1. The history of fisheries and ecological thought
3. The biological basis of sustainable harvesting
4. Ecosystem effects and interactions
5. The human ecology of fisheries
7. The current state and future of the world’s fisheries
Fisheries constitute the most significant example of exploitation of natural ecosystems to produce protein for human consumption. Fisheries are an important part of ecology, both because of their importance for humans and because of the impact fisheries have on almost all oceans, lakes, and rivers. A fishery consists, at a minimum, of an ecosystem and a collection of humans who exploit it. In most cases there is now a third component, a management system. This chapter explores the ecology of the exploited ecosystems and how they interact with the human ecology of exploiters and the managers.
bionomic equilibrium. The balance between fish stock abundance and the fishing fleet that a fishery will evolve to in the absence of regulation
by-catch. The unintended catch of a nontarget species in a fishery
fish stock. A population of a single species that is geographically distinct enough to be managed separately from other populations of the same species
fishery. The interaction between humans and an exploited fish stock
maximum sustained yield. The highest long-term average yield that can be obtained from a fish stock on a sustainable basis
trophic interaction. Interaction between species in an ecosystem as a result of predation or the consequences of predation
unfished or virgin biomass. The average stock size in an unexploited condition
Regulations to promote the conservation of fisheries originated in Europe in the fourteenth century over concern about Atlantic salmon. Similarly, in North America, where the salmon runs seemed inexhaustible, the need for restrictions on catch was recognized soon after the salmon fishery began to develop. However, the susceptibility of marine fish to overexploitation was recognized much more slowly, and Thomas Huxley (known as Darwin’s bulldog for his advocacy of the theory of evolution) championed the school of thought that the fecundity of fishes was so large that fishing could not have an impact on the abundance of fish in the sea, and “that the cod fishery, the herring fishery, the pilchard fishery, the mackerel fishery, and probably all the great sea-fisheries, are inexhaustible; that is to say that nothing we do seriously affects the number of fish. And any attempt to regulate these fisheries seems consequently… to be useless.”
Numerous European and North American scientists led the way in providing evidence that fishing not only could affect the abundance of marine fish but could reduce the abundance of certain fish stock so much that their potential yield was reduced. These early scientists also developed the theoretical basis for understanding fisheries production, as elaborated in a later section of this article, and from their work emerged the concept of maximum sustained yield (MSY), the maximum long-term average catch that could be removed from a population on a sustainable basis.
By the 1950s the concept of MSY was firmly entrenched in fisheries thinking as an objective of management and as an intrinsic property of most natural populations, and there had developed an elaborate set of methods for calculating it. The simple view of MSY of the 1950s has gradually faded as we have come to recognize the complexity of society’s objectives, the difficulty in estimating the productive potential of natural populations, the natural variability of ecosystems, the interaction between species in ecosystems, and the problems inherent in regulating the exploiters of the resources.
At the same time, economists were studying the nature of fisheries and determined that in the absence of regulation, fisheries would evolve toward the “bio-nomic equilibrium,” in which fishing boats and fleets could just meet their costs but not produce any true profit. So long as a fishery was profitable, more fishermen would enter the fishery and reduce the profit of everyone participating.
As a general rule, fisheries in Europe and North America were barely managed until the stocks had been depleted enough that fishermen were economically struggling, and some of the users recognized the need for regulation to reduce fishing effort. The consequence of this was that the natural trajectory of most stocks was to be exploited much harder than MSY and reduced to lower levels, and there was the now familiar situation of “too many boats chasing too few fish.” For the more aggressive fishermen, there was always another new fishery to explore and develop, and individuals and fleets pushed into deeper and farther waters in search of a fishery that had not been overexploited.
There were early attempts to regulate catch and keep stocks from becoming overexploited; the International Pacific Halibut Commission, founded in 1923, is one of the most successful national or international agencies. It has maintained the stock of halibut in a healthy condition for 85 years through strict catch limits. The major change in fisheries management came in the late 1970s with the signing of the United Nations Law of the Sea, which allowed states to extend their territorial waters out to 200 miles, thus bringing most of the world’s major fisheries under the control of coastal states. The Law of the Sea provided these states with the legal authority to exclude other countries and manage the fisheries for their own benefit. In the United States this coincided with the passing of the Magnuson Fisheries and Conservation act of 1976, which established regional Fisheries Management Councils that provide the ongoing basis for the attempt to produce MSY from U.S. fisheries.
A fishery consists of two essential elements: an exploited aquatic ecosystem and a human system of exploiters. In managed fisheries there is a third element, the management system.
Aquatic ecosystems are almost always highly complex and include everything from bacteria to whales, yet the species targeted by humans are usually a very small subset of the ecosystem. Most commonly, the fisheries initially target the species that are valuable in the marketplace, often top predatory fishes and high-value invertebrates. But as fisheries and markets have developed, fish lower down the food chain are increasingly being targeted, and it is now common for a very high proportion of the fish within an ecosystem to be exploited.
The second essential ingredient in ecosystem management is people and how they change aquatic ecosystems. We concentrate on fishing fleets and their impacts, but people also have major impacts through the introduction of exotic species, both intentionally and accidentally, habitat change, pollution, and climate change. It is important to remember that almost all forms of aquatic resource management involve changing the actions of people. Fisheries management is widely recognized to be people management. This is just as true when we consider the broader perspectives on aquatic ecosystems: you rarely manage the ecosystem; you almost always manage the people modifying the ecosystem.
Therefore, to understand why management regimes are relatively successful or unsuccessful, you need to look primarily at the people and how they behave and interact with the management regime. Changes in the ecosystem may be what you are interested in, but understanding the people is the way to understand why the ecosystem is changing.
The third key ingredient in understanding aquatic ecosystem management is the management system itself, the legal, political, and social constructs that modify human impacts. Some systems have no management, but this is increasingly rare, and most aquatic ecosystems are embedded within a framework of laws, institutions, and customs. What we see as we look deeper into a range of ecosystems is that it is these laws, institutions, and customs that determine the outcomes.
Within U.S. federal waters, a range of key legislation establishes the governance system. Most important is the Magnuson-Stevens Fisheries Management and Conservation Act, first enacted in 1976 and reauthorized by Congress in 2007. This act laid down the U.S. claim to the 200-mile exclusive economic zone and established the regional Fisheries Management Councils that effectively manage U.S. fisheries in federal waters. In one sense the Magnuson-Stevens act is primarily about regulation of harvest, but successive reauthorizations have included more and more frameworks for dealing with habitat and fishing impacts on nontarget species.
The biological basis for all sustainable harvesting is reproductive surplus. All natural populations are capable of net population growth under favorable conditions. A single pair of fish in a good habitat can often produce dozens of offspring that survive to breed again. The simple theory of single-species dynamics suggests that at low densities resources are abundant: there is plenty of food for each individual; the best hiding places from predators are not taken; and individuals have a high probability of survival and reproduction. As densities increase, food per individual becomes scarcer, the best protection from predators is taken, and the net population growth decreases until at some point there is no net population growth.
Competition for resources occurs in most animal populations, but in the study of exploited fish populations, the relationship between population size and reproductive surplus has been the subject of much controversy. It is now widely accepted that fishing does have a major impact on fish population abundance, but the debate over the relationship between spawning stock abundance and reproductive surplus continues. By the 1990s, however, it became increasingly accepted that heavy fishing pressure also reduces recruitment to the fishery.
The large yields available during the early stages of a fishery’s development often lead to expectations of larger yields than are sustainable. The exploiting industries almost inevitably develop infrastructure to harvest and process the nonsustainable yield, and once that yield is gone, they usually create great economic and political pressure to delay the needed reduction in fishing effort and catch. Any such delay is then likely to drive the stock below its most productive level, resulting in even more severe reductions in catch when the inevitable decline does come.
The theory of exploitation was initially developed for single-species population dynamics, and most of the world’s fisheries management agencies regulate fisheries on a species-by-species basis. Nevertheless, it is widely recognized that there are strong interactions among species, and fisheries frequently impact multiple species. One form of interaction is the catching of nontarget species, called “by-catch.” By-catch first became a major concern for charismatic species such as marine mammals, birds, and turtles that were incidentally caught in fishing gear. This has led many fisheries agencies to restrict fishing locations or gear or to require the use of “by-catch” avoidance devices to reduce or eliminate the by-catch of these species.
Another form of by-catch is the capture of nontarget fish that are often discarded because of low economic value. In the 1980s about 80 million tons of fish were landed worldwide, and 27 million tons were discarded. Globally, discards have declined dramatically since then because many of the fish that were formerly discarded are now retained and often used as feed in aquaculture operations.
A second form of ecosystem impact of fishing is trophic interaction between and among species. Such trophic interactions may take the form of fishing down predatory species, thereby allowing their prey to increase in abundance, or fishing down prey species and causing their predators to decline. As top predators such as cod have been fished down, many of their invertebrate prey items, such as lobsters, scallops, and prawns, have increased. In some cases these species may now provide more valuable catch than their predators did before they were depleted. Fisheries agencies are only now beginning to recognize that they cannot have maximum yield of both predators and prey.
Some fishing gear also impact the physical environment. In habitats with considerable vertical structure on the bottom, fishing gear such as trawls and dredges will eliminate much of this structure. For instance, coral communities are highly vulnerable to bottom-contact fishing gear. On soft-bottom habitats, the impacts of fishing gear are much less dramatic but still cause changes in the communities that live in the sand and mud habitats.
Fisheries are not static systems that can be manipulated and reshaped at will by management. Rather, the human element in fisheries has its own dynamics and consists of individuals or firms seeking to maximize their own well-being. Fisheries commonly begin with a period of discovery and spread of information about the existence of a potentially valuable stock. A few individuals discover that money is to be made exploiting a certain stock in a certain way. Then there follows a period of rapid growth of effort as others are attracted by the success of the initial fishermen. In this phase, profitability is high, individuals often increase their boat size or purchase additional boats, and new individuals are drawn into the fishery. Governments often subsidize boat construction during this development stage.
Next, the fishery reaches full development, where yields are near or perhaps a little above a long-term sustainable level. The rapid development results in declining rates of fishing success as the stock is reduced and more fishermen compete for the remaining fish. At this stage profits are reduced and possibly negative, and the incentives to build bigger boats or enter the fishery are gone. There is often a lot of political pressure both for increased subsidies and for permission to maintain allowable catches despite scientific advice that catches need to be reduced. The fishery often then enters an overexploitation stage, which may be followed by a collapse. If the collapse is not too catastrophic, there is often a period of declining fishing pressure as the less successful fishermen find it no longer worthwhile to pursue the stock. The stock may or may not recover somewhat on its own during this period. Where possible, fishermen seek new fishing opportunities and move on to less-exploited stocks.
At each stage in this process, individuals and firms are doing what is best for them given the incentives and information available. Some individuals will be able to catch more fish or have lower costs and still be profitable, whereas less efficient fishermen will, as the stock declines, no longer be making any profit and may not even be able to meet the costs of fishing. Where there are other opportunities available, these inefficient fishermen will leave the fishery, but often there are no alternatives available.
The most common consequences of unregulated fisheries are excess fleet size, depleted stocks, and impoverished fishing communities. To the extent that governments have subsidized fleet development, the level of overexploitation will be worse. Because of changes in human and natural environments, fishery systems may never really be at a true bionomic equilibrium, but it serves as a construct that lets us understand the human and biological dynamics.
The process described earlier is an idealized description in which each individual or firm acts independently. Garret Hardin outlined this process as typical of human society and “the tragedy of the commons.” Elinor Ostrom and her colleagues have shown how many societies manage commons to avoid this tragedy (see chapter VII.10). In looking at fisheries around the world, we often find that societies do have mechanisms to avoid the apparently inevitable over-exploitation and collapse.
Fisheries management in Western countries has evolved through a series of stages. The first stage is before there is any form of active management and is commonly referred to as unregulated open access. Individuals or companies are generally free to fish what they want, when they want, and where they want, with the only constraints being the economics of the marketplace and the technology currently available. The history of industrial whaling is a classic demonstration of unregulated open access, from its beginning with Basque whalers almost 1000 years ago until the advent of active regulation by the International Whaling Commission. As easily accessible stocks close to ports were depleted, the fisheries moved farther and farther offshore and often suffered economic declines when stocks declined or products became less valuable.
However, at some point almost all fisheries reach a point where there is an obvious need for management. Initial management usually consists of restrictions on fishing gear, perhaps banning highly efficient methods or restricting boats to a maximum size. Closed seasons or areas are also common elements of initial management. Such limitations usually fail to stop the decline in fish abundance, and Western countries generally then proceed either to restrict the number of fishing vessels (called limited entry) or the total catch by shortening fishing seasons. The management of Pacific halibut in Alaska, for example, is commonly cited as one of the great success stories of sustainable management. Catches were restricted by an increasingly short fishing season (declining to less than 2 days per year by the late 1980s) but did not employ a limitation on the number of vessels until the early 1990s.
At present, most Western fisheries are managed by a complex combination of gear restrictions, time and area closures, limited entry, and commonly restrictions on the total catch. When combined with effective enforcement and good science, these systems can be effective at maintaining stocks in a healthy, sustainable condition. However, the normal outcome is also one of little economic profitability and often severe economic hardship. The key cause of the poor economic profitability is excess fleet capacity. When limited-entry programs are put into place, there are usually too many boats already—it is the too many boats that has led to the need for additional regulation and limited entry.
Increasingly, Western countries are adopting some form of what is now known as “dedicated access” in which incentives are established to encourage the fishing fleets to match their harvesting capacity to the biological productivity of the resource. The most common form of dedicated access is Individual Transferable Quotas, in which individual license holders are allocated a share of the total catch, and these shares can be traded. The result is almost always that some individuals choose to remain in the fishery and buy catch share from other individuals who chose to sell out and leave the fishery. The consequence is a smaller fleet that is profitable, but with a significant drop in total employment.
Another form of dedicated access includes formation of cooperatives among harvesters who agree on how to share the catch and then operate only enough vessels needed to catch the available harvestable surplus. Again, the consequence is usually a more profitable smaller fleet.
A third form of dedicated access employs territorial fishing rights, in which communities or individuals are granted exclusive access to some portion of the ecosystem. The common theme of all of these forms of dedicated access is providing incentives to match the harvesting capacity to the productive capacity of the resource.
All of these Western management systems require a strong central government agency that collects data, evaluates stock size, and determines and enforces regulations.
Much of the world has evolved different approaches. In the coastal waters of Japan, regional cooperatives have been granted management authority: they determine how their members share in the harvest and often engage in very intensive enhancement activities by releasing juvenile fish or outplanting valuable invertebrates. The cooperatives are self-governing and largely autonomous.
The tradition in the Pacific Islands was for village control of local inshore resources. The villages employed a wide range of techniques including closed areas and times, limitations on fishing gear, and, above all, restrictive access.
The most important form of marine conservation used in Palau and many other Pacific Islands was reef and lagoon tenure. The method is so simple that its virtues went virtually unnoticed by Westerners. Yet it is probably the most valuable fisheries management measure ever devised. Quite simply, the right to fish in an area is controlled, and no outsiders are allowed to fish without permission. (Johannes, 1988)
In essence, the recognition of the potential for territorial fishing rights in Western fisheries is a belated recognition of the effectiveness of the management system in the Pacific Islands.
The management of Chilean artisanal fisheries has undergone an interesting transformation. The Chilean government went through the conventional Western sequence of attempting to regulate fisheries by total allowable catch and found that this system failed. In the last 15 years, they have switched to a system of territorial fishing rights with local community fishing cooperatives given exclusive access to sections of the coastline.
Popular media have publicized a number of alarmist articles in the last few years with such striking conclusions as “all the large fish in the oceans were gone by 1980” and “all the world’s fish stocks will be collapsed by 2048.” More careful analysis of the data reveals a more complex and generally less pessimistic view of world fisheries. Worldwide, fish landings reached a peak in the late 1980s and have been slightly declining on average since that time. Fisheries continue to employ millions of people around the world and provide the economic basis for thousands of fishing communities. The picture is very different region by region, with some areas such as the North Atlantic showing considerable declines in landings, while other areas continue to increase landings.
Few places conduct a systematic analysis of the status of their fished stocks. The Food and Agriculture Organization of the United Nations estimates that between 20 and 30% of the economically most important fish stocks in the world have been overexploited, and this number has fluctuated in that range since the late 1980s—no increasing trend in overexploitation is seen. In the United States the percentage of fish stocks that are overexploited has been declining and, as of 2006, was 26%, with a resultant loss of potential yield of perhaps 15%. In other places the situation is not nearly so optimistic. All cod stocks are overexploited to some extent in the North Atlantic; some, such as the stock off Newfoundland, are almost completely gone, but others in Iceland and Norway are quite abundant and technically only slightly overfished.
Within industrial nations, there is a broad range of fisheries health. The United States stands out as perhaps the most intensely managed for conservation, with restrictive catch regulations now the norm and more stocks increasing rather than decreasing. Iceland, Australia, New Zealand, and Canada also stand out as countries that have adopted quite conservative harvesting regimes. The European Union presents a more complex picture, where scientific advice for lower catches is frequently ignored in the political process of consensus required within the EU fisheries policy, and as a result, many European fish stocks remain heavily overexploited.
We know much less about the status of fish stocks in most of Africa and Asia, where the fisheries most commonly consist of a mixture of small-scale village artisanal fisheries and industrial fisheries based in the major ports. There is no infrastructure of scientific study to determine stock status, and the countries rarely have the institutional ability to enforce the regulations they may have on the books. It is therefore difficult to be at all optimistic about the future of most of these fisheries, where intense exploitation and potential collapse would seem to be a likely future.
The high seas present a quite different picture. The major fisheries on the high seas are for tuna, and with the exception of the highly valued bluefin tuna, most of the high-seas tuna stocks of the world are not yet overexploited and remain healthy and productive. However, the international organizations that regulate these fisheries generally require consensus in order to adopt catch regulation. It seems highly likely that, should the economics of these fisheries prove profitable enough to drive the stocks into overfished states, the management agencies will be unable to prevent the decline.
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