• Early marine growth patterns of Situk River steelhead, Oncorhynchus mykiss

      Catterson, Matthew R.; McPhee, Megan; Love, David; Sutton, Trent (2017-08)
      Steelhead Oncorhynchus mykiss exhibit complex life-history patterns described by variable freshwater and marine residency periods, maturation patterns, and reproductive characteristics. Over 300 small populations of Steelhead are present in Southeast Alaska, and similar trends in abundance among these populations suggest the influence of population-regulating forces operating on a regional scale. The Situk River, near Yakutat, Alaska, supports the largest known population of Steelhead in Alaska. Stock assessment studies on this river have collected the longest set of biological data and scale samples for Steelhead in the state. For this study, retrospective scale pattern analysis of samples from Situk River Steelhead was synthesized with regional abundance information to investigate patterns in early marine growth among different life-history and demographic groups, as well as to explore linkages between growth, abundance, and marine environmental variables. Positive correlations were identified between freshwater growth, first ocean-year growth, and adult length, while first ocean-year growth was negatively correlated with second ocean-year growth. Early maturing Steelhead were found to have increased first ocean-year growth and reduced adult length relative to later maturing Steelhead, confirming connections between growth and maturation. Correlations in abundance among Southeast Alaska Steelhead populations suggest that marine and climatic drivers may impact these populations in a regionally coherent manner. Correlations among patterns in abundance also varied along a distance gradient: populations located closer to the Situk River were more correlated with the Situk River than more distant populations. Positive relationships between Gulf of Alaska sea surface temperature, North Pacific Gyre Oscillation, and Situk River Steelhead abundance further supported the importance of climate-driven marine conditions to Steelhead productivity. While conservation concerns for Steelhead in Southeast Alaska are currently minimal, proactive investigations into life-history diversity and population linkages may become more relevant with increased marine ecosystem variability related to climate change.
    • Effects of milk intake, growth and suckling efficiency on suckling behavior of muskox (Ovibos moschatus) calves

      Tiplady, Barbara Ann (1990-12)
      General theory on parental provisioning predicts that mammalian offspring receiving more milk should show longer suckling bouts, greater total suckling time, longer intervals between bouts, and greater suckling success. For muskoxen I found that suckling bout duration and suckling success were positively correlated with milk intake during some but not all stages of lactation. Neither interval between suckling bouts, nor total suckling time, was correlated with milk intake. Growth of calves was positively related to milk intake, and among calves of the same age suckling efficiency (intake/min suckling) was highly related to body weight. Therefore, milk intake affects growth rate, which in turn affects suckling efficiency. The overriding influence of calf body size and suckling efficiency limits interpretation of differences in suckling behavior that can be attributed to milk intake by muskox calves and therefore to the provisioning strategy of the cow.
    • Environmental regulation of growth in black brant

      Herzog, Mark Paul (2002-08)
      Body size is an important determinant of life history traits such as survival and fecundity. There is a positive correlation between growth during the first summer and final body size in goose populations. I examined how environmental factors influence growth in Black Brant (Branta bernicla; hereafter brant) goslings. Growth declined seasonally and varied among brood-rearing areas. However, the pattern was not consistent among years. Models containing only environment and maternal effects explained 75% of variation in gosling mass, indicating that little of the observed variation in size is directly of genetic origin. Heritability did not differ from zero for both mother-daughter and father-daughter regressions. I also conducted an experiment to study the effect of gosling density on food abundance, feeding behavior, and development of brant goslings, in two habitat types important to brant: (1) Carex subspathacea grazing lawns and (2) slough levees which contain Triglochin palustris. Variation in grazing pressure was experimentally manipulated. Biomass and offtake of C. subspathacea was higher in lightly grazed plots than in heavily grazed plots even though goslings within heavily grazed plots spent more time feeding. Within slough levee habitat there were no differences between heavily and lightly grazed plots in either biomass or offtake of T. palustris. Peck rates were lower in slough levee habitat than in grazing lawns. Change in mass over an eight hour trial was positively correlated with the amount of forage biomass in the plot at the start of the trial. I found no variation in internal morphometrics or body composition among goslings. I also examined the relationship between forage available within a brood-rearing area, the number of birds using the area, and gosling growth. Annual variation in use of brood-rearing areas was correlated with forage availability. Gosling mass was negatively correlated with brood numbers when examined across all areas, however, within each brood-rearing area, the relationship between mass and numbers of birds was positive. I did not see a relationship between estimates of food availability (per m²) and brood numbers. Spatial variation in growth among habitats may result from habitats varying in quality and quantity of forage.
    • Evaluating short rotation poplar biomass on an experimental land-fill cap near Anchorage, Alaska

      Byrd, Amanda G. (2013-05)
      Biomass energy has enjoyed a resurgence of scientific interest recently. Indeed, biomass may have the potential to replace diesel fuel as the primary source of heating in some parts of Alaska. In addition to forest biomass, short rotation crops have been considered as a sustainable source of woody biomass, and a potential sink for carbon sequestration. In this study, Populus balsamifera was evaluated as a short rotation crop for use as an energy source in Southcentral Alaska. Growth and yield rates were measured on an established P. balsamifera stand under a two-year rotation, yielding an annual biomass production of 5,530 kg/ha/yr. A fertilizer application study was conducted and demonstrated no effect on growth. Energy content of P. balsamifera measured 19,684 kJ/Kg, with a total energy yield of 217,715 MJ/ha after two years. Carbon sequestered below ground was estimated at least 5,338 kg/ha. Biomass may not be carbon neutral, but the carbon emitted from burning biomass is at least partially renewable. With use in high-efficiency boilers, there is potential for biomass to offset costs, and even save money by displacing diesel heating fuel.
    • Evaluation of growth and migration trends on the survival and recruitment of chinook salmon in Southeastern Alaska rivers

      Berkman, Stephanie; Sutton, Trent; Adkison, Milo; Mueter, Franz (2017-12)
      Highly variable recruitment and declines in productivity and abundance of Chinook Salmon Oncorhynchus tshawytscha have created economic and cultural hardships for communities throughout Alaska. Although pre- and post-smolt growth are important for determining brood-year (BY) survival and productivity for Pacific salmon through size-mediated mortality, these relationships remain unclear for Chinook Salmon. As a result, it is necessary to better understand the relationships between environmental and biological factors that influence freshwater and marine growth, smolt outmigrations, and recruitment success. This study used retrospective growth to identify the importance of annual growth in determining BY survival and recruitment, determine if growth dependency between growth zones was present, and examine growth differences among age classes for Chinook Salmon in the Chilkat (BYs 1985 - 2007) and Stikine (BYs 1991 - 1998 and 2000 - 2007) rivers. Biological and environmental factors were also assessed to determine their influence on freshwater smolt production, smolt outmigration, and marine survival. Greater first-year marine growth was correlated with higher BY total return and productivity for Chinook Salmon from the Chilkat River and higher BY marine survival for Chinook Salmon from the Stikine River. Daily smolt outmigration of Chilkat River Chinook Salmon was positively correlated to water temperature and negatively correlated to discharge (Deviance explained = 68.5%), while timing of the start of outmigration was influenced by nearshore sea surface temperatures (R² = 0.57) and timing of the mid and end points were positively related to smolt length (R² = 0.72 and 0.34, respectively). Freshwater smolt production was negatively correlated to parr length and fall discharge and positively correlated to spring temperature and discharge (R²adj= 0.52). Marine survival of Stikine River Chinook Salmon was significantly related to smolt size (R² = 0.26), while Chilkat River Chinook Salmon were positively related to migration timing and smolt length and negatively related to discharge (R² = 0.5). These results support the importance of the early marine period in determining year-class strength and highlight the variation in mechanisms that influence recruitment success of Chinook Salmon stocks.
    • Feeding and growth of seasonal cohorts of larval walleye pollock (Theragra chalcogramma) in Auke Bay, Alaska

      Sterritt, David A. (1989-05)
      Larval walleye pollock, Theragra chalcogramma (Pallas), typically occur in the water column in synchrony with peak densities of prey. A primary objective of this investigation was to examine and compare growth rates of larval pollock. The growth rate of a synchronous cohort (hatched 10-14 May, 1986) was found to be significantly higher (P<0.05) than that of an earlier cohort (hatched 15-19 April, 1986) . Synchronous cohorts are larvae that occur simultaneously with the maximum densities of herbivorous copepods. Growth rates were determined by otolith analysis. Prey densities and water temperature were implicated as causes of the observed differences in growth. Prey densities were approximately 3 times higher for the synchronous cohort than the early cohort. Additionally, the early cohort experienced water temperatures 2-3°C colder than the synchronous cohort. Results suggest that synchronous larval walleye pollock have higher growth rates and may have higher survival rates.
    • Growth and post-harvest quality of selected Pacific oysters (Crassostrea gigas) cultured in Kachemak Bay, Alaska, and Puget Sound, Washington, in October of 2009 and June of 2010

      Thomas, Stuart Rendell; Oliveira, Alexandra; RaLonde, Ray; Eckert, Ginny; Langdon, Chris (2012-05)
      The primary objective of this project was to evaluate the growth, biochemical and fatty acid composition, physical and shell characteristics, and basic reproductive development of families of Pacific oysters (Crassostrea gigas) from the USDA-funded Molluscan Broodstock Program (MBP) planted in suspended culture in Kachemak Bay (KB), Alaska, and at an intertidal site in Thorndyke Bay (TB), Puget Sound, Washington. The MBP selects oysters to improve yields, growth, and survival, but little is known about the effects of selective breeding on other biological characteristics of selected oysters. Shell and meat characteristics of oysters from each of the seven highest-yielding MBP families were compared with those from non-selected control families at each site, which were sampled in October of 2009 and in June of 2010. Biometric and growth data, proximate compositions, fatty acid compositions, and basic degree of reproductive development were measured and compared by family, site, and sampling time. Selection improved yield, growth, and survival in MBP Cohort 20 oysters over three years of growout at KB. Colder water temperatures at KB relative to TB inhibited reproductive development, altering the biochemical composition of oysters within sites and between sampling times. Oysters grown at KB were slower growing and smaller when compared to TB, but higher in glycogen, Omega-3, and Omega-6 fatty acids (particularly docosahexaenoic acid: 22:6 Omega 3). Different latitudes and culture types were contributing factors for observed differences in growth, physiology, and composition, resulting in characteristically unique oysters from either site.
    • Inter-decadal change in sablefish, Anoplopoma fimbria, growth and maturity in the Northeast Pacific Ocean

      Howard, Katy B.; Adkison, Milo D.; Hillgruber, Nicola; Sigler, Michael F. (2008-08)
      Errors in growth and maturity estimates can drastically affect the spawner-per-recruit threshold used to recommend commercial fish catch quotas. Growth and maturity parameters for Alaskan sablefish, Anoplopoma fimbria, have not been updated for stock assessment purposes for 20 years, even though sablefish aging has continued. In this study, the old length-stratified data set (1981-1993) was updated and corrected for bias. In addition, newer, randomly collected samples (1996-2004) were analyzed, and new length-at-age, weight-at-age, and maturity-at-age and length parameters were estimated. A comparison of the two datasets showed that in recent years, sablefish are growing larger and maturing later and that growth and maturity differ somewhat among regions. The updated growth information improves data fits in the sablefish stock assessment model. It also provides results that are biologically reasonable. These updated and improved estimates of sablefish growth and maturity help ensure the continued proper management of this commercially important species in Alaskan waters.
    • The kinetics of glucose limited growth by a marine yeast

      McNab, Allen David (1969-05)
      The kinetics of glucose limited growth by a marine yeast, shown to be a Rhodotorula species, have been studied in a continuous culture apparatus. The saturation constant, in synthetic media, has been calculated to be 0.25 mg/l, on the assumption that saturation kinetics are followed, The maximum growth rate was determined in both synthetic media, and artificial sea water. On the basis of inhibition kinetics, the kinetic behavior of this yeast in the marine environment has been predicted. The effect of temperature on the maximum growth rate has been determined and, on the assumption of a similar effect on the saturation constant, the saturation constant has been postulated to be in agreement with similar values determined for other microorganisms.
    • Lake trout (Salvelinus namaycush) otoliths as indicators of past climate patterns and growth in Arctic lakes

      Torvinen, Eric S.; Falke, Jeffrey; Arp, Christopher; Zimmerman, Christian; Sutton, Trent (2017-05)
    • Roles of neighboring plants and temperature on growth and survival of white spruce seedlings along elevational gradients in Alaska

      Okano, Kyoko; Bret-Harte, M. Syndonia; Mulder, Christa P. H.; Juday, Glenn P. (2018-05)
      Seedlings are the most vulnerable stage of a tree's life and their successful survival and growth are critical to support future forests. Recent rapid warming in Alaska has promoted the movement of treeline upward in elevation, while trees at low elevations have decreased their growth. Understanding the direct effects of warming and the indirect effects induced by warming, such as species interactions, on the dominant treeline species, white spruce (Picea glauca) is key to sustaining boreal forests, from low elevations to above current treeline. The objectives of my thesis were to assess the roles that warming, neighboring interaction, habitat type, elevation and season play in the survival and growth of white spruce in Denali National Park and Preserve and Fairbanks, Alaska, USA. I planted spruce seedlings where I manipulated summer temperature and neighbor plants at seven sites (forest or tundra) along an elevational gradient that crossed treeline. I measured survival after winter and summer seasons, and harvested the seedlings for biomass after the third growing season. I found that competition -- particularly light competition where seedlings were shaded -- was the most important factor for seedling growth, while along elevational gradients, temperature and season had inverse effects on their survival: more seedlings at high elevations survived in summer and under warming, but more seedlings at low elevations survived in winter and under ambient temperatures. More seedlings with neighbors survived in summer and in forests, suggesting facilitation through shading. I found some evidence for a trade-off between growth and survival. Seedlings with a high relative growth in height (RGR height) in 2012 had a lower survival rate than seedlings with a low RGR height in the following hot and dry summer of 2013. More seedlings planted with neighbors that had a small diameter in 2012 also survived in 2013, but not without neighbors. These results suggest that a trade-off between survival and growth occurred only when competition for water can be expected. No difference in survival was found after the second winter and third summer. Altogether, I concluded the most important factor affecting seedling growth in my experiment was light competition, while the most important factors for seedling survival were warming and water availability for the first two years in the subarctic montane and interior Alaska.
    • The snowshoe hare filter to spruce establishment in boreal Alaska

      Olnes, Justin; Kielland, Knut; Ruess, Roger; Juday, Glenn; Genet, Helene; Mann, Daniel (2018-05)
      Interior Alaska is a heterogeneous landscape within the circumpolar boreal forest and is largely composed of black and white spruce (Picea mariana and P. glauca). Improving our understanding of the factors affecting patterns in spruce regeneration is particularly important because these factors ultimately contribute to shaping the boreal forest vegetation mosaic. Herbivory by snowshoe hares (Lepus americanus) is one factor that likely drives patterns in spruce establishment. The interaction between spruce and snowshoe hares provides an opportunity to study how plant-herbivore interactions can affect succession, vegetation community composition, and consequently, how herbivory influences landscape heterogeneity. I explored how herbivory by snowshoe hares alters the survival and growth of spruce seedlings across Interior Alaska's boreal forest. I hypothesized that the survival and growth rate of regenerating spruce is significantly reduced by snowshoe hare herbivory and that snowshoe hare herbivory influences the pattern of spruce establishment across time and space. To address this hypothesis, I conducted research in three distinct vegetation communities across the region: productive lowland floodplains (Chapters 1 and 2), treeline (Chapters 3 and 4), and recently burned stands of black spruce (Chapter 5). Together these five chapters reveal that snowshoe hares affect spruce establishment across much of boreal Alaska. Where and when hares are abundant, spruce can be heavily browsed, resulting in suppressed seedling growth and increased seedling mortality. The results of these studies also reveal a consistent and predictable pattern in which this plant-herbivore interaction takes place. The snowshoe hare filter acts as a 'spatially aggregating force' to spruce establishment, where the potential for optimal regeneration is highest during periods of low hare abundance and where hares are absent from the landscape.