Browsing University of Alaska Fairbanks by Subject "Prince William Sound"
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Copper mineral occurrences in the Wrangell Mountains-Prince William Sound area, AlaskaOn January 9, 1970, the U.S. Bureau of Mines entered into an agreement with the University of Alaska based upon a proposal submitted by the Mineral Industry Research Laboratory. Under the terms of this agreement, the Laboratory undertook to compile information on copper occurrences in eight quadrangles covering what are loosely known as the Copper River, White River, and Prince William Sound copper provinces. If time permitted four other quadrangles would be added, and this has been possible. Information was to be obtained by searching published and unpublished records of the Bureau of Mines, the U.S. Geological Survey, the State Division of Geological Survey, the University of Alaska, and the recording offices.
The feeding ecology of chum salmon fry (Oncorhynchus keta) in northern Prince William Sound, AlaskaA two year study of the feeding ecology of early outmigrating chum salmon fry, Oncorhynchus keta, in northern Prince William Sound, Alaska, demonstrated harpacticoid copepods and chironomid insects to be dominant food taxa with calanoid copepods, polychaete larvae, cladocerans and cirripeds also contributing. Examination of the IRI (Index of Relative Importance) values for harpacticoids and insects revealed fluctuating seasonal patterns. Low IRI values for harpacticoids and/or insects coincided with higher IRI values for calanoids, polychaetes, cladocerans and cirripeds. ANOVA analyses and t-tests results on stomach contents demonstrated spatiotemporal variations in diet. Early outmigrating chum fry inhabited tidal mudflats, rocky beaches and vertical rocky outcrops where harpacticoids and insects were prevalent. CTD data and plankton tows indicated that tidal advection supplied pelagic prey from Unakwik Inlet to Jonah Bay. Fluctuating IRI values by prey taxa suggest an opportunistic rather than selective feeding behavior for chum fry based on prey availability.
Pacific herring juvenile winter survival and recruitment in Prince William SoundSmall pelagic fish abundances can vary widely over space and time making them difficult to forecast, partially due to large changes in the number of individuals that annually recruit to the spawning population. Recruitment fluctuations are largely driven by variable early life stage survival, particularly through the first winter for cold temperate fishes. Winter survival may be influenced by juvenile fish size, energy stores, and other factors that are often poorly documented, which may hamper understanding recruitment processes for economically and ecologically important marine species. The goal of this research was to improve understanding of recruitment of Pacific herring (Clupea pallasii) within Prince William Sound (PWS) through recruitment modeling and by identifying factors influencing winter survival of young-of-the-year (YOY) herring. Towards this end, my dissertation addresses three specific objectives: 1) incorporate oceanographic and biological variables into a herring recruitment model, 2) describe patterns in growth and condition of PWS YOY herring and their relationship to winter mortality risks, and 3) compare the growth, condition, swimming performance, and mortality of YOY herring that experience different winter feeding levels. In the recruitment modeling study, annual mean numbers of PWS herring recruits-per-spawner were positively correlated with YOY walleye pollock (Gadus chalcogrammus) abundance in the Gulf of Alaska, hence including a YOY pollock index within a standard Ricker model improved herring recruitment estimates. Synchrony of juvenile herring and pollock survival persisted through the three-decade study period, including the herring stock collapse in the early 1990s. While the specific mechanism determining survival is speculative, size-based tradeoffs in growth and energy storage in PWS YOY herring indicated herring must reach a critical size before winter, presumably to reduce size-dependent predation. Large herring switched from growth to storing energy, and ate more high-quality euphausiid prey, which would delay the depletion of lipid stores that compelled lean herring to forage. Lipid stores were highest in the coldest year of the seven-year field study, rather than the year with the best diets. With diets controlled in a laboratory setting, spring re-feeding following restricted winter diets promoted maintenance of size and swimming ability, but had little effect on mortality rates compared to fish continued on restricted rations. Declines in gut mass, even among fully fed herring, and low growth potential suggest limited benefits to winter feeding. Mortalities due to food restriction compounded by disease were highest among herring that fasted through winter months, and among small herring regardless of feeding level. Taken together, these findings illustrate the importance of achieving a critical size and high lipid stores in the critical period before winter to promote YOY herring winter survival and ultimately recruitment.