Exotic Organisms: A Dilemma for Conservation Biology

Abstract: Human-induced problems in resource conservation fall into three categories: (1) inappropriate resource use, (2) pollution, and (3) exotic organisms. Problems of resource use and pollution are correctable; exotic organisms are frequently permanent and may be the most pervasive influence affecting biodiversity in many systems, particularly on oceanic islands. Invasive exotic organisms often have effects far in excess of what might be predicted by equilibrium island biogeographic theory; a single exotic species may cause numerous extinctions in addition to altering the physical environment. Exotic organisms frequently cause environmental crises. In such crises, calls for more research are commonplace, but research results may be an unaffordable luxury, providing information only for the eulogy. Programs to eradicate exotic organisms provide an opportunity to combine good science and good conservation into functioning conservation biology.     

Chilean Blue Whales as a Case Study to Illustrate Methods to Estimate Abundance and Evaluate Conservation Status of Rare Species

Abstract: Often abundance of rare species cannot be estimated with conventional design‐based methods, so we illustrate with a population of blue whales (Balaenoptera musculus) a spatial model‐based method to estimate abundance. We analyzed data from line‐transect surveys of blue whales off the coast of Chile, where the population was hunted to low levels. Field protocols allowed deviation from planned track lines to collect identification photographs and tissue samples for genetic analyses, which resulted in an ad hoc sampling design with increased effort in areas of higher densities. Thus, we used spatial modeling methods to estimate abundance. Spatial models are increasingly being used to analyze data from surveys of marine, aquatic, and terrestrial species, but estimation of uncertainty from such models is often problematic. We developed a new, broadly applicable variance estimator that showed there were likely 303 whales (95% CI 176–625) in the study area. The survey did not span the whales' entire range, so this is a minimum estimate. We estimated current minimum abundance relative to pre‐exploitation abundance (i.e., status) with a population dynamics model that incorporated our minimum abundance estimate, likely population growth rates from a meta‐analysis of rates of increase in large baleen whales, and two alternative assumptions about historic catches. From this model, we estimated that the population was at a minimum of 9.5% (95% CI 4.9–18.0%) of pre‐exploitation levels in 1998 under one catch assumption and 7.2% (CI 3.7–13.7%) of pre‐exploitation levels under the other. Thus, although Chilean blue whales are probably still at a small fraction of pre‐exploitation abundance, even these minimum abundance estimates demonstrate that their status is better than that of Antarctic blue whales, which are still <1% of pre‐exploitation population size. We anticipate our methods will be broadly applicable in aquatic and terrestrial surveys for rarely encountered species, especially when the surveys are intended to maximize encounter rates and estimate abundance.     

Conservation as Virtue: a Scientific and Social Process for Conservation Ethics

Abstract:  Most scientists take ethical arguments for conservation as given and focus on scientific or economic questions. Although nature conservation is often considered a just cause, it is given little further consideration. A lack of attention to ethical theory raises serious concerns for how conservation scientists conceive and practice ethics. I contrast two common ways scientists approach ethics, as demonstrated in the writings of Stephen Jay Gould and E. O. Wilson. Gould casts severe doubt as to whether any ethics are possible from science, whereas Wilson proposes science as the only path to ethics. I argue these two methods ultimately limit popular support for conservation and offer Alasdair MacIntyre's "virtue ethics" as an alternative. Unlike Gould and Wilson, MacIntyre provides an ethical theory that reconciles scientific inquiry and social traditions. Recent studies of the Civil Rights Movement in the United States affirm MacIntyre's claims and provide important insights for conservation today. These accounts argue that social solidarity and political success against segregation were possible only as rooted in the particular language, logic, and practices of a robust cultural tradition. If correct, conservation science should attend to several questions. On what basis can conservation achieve widespread cultural legitimacy? What are the particular social currencies for a conservation ethic? What role does science play in such a scheme? MacIntyre's careful positioning of scientific and social traditions provides a hopeful ethical direction for conservation.     

Cost-Effective Management Alternatives for Snake River Chinook Salmon: a Biological-Economic Synthesis

Abstract: The mandate to increase endangered salmon populations in the Columbia River Basin of North America has created a complex, controversial resource‐management issue. We constructed an integrated assessment model as a tool for analyzing biological‐economic trade‐offs in recovery of Snake River spring‐ and summer‐run chinook salmon (Oncorhynchus tshawytscha). We merged 3 frameworks: a salmon‐passage model to predict migration and survival of smolts; an age‐structured matrix model to predict long‐term population growth rates of salmon stocks; and a cost‐effectiveness analysis to determine a set of least‐cost management alternatives for achieving particular population growth rates. We assessed 6 individual salmon‐management measures and 76 management alternatives composed of one or more measures. To reflect uncertainty, results were derived for different assumptions of effectiveness of smolt transport around dams. Removal of an estuarine predator, the Caspian Tern (Sterna caspia), was cost‐effective and generally increased long‐term population growth rates regardless of transport effectiveness. Elimination of adult salmon harvest had a similar effect over a range of its cost estimates. The specific management alternatives in the cost‐effective set depended on assumptions about transport effectiveness. On the basis of recent estimates of smolt transport effectiveness, alternatives that discontinued transportation or breached dams were prevalent in the cost‐effective set, whereas alternatives that maximized transportation dominated if transport effectiveness was relatively high. More generally, the analysis eliminated 80–90% of management alternatives from the cost‐effective set. Application of our results to salmon management is limited by data availability and model assumptions, but these limitations can help guide research that addresses critical uncertainties and information. Our results thus demonstrate that linking biology and economics through integrated models can provide valuable tools for science‐based policy and management.