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Individuals relying on natural resource extraction for their livelihood face high income variability driven by a mix of environmental, biological, management, and economic factors. Key to managing these industries is identifying how regulatory actions and individual behavior affect income variability, financial risk, and, by extension, the economic stability and the sustainable use of natural resources. In commercial fisheries, communities and vessels fishing a greater diversity of species have less revenue variability than those fishing fewer species. However, it is unclear whether these benefits extend to the actions of individual fishers and how year-to-year changes in diversification affect revenue and revenue variability. Here, we evaluate two axes by which fishers in Alaska can diversify fishing activities. We show that, despite increasing specialization over the last 30 years, fishing a set of permits with higher species diversity reduces individual revenue variability, and fishing an additional permit is associated with higher revenue and lower variability. However, increasing species diversity within the constraints of existing permits has a fishery-dependent effect on revenue and is usually (87% probability) associated with increased revenue uncertainty the following year. Our results demonstrate that the most effective option for individuals to decrease revenue variability is to participate in additional or more diverse fisheries. However, this option is expensive, often limited by regulations such as catch share programs, and consequently unavailable to many individuals. With increasing climatic variability, it will be particularly important that individuals relying on natural resources for their livelihood have effective strategies to reduce financial risk.

Wolves are highly mobile predators and can disperse across a variety of habitats and over long distances. However, less is known about dispersal capabilities across water and among islands. The biogeography of island systems fosters spatially structured local populations, and their degree of connectivity may influence the dynamics and long-term viability of the regional population. We sought to quantify wolf dispersal rate, distance, and dispersal sex bias throughout Prince of Wales Island, a 6670 km2 island in southeast Alaska, and the surrounding islands that constitute the wildlife management unit (9025 km2). We also investigated patterns of dispersal in relation to hunting and trapping intensity and wolf population density. We used DNA data collected during 2012–2021 long-term monitoring efforts and genotyped 811 wolves, 144 of which (18%) were dispersers. Annual dispersal rates were 9–23% and had a weakly positive relationship with wolf density. Wolves dispersed 41.9 km on average (SD = 23.7 km), and males and females did not disperse at different rates. Of the dispersing wolves, 107 died, and the majority (n = 81) died before they were able to settle. The leading manner of death was trapping (97% of mortalities), and wolves tended to disperse from areas with low harvest density to areas where harvest density was relatively higher. Dispersal occurred both to and from small islands and the larger Prince of Wales Island, indicating bidirectional as opposed to asymmetrical movement, and the genetic overlap of wolf groups demonstrates connectivity throughout this naturally patchy system. Island ecosystems have different predator–prey dynamics and recolonization processes than large, intact systems due to their isolation and restricted sizes; thus, a better understanding of the degree of population connectivity including dispersal patterns among islands in the Prince of Wales archipelago could help inform the management and research strategies of these wolves.

1. Theory and previous studies have shown that commercial fishers with a diversified catch across multiple species may experience benefits such as increased revenue and reduced variability in revenue. However, fishers can only increase the species diversity of their catch if they own fishing permits that allow multiple species to be targeted, or if they own multiple single-species permits. Individuals holding a single permit can only increase catch diversity within the confines of their permit (e.g. by fishing longer or over a broader spatial area). 2. Using a large dataset of individual salmon fishers in Alaska, we build a Bayesian variance function regression model to understand how diversification impacts revenue and revenue variability, and how these effects have evolved since the 1970s. 3. Applying these models to six salmon fisheries that encompass a broad geographic range and a variety of harvesting methods and species, we find that the majority of these fisheries have experienced reduced catch diversity through time and increasing benefits of specialization on mean individual revenues. 4. One factor that has been hypothesized to reduce catch diversity in salmon fisheries is large-scale hatchery production. While our results suggest negative correlations between hatchery returns and catch diversity for some fisheries, we find little evidence for a change in variability of annual catches associated with increased hatchery production. 5. Synthesis and applications. Despite general trends towards more specialization among commercial fishers in Alaska, and more fishers exclusively targeting salmon, we find that catching fewer species can have positive effects on revenue. With increasing specialization, it is important to understand how individuals buffer against risk, as well as any barriers that prevent diversification. In addition to being affected by environmental variability, fishers are also affected by economic factors including demand and prices offered by processors. Life-history variation in the species targeted may also play a role. Individuals participating in Alaskan fisheries with high contributions of pink salmon — which have the shortest life cycles of all Pacific salmon — also have the highest variability in year-to-year revenue.

Catch quotas for walleye pollock Gadus chalcogrammus, the dominant species in the groundfish fishery off Alaska, are set by applying harvest control rules to annual estimates of spawning stock biomass (SSB) from age-structured stock assessments. Adult walleye pollock abundance and maturity status have been monitored in early spring in Shelikof Strait in the Gulf of Alaska for almost three decades. The sampling strategy for maturity status is largely characterized as targeted, albeit opportunistic, sampling of trawl tows made during hydroacoustic surveys. Trawl sampling during pre-spawning biomass surveys, which do not adequately account for spatial patterns in the distribution of immature and mature fish, can bias estimated maturity ogives from which SSB is calculated. Utilizing these maturity data, we developed mixed-effects generalized additive models to examine spatial and temporal patterns in walleye pollock maturity and the influence of these patterns on estimates of SSB. Current stock assessment practice is to estimate SSB as the product of annual estimates of numbers at age, weight at age, and mean maturity at age for 1983-present. In practice, we found this strategy to be conservative for a time period from 2003-2013 as, on average, it underestimates SSB by a 4.7 to 11.9% difference when compared to our estimates of SSB that account for spatial structure or both temporal and spatial structure. Inclusion of spatially explicit information for walleye pollock maturity has implications for understanding stock reproductive biology and thus the setting of sustainable harvest rates used to manage this valuable fishery.

Because fish stocks often straddle state, national, and international boundaries, there is a need to coordinate fishery management across jurisdictions. This is particularly important when the abundance or spatial distribution of the stock varies through time. This is best achieved when management objectives and strategies align, and there is coordinated decision‐making and catch accounting among jurisdictions such that each fish stock is managed over its full geographic range. However, legal constraints or differing management objectives may not permit such coordinated decision making and policy development. This study introduces a framework for effectively simulating fleet dynamics, fishery quota allocation, and the implications of alternative management strategies while allowing for determination of economically optimal management approaches at the community level. As a case study, an agent‐based model (ABM) was developed to examine the interplay between transboundary management scenarios on the economic viability of a nascent Alaska state‐waters trawl fishery for walleye pollock (Gadus chalcogrammus) in the Gulf of Alaska, given a longstanding federally managed fishery. Under conditions characteristic of the recent past, the management strategy that produced the best overall improvements, relative to status quo, involved a scenario that allows for community‐based cooperatives in federal‐waters and an open access strategy in state‐waters. This case study allows us to demonstrate more generally how using an ABM allows for quantifying the impacts of and informing managers on anticipated, and novel, results of alternative management strategies for complex socioecological systems before implementation. Recommendations for Resource Managers Agent‐based modeling provides a method to realistically simulate fleet behavior within a fishery. The approach enables a quantitative analysis of the effects of alternative management scenarios under consideration by policymakers. “Best practices” for fishery management should include simulation analysis of management alternatives before selection of the preferred alternative for real‐world implementation.

Ecosystem-based fishery management (EBFM) entails treating resource allocation and management as elements of a comprehensive framework that accounts for ecological linkages. The goal of EBFM is to maintain ecosystem resiliency in a manner that provides for the services desired e.g., fishery catch, species abundance, economic viability. Historically fisheries have been managed on a per species basis with a general focus on increasing or decreasing harvest rates. This management strategy often excludes meaningful processes such as interactions with other species, environmental changes, and economic effects of management changes. One feasible path for implementation of EBFM is through enhancement of existing single-species fishery management models. Contemporary age-structured stock assessment models generally use an estimate of spawning stock biomass (SSB), i.e., the biomass of female spawning fish, to approximate stock reproductive potential (RP). This approximation inherently assumes a proportional relationship between SSB and RP. Maturity at age or at length is a key aspect of reproductive biology that is central to estimating both RP and SSB. As a sequential augmentation to a single species management model the relationships among body condition, population abundance, the probability of being mature, relative fecundity, and environmental correlates were examined for female walleye pollock Gadus chalcogrammus in the Gulf of Alaska. Maturity data were corrected for spatial sampling bias using a mixed-effects generalized additive model. Once corrected for spatial bias, relationships between maturity, ocean temperature, body condition, ocean productivity (in the form of chlrophyll-a), and population abundance were explored. Estimates of fecundity were updated through the processing of archived samples and were also examined with mixed-effects generalized additive models to explore relationships between the previously listed covariates. Multiple measures of RP were examined to explore differences between methods currently incorporated into the stock assessment and updated measures of total egg production and time varying maturity. Walleye pollock body condition is density-dependent, declining with population abundance. However, after accounting for the effects of length, age, location, year, chlorophyll-a concentrations, summer ocean temperature and sample haul, condition has a positive effect on the probability of a fish being mature. Similarly, condition has a positive effect on relative fecundity, after accounting for length, age, egg diameter, chlorophyll-a concentrations, winter ocean temperature and sample haul. A positive relationship is observed between depth-integrated summer ocean temperature and maturity and depth-integrated winter ocean temperature and fecundity. Chlorophyll- a concentrations have a dome shaped relationship with maturity, peaking at 2.3 mg/m-3, and a negative relationship with fecundity. Variations in body condition have a direct influence on the estimated RP of the fish stock through both differences in the maturation schedule and total egg production. Over some periods these updated estimates of RP differ from estimates of female SSB from the annual stock assessment. Alternative estimates of annual RP, particularly total egg production, may provide better estimates of annual reproductive output than spawning stock biomass. In addition, relationships to density-dependent and density-independent factors provide informative predictions that can be incorporated into stock assessment analyses. Inclusion of spatially explicit information for walleye pollock maturity has implications for understanding stock reproductive biology and thus the setting of sustainable harvest rates used to manage this valuable fishery. Additionally, because management decisions have economic as well as biological consequences a suite of management strategies were simulated to examine the economic viability of a proposed small-vessel walleye pollock fishery in Alaska state waters in the Gulf of Alaska. As a case-study for straddling stocks, an agent-based model was developed to examine a suite of available federal and state management strategies as they relate to the economic viability of a nascent Alaska state-waters trawl fishery for walleye pollock that may develop after a long history of parallel state and federal waters management. Results of alternative strategies were compared in terms of indicators, such as variance of catch and quasi-rent value. Given the input characteristics of these simulations, the management strategy that produces the best overall improvements relative to status quo involved a federal-waters management strategy that allows for community-based cooperatives and an open access strategy in state-waters. Agent-based models may be used to inform managers of the underlying dynamics of catches and revenues in order to avoid unintended consequences of management decisions and to improve the likelihood of attaining fishery management objectives. This dissertation provides incremental additions to our knowledge of walleye pollock reproductive biology its spatial and temporal dynamics, and environmental correlates that may serve as ecological indices. These indices, coupled with an improved understanding of the socio-economic examinations of fishery management changes through agent-based modeling, may assist in producing more holistic management strategies, such as EBFM.

Vaccines are one of the most successful tools for protecting the public’s health. However, widespread vaccine hesitancy in the Southern United States is preventing effective mitigation of the current COVID-19 pandemic. The purpose of this study was to assess COVID-19 vaccine acceptance among adults living in a largely rural Southern state. This cross-sectional study collected data from 1,164 Arkansas residents between October 3 and October 17, 2020 using random digit dialing. The primary outcome was a multidimensional COVID-19 vaccine acceptance measure with scores between -3 to +3. The full COVID-19 vaccine acceptance scale was measured along with perceived vaccine safety, effectiveness, acceptance, value, and legitimacy subscales. Statistical analyses were conducted using multivariable linear regression. Results indicated Black participants had the lowest overall vaccine acceptance (0.5) compared to White participants (1.2). Hispanic participants had the highest scores (1.4). In adjusted models, Black participants had 0.81 points lower acceptance than White participants, and Hispanic participants had 0.35 points higher acceptance. Hispanic participants had the highest scores for all five vaccine acceptance subscales, relatively equivalent to White participants. Black participants had consistently lower scores, especially perceived vaccine safety (mean -0.2, SD 0.1). In conclusion, the lowest vaccine acceptance rates were among Black participants particularly on perceived vaccine safety. While Black participants had the lowest acceptance scores, Hispanic participants had the highest. This variability shows the value of a multidimensional vaccine acceptance measure to inform COVID-19 vaccination campaign strategies.

The Rocky Flats National Wildlife Refuge is located west of Denver, Colorado, USA along the central Front Range of the Rocky Mountains. The wildlife refuge property includes a former U.S. Department of Energy nuclear weapons facility, hereafter \"the former Rocky Flats site.\" Owing to the storage and use of aqueous film forming foam (AFFF) at the on-site fire department, industrial areas of the former Rocky Flats site has detectable concentrations of per- and polyfluoroalkyl substances (PFAS) in groundwater (range perfluorooctanesulfonic acid [PFOS]: not detected [ND] [<0.75]-350 ng/L, perfluorooctanoic acid [PFOA]: ND [<0.55]-160 ng/L) and surface water (range PFOS: 1.9-18 ng/L, PFOA: ND [<0.55]-13 ng/L). AFFF is a known source of PFOA and PFOS contamination in the environment. PFAS are a class of thousands of human-made chemicals considered ubiquitous in the environment globally. Exposure to these chemicals can negatively impact the health of both humans and wildlife. In March 2023, we used a draft version of the U.S. Environmental Protection Agency Method 1633 to analyze liver and muscle tissues from 17 Rocky Mountain elk (Cervus canadensis nelsoni) to detect the presence of PFAS. We collected samples from 15 elk residing at the former Rocky Flats site and 2 elk at locations with no known PFAS contamination (i.e., control locations). Neither PFOA nor PFOS was detected in elk muscle tissues collected at the former Rocky Flats site or the control locations. The average method detection limits for PFOA and PFOS in muscle tissues were 0.166 ng/g and 0.154 ng/g respectively. PFOS was detected within 100% of the liver tissues harvested from elk at the former Rocky Flats site and both control locations. The average PFOS concentrations in liver tissues collected at the former Rocky Flats site and control locations were 16.23 ± 4.40 ng/g (maximum concentration 34.20 ng/g) and 8.75 ± 3.02 ng/g (maximum concentration 9.40 ng/g), respectively. To the best of our knowledge, this is the first study examining PFAS concentrations in elk. Although we were unable to draw conclusions owing to the relatively small sample size, PFOS concentrations in liver tissues collected at the former Rocky Flats site were low, consistent with those detected in other species of wildlife studied in the United States with known PFAS contamination.

During periods of hydrologic stress, vegetation productivity is limited by soil moisture supply and atmospheric water demand. This study shows that atmospheric demand has a greater effect in many biomes, with implications for climate change impacts. Soil moisture supply and atmospheric demand for water independently limit—and profoundly affect—vegetation productivity and water use during periods of hydrologic stress 1 , 2 , 3 , 4 . Disentangling the impact of these two drivers on ecosystem carbon and water cycling is difficult because they are often correlated, and experimental tools for manipulating atmospheric demand in the field are lacking. Consequently, the role of atmospheric demand is often not adequately factored into experiments or represented in models 5 , 6 , 7 . Here we show that atmospheric demand limits surface conductance and evapotranspiration to a greater extent than soil moisture in many biomes, including mesic forests that are of particular importance to the terrestrial carbon sink 8 , 9 . Further, using projections from ten general circulation models, we show that climate change will increase the importance of atmospheric constraints to carbon and water fluxes in all ecosystems. Consequently, atmospheric demand will become increasingly important for vegetation function, accounting for >70% of growing season limitation to surface conductance in mesic temperate forests. Our results suggest that failure to consider the limiting role of atmospheric demand in experimental designs, simulation models and land management strategies will lead to incorrect projections of ecosystem responses to future climate conditions.

Healthcare systems in Africa suffer from neglect and underfunding, leading to severe challenges across the six World Health Organization (WHO) pillars of healthcare delivery. We conducted this study to identify the principal challenges in the health sector in Africa and their solutions for evidence-based decisions, policy development and program prioritization. The study was conducted as part of a recent African Epidemiological Association Meeting in Maputo, Mozambique with participants drawn from 11 African countries, Cuba, Portugal and the United Kingdom. Participants were divided into 10 groups, consisting of 7 to 10 persons each. Brainstorming approaches were used in a structured, modified nominal group process exercise to identify key challenges and strategies to mitigate healthcare service challenges in Africa. Identified challenges and solutions were prioritised by ranking 1-5, with 1 most important and 5 being least important. The first three challenges identified were inadequate human resources (34.29%), inadequate budgetary allocation to health (30%) and poor leadership and management (8.45%). The leading solutions suggested included training and capacity building for health workers (29.69%), increase budgetary allocation to health (20.31%) and advocacy for political support and commitment (12.31%). The underdeveloped healthcare systems in Africa need radical solutions with innovative thought to break the current impasse in service delivery. For example, public-private initiatives should be sought, where multinational companies extracting resources from Africa might be encouraged to plough some of the profits back into healthcare for the communities providing the workforce for their commercial activities. Most problems and their solutions lie within human resources, budget allocation and management. These should be accorded the highest priority for better health outcomes.