• Aquatic Invasive Species Change Ecosystem Services from the World�s Largest Wild Sockeye Salmon Fisheries in Alaska

      Schwoerer, Tobias; Little, Joseph; Adkison, Milo (Journal of Ocean and Coastal Economics, 6/3/2019)
      This study combines a multi-method approach to structured expert judgment with market valuation to forecast fisheries damages from introduced invasive species. The method is applied to a case study of Alaska�s first submersed aquatic invasive plant, Elodea spp., threatening Alaska�s salmon fisheries. Assuming that Elodea spp. remains unmanaged, estimated mean damages to commercial sockeye fisheries aggregated across Alaska amount to a potential $159 million annually with a 5% chance of exceeding $577 million annually ($2015 USD). The associated mean loss of natural capital amounts to $5.1 billion cumulatively over the next 100 years reaching $400 million after 10 years. Results from the expert elicitation indicate that there is a 35% chance of positive net benefits associated with the believed positive effects of Elodea spp. on sockeye salmon (Oncorhynchus nerka). Despite the potential for positive net gains, the magnitude of the most probable damage estimate may justify substantial investment in keeping productive freshwater systems free of aquatic invasive species. The damage estimate for Alaska is significantly larger than similar estimates in the Great Lakes where ecosystems are already impaired by multiple aquatic invasive species, underscoring the value of keeping functioning ecosystems with global market value productive. This study is the first to estimate ecosystem service loss associated with introduction of an aquatic invasive species to freshwater habitat that supports the world�s most valuable wild sockeye salmon fisheries. Important policy implications related to natural resource management and efficient allocation of scarce resources are discussed
    • Emerging Anthropogenic Influences on the Southcentral Alaska Temperature and Precipitation Extremes and Related Fires in 2019

      Berman, Matthew; Schmidt, Jennifer; Bhatt, Uma S.; Lader, Rick T.; Walsh, John E.; Bieniek, Peter A.; Thoman, Richard L.; Borries-Strigle, Cecilia; Bulock, Kristi; Chriest, Jonathan; et al. (MDPI, 2021-01-17)
      The late-season extreme fire activity in Southcentral Alaska during 2019 was highly unusual and consequential. Firefighting operations had to be extended by a month in 2019 due to the extreme conditions of hot summer temperature and prolonged drought. The ongoing fires created poor air quality in the region containing most of Alaska’s population, leading to substantial impacts to public health. Suppression costs totaled over $70 million for Southcentral Alaska. This study’s main goals are to place the 2019 season into historical context, provide an attribution analysis, and assess future changes in wildfire risk in the region. The primary tools are meteorological observations and climate model simulations from the NCAR CESM Large Ensemble (LENS). The 2019 fire season in Southcentral Alaska included the hottest and driest June–August season over the 1979–2019 period. The LENS simulation analysis suggests that the anthropogenic signal of increased fire risk had not yet emerged in 2019 because of the CESM’s internal variability, but that the anthropogenic signal will emerge by the 2040–2080 period. The effect of warming temperatures dominates the effect of enhanced precipitation in the trend towards increased fire risk.
    • Evaluating Differences in Household Subsistence Harvest Patterns between the Ambler Project and Non-Project Zones

      Guettabi, Mouhcine; Greenberg, Joshua; Little, Joseph; Joly, Kyle (National Park Service U.S. Department of the Interior, 2016-08-01)
      Western Alaska is one of largest inhabited, roadless areas in North America and, indeed, the world. Access, via a new road that would transverse Gates of the Arctic National Park and Preserve (GAAR), to a mining district in a vast roadless section of northwest Alaska has been proposed. Given the potential effects of the road on nearby communities, we analyzed how communities connected to the road system compare to their unconnected counterparts. Specifically, using zero inflated negative binomial models, we analyzed subsistence harvest data to understand factors that influence subsistence production at the household level. We found substantial difference in these factors between communities near the proposed road (project zone (PZ) communities and a comparable set of road accessible communities outside the region, and were affected by household characteristics such as the gender of the head of household, number of children, and income. Total subsistence production of project zone communities was 1.8 – 2.5 times greater than that of non-project zone communities. Communities with a higher percentage of Alaska Native residents had greater per capita subsistence harvests. Higher household income levels were associated with lower subsistence harvest levels. Roads can provide access for hunters from outside the region to traditional subsistence hunting grounds used by local residents that would not be very accessible if not for the road. Our proxy for competition (number of nonlocal moose hunters) indicates that resident moose harvest amounts are inversely related to the number of hunters in a particular area. If subsistence harvest patterns for project zone communities currently off the road changed to mirror existing non-project zone harvests due to the road, the financial cost would be USD $6,900 – 10,500 per household per year (assuming an $8/lb. ‘replacement’ cost for subsistence harvests). This represents about 33% of the median household income. Taken together, our results suggest that the proposed road should be expected to substantially impact subsistence production in communities that are not currently connected to the road system. The scale of our data did not allow for the comparison of the impacts of the different proposed routes but the impacts of different routes is likely minor in relation to the presence or absence of the proposed road
    • Hitchhikers on floats to Arctic freshwater: Private aviation and recreation loss from aquatic invasion

      Schwoerer, Tobias; Little, Joseph; Schmidt, Jennifer; Borash, Kyle (Springer Netherlands, 2019)
      This study of aviation-related recreation loss shows that a survey primarily aimed at collecting information on invasive species’ pathways can also be used to estimate changes in pathway-related ecosystem services. We present a case study for Elodea spp. (elodea), Alaska’s first known aquatic invasive plant, by combining respondents’ stated pre-invasion actual flights with stated post-invasion contingent behavior, plane operating costs, and site quality data. We asked pilots about the extent of continued flights should destinations become invaded and inhibit flight safety. We estimate a recreation demand model where the lost trip value to the average floatplane pilot whose destination is an elodea-invaded lake is US$185 (95 % CI $157, $211). Estimates of ecosystem damages incurred by private actors responsible for transmitting invaders can nudge actors to change behavior and inform adaptive ecosystem management. The policy and modeling implications of quantifying such damages and integration into more complex models are discussed.
    • Quantifying expert opinion with discrete choice models: Invasive elodea's influence on Alaska salmonids

      Little, Joseph; Hayward, Gregory D. (Elsevier, 2020-10-01)
      Scientific evidence should inform environmental policy, but rapid environmental change brings high ecological uncertainty and associated barriers to the science-management dialogue. Biological invasions of aquatic plants are a worldwide problem with uncertain ecological and economic consequences. We demonstrate that the discrete choice method (DCM) can serve as a structured expert elicitation alternative to quantify expert opinion across a range of possible but uncertain environmental outcomes. DCM is widely applied in the social sciences to better understand and predict human preferences and trade-offs. Here we apply it to Alaska's first submersed invasive aquatic freshwater plant, Elodea spp. (elodea), and its unknown effects on salmonids. While little is known about interactions between elodea and salmonids, ecological research suggests that aquatic plant invasions can have positive and negative, as well as direct and indirect, effects on fish. We use DCM to design hypothetical salmonid habitat scenarios describing elodea's possible effect on critical environmental conditions for salmonids: prey abundance, dissolved oxygen, and vegetation cover. We then observe how experts choose between scenarios that they believe could support persistent salmonid populations in elodea-invaded salmonid habitat. We quantify the relative importance of habitat characteristics that influence expert choice and investigate how experts trade off between habitat characteristics. We take advantage of Bayesian techniques to estimate discrete choice models for individual experts and to simulate expert opinion for specific environmental management situations. We discuss possible applications and advantages of the DCM approach for expert elicitation in the ecological context. We end with methodological questions for future research.