Application of the Endangered Species Act is typified by intense and sometimes acrimonious debate among parties with divergent ecological and economic viewpoints. Unfortunately, formal biological and economic input to the process of protecting species under the act is often underappreciated. Faced with the proposed listing of several salmon stocks in the Columbia River basin as endangered, the Pacific Northwest region has the opportunity to bring biological and economic analyses, such as those developed at Resources for the Future, to a more prominent position. Critical as they are, such analyses must reflect the enormous uncertainty about threatened and endangered populations.
Anadromous salmon (salmon that ascend rivers from the sea for breeding) are considered by many to be a critical component of the legacy and identity of the Pacific Northwest region of the United States. During the last 100 years, however, the annual runs of adult salmon in the Columbia River basin have declined by an estimated 75 to 85 percent, according to the Northwest Power Planning Council. Some runs are already extinct, while others (such as the run of sockeye salmon in the Snake River) have dwindled to a small fraction of their original size. Dams built throughout the region for power generation and flood control are thought to be the largest factor behind the declines. Other contributing factors are fishing, withdrawals of water for irrigation, and land-use practices that affect the stream habitat where adult fish spawn and the young spend their early lives.
On April 2, 1990, the Shoshone-Bannock Native American Tribe of Idaho petitioned the National Marine Fisheries Service (NMFS) of the U.S. Department of Commerce to list sockeye salmon in the Snake River as an endangered species. Following the tribe's lead, a coalition of environmental groups petitioned the NMFS to list coho salmon in the lower Columbia River, as well as the spring, summer, and fall runs of Chinook salmon in the Snake River, as endangered.
As required by the Endangered Species Act (ESA), the secretary of commerce had one year from the date of petitioning to decide whether to propose listing for any of the runs. In April 1991, the secretary proposed that the Snake River sockeye be added to the endangered species list, and in June the secretary proposed that the spring, summer, and fall runs of Chinook be listed as threatened, as opposed to endangered. (A threatened species is one which is deemed likely to become endangered within the forseeable future.) The secretary must make a final decision on the sockeye run by April 1992 and on the Chinook runs by June 1992. For any stocks listed as threatened or endangered, the NMFS must designate the critical habitat of the stocks and produce explicit plans for their recovery.
The part of the listing process that still remains (final listing decisions, critical habitat designations, and production of recovery plans) will not be easy. The process is complicated by the importance to the regional economy of human activities that have contributed to the decline in salmon populations. Numerous and often divergent ecological and economic viewpoints must be considered in the process if it is to be perceived as politically legitimate. Unfortunately, some of the interest groups representing these viewpoints—electric utilities, environmental advocates, the barge industry, recreational boaters, agricultural irrigators, logging and mining interests, the aluminum industry, government agencies, and commercial, sports, and tribal fishing interests—often have different values and assumptions, and common ground is difficult to find. For example, many fish advocates believe strongly that the Columbia and Snake rivers' salmon stocks should be preserved at all costs. Other groups, representing such interests as farming and commercial fishing, believe that the decision to list a stock as endangered must take into account the economic livelihood of humans.
Political forces will ultimately decide what to protect and how to protect it. Nonetheless, diverse values and viewpoints need to be integrated in the decision-making process through rational application of biological and economic analyses. Even in a rational atmosphere, however, the obstacles to clear analyses under the ESA are formidable. Questions about viable population sizes, what populations are covered, and the relevance and scope of economic analyses complicate the picture.
Minimum viable populations
A fundamental question in the ESA listing process is how small a population can be without being in serious danger of extinction. Small populations tend to lose their genetic variation, a phenomenon that is thought to compromise their evolutionary ability to adapt to variable conditions such as exposure to new diseases or climatic change. The viability and fecundity of these populations may also be reduced as a result of inbreeding among related individuals. In addition, small populations are more vulnerable than large populations to short-term environmental events (such as weather extremes and disease outbreaks) and to random failures of individuals to survive and reproduce. These factors create a feedback cycle known as an extinction vortex: the smaller the population, the greater the effects of these factors, which further reduce the population size, and so on.
As part of the listing process, scientists try to determine the minimum number of individuals needed to maintain a viable population. Typically, one of two criteria is used to define the minimum viable population (MVP): (1) the population size necessary to ensure a given probability that a population will persist for a given duration (for example, a 95 percent probability of persistence for 100 years), or (2) the size necessary to ensure that a population will continue to have the capacity to evolve. It is likely that the second criterion will give MVP sizes much larger than the first, but the actual population size necessary to satisfy either criterion is difficult to determine and likely varies for each population being considered.
Some interest groups say salmon stocks in the Columbia River basin should be preserved at all costs; other groups assert that protection of endangered stocks must not be allowed to threaten the region's economic livelihood
What populations are covered by the ESA?
Interpretation of the Endangered Species Act itself presents difficulties to those involved in the ESA listing process. One recurrent issue is how to apply the act—which affords protection to species, subspecies, and populations—to populations within a species. In the case of the Columbia River basin salmon, it is not biologically designated species that have been proposed for listing, but rather stocks—that is, populations that to some extent are isolated in time or space from other populations of the same species during breeding. Given that the American Fisheries Society has recently identified 76 native stocks of Pacific salmon and steelhead trout in the Columbia River basin that are at risk of extinction or are of special concern, a question arises about which stocks qualify for ESA coverage.
The NMFS has recently concluded that distinct stocks may be considered a species for the purposes of the ESA if two criteria apply. First, the stocks must be substantially isolated reproductively from other stocks of the same species. Second, they must represent an important component in the evolutionary legacy of the species—that is, they must contribute to the ecological and genetic diversity of the species as a whole. Stocks that would qualify most easily are those from large tributary systems and those with unique traits that reflect adaptation to local conditions. Preserving several geographically separate and distinct populations of a species is thought to be integral to the preservation of the species as a whole by protecting genetic variation and sources of recolonization.
Determination of reproductive and genetic isolation is complicated by several factors. Although adult salmon theoretically return to their natal stream to spawn, homing is not perfect, and there may be substantial straying among some stocks. Moreover, hatchery operations have been a major cause of stock mixing. Even if there is physical mixing of stocks, however, this need not imply that a large amount of genetic mixing has taken place or that population gene frequencies will be substantially altered. A combination of genetic analysis, geographic analysis, and physical tagging of fish would be required to provide evidence for or against reproductive and genetic isolation.
Relevance of economic concerns
Biological analysis is clearly important in the ESA listing process, but is economic analysis also relevant? The different values of various interest groups involved in the process, and misunderstandings about how the process works, often fuel debate concerning how large a role economics should play. The ESA stipulates that economics cannot play a role in the decision to list a species as endangered or threatened. This requirement reflects a belief that the preservation of animal and plant species takes priority over human economic activities. In other words, the benefits, however measured, of preserving a species and preventing an irreversible ecological change exceed the costs of preservation. Most would agree, however, that there are several informal as well as formal applications of economic analysis during both the pre- and post-listing process.
Guidelines that limit the scope of formal economic assessments may be difficult for decision makers to implement in practice.
Informal economic assessments often take place de facto, whereby special interest groups weigh the costs and benefits of a proposed listing and management actions associated with the listing, and decide to support or oppose a listing petition based partly on that assessment. This takes place outside the formal listing decision process, but obviously influences the deliberations in some qualitative sense since these groups submit scientific data to the secretary of the Interior or Commerce departments, who makes the listing decision. Furthermore, since the ESA requires the secretary to take into account existing efforts at preservation in the decision on whether to list a species, economic analysis is indirectly incorporated if it entered into the design of those existing preservation efforts.
A second use of economic analysis in the ESA listing process is supported by Section 4 of the Endangered Species Act. This section stipulates that the secretary of the Interior or Commerce department designate habitat critical for the survival of the endangered or threatened species after taking into consideration the economic impact, and any other relevant impact, of specifying a particular area as critical habitat. Thus, while the likelihood of economic impacts cannot formally influence the decision on whether to list a species as threatened or endangered, economic impacts can be used as criteria for developing critical habitat guidelines.
A third clear role for economic analysis lies in evaluating recovery plans that must follow designation of a species as endangered or threatened. A recovery plan must provide estimates of the costs associated with the measures proposed to achieve recovery. In the case of the ESA listing process for salmon, an economic analysis would attempt to explore the costs of recovery actions that produce fish or enhance their survival. These costs include the direct capital and operation and maintenance costs of actions, as well as the opportunity costs of removing resources from existing uses. An obvious example of the latter is the value of the hydropower losses that result from attempts to manage the hydrosystem to benefit fish rather than maximize power revenues. The annual opportunity cost to the Bonneville Power Administration (BPA), the federal agency that markets the hydroelectricity produced at federal dams on the Columbia-Snake river system, reaches $50 million.
The implementation of these guidelines for economic analysis is often difficult in practice. For example, even though the ESA clearly limits the scope of formal economic analysis, decision makers are subject to political pressures and thus understandably may have trouble keeping such analysis out of the decision on whether to list. Moreover, decision makers must be aware of the influence of informal economic analysis on the level, timing, and objectives of participation by special interest groups in the ESA process.
Biological and economic uncertainty
A high degree of uncertainty characterizes any biological or economic analysis. Therefore, analysts must explicitly address the issue of uncertainty in all ESA deliberations. On the biological side, there will always be limitations in our knowledge of the characteristics and functions of ecosystems, populations, and organisms. There is a general lack of accurate estimates of demographic parameters and population sizes, especially for populations threatened with extinction. Even those parameters that are relatively easy to measure often exhibit pronounced yearly fluctuations and are difficult to predict. In addition, the projected effects of actions to preserve populations are often based on theoretical rather than empirical considerations.
Most of the economic uncertainty is associated with post-listing recovery plans. Analysts probably can make reasonably accurate predictions of the direct costs of recovery actions—for example, the costs of bypass systems that divert fish from dam turbines. However, analysts are on less stable ground when they try to account for the adjustments that economic interests in the region may make in response to the indirect effects of recovery actions—for example, the decreased availability of irrigation water. Economic theory clearly indicates that adjustments in resource use and prices can occur. However, the extent of these adjustments is controlled by both rational and nonrational human behavior, and is thus difficult to predict.
In the context of traditional decision making, biological and economic uncertainty simply weakens arguments, and thus often becomes the basis for delaying action. Yet, to prevent the possible extinction of a species or population, biological and economic analyses must proceed as quickly as possible. Decision makers must accept the fact of uncertainty and incorporate it into the decision-making process. Any statement concerning the expected fate of a species or population, its response to mitigation, or the economic implications of mitigation, should be stated in terms of the probability that any one of a range of future states will occur. The acceptability of the probabilistic outcomes can then be evaluated on the basis of criteria established a priori.
Decision makers must accept the fact of biological and economic uncertainty and incorporate it in the decision-making process.
Relationship Between Costs of Species Protection and the Probability of Species Survival for Five Hypothetical Protection Strategies
A modeling approach
Faced with the need for a methodological approach that can deal with the inevitable uncertainties and time constraints encountered in every ESA listing process, reliance must be placed on mathematical models. These models address the need for an explicit, objective, and relatively quick method for evaluating the present and future danger to a species or population, as well as the economic costs associated with reducing that danger.
Mathematical models that depict biological processes have already contributed greatly to the assessment of several small populations threatened with extinction, such as the grizzly bear, the Florida panther, and the northern spotted owl. For modeling such populations, some type of stochastic model is generally used so that uncertainties about the future states of nature can be explicitly incorporated. The output of such models consists of probability distributions for summary measures such as the predicted number of years until extinction of the population.
On the economic side, one of the most common evaluative approaches is to use some form of cost-benefit analysis. This is inappropriate for the task, however, since species survival is given overriding importance and thus is perceived as having infinite benefits. A cost-effectiveness modeling approach avoids the issue of evaluating benefits by setting desired objectives a priori and searching for the lowest-cost ways of achieving these. It thus facilitates comparison among alternative recovery management plans. It does not provide a metric to decide how many fish to produce and at what cost, but it can allow elimination of those actions that cost more than equally or more effective alternatives or those that cost the same as more effective options. Such an approach also allows decision makers to build a "frontier" of cost-effective actions that highlights the higher marginal costs associated with producing additional plants and animals or ensuring greater survivability (see figure, p. 8). At some point, the small increase in the probability of survival may not justify the tremendous increase in costs.
Before the 1991 decisions by the Commerce Department on the proposal to list the sockeye and Chinook stocks, researchers at Resources for the Future (RFF) and BPA applied a stochastic simulation model developed at RFF to examine the likelihood that the petitioned stocks would survive under various scenarios. The RFF biological model covers the entire life cycle of anadromous fish in the Columbia River basin, and incorporates various sources of parameter variability. In addition to the biological model, RFF researchers have been developing an integer programming model for evaluating the cost-effectiveness of management actions aimed at mitigating the damage done to salmon populations. The model allows quick evaluation of the costs and effects of a number of management actions by assessing all the possible combinations of these actions and screening out all those that do not lie near the cost-effectiveness frontier. Actions that lie on or near the cost-effectiveness frontier can be explored more fully with the more detailed biological model.
The RFF models can contribute to the listing process in several ways. First, they provide information during the listing decision. For example, the results of the biological model suggest that if current conditions continue, Snake River fall Chinook will almost certainly become extinct in the next forty years. Snake River spring and summer Chinook have less than a 10 percent chance of becoming extinct in that time. Second, both the biological and economic models can play a role in the planning of recovery strategies by further refining predictions of the effects and costs of alternative actions, thus aiding the selection of management actions. Third, the models can help identify the necessary extent and probable cost of an effective monitoring program once a recovery plan is adopted. The ability to detect an increase in the abundance of salmon resulting from management actions (statistical power) is directly proportional to both the magnitude of the increase in numbers of salmon and the number of years that data are collected, but is inversely proportional to the amount of random variation in abundance. The RFF models can be used to examine the tradeoffs among statistical power, monitoring costs, the necessary effectiveness of mitigation, and the number of monitoring years.
Biological and economic models can play a role in the planning of recovery strategies and help identify the extent and cost of an effective program to monitor such strategies.
Future scientific input to the ESA
The Endangered Species Act by itself does not adequately protect biodiversity, or ecosystems, or even species in many cases. However, because the ESA can be brought to bear in a crisis, it is a useful and critical component of any conservation program. The scientific community therefore must continue to improve the quality of the information that it provides to the ESA during the listing process.
On the biological side, more basic research is needed on quantifying genetic change and variation and the interactions among environmental, demographic, and genetic factors. Also, the ability to build models that reflect these interactions must be improved.
On the economic side, more attention needs to be focused on economic changes that may result from measures taken to protect endangered species, and a better understanding is needed of the implications of such changes for regional economic activities. However, analysts must also be aware of ongoing structural changes in the regional economy that, while not themselves driven by the ESA, may interact with ESA-driven changes.
Over the last several years, application of the Endangered Species Act has highlighted the need to consider broad-scale biological and economic issues. The current widespread threat to Columbia and Snake river salmon populations raises serious questions about the ecological integrity of the river system. Moreover, long-term economic sustainability in the Pacific Northwest region also is in question because current patterns of resource use may conflict with the value that the region places on the preservation of salmon populations. The region has begun to address these issues through its approach to the ESA process. Further efforts to integrate species preservation, ecosystem integrity, and sustainability will provide a much needed example of a progressive approach to regional ecological conservation.
Jeffrey B. Hyman and Kris Wernstedt are fellows in the Quality of the Environment Division at RFF. This discussion draws on ongoing RFF research on evaluating fish and wildlife enhancement strategies in the Columbia River basin. This research is being conducted by the authors, senior fellows Allen V. Kneese and Walter 0. Spofford, Jr., and fellows Danny C. Lee and Charles M. Paulsen.
A version of this article appeared in print in the June 1991 issue of Resources magazine.
A version of this article appeared in print in the June 1991 issue of Resources magazine.
