Fisheries as Experimental Systems in Ecology
The exploitation of marine fish, shellfish, mammals, and other organisms has had a tremendous impact on individual populations, on biological communities, and on ecosystems. Historically, the primary motivation for this exploitation has been to obtain food, revenue, or recreation rather than scientific information. Therefore, in most cases, the data needed to better understand the ecological impacts of exploitation have not been collected. Consequently, management of wild populations has been complicated and often misinformed.
In an effort to bring together the often disparate efforts made by fishers, managers, and researchers, the Sustainable Biosphere Initiative Project Office organized a symposium titled "Fisheries as Experimental Systems in Ecology" for the 1997 Annual Meeting of the Ecological Society of America. This symposium provided a venue for academic ecologists, fishery biologists, and social scientists to interact and learn of each other's methods and experiences.
Addressing this interdisciplinary topic were a number of prominent researchers from a variety of fields. Anne Kapuscinski of the Department of Fisheries and Wildlife at the University of Minnesota discussed the need to treat hatcheries as experimental systems in the context of adaptive management. Ana Parma of the International Pacific Halibut Commission spoke about the limits of experimental fishing when dealing with a single population (or stock) of a long-lived species. Addressing opportunities for genetic experimentation in fisheries was David Policansky of the Board on Environmental Studies and Toxicology at the National Research Council. John Magnuson of the University of Wisconsin-Madison stressed the importance of fisheries as large-scale, real world experiments. Bonnie McCay of the Department of Human Ecology at Rutgers discussed two fisheries experiments that also turned out to be experiments in adaptive management. During the symposium, two broad themes emerged: 1) traditional views of fisheries as solely commercially important have left us with little information about what influences wild fish populations and 2) fisheries provide a unique opportunity for experimentation and results must be used to help create flexible management practices.
One example of how long-term fisheries data might contribute to more successful management is the Pacific halibut fishery. Like every fishery, Pacific halibut is managed in the face of considerable uncertainty about the size of the exploitable stock, as well as the factors that drive trends in productivity. Ana Parma noted that although experimental approaches aimed at separating the impacts of fishing from environmental effects were proposed as early as the 1940s, they were never implemented. Alternative hypotheses, involving density dependence and environmental forcing, were proposed in the 1980s to explain apparent cycles in year-class strength. Experimental management approaches were considered but never followed because of the risks involved. Instead, managers tried to implement strategies that were robust to the uncertainties concerning production dynamics.
Data collected over the following ten years now show that a major shift in climatic conditions around 1976 had a strong impact on halibut population dynamics. This impact was not anticipated under any of the scenarios considered plausible previously, leading Parma to say, "If Pacific halibut still support a healthy fishery, it is because of a management system that quickly responded to changes in abundance, not because of the ability to predict stock responses based on an understanding of the factors controlling productivity." Parma believes that we must develop policies and experiments that take all sources of uncertainty into account and emphasize monitoring and management response, as opposed to prediction. She also emphasized the difficulty of obtaining all the life-history information that would be needed for better predictions, and pointed out that even all that information would not be enough to eliminate uncertainty. Said Parma, "Be ready to expect the unexpected and have a management system in place that can respond to surprises in a timely manner."
Another example of the importance of treating fisheries as experimental systems comes from the Columbia River Basin. Focusing on the role of hatcheries in the life cycle of fish, Anne Kapuscinski noted that although the first hatchery was developed in the Columbia River Basin in 1877, there is little information on the impacts hatcheries have had on the life cycle of commercially important species. Kapuscinski says this is unfortunate because "if earlier examples had been treated as experiments, we would have a better historical understanding of the impacts of hatcheries. It is now difficult to compare the impacts hatcheries with those of other human activities such as dam building."
Kapuscinski believes changes are needed to treat hatchery programs as field experiments in an adaptive management context. From the beginning of the life cycle of commercially important species, the fish hatchery acts as a genetic "bottleneck" and has impacts on every stage of salmon's lives. Changes that should be made to manage hatcheries more effectively include setting goals and objectives, problem identification, action, and evaluation. Said Kapuscinski, "Hatchery programs should be compatible with the management goals of retaining or rehabilitating biodiversity and the natural regenerative capacity of these ecosystems."
In addition to having little information about what may lead to a collapse of fish populations or the impacts of hatcheries on the life cycle of fish, there is also little information available about the genetic effects of fishing. Said David Policansky, "For many fish populations, the opportunity to obtain genetic information has been lost, as considerable evolutionary change from decades of exploitation has already occurred." Although in a few cases, such as Hawaiian spiny lobsters, genetic information has been successfully taken from newly exploited populations, other attempts, such as with orange roughy, have been less successful because the studies began only after large fishing impacts had already occurred.
Increasing recognition of the need for appropriate data, and the opportunities for large scale experimentation, has led more investigators to consider fisheries as experimental systems. However, to take advantage of the unique opportunities provided by fisheries, we must begin to analyze the entire range of activities that affect fish populations and be responsive to new information through adaptive management. One case where researchers have begun to analyze the impacts of a whole suite of activities on fish populations comes from the Great Lakes. In studying the effects of climate change, the introduction of non-indigenous species, and the management of individual species, John Magnuson says that fisheries "provide real-world experiments that cannot be realized in any experimental facility or mesocosm." Magnuson believes that such long-term and large-scale experiments in the real world are important when dealing with complex issues such as climate change, overfishing, and habitat loss.
These types of complex issues also make adaptive management a necessity. For example, Bonnie McCay discussed two cases that involved a variety of stakeholders and social and scientific issues. The first was a small experiment to enhance recruitment of hard clams in a New Jersey bay. The second case was the Canadian government's much larger "experiment" as it tried to restore collapsed groundfish stocks off Newfoundland through a moratorium on fishing of all kinds: commercial, recreational, and subsistence. Although these cases differed in many ways, McCay said that both were characterized by "high levels of ecological uncertainty, scientific ignorance, and socio-cultural conflict and diversity, which call for a greater emphasis on adaptive management, particularly interventions that enable scientific and institutional learning to occur. Both cases show the importance of communication, trust, and collaboration among multiple stakeholders, particularly commercial fishers, scientists, and fishery managers, and both suggest difficulties and potentials for institutional adaptation." The results of the experiences were both disappointing and educational, pointing to the importance of management practices that are flexible in the face of uncertainty.
From ecological, social, and management perspectives, fisheries represent an opportunity for large-scale experimentation that could lead to the development of principles widely applicable to other ecological systems. Indeed, monitoring the changes in fish populations, the dynamics of the ecosystems of which they are a part, and the human influences on their habitats can provide insight to the nature of ecological systems over large spatial and temporal scales.
Dr. Elizabeth Stallman
Ecological Society of America
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