Now showing items 1-20 of 12182

    • The Economic Potential of Alaska’s Mining Industry

      Loeffler, Bob; Watson, Brett (2022-03-08)
    • Impact analysis of the marine sport fisheries of middle and lower Cook Inlet

      Hamel, Charles David; Hermann, Mark (2001-05)
      Impact analysis models such as Input-Output (I-O) can provide a view of the regional economic significance of a resource-based industry. Analysts often utilize impact analyses to predict the distributive outcomes of demand shocks to local industries; however, even if such forecasts are modeled appropriately within the impact assessment framework, the results are not particularly relevant if the motives and magnitudes of demand change are arbitrarily posed. In order for an impact analysis to be meaningful, it should not stand alone, but instead be part and parcel of a more encompassing modeling approach comprising a demand function. This paper describes a linkage between a regionally ground-truthed 1-0 model and a predictive model of participation rates for the Cook Inlet, Alaska, sport fisheries. The demand effects of environmental or regulatory induced change to the sport fishery are simulated and the resulting economic impacts are reported.
    • Use of hormones in assessing reproductive physiology of humpback whales (Megaptera novaeangliae) from Juneau, Alaska

      Atkinson, S.; Melica, V.; Teerlink, S.; Mashburn, K.; Moran, J.; Pearson, Heidi (Elsevier, 2023)
      Humpback whales (Megaptera novaeangliae) in Southeast Alaska have been studied for over 50 years, and are largely considered a recovery success since the cessation of commercial whaling. Reproductive physiology is an important factor to consider in studying population health and can provide important insights into the drivers contributing to population abundance fluctuations. Validated assays for progesterone and testosterone were used on blubber biopsies from humpback whales (N = 33 whales, 71 samples) near Juneau, Alaska, in 2020 and 2021. Long-term sighting histories were used to confirm detected pregnancies with calf sightings the following year. Blubber samples were divided into two seasonal bins (early and late summer). Pregnant females sampled in both early and late summer of both 2020 and 2021 showed elevated progesterone concentrations compared to other reproductive states (p < 0.05). Progesterone concentrations in adult male whales (0.3 ± 0.2 ng/g) were not significantly different from lactating or resting female whales. Blubber testosterone concentrations in adult male humpback whales ranged from 0.05 to 1.1 ng/g, and mean concentrations were approximately double those of female whales in any reproductive state. Pregnancy was detected in 5 of 11 and 4 of 9 adult females in 2020 and 2021 respectively, yielding summer season pregnancy rates for sexually mature females at 0.45, and 0.44, respectively. Calving rates were 0.36 and 0.22 in 2020 and 2021, respectively, and the annual growth rate for this subpopulation was calculated at 2.6 % per annum. One female had successful pregnancies for four consecutive years. These results demonstrate the synergistic value of combining immunoreactive assays and long-term sighting histories to further knowledge of reproductive physiology in individual humpback whales, which can be expanded to assessing the health of a population or ecosystem.
    • Macronutrient composition of sea otter diet with respect to recolonization, life history, and season in southern Southeast Alaska

      LaRoche, Nicole; King, Sydney; Fergusson, Emily; Eckert, Ginny; Pearson, Heidi (John Wiley & Sons, Inc., 2023-05-02)
      The sea otter (Enhydra lutris) population of Southeast Alaska has been growing at a higher rate than other regions along the Pacific coast. While good for the recovery of this endangered species, rapid population growth of this apex predator can create a human-wildlife conflict, negatively impacting commercial and subsistence fishing. Previous foraging studies throughout the sea otter range have shown they will reduce invertebrate prey biomass when recolonizing an area. The goal of this study was to examine and quantify the energy content of sea otter diets through direct foraging observations and prey collection. Our study area, Prince of Wales Island in southern Southeast Alaska, exhibits a gradient of sea otter recolonization, thus providing a natural experiment to test diet change in regions with different recolonization histories. Sea otter prey items were collected in three seasons (spring, summer, and winter) to measure caloric value and lipid and protein content. We observed 3523 sea otter dives during the spring and summer. A majority of the sea otter diet consisted of clams. Sea otters in newly recolonized areas had lower diet diversity, higher energetic intake rates (EIR, kcal/min), and prey had higher energy content (kcal/g). Females with pups had the highest diet diversity and the lowest EIR. Sea otter EIR were higher in the fall and winter vs. spring and summer. Sea cucumber energy and lipid content appeared to correspond with times when sea otters consumed the highest proportion of sea cucumbers. These caloric variations are an important component of understanding ecosystem-level effects sea otters have in the nearshore environment.
    • A deep learning approach to photo–identification demonstrates high performance on two dozen cetacean species

      Patton, Philip T.; Cheeseman, Ted; Abe, Kenshin; Yamaguchi, Taiki; Reade, Walter; Southerland, Ken; Howard, Addison; Oleson, Erin M.; Allen, Jason B.; Ashe, Erin; et al. (John Wiley & Sons, Inc., 2023-07-13)
      1. Researchers can investigate many aspects of animal ecology through noninvasive photo–identification. Photo–identification is becoming more efficient as matching individuals between photos is increasingly automated. However, the convolutional neural network models that have facilitated this change need many training images to generalize well. As a result, they have often been developed for individual species that meet this threshold. These single-species methods might underperform, as they ignore potential similarities in identifying characteristics and the photo–identification process among species. 2. In this paper, we introduce a multi-species photo–identification model based on a state-of-the-art method in human facial recognition, the ArcFace classification head. Our model uses two such heads to jointly classify species and identities, allowing species to share information and parameters within the network. As a demonstration, we trained this model with 50,796 images from 39 catalogues of 24 cetacean species, evaluating its predictive performance on 21,192 test images from the same catalogues. We further evaluated its predictive performance with two external catalogues entirely composed of identities that the model did not see during training. 3. The model achieved a mean average precision (MAP) of 0.869 on the test set. Of these, 10 catalogues representing seven species achieved a MAP score over 0.95. For some species, there was notable variation in performance among catalogues, largely explained by variation in photo quality. Finally, the model appeared to generalize well, with the two external catalogues scoring similarly to their species' counterparts in the larger test set. 4. From our cetacean application, we provide a list of recommendations for potential users of this model, focusing on those with cetacean photo–identification catalogues. For example, users with high quality images of animals identified by dorsal nicks and notches should expect near optimal performance. Users can expect decreasing performance for catalogues with higher proportions of indistinct individuals or poor quality photos. Finally, we note that this model is currently freely available as code in a GitHub repository and as a graphical user interface, with additional functionality for collaborative data management, via Happywhale.com.
    • High-latitude kelps and future oceans: A review of multiple stressor impacts in a changing world

      Farrugia Drakard, Veronica; Hollarsmith, Jordan; Stekoll, Michael (John Wiley & Sons, Inc., 2023-07-04)
      Kelp forests worldwide are threatened by both climate change and localized anthropogenic impacts. Species with cold-temperate, subpolar, or polar distributions are projected to experience range contractions over the coming decades, which may be exacerbated by climatic events such as marine heatwaves and increased freshwater and sediment input from rapidly contracting glaciers. The northeast Pacific has an extensive history of harvesting and cultivating kelps for subsistence, commercial, and other uses, and, therefore, declines in kelp abundance and distributional shifts will have significant impacts on this region. Gaps in our understanding of how cold-temperate kelp species respond to climate stressors have limited our ability to forecast the status of kelp forests in future oceans, which hampers conservation and management efforts. Here, we conducted a structured literature review to provide a synthesis of the impacts of multiple climate-related stressors on kelp forests in the northeast Pacific, assess existing knowledge gaps, and suggest potential research priorities. We chose to focus on temperature, salinity, sediment load, and light as the stressors most likely to vary and impact kelps as climate change progresses. Our results revealed biases in the existing literature toward studies investigating the impacts of temperature, or temperature in combination with light. Other stressors, particularly salinity and sediment load, have received much less focus despite rapidly changing conditions in high-latitude regions. Furthermore, multiple stressor studies appear to focus on kelp sporophytes, and it is necessary that we improve our understanding of how kelp microstages will be affected by stressor combinations. Finally, studies that investigate the potential of experimental transplantation or selective cultivation of genotypes resilient to environmental changes are lacking and would be useful for the conservation of wild populations and the seaweed aquaculture industry.
    • Pregnancy rate and reproductive hormones in humpback whale blubber: Dominant form of progesterone differs during pregnancy

      Atkinson, S.; Branch, T. A.; Pack, A. A.; Straley, Janice; Moran, J. R.; Gabriele, C.; Mashburn, K. L.; Cates, K.; Yin, S. (Elsevier, 2023-01-01)
      To better understand reproductive physiology of humpback whales Megaptera novaeangliae that reside in Hawai’i and Alaska, enzyme immunoassays were validated for both progesterone and testosterone in free-ranging and stranded animals (n = 185 biopsies). Concentrations were analyzed between different depths of large segments of blubber taken from skin to muscle layers of stranded female (n = 2, 1 pregnant, 1 non-pregnant) and male (n = 1) whales. Additionally, progesterone metabolites were identified between pregnant (n = 1) and non-pregnant (n = 3) females using high pressure liquid chromatography (HPLC). Progesterone concentrations were compared between juvenile (i.e., sexually immature), lactating, and pregnant females, and male whales, and pregnancy rates of sexually mature females were calculated. Based on replicate samples from ship struck animals collected at 7 depth locations, blubber containing the highest concentration of progesterone was located 1 cm below the skin for females, and the highest concentration of testosterone was in the skin layer of one male whale. HPLC of blubber samples of pregnant and non-pregnant females contain different immunoreactive progesterone metabolites, with the non-pregnant female eluate comprised of a more polar, and possibly conjugated, form of progesterone than the pregnant female. In females, concentrations of progesterone were highest in the blubber of pregnant (n = 28, 28.6 ± 6.9 ng/g), followed by lactating (n = 16, 0.9 ± 0.1 ng/g), and female juvenile (n = 5, 1.0 ± 0.2 ng/g) whales. Progesterone concentrations in male (n = 24, 0.6 ng/g ± 0.1 ng/g) tissues were the lowest all groups, and not different from lactating or juvenile females. Estimated summer season pregnancy rate among sexually mature females from the Hawai’i stock of humpback whales was 0.562 (95 % confidence interval 0.528–0.605). For lactating females, the year-round pregnancy rate was 0.243 (0.09–0.59), and varies depending on the threshold of progesterone assumed for pregnancy in the range between 3.1 and 28.5 ng/g. Our results demonstrate the synergistic value added when combining immunoreactive assays, HPLC, and long-term sighting histories to further knowledge of humpback whale reproductive physiology.
    • Effects of commercial otter trawling on essential fish habitat of the southeastern Bering Sea shelf

      Brown, Eloise (2003-05)
      Sediment properties and benthic community composition in areas subject to commercial bottom trawling were compared to control areas in a shallow sandy habitat of the southeastern Bering Sea. The top 3 cm sediments in the fished area were slightly better sorted, less variable, and contained fewer finer grains than those of the closed area. Infaunal species assemblages were distinct. The fished area was characterized by reduced infauna richness and biomass, but abundance and diversity were similar to the closed area. No shift in means of any sediment parameter were detected after experimental trawling, but significant increases in variability were observed for several grain size and organic matter parameters. Reduced richness, elimination of rare taxa, and patchy changes in infauna assemblage biomass were found, but there were no differences in abundance, diversity or total biomass relative to controls. A turbulent wake generated by the trawl was on the same order of magnitude as a winter storm wave, but of different seasonal timing and duration. Turbulence combined with friction from contact with fishing gear has the potential to erode sediments from deeper within the seabed than naturally occurring bottom currents. Trawling apparently removed finer grains from the upper sediment layers and altered infauna communities.
    • The relationship between fracturing, asymmetric folding, and normal faulting in Lisburne Group carbonates: West Porcupine Lake Valley, Northeastern Brooks Range, Alaska

      Shackleton, John Ryan (2003-05)
      The distribution of fold related fractures and other mesoscopic structures in asymmetrically folded Mississippian to Pennsylvanian Lisbume Group carbonates gives clues concerning the mechanism of folding. Since fracture sets pre-date and post-date folding, it is important, but sometimes difficult, to determine which fracture sets are related to folding. Higher density of fold related fractures and dissolution cleavage in the hinges than limbs of two folds in the study area is evidence for fixed hinge detachment folding. However, geometric modeling of box shaped folds in the study area suggests that some folds may have formed by either detachment folding or trishear fault propagation folding. Formulaic modeling of fracture density in a stratigraphic section using stratigraphic attributes such as lithology, bed thickness, and chert content predicts general trends in fracture density, but other factors such as slip along bed contacts may obscure the relationship between fracture density, lithology and bed thickness.
    • Alaska Fetal Alcohol Spectrum Disorders Data Systems Development: Gaps, Opportunities, & Recommendations

      Hedwig, Travis; Miller, Virginia; Parker, David; Payne, Troy C.; Gonzalez, Andrew; Kisarauskas, Yevgenii; Slone, Avram; Brown, Paulsen; Harvey, Hattie; Hiratsuka, Vanessa; et al. (UAA College of Health, 2021-06-28)
      The report, "Alaska Fetal Alcohol Spectrum Disorders Data Systems Development," was prepared for the Alaska Mental Health Trust Authority by the University of Alaska Anchorage (UAA) College of Health. This report was a partnership between the Alaska Justice Information Center, the Center for Alcohol and Addiction Studies, the Center for Human Development, and the Division of Population Health Sciences.
    • Sexual Violence in Alaska (Fast Facts)

      Gonzalez, Andrew; Johnson, Ingrid (Alaska Justice Information Center, 2023-10-24)
    • Sexual Violence in Alaska (Fast Facts)

      Gonzalez, Andrew; Johnson, Ingrid (Alaska Justice Information Center, 2023-10-23)
    • Engaging northern rural and Indigenous students: Case studies using One Health principles of educational resilience

      Cotter, Paul; Gildehaus, Lori; Chenoweth, Ellen; Straley, Janice; Hueffer, Karsten; Reynolds, Arleigh J. (University of Aberdeen, 2023)
      Indigenous and rural populations are underrepresented in many science-related educational fields, leading to underrepresentation in biomedical, science, and related professions. A contributing factor is the misalignment of Western education and engagement strategies and these cultures; this is especially true for northern subsistence cultures. We review the influence of a combined One Health/Quadripartite Model of Educational Resilience approach in promoting interest in, recruiting for, and retaining students in biomedical research and community health across three education levels. We suggest a One Health context resonates with Indigenous and rural populations and may be more culturally aligned than conventional education approaches. Implementing Quadripartite Model elements promotes educational accessibility and attractiveness to these populations across our programs. We suggest that 1) disciplines that may be perceived as remote and inaccessible to these populations can be culturally contextualized through a One Health lens and; 2) a more equitable sharing of responsibility for educational success may benefit students from underrepresented populations. Applying One Health/Quadripartite Model approaches may help increase representation of Indigenous and rural populations in a wide range of STEM, biomedical, and community health disciplines. We support continued efforts to modify conventional educational structures, institutions, and strategies to further engage these communities.
    • Woosh jín toolshát yeisú, Weʼre still holding each otherʼs hands : Relationships and revitalization in Lingít country

      Burge, Éedaa Heather Dawn (University of British Columbia, 2024)
      This dissertation examines the relationships the Lingít language revitalization movement has to concepts of gender, identity, organizations and academia. The Lingít language and the Lingít people reside within Southeast Alaska in the United States, as well as northern British Columbia and the southern Yukon territory in Canada. Relying on my own lived experience as a Lingít learner and educator, as well as interviews and conversations with Lingít community members, we discuss how relationality supports the larger goal of Lingít language and cultural revitalization. Specifically we talk about the role of women within the language movement, and what approaches can best support current and future female language learners and speakers. Next we discuss the role identity plays within Lingít language revitalization and how varying understandings of Indigeneity both support and add additional pressure to language learning. We also reflect on the various roles multiple institutions play in Lingít language work, and touch on some of the programming organizations have implemented. Last, we discuss the role universities in particular, and academia in general plays within language revitalization, and how that role has evolved over time. The thread throughout is relationality, how personal and collective relationships with individuals, organizations, and identities shape language work, and how that relationality can best support the larger goal of continued Lingít language resurgence.
    • Instability and retreat of a lake-calving terminus, Mendenhall Glacier, Southeast Alaska

      Boyce, Eleanor (2006-05)
      Mendenhall Glacier is a lake-calving glacier in southeastern Alaska that is experiencing substantial thinning and increasingly rapid recession. Long-term mass wastage linked to climatic trends is responsible for thinning of the lower glacier and leaving the terminus vulnerable to buoyancy-driven calving and accelerated retreat. Bedrock topography may play a role in stabilizing the terminus between periods of rapid calving and retreat. Lake-terminating glaciers form a population distinct from both tidewater glaciers and polar ice tongues, with some similarities to both groups. Lacustrine termini experience fewer perturbations (e.g. tidal flexure, high subaqueous melt rates) and are therefore inherently more stable than tidewater termini. At Mendenhall, rapid thinning and simultaneous retreat into a deeper basin leci to floatation conditions along approximately 50% of the calving front. This unstable terminus geometry lasted for ~ 2 years anci culminated in large-scale calving and terminus collapse during summer 2004. We used a 1-dimensional viscoelastic model to investigate the transient response of a floating glacier tongue to buoyant forcing. Results suggest that creep may be capable of accommodating buoyant torque if it is applied gradually. As unresolved bending stresses approach the tensile strength of ice, small rapidly applied perturbations may cause buoyancy-driven calving.
    • Big avalanches in a changing climate: Using tree-ring Derived avalanche chronologies to examine avalanche frequency across multiple climate types

      Peitzsch, Erich H.; Pederson, Gregory; Martin, Justin; Hood, Eran; Greene, Ethan; Birkeland, Kelly Elder; Wolken, Gabriel; Kichas, Nick; Stahle, Daniel; Harley, John R. (Montana State University Library, 2023-10-08)
      Large-magnitude snow avalanches pose a hazard to humans and infrastructure worldwide. Analyzing the spatiotemporal behavior of avalanches and the contributory climate factors is important for understanding historical variability in climate-avalanche relationships as well as improving avalanche forecasting. This study uses established dendrochronological methods to develop long-term regional avalanche chronologies for three different climate types: high-latitude maritime climate of southeast Alaska, intermountain climate of the northern Rocky Mountains, and continental climate of Colorado. In the maritime study area, we collected 434 cross sections throughout six avalanche paths near Juneau, Alaska. This resulted in 2706 identified avalanche growth disturbances between year 1720 and 2018 Common Era (CE), which allowed us to reconstruct 82 years with large magnitude avalanche activity across three sub-regions. By combining this tree-ring derived avalanche dataset with a suite of climate and atmospheric variables and applying a generalized linear model to fit a binomial regression, we found February and March precipitation and the Oceanic Niño Index (ONI) were significant predictors of large magnitude avalanche activity in the southeast Alaska study area. In the intermountain climate study area, tree-rings from 647 trees exhibited 2134 avalanche-related growth disturbances in the northern Rocky Mountains of northwest Montana from 1867 to 2019. The data show that the amount of snowpack across the northern Rocky Mountain region is directly related to avalanche probability. Coincident with warming and regional snowpack reductions, a decline of ~ 14% (~ 2% per decade) in overall large magnitude avalanche probability is apparent through the period 1950–2017 CE. In the continental climate of Colorado, we sampled 24 avalanche paths throughout the state and collected 1188 total samples with 4135 identified growth disturbances from 1698 to 2019. Preliminary results suggest years with large magnitude avalanche activity across the sub-regions of this study area are generally characterized by stormy winters with above average snowpack development but that early and late winter temperature and precipitation also play an important role in large avalanche activity. Characterizing historical climate-avalanche relationships across different climate types provides a broad baseline for understanding potential future changes in avalanche activity. Overall, this work helps forecasters and planners better understand the influence of climate on large magnitude avalanche frequency, and how potential changes in avalanche character and occurrence will affect their operations in the context of a warming climate.
    • Modeling coho salmon (Oncorhynchus kisutch) population response to streamflow and water temperature extremes

      Bellmore, J. Ryan; Sergeant, Christopher; Bellmore, Rebecca; Falke, Jeffery; Fellman, Jason (Canadian Science Publishing, 2023-01-06)
      Models that assess the vulnerability of freshwater species to shifting environmental conditions do not always account for short-duration extremes, which are increasingly common. Life cycle models for Pacific salmon (Oncorhynchus spp.) generally focus on average conditions that fish experience during each life stage, yet many floods, low flows, and elevated water temperatures only last days to weeks. We developed a process-based life cycle model that links coho salmon (Oncorhynchus kisutch) abundance to daily streamflow and thermal regimes to assess: (1) “How does salmon abundance respond to short-duration floods, low flows, and high temperatures in glacier-, snow-, and rain-fed streams?” and (2) “How does the temporal resolution of flow and temperature data influence these responses?”. Our simulations indicate that short-duration extremes can reduce salmon abundance in some contexts. However, after daily flow and temperature data were aggregated into weekly and monthly averages, the impact of extreme events on populations declined. Our analysis demonstrates that novel modeling frameworks that capture daily variability in flow and temperature are needed to examine impacts of extreme events on Pacific salmon.
    • Effects of landslides on terrestrial carbon stocks with a coupled geomorphic-biologic model: Southeast Alaska, United States

      Booth, A. M.; Buma, B.; Nagorski, Sonia (Wiley, 2023-06-16)
      Landslides influence the global carbon (C) cycle by facilitating transfer of terrestrial C in biomass and soils to offshore depocenters and redistributing C within the landscape, affecting the terrestrial C reservoir itself. How landslides affect terrestrial C stocks is rarely quantified, so we derive a model that couples stochastic landslides with terrestrial C dynamics, calibrated to temperate rainforests in southeast Alaska, United States. Modeled landslides episodically transfer C from scars to deposits and destroy living biomass. After a landslide, total C stocks on the scar recover, while those on the deposit either increase (in the case of living biomass) or decrease while remaining higher than if no landslide had occurred (in the case of dead biomass and soil C). Specifically, modeling landslides in a 29.9 km2 watershed at the observed rate of 0.004 landslides km−2 yr−1 decreases average living biomass C density by 0.9 tC ha−1 (a relative amount of 0.4%), increases dead biomass C by 0.3 tC ha−1 (0.6%), and increases soil C by 3.4 tC ha−1 (0.8%) relative to a base case with no landslides. The net effect is a small increase in total terrestrial C stocks of 2.8 tC ha−1 (0.4%). The size of this boost increases with landslide frequency, reaching 6.5% at a frequency of 0.1 landslides km−2 yr−1. If similar dynamics occur in other landslide-prone regions of the globe, landslides should be a net C sink and a natural buffer against increasing atmospheric CO2 levels, which are forecast to increase landslide-triggering precipitation events.
    • Alaska's new electoral system: Countering polarization or "crooked as hell"?

      Reilly, Benjamin; Lublin, David; Wright, Glenn (eScholarship University of California, 2023)
      In November 2020, Alaska introduced a new electoral system, combining a “top four” all-party primary with ranked choice voting (RCV) general elections. Supporters of this reform claimed it would reduce the partisan polarization and minority victories generated by closed primaries and plurality elections. But critics suggest that it could make polarization worse by weakening political parties—an important check on political extremism. These are high-stakes issues that go well beyond Alaska, given the problem of political polarization and the search for institutional reforms in America today. Placing the Alaskan reforms in this broader national context, this paper presents an initial assessment of Alaska’s new system at the 2022 primary and mid-term elections. We find the reform was both consequential and largely beneficial, promoting greater choice for voters, more accommodative campaigning, and generally more moderate outcomes than likely under the old rules.
    • Conformity and tradition are more important than environmental values in constraining resource overharvest

      Wright, Glenn; Salk, Carl; Magnuszewski, Piotr; Stefanska, Joanna; Anderson, Krister; Benavides, Jean Paul; Chazdon, Robin (PLOS, 2023-02-02)
      We present the results of a hybrid research design that borrows from both experimental techniques—experimental games—and observational techniques—surveys—to examine the relationships between basic human values and exposure to natural ecosystems, on the one hand, and collective action for resource governance, on the other. We initially hypothesize that more frequent exposure to forests, and more pro-environmental values will be associated with more conservation action. However, we find that other values—tradition and conformity—are more important than pro-environmental values or exposure to nature. Our results imply that resource governance is likely to be more successful where resource users hold values that facilitate cooperation, not necessarily strong pro-environmental values.