(CHILD PAGE 1--WRITEUP OF FISHING PRESSURE EXPLANATION)
"Fishing at a level and in a manner that it is reasonably believed can be sustained indefinitely, assuming proper responses to changes in the ecosystem," is a good goal, but what exactly should it mean to fishery managers? To answer this question, there are a few fisheries management concepts we need to understand.
The first such concept is maximum sustainable yield. A good definition is given by the Organization for Economic Cooperation and Development: "Maximum sustainable yield refers to the maximum use that a renewable resource can sustain without impairing its renewability through natural growth or replenishment" (OECD, 2001). For a fishery, maximum sustainable yield is the maximum amount of fish that can be taken in a particular time period without depleting the fishery.
The second concept is fishing death rate, which we will define as the total death rate of fish from fishing-related causes. These causes include being taken (legally or illegally) in a fishery and being unintentionally killed by fishing activity.
In an ideal world, biologists would study a fish stock and calculate its maximum sustainable yield. Then all that would be necessary to sustain the fishery would be to prevent fishers from taking more than this maximum sustainable yield.
But real-world managers must deal with the uncertainties in all of the data they use to make their decisions. Because of imperfect information about fish stocks, maximum sustainable yield cannot be precisely determined. Nor can the death rate associated with fishing be perfectly measured: Not all fishing is documented and it is also difficult to account for fish that die because of fishing-inflicted injuries, from being caught in lost fishing equipment, and other causes.
Ultimately, all we can hope for is to find some sort of probability distributions for the maximum sustainable yield and the fishing death rate.
We then propose the following guide for making management decisions: Management actions should be made with the intent of reducing to five percent (Dallal, 2007) or less the probability of the actual fishing death rate being greater than the actual maximum sustainable yield.
But many overfished stocks are not close to the population levels at which they could provide maximum sustainable yield. Clearly, these populations should be rebuilt. We therefore suggest that for populations below the level at which they could provide maximum sustainable yield, fishing should be limited so that they can reach the population associated with maximum sustainable yield in a specific period of time. The length of this rebuilding period should vary depending on the characteristics of the fishery in question.
In addition, real fish stocks are parts of an ecosystem. The interactions between the species being fished and the other species present must also be considered when making management decisions. We will not further discuss this issue here, except to note that this aspect of the problem is highly complex.
We recognize that this analysis has been done largely in terms of a single-stock approach to fisheries management. Information and comment regarding an ecosystem-based management approach is here—INSERT LINK TO EBFM PART OF MANAGEMENT METHODS PAGE.
Works Cited
Dallal, G. E. (2007, August 10). Why P=0.05? Retrieved November 24, 2007, from The Little Handbook of Statistical Practice: http://www.tufts.edu/~gdallal/p05.htm
OECD (Organization for Economic Cooperation and Development). (2001, November 14). OECD Glossary of Statistical Terms--Maximum Sustainable Yield. Retrieved November 21, 2007, from OECD Web site: http://stats.oecd.org/glossary/detail.asp?ID=3075
(END CHILD PAGE 1)
Management Methods
Introduction
One of the great challenges standing in the way of saving the global fishery is the difficulty of identifying the specific goals of fishery management and the most useful methods for accomplishing them. This section of our proposal will discuss what fishery management should do, and then review some factors that need to be considered when making management decisions. We will look at the available regulatory tools and review the possibilities for ecosystem-based fishery management. Finally, we will make some recommendations regarding fishery management practices.
Why do we manage fisheries?
The goal of fishery management ought to be the creation and protection of sustainable fisheries. For purposes of this study, we define sustainable fishing as fishing at a level and in a manner that it is reasonably believed can be sustained indefinitely, assuming proper responses to changes in the ecosystem. A more precise and quantitative explanation is [here---LINK TO WRITEUP OF FISHING PRESSURE EXPLANATION]. A related concept, maximum sustainable yield or MSY, is defined as "the largest average catch or yield that can continuously be taken from a stock under existing environmental conditions" (FAO Fisheries Department).
Sustaining a Fishery: Factors to Consider
Controlling the exploitation of a commercially valuable fish stock is not the only task fishery managers must accomplish, because fishing has many complex environmental impacts and is not the only influence on the status of the targeted fish stock.
One such impact of fishing is by-catch, the accidental capture of unwanted fish or other animals. By-catch animals are often dead when they are thrown overboard from fishing boats, and those that are discarded alive sometimes later die from the effects of being captured. The by-catch in some fisheries includes endangered species. Fortunately, appropriate technology can help address the problem. For example, the by-catch of sea turtles in Australian fisheries was reduced by 99% after the introduction of so-called turtle excluder devices (Catherine, Loneragan, Brewer, & Poiner, 2007), which divert turtles from fishing nets (Valdemarsen & Suuronen, 2003). The same piece of equipment also reduced the by-catch of sharks by 91% (Catherine, Loneragan, Brewer, & Poiner, 2007).
A turtle escapes from a shrimp trawl net
source: NOAA Fisheries: Office of Protected Resources http://www.nmfs.noaa.gov/pr/species/turtles/teds.htm
Another issue that will become increasingly important to fishery management is climate change. Climate change will affect each region in different ways (Harley, 2006). To effectively respond to global warming, management systems need to be flexible so that policy can adapt as the effects of climate change become more evident. See the "Business as Usual" and "Climate" sections for more on climate change projections.
Regulations: The Tools of Fisheries Management
Many different kinds of regulations can be used to manage fishing. Most possible fishery regulations can be grouped into one of three basic categories: Input controls are regulations restricting how much, how hard, and with what equipment fishing can be done, and output controls limit how much fish can be taken. The third category, technical measures, consists of regulations that do not fit into either of the other categories, such as closing particular areas of a fishery (Sutinen & Soboil, 2003).
Management Methods
Introduction
One of the great challenges standing in the way of saving the global fishery is the difficulty of identifying the specific goals of fishery management and the most useful methods for accomplishing them. This section of our proposal will discuss what fishery management should do, and then review some factors that need to be considered when making management decisions. We will look at the available regulatory tools and review the possibilities for ecosystem-based fishery management. Finally, we will make some recommendations regarding fishery management practices.
Why do we manage fisheries?
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The goal of fishery management ought to be the creation and protection of sustainable fisheries. For purposes of this study, we define sustainable fishing as fishing at a level and in a manner that it is reasonably believed can be sustained indefinitely, assuming proper responses to changes in the ecosystem. A more precise and quantitative explanation is \[here---LINK TO WRITEUP OF FISHING PRESSURE EXPLANATION\]. A related concept, maximum sustainable yield or MSY, is defined as "the largest average catch or yield that can continuously be taken from a stock under existing environmental conditions" (FAO Fisheries Department). |
Sustaining a Fishery: Factors to Consider
Controlling the exploitation of a commercially valuable fish stock is not the only task fishery managers must accomplish, because fishing has many complex environmental impacts and is not the only influence on the status of the targeted fish stock.
One potentially environmentally disruptive aspect of fishing is by-catch, the accidental capture of unwanted fish or other animals. The by-catch is often dead when it is thrown overboard from fishing boats. In addition, some of the fish discarded alive later die from the effects of being captured. Sometimes by-catch species are endangered. Fortunately, appropriate technology can help address the problem. For example, the by-catch of sea turtles in Australian fisheries was reduced by 99% after the introduction of so-called turtle excluder devices (Catherine, Loneragan, Brewer, & Poiner, 2007), which divert turtles from fishing nets (Valdemarsen & Suuronen, 2003). The same piece of equipment also reduced the by-catch of sharks by 91%.
A turtle escapes from a shrimp trawl net
source: NOAA Fisheries: Office of Protected Resources http://www.nmfs.noaa.gov/pr/species/turtles/teds.htm
Another issue that will become increasingly important to fishery management is climate change. Climate change will affect each region in different ways (Harley, 2006). To effectively respond to global warming, management systems need to be flexible so that policy can adapt as the effects of climate change become more evident. See the "Business as Usual" and "Climate" sections for more on climate change projections.
Regulations: The Tools of Fisheries Management
Many different kinds of regulations can be used to manage fishing. Most possible fishery regulations can be grouped into one of three basic categories: Input controls are regulations restricting how much, how hard, and with what equipment fishing can be done, and output controls limit how much fish can be taken. The third category, technical measures, consists of regulations that do not fit into either of the other categories, such as closing particular areas of a fishery (Sutinen & Soboil, 2003).
One common form of input control is licensing of fishers, which attempts to restrict the catch by limiting who can fish in the first place (Kura, Revenga, Hoshino, & Mock, 2004). Other forms of input control include restricting the amount of time fishers can spend fishing and regulating the kinds of fishing gear that can be used (Sutinen & Soboil, 2003).
The simplest kind of output control is a limit on the total amount of fish that can be caught in a certain time period, often a year or fishing season. Called a total allowable catch (TAC) limit, such a regulation typically imposes a cap on the total mass of fish that is allowed to be taken (OECD, 2001).
Many of the other output controls are variations of or additions to a TAC limit. Shares of an overall TAC limit can be divided among fishers, fishing vessels, or fishing communities. These schemes will be considered in more detail below.
Finally, examples of common technical measures are limitations on the size of fish that can be taken and restrictions on where fishing can be done (Sutinen & Soboil, 2003).
All of these possibilities have advantages and disadvantages, and perhaps the most important thing to keep in mind is that no single measure is likely to succeed in creating a sustainable fishery: nature and human behavior are too complex for that to be possible (Stefansson, 2003). Instead, management tools must be integrated to keep a fishery sustainable.
Comparing and Contrasting Management Tools
complex for that to be possible (Stefansson, 2003). Instead, management tools must be integrated to keep a fishery sustainable.
Input Controls
One common form of input control is licensing of fishers, which attempts to restrict the catch by limiting who can fish in the first place (Kura, Revenga, Hoshino, & Mock, 2004). Other forms of input control include restricting the amount of time fishers can spend fishing and regulating the kinds of fishing gear that can be used (Sutinen & Soboil, 2003)The mere existence of management in a fishery does not guarantee that it is sustainable. The management scheme used must always keep the catch within sustainable levels, and not all management measures are equally good at doing this.
The advantage of input controls is that they do not require an often-difficult assessment of the size of the fish stock in question (Walters, 2004). This is because, theoretically, the ease of catching fish is proportional to the stock size so the percentage of the stock that will be caught with a given fishing effort is independent of the stock size.
However, experience Experience has shown, however, that input controls are frequently ineffective when used alone without adequate controls on output, because limitations on fishing effort consistently fail to factor in the effects of technology-driven efficiency increasesto factor in the effects of technology-driven efficiency increases. Worse, the effort limitation encourages fishers to invest in such efficiency improvements (Stefansson, 2003). A study conducted by the Organisation for Economic Cooperation and Development found that stocks had declined in 11 of 18 fisheries managed with input controls (Morgan, 2001). Worse, the effort limitation encourages fishers to invest in such efficiency improvements (Stefansson, 2003).fisheries managed solely with input controls (Morgan, 2001).
Output Controls
The simplest kind of output control is a limit on the total amount of fish that can be caught in a certain time period, often a year or fishing season. Called a total allowable catch (TAC) limit, such a regulation typically imposes a cap on the total mass of fish that is allowed to be taken (OECD, 2001).
But even Even the apparently simple and effective total allowable catch limit often fails: 16 of 22 TAC-managed fisheries analyzed in an OECD study had seen fish stocks decline or collapse while the system was in use. This should not be too surprising, because ; in many cases TACs are , despite regulatory measures, the TACs were still exceeded (Morgan, 2001). A serious failure of TAC quotas is that they encourage a phenomenon called the race-to-fish. Because (at least in theory) only a limited number of fish is allowed to be taken from the fishery, all of the participants fish as much as possible until the TAC is reached, in hopes of getting the largest possible shares of the total catch. In two extreme Canadian cases, the entire year's TAC was caught in a few days. Among the many problems caused by such a system are dangerous fishing practices and the appearance of large amounts of fish on the market at once, which depresses the price received by fishers (Kura, Revenga, Hoshino, & Mock, 2004). Wasteful overinvestment over-investment in fishing and processing equipment also occurs (Sutinen & Soboil, 2003).
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Although individual quotas have been reasonably effective in stopping the race-to-fish and keeping the catch below the TAC limit , they are not perfect (Sutinen & Soboil, 2003). Criticisms include , critics point to the potential for consolidation of the quota share in the hands of a few hands individuals or companies and the issue of finding a fair way to allocate the quota initially (National Research Council, 1999). There is also the difficulty of administering any sort of quota scheme in a multispecies fishery (Morgan, 2001). ITQs have sometimes encouraged fishers to discard low-value fish in order to save their quota share for more valuable catches (Kura, Revenga, Hoshino, & Mock, 2004). But these problems are addressable with further regulations: A New Zealand ITQ program includes restrictions on how much quota share any single entity can own, and discarding could be banned as it is in Norway.
Even if all fishery participants follow the rules perfectly, both conventional TAC and ITQ schemes can still fail if managers mistakenly set the TAC too high. The stock can then be seriously overexploited, as occurred in the Newfoundland cod fishery. Complicating the problem, current stock assessment methods often overestimate the abundance of a stock during periods of decline. Therefore, overestimation of stock abundance results in a '"vicious circle' " in which overexploitation leads to more rapid decline, which in turn causes scientists to overestimate stock abundance (Walters, 2004).abundance (Walters, 2004).
Technical Measures
Finally, examples of common technical measures are limitations on the size of fish that can be taken and restrictions on where fishing can be done (Sutinen & Soboil, 2003). The effectiveness of time and area closures is not always clear, although closed areas in the northeastern United States fishery have substantially benefitted scallops and yellowtail flounder (Sutinen & Soboil, 2003). Rules constraining the size and sex of fish that can be taken are not useful unless the fish that must be discarded survive being caught. Too often, this is not the case (Kura, Revenga, Hoshino, & Mock, 2004).
Ecosystem-based Fishery Management
Ecosystem-based fishery management (EBFM) is an ambitious proposal to more effectively manage fish populations and their ecosystems. It has been widely touted by the scientific community as essential for healthy, sustainable marine life. Current fishery management regulations largely focus on controlling the population levels of specific target species; EBFM recognizes the need for a more holistic approach to fishery management that focuses on the health of entire ecosystems - target species, non-target species, and the natural environment (Pikitch, et al., 2004). Fish populations do not exist in isolation. They are parts of complex marine ecosystems that contain numerous species. Ensuring sustainable harvesting of a marine species requires not merely knowledge of the biology of the species, but also an understanding of its place in the ecosystem - its habitat, food, predators, and other relevant characteristics (Ecosystem Principles Advisory Panel, 1998).
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Also, EBFM is complicated by the fact that ecosystems do not follow jurisdictional boundaries that humans have established (Ecosystem Principles Advisory Panel, 1998). Marine policy is implemented in artificially bounded jurisdictional regions, while ecosystems readily cross these boundaries. Effective EBFM policy will require significant regional and international cooperation.
Conclusions
Our group's recommendations are as follows:
Recommendations and Conclusion
We cannot emphasize enough the need to manage cautiously. None of the regulatory tools are "silver bullets" and fishery managers must make sure that the systems they create are complex enough to be truly effective. Too often relevant Relevant biological knowledge is often not sufficiently taken into account in management decisions (Young, et al., 2006). This is a shame, because physiology and other non-population aspects of fish biology can make significant contributions to management. For example, physiological knowledge can be used to predict migratory mortality of Pacific salmon (Cooke, et al., 2006), which could be useful information to have when setting a total allowable catch. The evolutionary effects of fishing (Helfman, 2007) should also be considered by managers.
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Input controls are not generally enough; some form of output control must be used. The total allowable catch figures that are needed to run an output control system should be calculated conservatively. One way to set a conservative TAC is base it on a quantity called the proven production potential, which is calculated by multiplying the minimum possible stock size by the fraction of the stock that can safely be taken (Walters, 2004). In such a system, the government is responsible for calculating the fraction of the stock that can be taken sustainably, while fishers and government agencies work together to determine the minimum possible stock size. Such a system creates an incentive for fishers to invest in stock assessment and also prevents overestimation of stock abundance.
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Although individual transferable quotas are not perfect, they are clearly effective in limiting the amount of fishing done in a fishery. Therefore, their further use is encouraged. However, we also urge those considering instituting ITQs to carefully study and attempt to address problems such as quota allocation and consolidation and undesirable environmental effects.unmigrated-wiki-markup
In the long term, it may become possible to manage many fisheries by appropriate taxation of catches. Further details of this proposal are \ [here---INSERT LINK TO TAX PROPOSAL.\]
The effects of fishing on whole ecosystems must be considered as part of any long-term program for creating sustainable fisheries. But until scientists and politicians develop more concrete methods of translating ecological knowledge into policy, EBFM will remain more of a goal than a practice. The need for EBFM has gained widespread acceptance; now the world must do the work necessary to make it happen.
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Morgan, G. R. (2001). Individual Quota Management in Fisheries - Methodologies for Determining Catch Quotas and Initial Quota Allocation. Retrieved 11 November 21, 2007, from FAO (Food and Agriculture Organization) Corporate Document Repository: http://www.fao.org/DOCREP/003/W7292E/W7292E00.HTM
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