• Factors affecting body mass of prefledging emperor geese

      Lake, Bryce Cameron (2005-08)
      Body mass of pre fledging geese has important implications for fitness and population dynamics. To address whether interspecific competition for forage was broadly relevant to prefledging emperor geese, I investigated the factors affecting body mass at three locations across the Yukon-Kuskokwim Delta, Alaska. From 1990 - 2004, densities of cackling geese more than doubled and were 2-5x higher than densities of emperor geese, which were relatively constant over time. During 2003 - 2004, body mass of emperor geese increased with net above-ground primary productivity (NAPP) and grazing lawn extent and declined with interspecific densities of geese (combined density of emperor and cackling geese). Grazing by geese resulted in consumption of 90% of the NAPP that occurred during the brood rearing period, suggesting that interspecific competition was due to exploitation of common food resources. At six sampled locations, grazing lawn extent varied among- and within-locations, and was stable or declined slightly during 1999-2004, indicating reduced per capita availability. I conclude that negative effects of interspecific goose densities on body mass of pre fledging geese are partially responsible for recent declines in the fall age ratio of emperor geese because of a positive correlation between body mass and survival to fall staging areas. Management to increase the population size of emperor geese should consider interspecific densities of geese and interactions between interspecific densities and forage.
    • Feeding ecology of black oystercatcher (Haematopus bachmani) chicks

      Robinson, Brian H.; Powell, Abby; O'Brien, Diane; Konar, Brenda (2016-05)
      The Black Oystercatcher is an internationally recognized bird species of conservation concern and the focus of multiple monitoring programs due its small global population size, restricted range, vulnerability to human and natural threats in nearshore marine ecosystems, and the important role it plays as a top-level consumer in the intertidal food web. I studied a population of Black Oystercatchers in Kenai Fjords National Park, Alaska in 2013 and 2014, examining variation in chick diet, assessing methods used to monitor diet, and investigating the influence of provisioning on brood survival. To better understand the biases and limitations associated with the quantification of prey remains, I compared diet estimates from prey remains with two other methods: direct observation of adults feeding young, and diet reconstruction by stable isotope analysis. Estimates from collected prey remains over-represented the proportion of limpets in the diet, under-represented the proportion of mussels and barnacles, and failed to detect soft-bodied prey such as worms. I examined age- and habitat-specific variation in chick diet and found no relationship between diet and age of chicks; however, diet differed between gravel beach and rocky island nesting habitats. To determine the importance of diet on brood survival, I modeled daily survival rates of broods as a function of energy intake rate and other ecological factors and found that broods with higher intake rates had higher growth rates and daily survival rates. Given the consequences of reduced energy intake on survival, changes in the abundance and composition of intertidal macroinvertebrates as a result of climate change may have significant impacts on Black Oystercatcher populations. These findings highlight the importance of diet and provisioning to chicks and identify limitations of using prey remains to characterize Black Oystercatcher diet.
    • Foods and foraging ecology of oldsquaws (Clangula hyemalis L.) on the arctic coastal plain of Alaska

      Taylor, Eric John (1986-09)
      The study was conducted from June to September during 1979 and 1980 in the the West Long Lake area of the National Petroleum Reserve-Alaska. Additional oldsquaws were collected in the inland wetlands near the northwest boundary of the reserve at Ice Cape. West Long Lake and the adjacent Goose Lake are located 15 miles south of the Beaufort Sea and immediately west of Teshekpuk Lake.
    • Foraging behavior of caribou on a calving ground in northwestern Alaska

      Kuropat, Peggy JoAnn (1984-12)
      Habitat selection, foraging behavior, and forage intake rates by caribou were studied on a calving ground in northwestern Alaska. The pattern of emergence of new plant growth determined habitat use. The grazing pattern reflected a balance between selection for nutrients and plant biomass, and avoidance of plant secondary metabolites. Habitat use was also influenced by predator avoidance. At the time of calving, meteorological conditions provide a snow-free "window" of available Eriophorum vaginatum inflorescences that are of high nutritive value. Subsequently, topographic variation results in a diversity of forbs and shrubs confined in time and space at the time of peak nutritional demands for lactation and growth of calves during June. Intake of deciduous shrub leaves averaged 3.7 g/min and the intake of E. vaginatum inflorescences was 1.1 g/min. Highest observed intake was 5.5 g/min on forbs. Forage selected was of high nutritive value and high digestibility. Thus, caribou selected productive microsites and habitats where intake of preferred forage could be maximized.
    • Genetic variation in muskoxen (Ovibos moschatus)

      Fleischman, Claire L. (1986-05)
      Populations of Alaskan muskoxen (Ovibos moschatus) are derived from 34 animals transplanted from East Greenland in the 1930s. The possibility of a founder effect following this transplant was investigated. Muscle, liver and plasma samples from 87 Alaskan animals and 39 Greenlandic animals were analyzed using polyacrylamide and starch gel electrophoresis. A total of 38 enzyme and non-enzymatic protein systems, coded by 58 presumptive loci, was tested for activity; 28 loci were considered usable. One locus (Esterase-2) was polymorphic; the proportion of polymorphic loci was 0.036 (95% criterion). The mean heterozygosity per individual was 0.006 in the Greenlandic population and 0.011 in the Alaskan population. The allele frequencies at the Est-2 locus were similar in both populations. No heterozygote deficiency and no evidence of a founder effect were seen in the Alaskan population. This may be a consequence of the low level of allozymic variation seen in muskoxen in general.
    • Geomorphology and inconnu spawning site selection: an approach using GIS and remote sensing

      Tanner, Theresa Lynn; Margraf, T. Joseph; Wipfli, Mark S.; Verbyla, David (2008-08)
      This study examined the spatial components of inconnu Stenodus leucichthys spawning habitat use in the Selawik River, Alaska. Little is known about inconnu critical habitat needs; however, current studies of inconnu spawning behavior suggest a high level of habitat selectivity. This level of selectivity implies that there are specific habitat characteristics that these fish require for spawning. The purpose of this study was to build a heuristic habitat model that can be used to better understand inconnu spawning site selection in remote Alaskan watersheds. Using readily available, low- or no-cost remote sensing data layers, geographical information systems (GIS) were used in conjunction with multivariate statistics in an attempt to clarify relationships between geomorphologic features and spawning site selection. Spatial resolution of the remotely sensed data available in this study did not provide sufficient spatial detail to generate statistical correlations between spawning habitat selection and landscape characterizations. However, spawning occurred in areas of transition from high to low gradients, and in reaches typified as having very low slopes with very high sinuosity. Additionally, exploratory use of Radarsat fine beam 1 data favored its future application in fisheries investigations. This study is an initial step toward more research into inconnu spawning habitat.
    • Growth and Energetic Condition of Dolly Varden Char in Coastal Arctic Waters

      Stolarski, Jason T.; Prakash, Anupma; Sutton, Trent; Margraf, Joseph; Rosenberger, Amanda (2013-05)
      Dolly Varden char Salvelinus malma are a dominant member of the nearshore Arctic icthyofauna and support one of the largest subsistence fisheries within Arctic coastal communities in Alaska. Despite this importance, numerous aspects of Dolly Varden ecology remain poorly understood, which inhibits efforts to assess the biological consequences of anthropogenic disturbances such as hydrocarbon extraction and climate change within nearshore areas. The goal of this research was to develop and apply new techniques to measure and assess the biological integrity of Dolly Varden populations. To do so, I evaluated the precision of age determination generated from scales, otoliths, and fin rays, developed and validated bioelectrical impedance analysis (BIA) models capable of predicting non-lethal estimates of Dolly Varden proximate content, calculated and correlated retrospective estimates of Dolly Varden growth from archived otolith samples to broad-scale environmental variables, and investigated trends in whole body and tissue proximate content among years and demographics (i.e. reproductive versus non-reproductive individuals). Dolly Varden age determinations can be produced non-lethally using scales for fish up to age 5, while otoliths should be used for fish age 6 and greater. Multi-surface BIA models produced estimates of whole body proximate content with high precision. Retrospective growth analyses indicated growth increased significantly during the early 1980s, and was positively correlated to air temperature, sea surface temperature, and discharge and negatively correlated to ice concentration. Analyses of proximate content suggested that non-reproductive fish contained greater lipid concentrations than reproductive fish. Growth and condition analyses suggest that these metrics vary among years and are a function of reproductive cycles and environmental variability operating at multiple temporal and spatial scales. The adoption of scale-based aging and BIA technology will increase the precision of age-based biological statistics and aid in the detection of change within future Dolly Varden research and monitoring.
    • Growth and maturity of the Pacific razor clam in eastern Cook Inlet, Alaska

      McKellar, Jamie M.; Sutton, Trent; Iken, Katrin; Horstmann-Dehn, Lara; Hardy, Sarah; Erickson, Jack (2014-12)
      In Alaska, the only road-accessible fishery for the Pacific razor clam, Siliqua patula, is located in eastern Cook Inlet, and has been monitored by the Alaska Department of Fish & Game (ADF&G) since 1964. In recent years, a shift has been observed in size, age, and number of clam cohorts in this region, yet little is known about the early life history of razor clams in this region. This study aimed to provide information on length and age at maturity, growth rates, and spawn timing at two beaches in eastern Cook Inlet, Ninilchik and Clam Gulch, in 2009 and 2010. At Clam Gulch, only 20% of the sampled population was reproductive, compared with 83% at Ninilchik. At Ninilchik, clams were reproductive at a smaller size and younger age (p<0.05) than previously documented. The Ninilchik clams grew faster and had a larger size at age (p<0.05) than at Clam Gulch. A body condition index of clams from Clam Gulch was consistently 50% lower than at Ninilchik. Despite the relative proximity (25 km) of these locations, it is possible that environmental conditions may be different, resulting in differences in growth and reproductive output. This information is of special interest to fisheries managers as they address recent declines in the eastern Cook Inlet razor clam population and provides a benchmark for future management decisions.
    • Growth of juvenile chinook salmon (Oncorhynchus tshawytscha) as an indicator of density-dependence in the Chena River

      Perry, Megan T. (2012-08)
      In management of Pacific salmon, it is often assumed that density-dependent factors, mediated by the physical environment during freshwater residency, regulate population size prior to smolting and outmigration. However, in years following low escapement, temperature may be setting the upper limit on growth of juvenile chinook salmon Oncorhynchus tshawytscha during the summer rearing period. Given the importance of juvenile salmon survival for the eventual adult population size, we require a greater understanding of how density-dependent and independent factors affect juvenile demography through time. In this study we tested the hypotheses that (1) juvenile chinook salmon in the Chena River are food limited, and (2) that freshwater growth of juvenile chinook salmon is positively related with marine survival. We tested the first hypotheses using an in-situ supplemental feeding experiment, and the second hypothesis by conducting a retrospective analysis on juvenile growth estimated using a bioenergetics model related to return per spawner estimates from a stock-recruit analysis. We did not find evidence of food limitation, nor evidence that marine survival is correlated with freshwater growth. However, we did find some evidence suggesting that growth during the freshwater rearing period may be limited by food availability following years when adult escapement is high.
    • Growth of young-of-the-year salmonids in the Chena River, Alaska

      Walker, Robert J. (1983-12)
      Growth of young-of-the-year Arctic grayling (Thvmallus arcticus), chinook salmon (Oncorhynchus tshawytscha) and round whitefish (Prosopium cylindraceum). was examined in the Chena River during 1981 and 1982. Each species exhibited a gradient of growth within the main river; faster growing fish were found downstream. Highest growth rates occurred in Badger Slough, a clearwater tributary that parallels the lower river. Fish condition followed a similar pattern; faster growing fish were heavier at a given size. Between year differences in environmental conditions affected the first appearance, distribution and growth of these species. Growth pattern was reflected on the scales of Arctic grayling. Faster growing fish had a greater number of circuli that were more widely spaced. For fish from the lower river and Badger Slough, the number of circuli formed by the end of the growing year was not significantly different between years. This characteristic may be used to identify Chena River Arctic grayling stocks.
    • Growth, foraging behavior and distribution of age-0 Arctic grayling in an Alaskan stream

      Dion, Cheryl Ann (2002-12)
      I evaluated the ability of three models to relate habitat characteristics to habitat quality for age-0 Arctic grayling Thymallullus arcticus in an Alaska stream. A temperature-based growth model made accurate predictions, showing it can reliably assess thermal habitat quality. Deviations between predicted and observed growth were useful because they identified the timing of possible critical periods, when competition for food or space may cause density-dependent mortality and emigration. A foraging model consistently overestimated the mean prey size of fish, showing that such models need further work before then can accurately assess food availability from invertebrate drift. A habitat selection model accurately predicted small fish would occupy the stream margins and the ontogenetic shift into faster, deeper water, but its detailed predictions for larger fish were not very precise. These models were useful tools for assessing habitat quality and gave insight into possible interactions between habitat characteristics and population dynamics.
    • Habitat associations, distribution, and abundance of Smith's longspur (Calcarius pictus), an uncommon species of concern in the Brooks Range, Alaska

      Wild, Teri Corvus; Powell, Abby; Verbyla, Dave; Kendall, Steve (2013-12)
      Smith's Longspur (Calcarius pictus) is a species of conservation concern in the U.S. and Canada, yet few studies have been conducted on their breeding grounds in the Arctic, which are expected to undergo dramatic changes due to climate change. For effective conservation, we need information on breeding distribution and abundance; thus I conducted surveys for Smith's Longspur and habitat characteristics across a broad geographic range that included twelve sites within Alaska's Brooks Range, June 2003-2009. My main objectives were to (1) locate breeding populations (2) describe habitats at local and broader geographic scales, (3) develop a predictive distribution map based on habitat characteristics, and (4) estimate densities and abundance of Smith's Longspurs. Smith's Longspurs were detected at seven of twelve sites and were associated with mixed sedge and shrub habitats with high cover of moss and sedges. Across the Brooks Range, I predicted patchy occurrence in valleys and foothills in the north- and south-eastern mountains and in upland plateaus in the western mountains. Density estimates varied, ranging from 0 - 0.39 males/ha due to their patchy distribution within and among sites. I estimated abundance as ~30,000 males in the Brooks Range. My data provides a baseline for future monitoring of this little-known species.
    • Habitat relationships and activity patterns of a reintroduced musk ox population

      Jingfors, Kent T. (1980-12)
      A reintroduced muskox herd in arctic Alaska was studied over a 2-year period to assess seasonal changes in activity patterns and feeding behavior. This large herd showed high calving rates and early breeding in females, characteristic of a rapidly expanding population. Age- and sex-specific differences in activity budgets reflect seasonal energy demands of the different cohorts. Comparison with high arctic muskoxen shows that characteristics of suckling behavior provide a more sensitive indicator of differences in range quality than does variation in summer activity patterns. In summer, muskoxen appear to select vegetation types on the basis of abundance and phenological stage of preferred forage species; snow characteristics strongly influence habitat selection in winter. The herd remained within a limited home range with overlapping seasonal ranges and a distinct calving area. The restricted movements and conservative activity budgets permit minimization of energy expenditure and forage requirements, allowing for a year-long existence in areas of low primary productivity.
    • Habitat selection and sightability of moose in Southeast Alaska

      Oehlers, Susan A. (2007-08)
      We examined the role of scale and sex in habitat selection by radiocollared Alaskan moose (Alces alces gigas) on the Yakutat forelands, Alaska, USA. We used conditional logistic regression to quantify differences in habitats selected between sexes and seasons at 3 different spatial scales (250, 500, and 1000 m), and multi-response permutation procedure (MRPP) to test for differences in spatial distribution between the sexes. Sexes selected for habitats similarly during the mating season, when sexes generally were aggregated, whereas sexes exhibited differential habitat selection during the non-mating season when sexes were segregated. Both sexes selected habitats at the 1000 m scale; models limited to 2 variables, however, demonstrated differences in scales selected by the sexes. There was a significant difference between male and female spatial distribution during all months (MRPP; P <0.0001), and distances between individuals were higher in females than in males, particularly during spring. We also developed a sightability model for moose with logistic regression, and used Distance Sampling to develop sightability correction factors (SCFs). Application of the sightability model and Distance Sampling to a sample data set of 600 moose yielded population estimates of 652-1124 (x̄= 755) and 858-1062 (x̄ = 954) moose, respectively.
    • Habitat selection by calving caribou of the Central Arctic Herd, 1980-95

      Wolfe, Scott Adrian (2000-12)
      Habitat selection by calving caribou (Rangifer tarandus granti) of the Central Arctic Herd, Alaska, was assessed in relation to distance from roads, vegetation type, relative plant biomass (NDVI; Normalized Difference Vegetation Index), accumulation of plant biomass during early lactation (NDVIrate), snow cover, and terrain ruggedness. From 183 calving sites of 96 radio collared- females, 1980-95, calving distribution was estimated in reference (no development) and treatment (oilfields present) zones east and west of the Sagavanirktok River, respectively. In the reference zone, caribou regularly selected wet-graminoid vegetation, above-median NDVIrate, and non-rugged terrain; concentrated calving remained in habitats with zonal average NDVI on 21 June (NDVI621). In the treatment zone, selection patterns were inconsistent; concentrated calving shifted inland to rugged terrainwith low NDVI621 and away from development. Repeated use of lower-quality habitats in the treatment zone could compromise nutrient intake by calving females, thereby depressing reproductive success of the western-segment of the herd.