• Effects of jet boats on salmonid reproduction in Alaskan streams

      Horton, Gregg E.; Reynolds, James; Kane, Douglas; Barry, Ronald; Kavanagh, Ross (1994-09)
      Freshwater angling has increased dramatically in recent years in southwestern Alaska, and jet boat operators serve some of these anglers. Resources agencies are under pressure to regulate use of jet boats in waters that support spawning populations of salmonids, but they need more information regarding these potential effects. This thesis describes the methods and results of experiments to determine the effects of water turbulence from passing boats on embryo mortality and behavior of spawning adults. Field experiments on sockeye salmon were conducted in American Creek (in the Naknek drainage in Katmai National Park and Preserve) in 1992 and 1993. Laboratory experiments on rainbow trout were conducted at Fort Richardson Hatchery. These two species were viewed as surrogates for all species of genus Onorhynchus.
    • Quantifying fisher responses to environmental and regulatory dynamics in marine systems

      Watson, Jordan T.; Mueter, Franz; Haynie, Alan C.; Sigler, Michael F.; Sullivan, Patrick J. (2017-12)
      Commercial fisheries are part of an inherently complicated cycle. As fishers have adopted new technologies and larger vessels to compete for resources, fisheries managers have adapted regulatory structures to sustain stocks and to mitigate unintended impacts of fishing (e.g., bycatch). Meanwhile, the ecosystems that are targeted by fishers are affected by a changing climate, which in turn forces fishers to further adapt, and subsequently, will require regulations to be updated. From the management side, one of the great limitations for understanding how changes in fishery environments or regulations impact fishers has been a lack of sufficient data for resolving their behaviors. In some fisheries, observer programs have provided sufficient data for monitoring the dynamics of fishing fleets, but these programs are expensive and often do not cover every trip or vessel. In the last two decades however, vessel monitoring systems (VMS) have begun to provide vessel location data at regular intervals such that fishing effort and behavioral decisions can be resolved across time and space for many fisheries. I demonstrate the utility of such data by examining the responses of two disparate fishing fleets to environmental and regulatory changes. This study was one of "big data" and required the development of nuanced approaches to process and model millions of records from multiple datasets. I thus present the work in three components: (1) How can we extract the information that we need? I present a detailed characterization of the types of data and an algorithm used to derive relevant behavioral aspects of fishing, like the duration and distances traveled during fishing trips; (2) How do fishers' spatial behaviors in the Bering Sea pollock fishery change in response to environmental variability; and (3) How were fisher behaviors and economic performances affected by a series of regulatory changes in the Gulf of Mexico grouper-tilefish longline fishery? I found a high degree of heterogeneity among vessel behaviors within the pollock fishery, underscoring the role that markets and processor-level decisions play in facilitating fisher responses to environmental change. In the Gulf of Mexico, my VMS-based approach estimated unobserved fishing effort with a high degree of accuracy and confirmed that the regulatory shift (e.g., the longline endorsement program and catch share program) yielded the intended impacts of reducing effort and improving both the economic performance and the overall harvest efficiency for the fleet. Overall, this work provides broadly applicable approaches for testing hypotheses regarding the dynamics of spatial behaviors in response to regulatory and environmental changes in a diversity of fisheries around the world.
    • Trace metals in Arctic fast ice

      Domena, Vincent; Aguilar-Islas, Ana; Rember, Robert; McDonnell, Andrew (2017-12)
      Trace metals in the marine environment are found in trace amounts, but are important tracers of oceanographic processes, and bioactive trace metals can impact ocean biogeochemistry through their nutrient or toxic influence of microbial populations. Sea ice is an intrinsic feature of the Arctic Ocean that likely plays a key role in the cycling of trace metals, given that this substrate can concentrate, alter, and transport these elements. Warming conditions in the Arctic have decreased sea ice cover over the past decades and the loss of sea ice threatens to drastically change the Arctic ecosystem, but the implications are not entirely understood. The scarcity of studies on Arctic sea ice entrained trace metals is due in part to the lack of commercially available sampling equipment capable of collecting sea ice without introducing contamination, and in part to the logistic and economic difficulties in accessing remote Arctic sea ice sites. Natural heterogeneity related to large sediment loads incorporated in uneven patches across Arctic fast ice poses a challenge when designing observational studies of trace metals in sea ice. The scope of this thesis is on the study of trace metals in Alaskan Beaufort Sea fast ice environment. The study includes snow, sea ice and seawater under the ice. Analysis of dissolved (Mn, Fe, Cu and Zn) and particulate (Al, Mn, Fe, Cu and Zn) phases was carried out from 50 ice cores collected with a trace metal clean ice corer developed at the University of Alaska Fairbanks. The results of this study indicated that the ice corer developed at UAF was able to collect uncontaminated samples. Highly variable and elevated concentrations of particulate (> 0.2 μm) trace elements were observed due to the notable variability in the amount of sediment incorporated within ice cores, but surprisingly dissolved (< 0.2 μm) metal concentrations were relatively low and consistent. The observed low dissolved metal concentrations, along with low bulk salinity and low percent leachable particulate trace metal fractions, suggest that desalination removed reactive metals from the ice matrix prior to sampling. Spatial variability of dissolved and particulate trace metals was statistically analyzed and indicated generally negligible variability on the meter scale, but significant variability on the kilometer scale, for both size classes. These results emphasize that future studies of trace metals in sea ice should include temporal and spatial considerations.