• Relative sea level change in western Alaska estimated from satellite altimetry and repeat GPS measurements

      DeGrandpre, Kimberly Grace; Freymueller, Jeffrey; Kinsman, Nicole; Nadin, Elisabeth (2015-08)
      Western Alaska is a remote region populated by small coastal communities that are sensitive to variations in local relative sea level (RSL). The focus of this thesis is to address two main questions; what are the RSL trends in Western Alaska and what are the geophysical processes that contribute to the changes observed? Quantification of RSL variation requires measuring vertical velocities for both land surface motion (onshore component) and the ocean surface (offshore component). This study presents a new method for coastal satellite altimetry estimation, the collection of historic water level measurements, analysis of tide gauge measurements from various sources, GPS vertical velocity model for Western Alaska, estimation of an Earth model and glacial isostatic adjustment (GIA) vertical velocities for Northern and Western Alaska, and RSL change model for Western Alaska. The findings of this study result in a GIA model that predicts measured GPS velocities well. The predicted GIA vertical velocities average -1.06 mm/yr in Western Alaska and are combined with the averaged satellite altimetry cells that exhibit a mean sea level change offshore of Western Alaska of -0.27 mm/yr to produce a RSL change model for Western Alaska that increases approximately +0.79 mm/yr in the region.
    • Reliability analysis of reconstructing phylogenies under long branch attraction conditions

      Dissanayake, Ranjan; Allman, Elizabeth; McIntyre, Julie; Short, Margaret; Goddard, Scott (2018-05)
      In this simulation study we examined the reliability of three phylogenetic reconstruction techniques in a long branch attraction (LBA) situation: Maximum Parsimony (M P), Neighbor Joining (NJ), and Maximum Likelihood. Data were simulated under five DNA substitution models-JC, K2P, F81, HKY, and G T R-from four different taxa. Two branch length parameters of four taxon trees ranging from 0.05 to 0.75 with an increment of 0.02 were used to simulate DNA data under each model. For each model we simulated DNA sequences with 100, 250, 500 and 1000 sites with 100 replicates. When we have enough data the maximum likelihood technique is the most reliable of the three methods examined in this study for reconstructing phylogenies under LBA conditions. We also find that MP is the most sensitive to LBA conditions and that Neighbor Joining performs well under LBA conditions compared to MP.
    • Remote sensing and GIS analysis of the spatial and morphological changes of thermokarst lakes: Kolyma lowlands, northeast Siberia

      Tillapaugh, Meghan L. (2011-05)
      Thermokarst lakes develop when changes in the permafrost thermal regime cause degradation leading to surface subsidence and ponding. The degree of thermokarst development depends upon permafrost characteristics, topography, and geology. Changing thermokarst lake dynamics affect arctic ecosystems, hydrological patterns, albedo, and the carbon cycle through the mobilization of organic matter in the permafrost. This study used remote sensing and GIS techniques to relate lake dynamics in the Kolyma Lowlands, Siberia, to geology, elevation, geomorphological features, hydrology, and air temperature. Highest limnicity and largest lake sizes were found in regions with low elevation, limited alluvial processes, high ground-ice content, and lithologies with small particle sizes. New lake development and erosion occurred as well. One subregion studied showed lake area increases (Cherskii: +7.6%) while another showed a decrease (Duvanny Yar: -5.2%). Differences are attributed to variations in elevation and fluvial influences. A major cause of drainage was river tapping of lakes. Lake coalescence, flooding during river water level high stands, and lakeshore erosion were the main causes of lake expansion. The Kolyma Lowland soils have high ice and organic matter contents as well making the monitoring of thermokarst lake dynamics important as large amounts of freshwater and carbon could potentially be released.
    • Remote Sensing of Arctic Landscape Dynamics

      Jones, Benjamin M.; Grosse, Guido; Arp, Christopher; Mann, Daniel; Romanovsky, Vladimir; Verbyla, David (2013-12)
      Amplified warming in the Arctic has likely increased the rate of landscape change and disturbances in northern high latitude regions. Remote sensing provides a valuable tool for assessing the spatial and temporal patterns associated with arctic landscape dynamics over annual, decadal, and centennial time scales. In this dissertation, I focused on remote sensing studies associated with four primary components of arctic landscape change and disturbance: (1) permafrost coastline erosion, (2) thermokarst lake dynamics, (3) tundra fires, and (4) using repeat airborne LiDAR for the measurement of vertical deformation in an arctic coastal lowland landscape. By combining observations from several high resolution satellite images for a 9 km segment of the Beaufort Sea Coast between 2008 and 2012, I demonstrated that the report of heightened erosion at the beginning of the 2000s was equaled or exceeded in every year except 2010 and that the mean annual erosion rate was tightly coupled to the number of open water days and the number of storms. By combining historical aerial photographs from the 1950s and 1980s with recent high-resolution satellite imagery from the mid-2000s, I assessed the expansion and drainage of thermokarst lakes on the northern Seward Peninsula. I found that more than half of the lakes in the study area were expanding as a result of permafrost degradation along their margins but that the rate of expansion was fairly consistent (0.35 and 0.39 m/yr) between the 1950s and 1980s and 1980s and mid-2000s, respectively. However, it appeared that in a number of instances that expansion of lakes led to the lateral drainage and that over the 55-year study period the total lake area decreased by 24%. While these studies highlight the utility of quantifying disturbance during the remotely sensed image archive period (~1950s to present) they are inherently limited temporally. Thus, I also demonstrated techniques in which field studies and remote sensing data could be combined to extend the identification of landscape disturbance events that occurred prior to the remote sensing archive. I identified two large regions indicative of past disturbance caused by tundra fires on the North Slope of Alaska, which doubled the delineated area of tundra fire disturbance on the North Slope over the last 100 to 130 years. I conclude the dissertation by demonstrating the utility of repeat airborne light detection and ranging (LiDAR) data for arctic landscape change studies, in particular vertical surface deformation, and provide momentum for going forward with this emerging technology for remote sensing of arctic landscape dynamics. The quantification of arctic landscape dynamics during and prior to the remote sensing archive is important for ongoing monitoring and modeling efforts of the positive and negative feedbacks associated with amplified Arctic climate change.
    • Remote sensing of burn severity and the interactions between burn severity, topography and vegetation in interior Alaska

      Epting, Justin Frederick (2004-08)
      A variety of single-band, band ratio, vegetation index, and multivariate algorithms were evaluated for mapping burn severity using Landsat TM and ETM+ imagery across four burns in interior Alaska. The Normalized Burn Ratio (NBR) outperformed all algorithms, both when tested as a single post-fire value and when tested as a differenced (prefire-postfire) value. The NBR was then used to map burn severity at a historical burn near Yukon-Charley Rivers National Preserve and a time-series of images from 1986 to 2002 was analyzed to investigate interactions between vegetation, burn severity, and topography. Strong interactions existed between vegetation and burn severity, but the only topographic variable that had a significant relationship with burn severity was elevation, presumably due to the strong control of elevation on vegetation type. The highest burn severity occurred in spruce forest, while the lowest occurred in broadleaf forest. Areas with high burn severity experienced disproportionately more shifts toward spruce woodland and shrub classes, while areas with low to moderate severity were less likely to change vegetation type. Finally, vegetation recovery, estimated using a remotely-sensed vegetation index, peaked between 8-14 years post-fire, and recovery was highest for areas with the highest burn severity.
    • Remote sensing of erosion and shallow water bathymetry to aid river navigation on the Colville River, Nuiqsut AK

      Payne, Cole S.; Panda, Santosh; Prakash, Anupma; Brinkman, Todd (2018-08)
      The Colville is the longest river (~600 km) in Arctic Alaska. Nuiqsut is an established Alaska Native community of ~400 people on the Colville River. Its residents rely heavily on the Colville for subsistence needs, however, changing river dynamics caused by accelerated bank erosion, river siltation, low water, and shifting and drying channels are causing concern and making boat travel increasingly difficult and dangerous. Recently, local residents have reported increased erosion at bluff sites along the Colville, which threatens existing infrastructure. Also reported are unexpected shallow water sections along the main channel of the Colville, limiting their access to subsistence food sources. Residents have expressed a need for monitoring erosional rates on the Colville as well as a map product that could aid in river navigation. These concerns shaped the main goals of this Thesis: 1) To use remote sensing techniques to map and quantify erosion rates and the volume of land loss at selected bluff sites along the main channel of the Colville, and to assess the suitability of automated methods of regional erosion monitoring. 2) To use optical satellite images for mapping river bathymetry and generate GIS map products that show potential shallow water sections (<2m) and poor channel connections, and to assess the feasibility of future monitoring based off our methods that rely on extracting relative water depth values from publicly available optical remote sensing images. For our erosional study we used orthomosaics from high resolution aerial photos acquired in 1955 and 1979/1982, as well as high resolution WorldView-2 images from 2015 to quantify long-term erosion rates and the cubic volume of erosion. We found that, at the selected sites, erosion rates averaged 1 to 3.5 m per year. The erosion rate remained the same at one site and increased from 1955 to 2015 at two of the four sites. We estimated the volume of land loss to be in the magnitude of 166,000 m³ to 2.5 million m³ at our largest site. We also found that estimates of erosion were comparable for manual hand-digitized and automated methods, suggesting our automated method was effective and can be extended to monitor erosion at other sites along river systems that are bordered by bluffs. For our bathymetry study we used summer 2017 scenes from three optical sensors (PlanetScope 3m, Sentinel 2 10m, and Landsat 30m) along with field measurements on the river to map shallow water bathymetry along a 45 km stretch of the Colville. We found a strong correlation (R²=0.89) between field-measured water depths and image-derived reflectance quantity (natural log ratio of green over red bands). We analyzed the two essential criteria for suitable bathymetry mapping from optical images: clear weather and clear water conditions. We expect several days (≈16) of suitable conditions during the ice-free season to facilitate reliable bathymetry mapping and remote monitoring of shallow water sites. We also discuss a relative depth mapping technique which is useful for boat navigation in the absence of ground truth measurements. We deliberately employed simple and robust empirical techniques that could serve as a basis for a fully developed river monitoring project in the near future led by local community residents. An implementation of our methods by the community, in order to develop a river depth monitoring program, would be an important step forward for the advancement of community-based science and the co-production of knowledge. Our technique may help address emerging environmental and societal issues in other regions where sufficient river navigation fosters local livelihoods.
    • Remote sensing of lake dynamics in Alaska

      Lindgren, Prajna R.; Grosse, Guido; Walter Anthony, Katey M.; Meyer, Franz J.; Romanovsky, Vladimir E. (2016-05)
      Lakes are abundant in high northern latitude permafrost regions. They are important ecosystem components forming a complex and dynamic landscape with repeated cycles of lake formation and drainage affecting regional hydrological and terrestrial characteristics, biogeochemical processes and carbon cycling, wildlife habitats, and human communities living in the permafrost region. Remote sensing is a useful tool to map the spatial distribution of lakes and assess its change, understand lake dynamics, and to extract useful information to study their associated feedbacks in a changing climate. In this dissertation, I focused on remote sensing studies associated with (1) methane ebullition from a thermokarst lake, (2) post-drainage succession patterns in drained thermokarst lake basins, and (3) lake change dynamics. I developed a semi-automatic classification method based on an Object-based Image Analysis (OBIA) framework to detect methane ebullition bubbles trapped in a snow-free ice-covered lake using high-resolution airborne images of Goldstream lake, Fairbanks, Alaska acquired following freeze up in October of 2011 and 2012. This study showed that remote sensing is a valuable tool to map ebullition bubbles (bubble patches) on the entire lake surface with an accuracy of > 95%, a task that is difficult to achieve through field-based survey alone. The image analysis performed by combining the mapping results from the OBIA and field-based observations showed a relationship between bubble patch brightness and ground-measured methane flux, which was then used to estimate the whole-lake methane flux. A strong inverse exponential relationship (R2 >= 0.79) was found between the percent of the surface area of lake ice covered with bubble patches and distance from the active thermokarst lake margin, indicating high methane production as a response to thermokarst activity that released labile organic-rich carbon along the eroding lake margin. Despite the influence of atmospheric pressure conditions on distribution of ebullition bubble patches following the lake freeze-up events, the spatiotemporal regularity of bubble patches revealed that a larger number of seeps are stable over at least annual timescales. This remote sensing technique is applicable to other regions for mapping ebullition bubbles trapped in snow-free ice-covered lakes, identifying their relative flux, and assessing their spatiotemporal dynamics. By using TerraSAR-X (TSX) Synthetic Aperture Radar (SAR) backscatter data and the Normalized Difference Vegetation Index (NDVI) derived from a Landsat-5 image from the year 2009, I characterized drained thermokarst lake basins (DTLBs) of various age ranging between 0 to 10,000 years since drainage in the northern Seward Peninsula, Alaska. In the study I found logarithmic relationships of basin age from 0 to 10,000 years with mean basin TSX backscatter (R2 = 0.36) and with mean basin NDVI (R2 = 0.53). However, TSX data performed much better to discriminate older basins in the age class 50–10,000 years with R2 = 0.58, while no significant relationship was found between NDVI and basin age. Results of this study demonstrated the potential application of X-band SAR data in combination with NDVI data to enhance differentiation of soil moisture and vegetation status on drained basins for mapping long-term succession dynamics of DTLBs. Finally, I demonstrated the utility of Landsat imagery to identify lake distribution patterns and changes between 1972 and 2014 in six major lake-rich study regions across various permafrost zones covering an area of 68,830 km2 in western Alaska. Even though lake area change was found to be positive (increase by less than 4%) in some study areas while negative (decrease by 4-15%) in others, there was a widespread drainage of mainly large lakes in all regions creating remnant ponds that increased the abundance of lakes <10 ha in all study regions by 2-27%. The average lake area decline observed in various permafrost zones did not represent the trend of individual sites due to spatial heterogeneity in lake characteristics. While lake drainage dominated the non-continuous permafrost zones, areas of continuous permafrost showed both trends of negative and positive lake area change accompanied by major lake drainage events that led to a regional lake area loss in the continuous permafrost zone. This remote sensing technique proved to be useful in identifying ongoing lake drainage and expansion events within study regions and a regional shift in lake distribution (i.e. lake area loss) that is happening in western Alaska. Based upon my research, there is an immense opportunity to use and combine various remote sensing tools to study lake dynamics and to evaluate associated environmental changes. Future work should be directed towards collaborative research for combining field-based observations and remote sensing tools to improve the understanding of how lakes and drained lake basins change in a changing climate as well as extend the scale of observations of methane ebullition features by covering many lakes in an environmentally diverse set of regions. This will guide us to understanding the feedback of lake dynamics to the surrounding ecosystem, global carbon budget, and to upscale the response of lakes to changing climate and permafrost environments to larger regions.
    • Remote sensing of surface albedo and cloud properties in the Arctic from AVHRR measurements

      Han, Wei; Stamnes, Knut; Bowling, Sue Ann; Harrison, William; Li, Shusun; Lubin, Dan; Watkins, Brenton (1996)
      Based on a comprehensive radiative transfer model, algorithms suitable for arctic conditions are developed to retrieve broadband surface albedo and water cloud properties from National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) narrowband measurements. Reflectance anisotropy of snow surfaces is first simulated by an discrete ordinates radiative transfer formulation, and is then included in the comprehensive model for the retrieval. Ground-based irradiance measurements made by NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) in Barrow, Alaska are compared with retrieved albedo and downwelling irradiances computed from retrieved cloud optical depth and effective radius. Good agreement is found between satellite estimates and ground-based measurements, which indicate that the retrieval algorithms proposed in this thesis are suitable for arctic conditions. It is found that the effects of snow bidirectional reflectance on the retrieval of the broadband albedo are significant, and that the Lambertian approximation could lead to a 30% underestimate of the surface albedo. It is also found that cloud effective radius in the Arctic is generally smaller as compared with mid- and low-latitudes.
    • A remote sensing-GIS based approach for assessment of chinook salmon rearing habitat in the Unuk river floodplain

      Smikrud, Kathy M. (2007-05)
      Remote sensing offers an alternative method to managers in mapping and monitoring the habitat within large rivers. Large rivers are not accommodating for traditional (foot) fish habitat surveys due to their size and typically complex habitat. This study investigates the use of digital aerial photos and thermal infrared images acquired in spring 2003-2005 to map and quantify juvenile chinook salmon (Oncorhynchus tshawytscha) habitat in a 12-river km section of the Unuk River floodplain in Southeast Alaska. Images were processed and analyzed to produce a fluvial landscape classification (7 landcover classes with an overall classification accuracy of ~84%) using a combination of aerial and thermal images. Change detection of large woody debris (LWD) was also examined and revealed both quantitative and distributional changes during the 3 years. A GIS-based habitat suitability analysis was used to identify potential chinook salmon rearing habitats including: river channel edges, sloughs, braids, pools associated with LWD and primary river channels. Overall 77.82 hectares of potentially medium/high chinook rearing habitats were identified. Results from this study provide a promising foundation towards mapping and monitoring salmon habitat in large river systems for purposes of protection, conservation and monitoring to ensure sustainable stocks of salmon.
    • Remotely accessible hardware-in-the-loop robot simulator

      Turan, Ali (2006-08)
      In this thesis, a novel and remotely accessible hardware-in-the-loop simulator (HILS) is developed for the real-time simulation of a variety of robotic systems for on-site and remote education and research. In that sense, the thesis contributes to the first known application of the HILS concept in the field of robotics and mechatronics that is remotely accessible. The HILS set-up incorporates most of the crucial hardware that takes part in the actual mechatronics/robotics system, thus enabling a more realistic simulation of the dynamics and control than would be possible with computer simulations. Any given robotic configuration can be simulated by using the developed HILS set-up, thus enhancing the flexibility and repertoire of expensive robotics laboratories. Besides the establishment of the hardware/software of the HILS setup, the major contribution of this thesis is the developed communication method between client and server that enables remote users to perform experiments on the HILS setup at the UAF Robotics and Control Laboratory. The main communication code is written in C/C++ with the use of wxWidgets. The protocol used in this study is TCP/IP for the sequential and error-free transmission of data. The MATLAB® Engine is used to establish the link between MATLAB® and the C/C++ code. For data capturing, a code is written in Python® programming language, which is compatible with ControlDesk. Finally, animations are prepared using the V-Realm Builder for the data collected from HILS experimentation. The experimentation results are sent to remote users as mat files, jpeg files and animations. The developed communication method can be used with all systems using MATLAB® Simulink® and is not limited to use with the HILS system only. Several case studies developed remotely (via the use of the internet) are also presented in the thesis as remote lab experiment and animation examples.
    • Renewable energy development in Alaska: policy implications for the development of renewable energy for remote areas of the circumpolar Arctic

      Holdmann, Gwen Pamela; Johnson, Ronald; Peterson, Rorik; Greenberg, Joshua; Sfraga, Mike (2019-12)
      The territories that comprise the Arctic region are part of some of wealthiest and most advanced countries on the planet; yet, rural Alaska, northern Canada, the Russian Far East and Greenland--characterized by off-grid communities, regional grids, and higher degrees of energy insecurity--have more in common with the developing world than the southern regions of their own country. This thesis explains this paradox of energy development in the Circumpolar North and tackles the issue of developing renewable energy in remote areas where technical and socioeconomic barriers are significant. The primary research questions are two-fold: 1) Why did the Alaska electrical system develop as a non-integrated patchwork of regional and isolated grids? and 2) What are the major factors in Alaska that have resulted in a greater uptake of renewable energy systems for remote communities, compared to other similar places in the Arctic? This thesis demonstrates that state-building theory provides a cogent framework to understand the context of electrical build-out in the Circumpolar North. A major finding of this thesis is that the buildout of electric infrastructure in the non-Nordic countries, including Alaska, exemplifies a process of incomplete nation-building. Interconnected regional grids, where they exist, are largely due to the twin national priorities in infrastructure development in the north: extracting natural resources and enhancing national security. This thesis also draws on sociotechnical transition theory to explain why Alaska exhibits such high levels of energy innovation when compared to other similar regions across the Arctic. This research concludes that drivers such as extremely high energy costs, a highly deregulated utility market with dozens of certificated utilities, state investment in infrastructure, and modest subsidies that create a technological niche where renewable energy projects are cost-competitive at current market prices have spurred energy innovation throughout Alaska's communities, remote or otherwise. Many of the evolving technical strategies and lessons learned from renewable integration projects in Alaska's remote islanded microgrids are directly applicable to project development in other markets. Despite differences in climate and geography, lessons learned in Alaska could prove invaluable in increasing resiliency and driving down energy costs in remote communities world-wide.
    • Representation and marginalization: a case study from contemporary Alaska Native art

      Biddison, Dawn Drake; Lee, Molly; Jonaitis, Aldona; Koester, David (2002-12)
      In Alaska, contemporary Native artists are creating compelling works of art, yet, in the literature and exhibitions about Native North American contemporary art, Alaska Native art receives little if any attention. In this study, I assess how contemporary Alaska Native art is presented to the public to evaluate whether these representations marginalize this artwork. I examine the creation, exhibition and reception of contemporary Alaska Native art based on the perspectives of the artists, exhibit evaluations and viewer responses. My goal in this study is to substantiate the need to address the way Alaska Native art is presented and to analyze current practices. In particular, I seek to emphasize the importance of creating contextualized presentations of contemporary Alaska Native art using multiple perspectives and interpretive media based on collaboration between the exhibitors of public art and Native artists and communities. By creating more inclusive, informative representations of Alaska Native art, presentations can begin to address the differing requirements of a variety of audiences, utilize the critical attention given to Native American and Euro-American art elsewhere and provoke a re-thinking of preconceptions that continue to diminish the accomplishments of Alaska Native artists.
    • Reproductive and larval biology of northern shrimp, Pandalus borealis Kroyer, in relation to temperature

      Nunes, Pepsi (1984-05)
      The northern shrimp, Pandalus borealis Kr^yer, is an important fishery resource in Alaska. However, a drastic decline in the commercial catch since 1978 poses a serious problem for the fishery. This study examined the effects of temperature on reproduction and larval survival of P. borealis. These are factors though to be vital to the determination of year class strength. P. borealis was found to have narrow thermal requirements for egg production with moderate (6°C) to low (3°C) temperatures generally more favorable than high (9°C) temperatures. In contrast with egg production, larval survival was enhanced by higher (6 and 9°C) temperatures. This study provides useful information for management of the fishery by demonstrating that temperature can trigger flucuations in the commercial catch from 5-50% through its effects on rates or reproduction and larval survival, and thereby population size. In warm water areas averaging >6°C, temperature exerts its main influence on reproduction, causing fecundity to vary by as much as 50%. While in colder areas average <3°C, fecundity and larval survival can vary with temperature by as much as 20 and 40%, respectively. Use of the information derived here requires monitoring temperature in the major fishery areas to detect changes in abundance of ovigerous females, egg number and larval mortality. Changes in these parameters are valuable indicators of stock condition when combined with abundance surveys and fishing intensity estimates.
    • Reproductive behavior and related social organization of the muskox on Nunivak Island

      Smith, Timothy E. (1976-05)
      The sexual behavior and social organization of the muskox (Ovibos moschatus wardi Zimmerman) were studied on Nunivak Island, Alaska, in fall 1972 and summer and fall 1973. Observation effort was concentrated on a single harem group for two months, during the height of courtship activity. Movements and fluctuations in the structure of this group are documented. There was no significant change in mean herd size as a result of the rut, suggesting the existence of a basic social unit independent of the influence of harem bulls. Harem bulls were in the 6-10 year age class. They exerted a stabilizing influence on the harem but did not direct its movements. The rut extended from early July to mid-October. Copulation occurred on September 4 and 5. General patterns of sexual and agonistic behavior are described. Changes in activity patterns as a result of the rut are shown. Bulls displayed more marked changes than cows or juveniles. The proportion of time allocated to sexual and agonistic behavior increased at the expense of maintenance activity as the rut progressed.
    • The reproductive biology and management of walleye pollock (Gadus chalcogrammus) in the Gulf of Alaska

      Williams, Benjamin C.; Kruse, Gordon; Criddle, Keith; Dorn, Martin; Quinn, Terrance II (2018-08)
      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.
    • Reproductive cycle of the dungeness crab, Cancer magister, in Southeastern Alaska

      Swiney, Katherine Marie (1999-12)
      This study examined if female Dungeness crabs in Alaska reproduce annually. Crabs (287) were reared in flow-through tanks for one year and gonadosomatic indexes (GSI) and oocyte areas were calculated for seven months. Non-reproducing females had higher GSI and oocyte areas than reproducing females (<0.0001); resorption of gonads was observed. Male GSI varied significantly over the year. Crabs (27,506) were sampled with commercial pots and scuba in April and September in Glacier Bay, Alaska from 1992 to 1998. A large percentage (86%) of non-ovigerous females were observed in the spring when females should be brooding eggs. Molting probability is reduced as females become larger and they rely on stored sperm to fertilize eggs. A tagging study confirmed some females skip at least one mating season and extrude eggs in another season without ecdysis. This study demonstrated not all mature female Dungeness crabs in Alaska, especially larger females, reproduce annually.
    • Reproductive decisions by black brant: mechanisms to synchronize hatch and spatial variation in growth rates of goslings

      Nicolai, Christopher Andrew (2003-08)
      I investigated two aspects of reproductive decisions in Black Brant: synchronous hatch within clutches and areas in which to rear their broods. It has been hypothesized that Anatidae facilitate a synchronous hatch through vocalizations among embryos within the same clutch. I performed manipulative experiments in which variation was controlled for both genetic and incubation pattern sources in incubation period length. Our results suggest that vocalizations are not responsible for a synchronous hatch, and I suggest that inherent properties of the eggs themselves are responsible for a synchronous hatch. Additionally, I compared gosling growth rates from areas of low nest densities with those from a main colony to test the hypothesis that broods using dispersed areas were escaping density dependent effects. I found that goslings from dispersed nesting areas did not escape density dependent effects and may actually constitute a sink for the population from additional effects of increased nest mortality in dispersed nesting area.
    • Reproductive ecology and morphometric subspecies comparisons of Dunlin (Calidris alpina), an arctic shorebird

      Gates, Heather River; Powell, Abby N.; Hunter, Christine M.; Lanctot, Richard B. (2011-12)
      The Arctic region provides globally important breeding and migratory habitat for abundant wildlife populations including migratory shorebirds. Due to their remote breeding locations, basic information on breeding ecology, annual productivity, and factors that regulate their populations are poorly studied. Wildlife biologists managing migratory bird populations require detailed information on avian breeding biology, in addition to information on migration ecology including connectivity of migratory stopover and wintering locations. To address information gaps in fecundity, I conducted an experimental study investigating the renesting ecology of Dunlin (Calidris alpina arcticola) by removing clutches at two stages of incubation and by following adults marked with radio transmitters to their replacement clutch. In contrast to predictions for arctic-breeding species, Dunlin had high (82-95%) rates of clutch replacement during early incubation and moderate (35-50%) rates during late incubation. Female body condition and date of clutch loss were important variables explaining propensity for females to replace a clutch; larger females that lost their nest early in the season were more likely to renest than smaller females who lost their nest later in the season. To delineate Dunlin subspecies in areas where they overlap, I used morphological and molecular approaches to determine sex and subspecies of five subspecies of Dunlin breeding in Alaska and eastern Russia. This analysis yielded discriminant function models to correctly classify unknown individuals to sex (79-98%) and subspecies (7385%) via morphometric measures. Correct classification of mixed assemblages of subspecies improved when sex, determined though molecular techniques, was known. The equations I derived using discriminant function models can be used to identify the sex and subspecies of unknown Dunlin individuals for studies investigating breeding and migration ecology.
    • Reproductive indices of male snow crab, Chionoecetes opilio, from the Eastern Bering Sea

      Zaleski, Marilyn Fox; Tamone, Sherry L.; Kruse, Gordon; Eckert, Ginny (2012-08)
      The reproductive success of male snow crab (Chionoecetes opilio) is complicated by two different life history stages; male C. opilio undergo a terminal molt prior to adulthood which is marked by an allometric change in chela size. While adolescent males can produce spermatophores, terminally molted males are most successful in mating and reproduction. Molting and mating are hormonally linked, with molting regulated primarily by ecdysteroids and mating regulated by the putative reproductive hormone methyl farnesoate (MF). Methyl farnesoate is structurally related to the insect juvenile III hormone and, in addition to reproduction, may have a role as a juvenilizing hormone in crustaceans. The purpose of this study was to determine how molting affects the reproductive biology of snow crab by comparing the gonadosomatic index(GSI) and concentrations of circulating MF in adolescent and adult males. I used shell condition as a rough estimate of time post molt to compare GSI and MF between new-shell males, those that had molted within one year, and old-shell males, those that had not molted for at least 1 year. I measured GSI as the ratio of gonad weight to whole crab weight and used GSI as a proxy for reproductive fitness; I quantified circulating MF using high performance liquid chromatography. New-shell adolescent and adult males had significantly lower GSI than old-shell males; thus molting compromises the reproductive physiology of male C. opilio. New-shell adolescent males had significantly higher MF levels than old-shell adolescent males, and MF levels remained low after the terminal molt, supporting a juvenilizing role for MF in C. opilio.