish populations also vary in response to climate changes, which affect water temperatures, dissolved oxygen content (the warmer the water, the less the oxygen), and the amount, timing, and location of precipitation supplying water to rivers and lakes.
Impacts and Issues
Anthropogenic (human-caused) climate change adds stress to fishery ecosystems that are already under historically unprecedented stress from over fishing. The most general result of modern anthropogenic global climate change is warming, which has several effects. First, temperature affects the species mixture and abundance of plankton. Plankton are tiny animals (zooplankton) and green plants (phytoplankton) that float in the upper layers of bodies of water. Phytoplankton play an ecological role similar to that of green plants on land, capturing the energy of sunlight and passing it up the food chain to larger organisms. Almost all oceanic fish are dependent on plankton either directly (as filter feeders, for example, the tiny shrimp called krill) or indirectly (as predators on smaller fish).
Plankton productivity—the amount of plankton for a given area of water surface—is altered by climate variations. Satellite observations show that plankton productivity decreases as sea surface temperature increases: warming of surface waters decreases upwelling of deeper waters, which contain nutrients that phytoplankton need. Decreased upwelling occurs because the warmer that the surface water is, the less dense it is, and the more stably it floats on deeper, cooler waters. Warming therefore decreases planktonic productivity, which inevitably decreases populations of animals higher up in the food chain, such as fish. Such decreases can happen naturally, as for example during the El Niño/Southern Oscillation climate cycle, when the climate and surface waters of the central Pacific warm. It also occurs as a result of anthropogenic global warming. Some studies forecast a possible shift to permanent El Niño conditions as a result of anthropogenic warming.
A general effect of global warming involves migration toward the Poles by animal and plant species, both in water and on land, as species track the climate zone in which they are adapted by evolution to thrive. In the Northern Hemisphere, both fish and plankton species have already been observed to shift their ranges northward. In the North Sea, for example, where waters warmed by 1.9°F (1.05°C) from 1977 to 2001, a study by A. L. Perry and colleagues published in 2005 showed that the ranges of 15 out of 36 fish species had shifted northward by distances ranging from 30 mi (48 km) to 250 mi (403 km).
Other effects on fisheries may be less direct. For example, general circulation models (computer simulations of global climate) predict that with the doubling of atmospheric CO2, which is possible within the next century, freshwater discharge from the Mississippi River into the Gulf of Mexico might increase by 20%. The Gulf of Mexico is the site of the world's largest and most severe oxygen-depleted zone, sometimes called a dead zone because no fish can live in it. Agricultural chemicals in the river water are the cause of the dead zone, already up to 7,700 mi2(20,000 km2) in size. Increased river discharge is expected to enlarge the dead zone, affecting food webs in the Gulf and probably decreasing fish populations.
Increased stratification—the stabilization of warmer surface waters, with less mixing of nutrient-rich deeper waters up to sunlit layers where phytoplankton can exploit both nutrients and sunlight—is an important climate impact on some large freshwater fisheries. For example, the world's second-largest lake, Lake Tanganyika in Africa, is home to hundreds of species of fish and is a major freshwater fishery, supplying a harvest of 165,000–200,000 metric tons of fish per year, 15–40% of the protein intake of the inhabitants of the four countries that border the lake, namely Burundi, Tanzania, Zambia, and Congo. Since the 1970s, catches of the two primary species of the fishery (both members of the clupeid family, which includes herrings and sardines) have declined by 30–50%, though the lake is not over fished.
Until the early 2000s, the decline was attributed to some unknown environmental factor. This factor was finally shown to be climate warming. Steady atmospheric warming at Tanganyika since 1950 has caused the surface layer of the lake to warm, decreasing mixing of that layer with cooler, nutrient-rich waters from the depths. As of 2003, plankton density in Lake Tanganyika was less than one third than it had been 25 years earlier. Since plankton are the basis of the marine food chain, fish stocks declined along with plankton, and were 30% smaller in 2003 than they were 80 years before. Over the next 80 years, the climate in Tanganyika's area is predicted to warm by a further 2.3–3°F (1.3–1.7°C). This is likely to further increase stratification, reduce mixing, deplete plankton, and shrink the fishery, with possible consequences for human well-being in the surrounding areas.
Primary Source Connection
One potentially catastrophic effect of global climate change is a predicted change in Earth's hydrologic (water) cycle, including an increase in freshwater runoff. This source states that climate models indicate increased freshwater runoff in most of the world's major river systems. Greater discharge of freshwater will result in increased hypoxic zones in oceans, causing major disruptions in coastal ecosystems. Hypoxic zones are coastal waters with depleted oxygen content due to fertilizers and other sediments that are carried by freshwater runoff. Hypoxic zones are sometimes referred to as “dead zones” because the oxygen content is so low that the waters cannot support life. One of the largest hypoxic zones in the world is in the Gulf of Mexico where the Mississippi River discharges. The Gulf of Mexico hypoxic zone covers an approximate area of 22,000 km2.
CLIMATE, HYPOXIA AND FISHERIES: IMPLICATIONS OF GLOBAL CLIMATE CHANGE FOR THE GULF OF MEXICO HYPOXIC ZONE
There is a growing consensus among scientists that human activities, which have increased atmospheric concentrations of carbon dioxide (CO2) by one-third during the last 100 years, may be responsible for an increase in global Earth's temperatures. This so-called “global warming” theory is not without challengers who argue that scientific proof is incomplete or contradictory, and that there remain many uncertainties about the nature of climate variability and climate change. Nevertheless, global temperature averages increased by almost 1°C during the last 150 years, and further temperature increase seems probable. General circulation models (GCMs) forced by enhanced greenhouse gas concentrations have projected a global temperature increase of 2 to 6°C over the next 100 years. An increase in global Earth's temperature of 2 to 6°C would likely produce an enhanced global hydro-logic cycle that would be manifested in altered freshwater runoff. This hypothesis is supported by several lines of evidence, including “paleofloods,” decadal trends in the freshwater runoff and GCM's scenarios.
In the United States, there is historic evidence suggesting that a change in climate enhances the frequency of extreme flood events. An analysis of a 5000-yr old geological record for the southwestern United States suggested that floods occurred more frequently during transitions from cool to warm climate conditions. Apparently, modest changes in climate were able to produce large changes in the magnitude of floods. Additional evidence in support of the above hypothesis came from a 7000-yr old record of over bank floods for the upper Mississippi River tributaries. Approximately 3300 years ago, an abrupt shift in flood behavior occurred, with frequent floods of a magnitude that now recurs every 500 years or more. Also, an analysis of the data collected by the U.S. Geological Survey indicated statistically significant increasing trends in monthly streamflow during the past five decades across most of the conterminous United States. These results seem to support the hypothesis that enhanced greenhouse forcing produces an enhanced hydrologic cycle. One of the GCM studies has examined the impact of global warming on the annual runoff of the 33 world's largest rivers. For a 2xCO2 climate, the runoff increases were detected in all studied rivers in high northern latitudes, with a maximum of +47 %. At low latitudes there were both increases and decreases, ranging from +96% to -43%. Importantly, the model results projected an increase in the annual runoff for 25 of the 33 studied rivers.
The northern Gulf of Mexico, which receives inflows of the Mississippi River—the eighth largest river in the world, is one of the coastal areas that may experience increased freshwater and nutrient inputs in the future. According to a GCM study referenced above, the annual Mississippi River runoff would increase 20% if the concentrations of atmospheric CO2 doubles. This hydrologic change would be accompanied by an increase in summer and winter temperatures over the Gulf Coast region of 2°C and 4°C, respectively. A higher runoff is expected during the May-August period, with an annual maximum most likely occurring in May. While there are no other GCM estimates of the Mississippi River runoff, this result is in agreement with a projected 2xCO2 increase in rainfall over the Mississippi River drainage basin.
Here we review probable implications of climate change for the Gulf of Mexico hypoxic zone, focusing on two areas: (1) coupling between climate variability, freshwater runoff of the Mississippi River, and hypoxia in the coastal northern Gulf of Mexico, and, (2) potential implications of global climate change for coastal fisheries in the hypoxic zone. In this analysis we use our previously published physical biological model and extensive long-term data sets collected at station within the core of the Gulf of Mexico hypoxic zone.
WORDS TO KNOW
EL NIÑO/SOUTHERN OSCILLATION: Global climate cycle that arises from interaction of ocean and atmospheric circulations. Every 2 to 7 years, westward-blowing winds over the Pacific subside, allowing warm water to migrate across the Pacific from west to east. This suppresses normal upwelling of cold, nutrient-rich waters in the eastern Pacific, shrinking fish populations and changing weather patterns around the world.
PHYTOPLANKTON: Microscopic marine organisms (mostly algae and diatoms) that are responsible for most of the photosynthetic activity in the oceans.
UPWELLING: The vertical motion of water in the ocean by which subsurface water of lower temperature and greater density moves toward the surface of the ocean. Upwelling occurs most commonly among the western coastlines of continents, but may occur anywhere in the ocean. Upwelling results when winds blowing nearly parallel to a continental coastline transport the light surface water away from the coast. Subsurface water of greater density and lower temperature replaces the surface water and exerts a considerable influence on the weather of coastal regions. Carbon dioxide is transferred to the atmosphere in regions of upwelling.
Coupling Between Climate and Hypoxia
Climate change, if manifested by increasing riverine freshwater inflow, may affect coastal and estuarine ecosystems in several ways. First, changes in freshwater inflow will affect the stability of the water column, and this effect may be enhanced due to changes in sea surface temperatures. Vertical density gradients are likely to increase, that could decrease vertical oxygen transport and create conditions in the bottom water favorable for the development of severe hypoxia or anoxia. Second, the concentrations of nitrogen (N), phosphorus (P), and silicon (Si) in riverine freshwater inflows are typically an order of magnitude higher than those in coastal waters. The mass fluxes of riverine nutrients are generally well-correlated with integrated runoff values. Consequently, the nutrient inputs to the coastal ocean are expected to increase as a result of the increasing riverine runoff, which could have an immediate effect on the productivity of coastal phytoplankton. Third, the stoichiometric ratios of riverine nutrients, Si:N, N:P and Si:P, may differ from those in the coastal ocean. Increased freshwater inflow, therefore, may also affect coastal phytoplankton communities by increasing or decreasing a potential for single nutrient limitation and overall nutrient balance. Thus, it appears that there is a plausible link between global climate change and the productivity of river-dominated coastal waters.
Changes in the areal extent of hypoxic (<2 mg O21-1) bottom waters provide a representative example of the riverine influence on coastal productivity processes. The northern Gulf of Mexico is presently the site of the largest (up to 20,000 km2) and most severe hypoxic zone in the western Atlantic Ocean. Hypoxia normally occurs from March through October in waters below the pycnocline, and extends between 5 and 60 km offshore. During the drought of 1988 (a 52-year low discharge record of the Mississippi River), however, bottom oxygen concentrations were significantly higher than normal, and formation of a continuous hypoxic zone along the coast did not occur in midsummer …. The opposite occurred during the Great Flood of 1993 (a 62-year maximum discharge for August and September), when the areal extent of summertime hypoxia doubled with respect to the average hydrologic year. Hypoxia in the coastal bottom waters of the northern Gulf of Mexico develops as a synergistic product of high surface primary productivity, which is also manifested in a high carbon flux to the sediments, and high stability of the water column. Likewise, the 1993 event was associated with both an increased stability of the water column and nutrient-enhanced primary productivity, as indicated by the greatly increased nutrient concentrations and phytoplankton biomass in the coastal waters influenced by the Mississippi River….
Projections of general circulation models suggest that freshwater discharge from the Mississippi River to the coastal ocean would increase 20% if atmospheric CO2 concentration doubles. A higher Mississippi River runoff would be accompanied by an increase in winter and summer temperatures over the Gulf Coast region of 4.2°C and 2.2°C, respectively. This is likely to affect the global oxygen cycling of the northern Gulf of Mexico, which is presently the site of the largest (up to 20,000 km2) and the most severe coastal hypoxic zone (<2 mg O21-1) in the western Atlantic Ocean. Model simulations suggest a close coupling between climate variability and hypoxia, and indicate a potential for future expansion of the Gulf's hypoxic zone as a result of global warming. In simulation experiments, a 20% increase in annual runoff of the Mississippi River, relative to a 1985–1992 average, resulted in a 50% increase in net primary productivity of the upper water column (0–10 m) and a 30-60% decrease in summertime subpycnoclinal (10–20 m) oxygen content within the present day hypoxic zone. Those model projections are in agreement with the observed increase in severity and areal extent of hypoxia during the flood of 1993. Because of large uncertainties in the climate system itself, and also at different levels of biological control, it is difficult to predict how climate change may affect coastal food webs. Nevertheless, future expansion of the coastal hypoxic zones would have important implications for habitat functionality and sustainability of coastal fisheries.
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Fishing was an established part of preconquest subsistence and exchange in Latin America. Archaeological evidence from the Peruvian coastal plain, for example, suggests that the population around 2,500 to 2,000 bce was heavily reliant on shellfish, seabirds, and marine mammals and fish caught using lines or beach nets. In the Classic Period (500–900 ce) hunting and fishing from boats using lines, nets, and harpoons was integral to coastal livelihoods. Fishing was also important to the Inca civilization, and fish supplemented the basic vegetarian diet of the Aztecs. Fishing was not merely a subsistence activity in precolonial times—the Mayans traded conserved fish, fairs (which proved integral to the development of north-south trade) were organized around the Orinoco turtle fisheries, and both dried and smoked fish products contributed to subsistence and exchange activities in the south Atlantic region.
THE COLONIAL AND EARLY POSTCOLONIAL PERIODS
Regional colonial and early postcolonial histories make only infrequent references to fishing. However, there is evidence that Catalan fishermen were active in the sea bream and conger eel fisheries off Chile in the 1770s, drying and exporting their catches to Peru's mining towns. Nicholas de Arredondo (viceroy of Rio Plata, 1789–1795) promoted whaling and fishing off Patagonia through a royal monopoly. Fur and elephant seals were early targets of colonial seafarers and fishers; the trade in skins peaked in 1822 when more than 1.2 million animals were slaughtered on the island of South Georgia alone. In Brazil a state whaling monopoly coexisted alongside artisanal fishing by slaves until the turn of the twentieth century, though evidence shows that social elites preferred to import salted cod from Portugal. Efforts to introduce modern fishing practices in the late nineteenth century, including the recruitment of British fishermen to develop a Chilean trawl fishery, were largely unsuccessful.
Catches increased modestly through the early twentieth century, reaching some 255,850 tonnes in 1938. Brazil accounted for around 40 percent of the regional catch, as Portuguese and Spanish migrants employed ever larger boats to fish for sardines out of Brazil's southern states. Migrants—this time, Italian and Spanish migrants venturing out from Mar de Plata—also provided the bulk of Argentine catches (22% of the regional catch). By the outbreak of World War II, Latin America contributed a mere 1.2 percent of world production.
THE EMERGENCE OF A MODERN FISHING INDUSTRY
The situation changed markedly in the second half of the twentieth century. Concerned at the growing incursion of foreign vessels into territorial waters, Mexico approved legislation in 1947 and 1949 that granted the cooperative sector exclusive access to the nine most important inshore marine and shellfish fisheries, and limited foreign fishing within the coastal zone. In Brazil the state-sponsored formation of fishermen's guilds in the early 1920s was an early harbinger of a statist development strategy that reached its apogee with the introduction of an extensive national fisheries development program in the 1960s.
The most notable postwar change occurred in Peru. Frustrated by the national government's failure to control the extensive operations of the Japanese tuna fleet off the Peruvian coast during the late 1940s and early 1950s and a growing inability to compete with Japanese exporters in the U.S. canned tuna market, Peruvian fishing entrepreneurs switched their attention to the anchovy instead.
Anchovy catches grew swiftly following the collapse of the Californian sardine fishery in 1949 to 1950 as redundant capital equipment and expertise migrated southwards, with Peru's first fishmeal plant established in 1953. The relaxation of domestic constraints (export taxes and restrictions on fishing activity) that had protected the Guano Administration Company, allied to the adoption of modern fishing techniques, saw an extraordinary escalation in production and exports (see Figure 1). At its peak in 1970 the industry employed more than 1,400 boats and 21,700 fishers to catch 12.3 million tonnes of anchovy, nearly one-quarter of world marine fisheries production and approximately five-sixths of the regional marine catch. This was converted by some 170 factories, employing more than 9,000 workers, into fishmeal, which supplied one-third of the country's export earnings. The bonanza proved shortlived, and the abrupt collapse in anchovy stocks—due to overfishing and the 1972 to 1973 El Niño event—led to the fishery's nationalization.
NEOLIBERALISM AND CONTINUED FISHERIES EXPANSION
The emergence of neoliberal governments and their commitment to export-oriented growth provided a substantive boost to fisheries production across the region (see Figure 1). In Chile, the privatization after 1974 of the northern pelagic fleet (catching fish that shoal on the surface), the gradual exclusion of foreign vessels from national fishing grounds, and the removal of access restrictions to pelagic stocks were supplemented by aggressive exchange-rate and export-promotion strategies—and saw Chile displace Peru as the region's leading fish exporter in 1980. New investment swiftly entered the Peruvian fisheries sector after the neoliberal government of Alberto Fujimori (1990–2000) privatized anchovy fishing and processing, introduced a more competitive exchange rate, and established fiscal and monetary regimes favoring exporters. However, although investment encouraged a reduced dependency upon the anchovy fishery, the industry remains critically exposed to a repeat of the crisis it experienced in the early1970s, as was evidenced in 1997 to 1998.
In Argentina, the decisions by the administration of Carlos Menem (1989–1999) to exempt new vessels from trade taxes, to allow Argentine firms to lease foreign vessels, and to simplify procedures for "naturalizing" foreign vessels saw the rapid incorporation of new factory and freezer vessels into the Argentine fleet. But as catches increased, so did the number and intensity of fishery conflicts. Mexico was an exception insofar as industrial expansion preceded neoliberalism: The gross registered tonnage of the Mexican fleet rose swiftly, from 8,000 to 289,000 tonnes, between 1970 and 1988. Tuna was the newly targeted resource, though U.S. embargoes on Mexican tuna exports in 1980 and 1986 and a worsening macroeconomic environment saw the sector become overly reliant on state support. Carlos Salinas de Gortari's neoliberal regime (1988–1994) sharply cut this support and also rescinded the cooperative's exclusive fishing rights, causing fishery conflicts to intensify while catches remained static. Other examples of neoliberal governments encouraging domestic and foreign investment into the sector include the reflagging of Spanish tuna boats in Costa Rica, Norwegian investment in Nicaragua's shellfish industries, Spanish and Venezuelan joint ventures, and Taiwanese and U.S. participation in Uruguayan fisheries. The intensification of fishing across the region has brought many of the major commercial fisheries to the point of collapse (see Table 1).
|Principal Latin American marine fisheries and present status of exploitation (as defined by FAO)|
|Status||Species (pelagic species in italics)||Participating Countries|
|Note: Criterion for inclusion as a "principal" fishery: catches exceeding 50,000 metric tons in at least one country over the period 1980–1995.|
|Source: Thorpe and Bennett (2000), p. 151 and FAO (2004).|
|Fully to overexploited||Peruvian anchovy|
South American pilchard
Chilean jack mackerel
Argentine, South Pacific and Patagonian hake
|Peru, Chile, Ecuador, Argentina and Uruguay|
|Fully exploited||Yellowfin tuna|
Southern blue whiting
|Mexico and Venezuela|
|Moderately to fully exploited||Californian pilchard|
|Panama, Chile, Peru, Ecuador, Mexico, Argentina|
|Moderately exploited||Chub mackerel||Chile, Ecuador, Peru|
|Status unknown||Round sardinella||Venezuela|
The response to this crisis has been two-fold. First, greater attention is being paid to stock management, with a number of countries (most notably Argentina, Mexico, Peru, and Chile) employing or moving toward the use of individual transferable quotas (ITQs) as a method of apportioning TACs (Total Allowable Catches) in regulating marine fishing activity. Second, recognition of the limited opportunities for future capture fisheries growth has led to ever greater emphasis on the development of regional aquacultural activities (see Figure 2).
AQUACULTURE AS A SOLUTION TO THE CRISIS IN MARINE FISHERIES?
Commercial salmon and trout farming evolved in Chile during the early 1980s and, benefiting from the economic incentives offered to exporters by neo-liberal governments, grew rapidly from 500 tonnes in 1985 to 25,000 tonnes in 1990. By 2000 342,000 tonnes were exported; this leaped to 563,000 tonnes, worth U.S.$2.3 billion, by 2004. In 2007 aquaculture was Chile's fourth largest export earner by value, and the country was likely to become the world's largest salmon producer in the next few years. Elsewhere, the emphasis has been on shrimp culture. Led by Ecuador, where shrimp farming began in the late 1970s, Latin America now harvests 287,000 tonnes of shrimp worth U.S.$1.3 billion, around one-quarter of the world's cultivated shrimp production. Shrimp production and exports are particularly important in Brazil, Belize, Colombia, Honduras, and Venezuela. However, scientists have raised concerns about the ecological problems caused by aquacultural activities—in particular the widespread destruction of coastal mangroves, in the case of shrimp farming, and the disposal of effluent waste, in the case of salmon and shrimp farming.
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The modern fishing industry, with fleets of large capital-intensive vessels, can be traced back to the introduction of the trawler early in the twentieth century. Those ships enabled fishers to reach distant fishing grounds more quickly, stay out fishing longer, and catch more fish per trip. Subsequent growth in the number, size, and technological sophistication of trawlers steadily increased harvesting capacity and corresponding pressures on fish stocks. The introduction of “factory” trawlers in the early 1960s allowed even longer and more distant fishing trips and intensified fishing pressure on previously neglected fish stocks.
A little over 130 million metric tons of fish was harvested worldwide in 2003, almost 80 percent of which was for human consumption (United Nations Food and Agricultural Organization 2004). Reversing earlier trends, the output from ocean harvesting remained fairly constant in the early years of the twenty-first century, accounting for almost 60 percent of consumption. Around 7 percent of the harvest comes from inland waters, and the rest comes from aquaculture, most of which is conducted in fresh waters.
Developing countries provide around 70 percent of the total world supply of fish for human consumption, much of which is harvested using traditional small-scale and labor-intensive technologies. The top countries in 2002 were China, Peru, the United States, Indonesia, and Japan in that order, with China harvesting over twice the amount taken by Peru. One-third of global ocean harvesting occurs in the northwestern Pacific, roughly 20 percent in the southeastern Pacific, 16 percent in the northeastern Atlantic, and 15 percent in the western central Pacific. The major ocean stocks, which are harvested largely by factory fleets, are anchovies (a relatively low-value product), pollock, tuna, herring, and mackerel.
In contrast to the marine fishery, aquaculture production grew at an average annual rate of 6 percent per year after 2000, with China accounting for almost 70 percent of world aquaculture production in 2002, followed by India, Indonesia, Japan, and Bangladesh. The most important aquaculture species is carp, followed by various types of higher-value shellfish, such as oysters and clams.
Trade in fisheries products grew 45 percent from 1992 to 2002, and the value of fisheries exports reached $58.2 billion in 2002. Around 90 percent of this trade involves processed (frozen, salted, dried, and canned) fish products. China is the major exporter of fish, followed closely by Thailand and then the United States, Canada, Denmark, and Vietnam. Developed countries purchase over 80 percent of the total dollar value of traded fish products, with Japan accounting for 22 percent of world imports in 2002, followed by the United States (16%), Spain (6%), and France (5%).
Although it is difficult to generalize about the structure of the fishing industry worldwide, the large-vessel fleet is aging and there has been a decline in the number of very large vessels being added to fleets (United Nations Food and Agricultural Organization 2004). Large factory vessels and distant-water fleets account for the majority of the harvest, but around 90 percent of all fishers, most of whom are in Asia, work on small vessels (International Labour Organization 2004). Although much of the small-scale fishing sector uses traditional technologies that limit harvesting to heavily fished near-shore waters, there is a growing group of small to midsize vessels with advanced technologies that can access more abundant offshore stocks that can be brought to market quickly enough to command premium prices for fresh fish.
The fishing industry represents a classic example of the common property problem. Unlike land-based agriculture, ocean fish stocks are a resource for which individuals traditionally do not hold property rights. There is a substantial literature documenting how, in the absence of ownership or regulation of fishing stocks, economic incentives motivate the owners of individual vessels to overfish the resource by harvesting as many fish as possible as quickly as possible (Anderson 1986).
Technological changes that have made harvesting more efficient, coupled with the growth of large-scale fleets and international fish markets, made this common property problem a global concern beginning in the midtwentieth century. As fisheries stocks become depleted, the scarcity of fish drives up prices, and harvesting incentives become even stronger, threatening the sustainability of the resource. As a result, many of the world’s fish stocks have been classified as having been fished beyond sustainable levels and concerns are being raised about the possible extinction of overfished species.
One response to depleted stocks has been to shift fishing efforts to previously underutilized species. However, experience has shown that those species soon become threatened and that the shifting species mix can have adverse effects on the ecosystem. A second outcome has been the rapid growth of aquaculture, much of which is conducted in areas where property rights can be established, but that has added to the growing concern about environmental pollution in marine and inland waters and its impact on the safety of fish products for human consumption.
Economists have argued that regulation is the only longterm method to achieve the biological, economic, and environmental sustainability of the fishing industry. They also have advocated a form of regulation that relies heavily on markets and property rights to counter common property problems. In practice, however, fisheries regulation has relied on indirect methods to reduce incentives for overfishing.
Initially, the most widely adopted policy was to reduce the access of large-scale foreign fishing fleets to continental fishing stocks to conserve the stocks for domestic fishers. Many coastal nations imposed limits on distant-water fleets in the 1970s by establishing Exclusive Economic Zones (EEZs) that extended territorial control over ocean resources up to 200 miles from their coastlines. The result in many cases, however, was that domestic fleets with increasingly sophisticated harvesting technologies took the place of foreign fishing vessels, and so the pressures on fish stocks continued to increase.
Thus, the focus of national regulatory policies shifted to fishing pressures within EEZs. The most common policy instruments have involved indirectly limiting harvesting activity through seasonal or permanent closures of fishing grounds, reducing fleet size by limiting entry and offering vessel buyouts, and raising the costs of fishing by constraining harvesting technologies, for example, limiting vessel size and power, increasing the minimum mesh size of nets, and reducing the number of days of fishing allowed. Those policies, however, often have proved costly to monitor and easy to evade, allowing overfishing to continue.
As a consequence, pressures have increased to restrict harvesting further. In the United States the 1996 and 2006 reauthorizations of federal fisheries management legislation were designed to force regulators to set allowable harvesting levels lower than the previous levels. The new levels are below what would be needed to ensure biological sustainability to take into account both the environmental and the economic costs of harvesting fish.
Although most management regulations continue to rely largely on indirect regulation of fishing effort, there has been increasing international interest in individual transferable quotas, one of the policies most often advocated by economists. The individual transferable quota policy involves allocating shares (quotas) of the allowable harvest that can be bought or sold. Ownership of a share gives a fisher a property right to a portion of the allowable harvest that essentially privatizes the resource and eliminates the incentive for fishers to compete for the same common stock of fish. Such market-based regulation can both reduce overfishing pressures and ensure the overall efficiency of the industry.
Regardless of the management methods adopted, there has been movement worldwide toward establishing stricter fisheries management controls that are intended to protect fish stocks more aggressively from the threat of extinction. As fish continue to play a major role in world trade and the food supply, most fisheries biologists and economists believe that continued vigilance is required to ensure that this resource remains available for future generations by using fishing methods that are economically sound and environmentally sustainable.
SEE ALSO Developing Countries; Industry; Technological Progress, Economic Growth; Tragedy of the Commons
Anderson, Lee G. 1986. The Economics of Fisheries Management, rev. and enl. ed. Baltimore, MD: Johns Hopkins University Press.
International Labour Organization. 2004. Conditions of Work in the Fishing Sector: A Comprehensive Standard (a Convention Supplemented by a Recommendation) on Work in the Fishing Sector. International Labour Conference, 92nd Session. Geneva: International Labour Office.
United Nations Food and Agriculture Organization. 2004. The State of the World Fisheries and Aquaculture. Editorial Production and Design Group, Publishing Management Service. Rome: Food and Agricultural Organization.
United States Department of Commerce. 1999. Our Living Oceans: Report on the Status of U.S. Living Marine Resources 1999. Washington, DC: National Marine Fisheries Service.
David G. Terkla
Peter B. Doeringer
Fishing Industry (Commercial)
FISHING INDUSTRY (COMMERCIAL)
Although the U.S. commercial fishing industry had seen many changes since its earliest days, it has remained an important part of the economy for many communities, states, and countries. Throughout the twentieth century, an ever-increasing population fueled many changes in the industry, including technological advances in fishermen's ability to catch, successfully transport, and sell products. It also caused a constant increase of the number of fishing fleets around the world. These changes were a mixed blessing for the industry. A widespread demand in the use of ocean products (ranging from the use of fish protein as an additive in livestock feed to fish burgers at the local drive-through window) made the industry extremely profitable. On the other hand, this increase in demand also meant an increase in the number of fleets, industry investors, and fisherman, which eventually ended in the world's oceans becoming over-fished.
The first fishing vessels were powered by sail, and they were developed to fill the needs of the particular fishing region. This meant that the design of boats from different regions varied according to a particular environment or fishery. In the nineteenth century larger steam-driven winches replaced sailboats, allowing for heavier fishing gear and larger crews. By the end of the nineteenth century the internal combustion engine supplanted steam, and in the early twentieth century the inboard diesel engine had become accepted worldwide as the propulsion of choice.
These improvements in the overall size, speed, and range of fishing vessels led to advances in the methods used by fisherman to increase fish hauls. Larger catches, translating into larger profits, could now be obtained by increasing the number of hooks per line from one to over one thousand. Single traps were networked into a system of hundreds of connected traps. Nets became much larger, and their development even initiated a sub-industry in support of commercial fishing. Net-making is an industry that evolved from the making of nets from linen and hemp to the making of nets from cotton and hard fibers woven by rapidly moving machines. Small family fishing boats and cast netters were finding it tough to compete with the volume and subsequent lower price produced by the larger commercial fishing fleets.
Several developments during the 1940s and 1950s had a very significant impact on the profitability and stability of the commercial fishing industry. Mechanization made significant advances in netting methods when the power block was invented, which made it easier for fishermen to haul and store gear while purse seining (a method of fishing using a net that is weighted at the bottom and has floats along the top). Also important was the introduction of devices such as the power-driven drum designed to carry and store seine nets, gill nets, purse seines, and even the large trawl nets. Perhaps the most important development of the decade came with the invention of stern trawlers that processed their catch on board. Developed by the British, this idea was eagerly copied by many countries, including the Soviet Union, Japan, Poland, and Spain. The importance of this technology went beyond the vast quantities of ocean products that could now be processed at sea and sold more quickly back on land. The new technology brought about the collapse of some resources harvested by these highly efficient seiners and with it the realization that these resources were not limitless and needed to be protected.
In 1972 Iceland became the first country to claim an extended fisheries limit of 50 miles. In 1975 it extended this limit to 200 miles. Several countries followed Iceland's lead and soon the Law of the Sea was passed. This allowed for an exclusive economic zone of 200 miles off the coast of each country.
Many coastal communities in the United States are today supported by the commercial fishing industry, which became the largest private employer in states such as Alaska. According to government statistics printed in U.S. Industry Profiles in 1995, 364,000 people were employed in fishing industries in 1988. Of that number, 274,000 were fishermen and 90,000 were shore workers.
Although the industry is quite large in certain areas, pay levels are low. Compensation of fishermen is usually based on the percentage of the catch brought in by their captain's boat. Based on the earnings information of 1988, published in U.S. Industry Profiles, an inshore fisherman working within three miles of shore received an average salary of between $15,000 and $20,000, while an off-shore fisherman working outside the three mile limit earned an average of $30,000.
Not all of the profits generated from the commercial fishing industry come from the sale of ocean products. Freshwater fishing, carried out in lakes, rivers, or streams, does contribute a small percentage of the fish consumed globally. Fresh water fisheries tend to be more specialized depending on the species of fish they are producing. Fish such as the salmon and sturgeon that live in the sea but spawn in fresh water, and the eel that lives in fresh water but spawns in the sea, have forced these fisheries to become as specialized as they are. Other contributions to the specialty of fresh water fishing are the variations in the physical and chemical properties of fresh water in different areas and the overall size of the body of water itself.
Fish farming in aquatic hatcheries is another form of revenue supporting the fishing industry. Fish farming is the practice of raising generations of fish in controlled environments free from predators and maintained in optimal conditions. These fish farms supply plants and animals for a variety of purposes, including the production of animals for live bait, stocking purposes for sport fisheries, as well as the needs of the pharmaceutical industry. Many of the products of fish farms are the high-priced species that are sold as fresh products. Among these are shrimp, salmon, and oysters. The depletion of natural sources has helped provide more demand to support these hatcheries and it has allowed them to expand their production to other species, some of which are fresh water varieties, like catfish and trout.
Although fish farms offered the fishing industry several alternative methods of production, industry experts maintained concern with the depletion of resources in the world's oceans. Traditional techniques for managing fishery resources remain under close scrutiny, and calls for greater regulation of the industry have grown in number. According to Amos Eno, spokesperson for the National Fish and Wildlife Association, marine fisheries were the single most threatened resource in the United States in the late 1990s.
Bay-Hansen, C. D. Fisheries of the Pacific Northwest Coast: Traditional Commercial Fisheries. New York: Vantage Press, 1992.
Oakley, Barbara A. Hair of the Dog: Tales from Aboard a Russian Trawler. Pullman, WA: Washington State University Press, 1996.
Sainsbury, John C. Commercial Fishing Methods: An Introduction to Vessels and Gears. Boston: Blackwell Science Inc., 1996.
By the 17th cent. fish had become a growing item of trade, especially for the Scots and Irish, but the wealth of the offshore grounds also benefited the Dutch, who were active mainly in the North Sea. Indeed the competition of the Dutch caused much alarm and encouraged government policy to promote native fisheries still further, notably in Scotland under the Board of Trustees for Fisheries and Manufactures, established in 1727. Although bounties (or grants) were offered on vessels fitted out for herring fishing, other legislation on fishing practices and the high duty on salt needed for curing handicapped expansion. The establishment of the British Fisheries Society in 1786 coincided with a new attitude. Bounties were promised on herring catches and on fish exports and the Salt Laws were relaxed soon after in favour of the fisherman.
During the 19th cent. the fishing industry experienced dramatic expansion and by the 1850s the herring fishery on the east coast was the largest in Europe. The fishing population and communities grew accordingly, with Lowestoft, Hull, and Aberdeen the main fishing ports. As with agricultural produce the growth of the market for fresh fish coincided with the development of the railways and of refrigeration and these encouraged the introduction of steam trawling, initially in inshore waters, after 1880. Deep-sea fishing had meantime been pioneered by whalers working out of British ports, including Hull and Dundee.
By 1914 the industry was large scale, capital intensive, and, despite an important domestic market, much dependent on foreign exports. It experienced the same painful adjustment to changing circumstances as other industries during the depression. Falling prices and deteriorating equipment were the main problems, so that by 1939 the industry had shrunk from its peak at the turn of the century. Herring fishing never regained its previous significance, even when revitalization ultimately came after 1945, and white fishing became the mainstay of the industry.
As stocks were progressively exhausted through over-fishing, access to fishing grounds became a major source of conflict between Britain and other nations, especially with Iceland to the north and Spain to the south. Relations between Britain and Iceland reached crisis point during a series of ‘cod wars’ in the 1960s and the fishing of southern waters by Spain was a continuing grievance of the Cornish industry. The European Community and its successor, the European Union, as well as national governments, attempted to regulate catches through quota systems and the Common Fisheries Policy, but not without sustained resistance from the fishing industry. Whaling was abandoned on environmental and conservation grounds. Rising prices made fish-farming in inshore waters more viable and since the 1970s this has become an increasingly important source of supply and export earnings, especially at the luxury end of the market.
fish·er·y / ˈfishərē/ • n. (pl. -er·ies) a place where fish are reared for commercial purposes. ∎ a fishing ground or area where fish are caught. ∎ the occupation or industry of catching or rearing fish.