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Recent SFOS Student Theses and Dissertations

Fall 2010 Abstracts

Variation in the trophic position of spiny dogfish (Squalus acanthias) in the northeastern Pacific Ocean: An approach using carbon and nitrogen stable isotopes

Alexander Andrews, M.S. Fisheries
School of Fisheries and Ocean Sciences
Advisor: Gordon Kruse.

Abstract: Spiny dogfish (Squalus acanthias) are among the most abundant shark species in the Gulf of Alaska (GOA). An increase in relative biomass of spiny dogfish in 2003 and 2007 inspired interest in this species as a commercial resource. However, very little was known about the ecology of this species in the GOA. This study investigated the trophic role of spiny dogfish in the GOA, British Columbia (BC), and Washington using stable isotope analysis of carbon and nitrogen. Specifically, we examined the trophic position (TP) of spiny dogfish in relation to length, sex, and geographic region. Weathervane scallops (Patinopecten caurinus) were used as a stable isotopic baseline organism. Spiny dogfish between 52 to 113 cm length had δ15N values that ranged geographically from 10.8‰ to 15.6‰; δ15N was linearly related to length. In contrast, lipid-nornalized δ13C values ranged from -21.2‰ to -16.8‰ and were not linearly related to length. In the GOA, TP of spiny dogfish ranged fiom 3.3 to over 4.1, with Kodiak having the highest TPs for spiny dogfish of a given length. Our results indicated that size-based ontogenetic changes in TP of spiny dogfish are important and should be incorporated into mass-balance, food-web models such as Ecopath.

Development and application of a methodology to estimate regional natural conditions for trace metals in marine sediments of southcentral Alaska's coastal region

Douglas Dasher, Ph.D. Interdisciplinary
School of Fisheries and Ocean Sciences
Advisor: John Kelley.

Abstract: Increasing levels of resource development and population growth along Alaska's relatively pristine coastline require responsible environmental stewardship that is based on scientifically defensible monitoring and assessment. This thesis develops a methodology to assess the spatial distribution of coastal sediment trace metals and estimate their natural condition along Alaska's coastline. Marine sediments provide a better integrated long-term signal for naturally occurring and anthropogenic chemicals than repeated water measurements. The first of three manuscripts reports on marine sediment trace metal concentrations from a probabilistic sampling survey of Alaska's South central coastal region. Results are described on a proportional basis, i.e., percent of estuary area, for the distribution of As, Cd, Cr, Cu, Pb, Hg, Ni, Ag, and Zn in the sediments. With the exception of naturally elevated Cr and Ni at a site bounded by a chromite ore body, sediment trace metal concentrations measured represent nonanalmous levels. The second manuscript develops natural conditions for fluvial trace metal inputs from two major Southeast Alaska coastal watersheds: Cook Inlet and Copper River. The stream sediment trace metal natural conditions place levels in the adjacent coastal sediments into context. Two exploratory data analysis techniques, the Tukey Box plot and Median + 2 Median Absolute Deviation, combined with geochemical mapping are used to develop stream sediment trace metal natural conditions. The third manuscript builds on the first two to develop a methodology to estimate coastal sediment natural conditions. Population estimates for the cumulative area 90% UCB 95% sediment trace metal of interest obtained from the sampling survey methodology and screened reference sites is used to establishing an upper threshold value for regional natural conditions. While this work establishes natural condition marine sediment trace metal levels for this region, the significance of these levels from an ecotoxciological perspective remains to be established. Additional studies are needed along other sections of Alaska's coastline, coupled with biological assessments, if Alaska is to develop relevant sediment quality guidelines.


Melissa Deiman, M.S. Marine Biology
School of Fisheries and Ocean Sciences
Advisors: Brenda Konar and Katrin Iken.

Abstract: Canopy-forming kelps species provide structural complexity within the nearshore for associated communities. The establishment of algal spores plays an essential role in kelp distribution and abundance patterns. Light and sedimentation are key variables regulating algal spore establishment and success. These environmental variables may control species-specific dominance in the field. The objectives of this study were to determine the attachment, survival, and germination rates of the spores of two Alaskan canopy-forming kelps, Nereocystis luetkeana and Eualaria fistulosa, to 1) various light levels and 2) sediment loads. Nereocystis luetkeana and Eualaria fistulosa spores had similar attachment success and germination rates under all light levels tested; however, E. fistulosa exhibited larger germ tubes after 48 hours. Spore attachment for both species was significantly affected by suspended particles, settled sediment covering the substratum, and by smothering of settling sediment. These results suggest that increases in sedimentation may constrain the success of the microscopic spore stages and thus kelp abundance and distribution within Alaska's nearshore. An understanding of the environmental variables controlling the temporal and spatial establishment of kelp forests in Alaska will help us understand how changes in these variables may affect nearshore communities.

First-generation effects on development time of outcrossing between geographically isolated and seasonally isolated populations of pink salmon (Oncorhynchus gorbuscha)

Jesse Echave, M.S. Fisheries
School of Fisheries and Ocean Sciences
Advisor: Milo Adkison.

Abstract: Bootstrap analyses of hatch data collected during two independent experiments revealed that hybridization between pink salmon (Oncorhynchus gorbuscha) breeding populations separated at either a large geographic scale or a fine temporal scale can influence development time. Restricted maximum likelihood estimators also revealed that sire, dam, cross, and parental interaction can influence genetic variance associated with development time at either scale. Few studies have investigated the extent of local adaptation that results from fine-scale ecological variation, the genetic underpinnings of that adaptation, or the potential impacts outbreeding at that level may have on fitness. We tested whether or not local adaptation contributed to genetic divergence among subpopulations of pink salmon that overlap temporally within the same spawning habitat (early-run fish and late-run fish within Auke Creek, near Juneau, Alaska) by determining whether or not outbreeding influenced development time (a fitness-related trait) in first-generation hybrids. We examined genetic divergence among populations isolated at a much broader scale (Pillar Creek on Kodiak Island, Alaska, and Auke Creek, 1,000 km great circle distance) as a more extreme reference to local adaptation. Results provide evidence that development time is locally adapted and expressed primarily in a locus-by-locus manner.

Describing forage fish availability in coastal waters of the Kodiak archipelago, Alaska

Lei Guo, Ph.D. Marine Biology
School of Fisheries and Ocean Sciences
Advisors: Kate Wynne and Robert Foy.

Abstract Assessing the availability of forage fishes is key to understanding fluctuations in populations of apex predators that prey upon them, including pinnipeds and seabirds in the Gulf of Alaska. In this study, multiple aspects of forage fish availability were measured in coastal waters of the Kodiak Archipelago, Alaska, in May (2004 & 2005), August (2004 & 2005), November (2006), and April (2007). Efforts were focused on four pelagic species that consistently dominated midwater trawl catches and have been described as important prey for upper trophic level predators around the Archipelago: walleye pollock (Theragra chalcogramma), Pacific herring (Clupea pallasii), capelin (Mallotus villosus), and eulachon (Thaleichthys pacificus). Fatty acid and stomach content analyses were combined to estimate the diet composition of these forage fishes as a means of identi1'ying the immediate source of energy they transfer to upper trophic level taxa. Values of copepod-originated fatty acids indicated underestimation of dietary copepods by stomach content analysis, which suggests that fatty acid analysis should be used to supplement conventional methodologies in forage fish field studies. Lipid content and fatty acid composition were highly variable within species, suggesting that the use of average values at the species level should be avoided in fine-scale ecological investigations. Mesoscale horizontal distribution and energy density of forage fishes were measured in May and August (2005) to assess the prey fields available to local apex predators over critical periods of their life history. Dense post-spawning aggregations formed seasonal energetic "hotspots", exemplified by herring schools on the northwest side of the Archipelago in May and capelin schools on the northeast side in August. Results presented in this dissertation offer key information needed to identity energetic pathways of significance to upper trophic level consumers in the Kodiak Archipelago. Understanding local trophic interactions and their role in regional apex predator population fluctuations will improve efforts to develop trophodynamic models and ecosystem-based fishery management plans in the North Pacific Ocean.

Idealized modeling of circulation under landfast ice

Jeremy Kasper, Ph.D. Oceanography
School of Fisheries and Ocean Sciences
Advisor: Thomas Weingartner.

Abstract: Idealized analytical and numerical models are used to elucidate the effects of a spatially variable landfast ice cover on under ice circulation. Three separate forcing mechanisms are investigated; lateral inflow onto an ice covered shelf (an elevated sea level at the western boundary), a spatially uniform upwelling wind blowing along the seaward landfast ice edge and a buoyant inflow under the ice cover that enters the domain through the southern coastal wall. The idealized models are configured to resemble the shallow Alaskan Beaufort Sea shelf. Models show that the inclusion of landfast ice means shelf response is significantly different from an ice free shelf. In the case of a lateral inflow, landfast ice spreads the inflow offshore (in a manner similar to bottom friction) but the change in surface stress across the ice edge (from ice covered to ice free) limits the offshore spreading. In the case of an upwelling wind along the ice edge, the low sea level at the ice edge (due to ice edge upwelling) leads to a cross-shore sea level slope between the coast (high sea level) and the ice edge (low sea level) which drives a geostrophically balanced flow upwind. In the absence of along-shore changes in wind or ice the circulation does not vary along the shelf and currents near the coast are near zero. Along- and cross-shore variations in the ice ocean friction coefficient introduce differences in the response time of the under ice flow and can lead to along-shore sea level slopes which drive significant along-shore flows near the coast (< 0.06 m s-1). In the case of a time dependant buoyant inflow, the landfast ice spreads the buoyant inflow much further offshore (~9 times the local baroclinic Rossby radius, ~45 km) than in the ice free case (< 30 km). When the ice width is finite, the change in surface across the ice edge acts to restrict offshore flow (in the anti-cyclonic bulge) and inhibits onshore flow further downstream.

The colonization mechanism of pink salmon populations in Glacier Bay, Alaska, based on genetic data

Christine Kondzela, Ph.D. Fisheries School of Fisheries and Ocean Sciences
School of Fisheries and Ocean Sciences
Advisor: A.J. Gharrett.

Abstract: Following retreat of the last glacial advance in the early 1700s, pink salmon Oncorhynchus gorbuscha colonized many watersheds in Glacier Bay, Alaska. Streams in the lower Bay were populated first, and colonization proceeded up the Bay during the last 200 years. The objective of this study was to use analyses of genetic data–microsatellite and allozyme loci, and mitochondrial DNA haplotypes----to elucidate the colonization mechanism. The even- and odd-year broodlines served as replicate experiments; the mechanisms of colonization for the two broodlines were similar in most respects. The population genetic structure. based on allele/haplotype frequencies and genetic diversity (Fsr), suggested that in general, deglaciated streams were populated by colonists from nearby locations. The populations in lower Glacier Bay were likely established by colonists from populations outside Glacier Bay. In turn, the lower Bay populations contributed colonists to populations farther up the Bay, which subsequently provided colonists to the most recently deglaciated locations in the upper Bay, although in the even-year there appeared to be some contribution to the youngest populations from older populations, outside of or in lower Glacier Bay. Few genetically divergent donor sources contributed colonists based on the limited linkage disequilibrium, higher relatedness, and lower allelic diversity within Glacier Bay populations. The number of fish involved in initial colonization was not large, based on slightly reduced genetic diversity within Glacier Bay, but minimal founder effect signals precluded very small numbers of fish as well. Most of the genetic variation appeared early in the formation of populations and effective population size estimates were> 1 00 fish in every population. Some gene flow after initial colonization is supported by the increased allelic diversity and decline in relatedness with population age, but heterogeneity within Glacier Bay suggested that gene flow must be limited among some populations. Colonization of the youngest streams coincided with the historically high abundance of pink salmon in Southeast Alaska during the 1990s; I speculate that the rapid expansion in the size of these populations subsequent to this study was the result of high survival rather than extensive gene flow.

Ontogenetic considerations in the trophic level of commercial groundfish species in the Gulf of Alaska

Jennifer Marsh, M.S. Fisheries
School of Fisheries and Ocean Sciences
Advisors: Nicola Hillgruber and Robert Foy.

Abstract: Trends in trophic level (TL) estimates of commercial fishery catches are used as ecosystem-based indicators for sustainability, but these estimates often do not incorporate species-specific interannual and ontogenetic feeding patterns. This study provides a finer resolution of ontogenetic and temporal variations in the trophic position of four groundfish species in the central Gulf of Alaska (GOA), walleye pollock (Theragra chalcogramma), Pacific cod (Gadus macrocephalus), arrowtooth flounder (Atheresthes stomias), and Pacific halibut (Hippoglossus stenolepis), using stable isotope analysis to assess TL and diet source. Samples were collected from the northeastern side of Kodiak Island, Alaska, from 2000-2004. Several Analysis of Covariance models were tested, allowing TL to co-vary with length, to detect possible variation among years and seasons and to estimate TL of catch for each study species. For each species, TL increased with length. Significant annual differences in δ13C and δ15N were detected for all groundfish, indicating a lower TL, pelagic diet in 2003 and a higher TL, benthic diet in 2001. Overall, TL of GOA commercial catches appeared to remain stable over 1990-2009, with the exception of walleye pollock after 1999. This study shows that including length data could lead to an earlier detection of decline in TL estimates.

Habitat function in Alaska nearshore marine ecosystems

Jodi Pirtle, Ph.D. Fisheries
School of Fisheries and Ocean Sciences
Advisors: Ginny Eckert and Jennifer Reynolds.

Abstract: This research demonstrates how habitat structures subtidal communities and supports individual species in Alaska nearshore marine ecosystems. This was accomplished through a case study of southeast Alaska coastal regions, and an in-depth investigation of red king crab Paralithodes camtschaticus early life stage ecology and nursery habitat.

How subtidal communities reflect variation in the marine environment of southeast Alaska is poorly understood. The purpose of the first part of this body of research was to identify and compare patterns of community structure for macroalgae, invertebrate, and fish communities at shallow subtidal depths between inner coast and outer coast regions, and link patterns of community structure to environmental variability in southeast A1aska. The major hydrographic gradient of decreasing salinity and increasing temperature from the outer coast to the inner coast affected regional community structure, with greater species diversity at the outer coast Species distribution for invertebrate communities was linked to variation in benthic habitat at local scales among sites within regions. This study improves understanding of processes that structure marine communities to better predict how environmental change will affect Alaska marine ecosystems.

Many Alaska red king crab populations have collapsed and continue to experience little recovery, even for areas without a commercial fishery. Several aspects of red king crab early life stage ecology were investigated because reasons for the lack of recovery may be related to the early life history of this species. Field experiments were conducted in southeast Alaska. Settlement tinting was consistent between study years (2008-09) and with historical data for this region. Local oceanographic processes that influence larval transport may be responsible for spatial variation in larval supply. In laboratory and field experiments, early juvenile crabs (age 0 and 1) demonstrated refuge response behavior to a predator threat that changed with crab ontogeny. When predators were absent, juvenile crabs preferred highly structured biogenic habitats due to foraging opportunities, and associated with any structural habitat to improve survival when predators were present. This research shows how availability of high quality nursery habitat affects red king crab early life stage success and potential for population recovery.

Combining Traditional Knowledge and Fisheries Science in a Study of Bering Cisco Coregonus laurettae in the Yukon River Delta, Alaska

David M. Runfola, M.S. Fisheries
School of Fisheries and Ocean Sciences
Advisor: Trent Sutton.

Abstract: Relatively little is known about the biology and ecology of whitefishes (subfamily Coregoninae) in Alaska. To address this shortcoming, I incorporated both social and biological science methods to examine whitefish life history in the region of Scammon Bay, Alaska. The objectives of this study were twofold: (1) provide Yup'ik subsistence fishers an opportunity to share their knowledge of whitefish, and record their interviews for the benefit of their community and fisheries scientists; and (2) describe the ecology and life-history of Bering cisco Coregonus laurettae. In August 2004, subsistence fishers participated in interviews during which they discussed traditional knowledge of whitefish. Participants shared knowledge of Bering cisco and other whitefish species. Interviews demonstrated the need for greater awareness of traditional knowledge, and the importance of communicating this knowledge with fisheries scientists. In addition, 120 Bering ciscoes were collected in August 2005 and 2006 with gill nets in the Black and Kun rivers on the Yukon River delta, Alaska. Bering ciscoes ranged in fork length (FL) from 146 to 490 mm (mean = 321 mm) and in weight from 32 to 735 g (mean = 304 g). Fish ranged in age from 0 to 6, with one age-11 fish observed. Diet analysis showed that Bering cisco fed primarily on sticklebacks. These results suggest that juvenile Bering cisco rear in the coastal marine Yukon River delta, feeding on sticklebacks. This study advances our understanding of Bering cisco, and provides information on the socioeconomic and biological characteristics of the species.

Injected or vacuum-tumbled marinade effects on the shelf life of once- and twice- frozen fresh Pacific chum salmon (Oncorhynchus keta) fillets

Carey Vorholt, M.A. Interdisciplinary School of Fisheries and Ocean Sciences
School of Fisheries and Ocean Sciences
Advisor: Charles Crapo.

Abstract This project investigates functional marinade systems incorporated with food-grade antioxidants, phosphate and salt for Pacific chum salmon as a method of frozen storage shelf life extension by minimizing moisture loss, reducing lipid oxidation and protecting protein functionality for once- and twice-frozen fillets when compared to untreated fillets. Marinade combinations of food grade additives were applied through vacuum tumble (VAC) and injection (INJ). Proximate composition, lipid oxidation, protein degradation, raw and cooked fillet texture and color at 1, 3, 6 and 9 months were determined. All marinades contained an agglomerated phosphate blend and salt and both application methods retained moisture, increased ash content, reduced lipid oxidation and protected pigments. However, for once-frozen fillets, a marinade consisting of 3% sorbitol, 1.5% sodium erythorbate, 3% phosphate and 3% salt produced consistent raw and cooked texture during nine months of frozen storage. Cooked twice-frozen fillets tended to be softer than cooked once-frozen fillets.

Resource partitioning among sympatric Steller sea lions and northern fur seals on Lovushki Island, Russia

Jason Waite, Ph.D. Marine Biology
School of Fisheries and Ocean Sciences
Advisor: Russell Andrews.

Abstract: The competitive exclusion principle maintains that one of two non-interbreeding species occupying the same ecological niche and the same geographical territory will be displaced if population growth is not the same between species. Steller sea lions (Eumetopias jubatus; SSL) and northern fur seals (Callorhinus ursinus; NFS) breed sympatrically on four rookeries in the Russian Far East, creating the potential for inter-specific competition for limited prey resources. Approximately 1,000 SSL and 14,000 NFS breed on Lovushki Island in the Kuril Island chain. An additional 13,000-14,000 juvenile NFS are present during the breeding season. The partitioning of forage resources among SSL and both breeding and non-breeding NFS from 2003-2008 was examined through analysis of prey remains recovered from scats and spews, stable isotope (SI) analysis of vibrissae, fatty acid (FA) analysis of blubber, and analysis of foraging behavior through satellite-linked telemetry. Analysis of prey remains indicated a biologically significant overlap in the prey species and size selection of SSL and juvenile NFS and significant differences between the diets of SSL and breeding NFS. SSL fed primarily on Atka mackerel while breeding NFS fed primarily on cephalopods and northern smoothtongue. SI analysis indicated significant differences in the trophic level and relative foraging location. SSL foraged at a higher trophic level, near-shore, and benthically, while NFS foraged at a lower trophic level, off-shore, and pelagically. Analysis of FA signatures also suggested significant differences in the relative diets of breeding NFS and SSL. Foraging behavior analysis also indicated that SSL foraged near-shore and benthically and breeding NFS foraged off-shore and pelagically. The combination of these four methodologies suggests breeding NFS and SSL partition their forage resources by prey type and prey size, as well as spatially. This partitioning of resources between breeding animals currently allows both species to coexist within the same geographical region and likely reflected the differences in foraging abilities and provisioning strategies of the adults, as well as the fasting abilities of their pups. However, continued growth of the non-breeding NFS population on Lovushki Island may lead to the competitive exclusion of SSL due to inter-specific competition for food resources.

Summer 2010 Abstracts


Patrick D. Barry, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisors: Dr. David Tallmon & Dr. Sherry Tamone, Co-Advisors. 

Abstract: In recent years there has been a renewed interest in a directed fishery for North Pacific giant octopus, Enteroctopus dofleini.  This species continues to be managed as a bycatch only species through the use of commisioner's permits primarily due to the lack of information regarding the basic ecology of E. dofleini and the logisitics of management.  In the summer of 2007 we completed a survey in Kachemak Bay to determine the efficiency of different gear types for targeting E. dofleini, compared different methods of tagging individuals for movement and abundance estimates, and collected tissue samples for use in a genetic analysis of population structure.  If a directed fishery develops in Alaska, our data suggest that unbaited lair pots may be the most effective means of capture while minimizing bycatch of other commercially important species.  Most regions in Alaska lack sufficient data to estimate abundance and often estimates using catch-perunit of effort can be inaccurate.  If mark-recapture methods are used to estimate abundance of octopus populations, then results from our tagging indicate that visible implant elastomer may be a more effective means of marking individuals.  Genetic analysis of E. dofleini populations revealed an enigmatic pattern of population structure with two haplotype lineages.  The large amount of sequence divergence at the COI locus may indicate the presence of a cryptic species within the E. dofleini complex. 


Cindy A. Tribuzio, Ph.D. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Gordon Kruse.

Abstract: The spiny dogfish (Squalus acanthias) is a small, cosmopolitan shark species, common in sub-tropical and sub-arctic waters.  The species is often targeted commercially in most areas of the world throughout it's range, and in some cases it is overfished or the subject of conservation concern.  In the Gulf of Alaska, spiny dogfish are not targeted and not generally retained, but incidental catch can be high for this schooling species.  Previously, biological parameters for spiny dogfish in the Gulf of Alaska were assumed from estimates for this species neighboring areas, including British Columbia and Washington State.  The purpose of this study was to examine spiny dogfish in the Gulf of Alaska and estimate important parameters for stock assessment in four stages: (1) general biology, distribution and life history; (2) modeling age and growth; (3) population demographic modeling; and (4) ecological interactions revealed by diet analysis.  Spiny dogfish are similar in length in the Gulf of Alaska to neighboring regions, but mature at larger sizes and have a greater fecundity than reported elsewhere.  There is high natural variability in estimated ages for the species, which is reflected in the poor fit of the growth models, possibly owing to measurement error from using the dorsal fin spine as the aging structure.  A two-phase growth model provided the statistical best fit.  However, questions were raised about the biological interpretation of the model and whether more traditional models (e.g., von Bertalanffy and Gompertz) may be more appropriate.  Using the life history and growth data, Leslie matrix type age- and stage-based demographic models were created to estimate sustainable fishing mortality rates and to examine the risk of harvest scenarios.  Female Gulf of Alaska spiny dogfish can support up to a 3% annual harvest rate; fisheries that target juveniles have the greatest risk of population decline below threshold levels.  Spiny dogfish are generalist opportunistic feeders that feed on whichever prey is available, however shrimp are the most important prey type, followed by cephalopods.  Results of this study will be used in future ecosystem modeling and stock assessments for this species.


Aaron Wayne Dupuis, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Trent Sutton.

Abstract: Humpback whitefish Coregonus pidschian and least cisco C. sardinella are two species of coregonids common to the interior of Alaska and are a food resource for rural and urban communities.  These fishes exhibit variation in life-history characteristics throughout their range, and many basic life-history questions remain unanswered.  My objectives were to describe the spawning movements and identify the current distribution of putative spawning areas for humpback whitefish, and to assess the reproductive biology of humpback whitefish and least cisco in the Minto Flats-Chatanika River complex.  Observed movement patterns indicated that humpback whitefish exhibited complex dispersals to putative spawning areas.  Two putative spawning areas were identified: one in the Chatanika River downstream of the Elliot Highway Bridge and the other in the Tanana River near Fairbanks.  Mean absolute fecundity was 45,000 eggs ∙ female-1 for humpback whitefish and 41,780 eggs ∙ female-1 for least cisco.  This examination of reproductive biology suggested that larger-bodied females associated with higher gonadosomatic index values produce more and larger eggs per unit body weight than smaller females.  This study increased our understanding of the life history and biology of whitefishes in Alaska and can assist managers with developing appropriate management strategies for these fishes in the future.


Lisa M. South, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Amanda Rosenberger.

Abstract: At northern extremes, fish habitat requirements are often linked to thermal preferences and the presence of overwintering habitat.  The goal of this study was to identify spawning habitat for fall chum salmon Oncorhynchus keta and model habitat selection from spatial distributions of tagged individuals in the mainstem Tanana River, Alaska.  I hypothesized that the presence of groundwater, which provides thermal refugia for overwinter incubation, would be most important for fall chum salmon.  Models included braiding, sinuosity, open water surface area (indicating significant groundwater influence), and open water persistence (consistent presence of open water for a 12 year period according to satellite imagery).  Candidate models containing open water persistence were selected as most likely.  Persistent open water areas were further examined using forward-looking infrared (FLIR) imagery; marked differences between sites were observed in the extent of thermal influence by groundwater.  Persistent open water sites with strong groundwater influence appear to serve as core areas for spawning salmon; the importance of stability through time suggests the legacy of successful reproductive effort in these areas for this homing species.  This study indicates that not only the presence of groundwater is important for spawning chum, but its persistence and extent of groundwater influence.


Kelly A. Mansfield, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisors: Amanda Rosenberger and Trent Sutton.

Abstract:Fish are stocked for a variety of reasons, including the providence of diverse angling opportunities.  Rainbow trout Oncorhynchus mykissare the most widely stocked sport fish species in North America.  In interior Alaska, over 90 of the 137 lakes chosen for stocking are stocked with rainbow trout.  To optimize fish stocking programs, managers require a better understanding of the lake characteristics associated with success in meeting program objectives, for assessment of potential lakes proposed for stocking, and to address angler inquiries.  For my project, I used a model-selection process with lake morphometric and biotic data from 36 stocked lakes in interior Alaska to develop a predictive model for rainbow trout stocking success defined by pre-set mean length-at-age standards.  Average stocking density, lake surface area, and shoreline development explained 46% of the variation in rainbow trout lengths.  Model cross-validation, however, called into question the predictive capabilities of the model.  In addition, limnological data collected from 10 lakes in 2009 identified water temperature as a correlate with rainbow trout length.  This study provided an approach that can be used by managers to evaluate rainbow trout length in stocked lakes, and serves the basis for improving stocking programs while providing satisfactory fishing experiences. 


Brenna McConnell, M.S. Marine Biology
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Rolf Gradinger.

Abstract: Arctic coastal fast ice supports high densities of sea ice algae, and is thermally stable at the ice-water interface at around the freezing point of sea water, providing a suitable environment for sympagic meiofauna feeding on the sea ice algae during spring months.  Changes in water temperature due to seasonality and climate change may affect physiological processes of these organisms.  We tested the hypothesis that juvenile growth rates of a common sympagic polychaete, Scolelepis squamata (Polychaeta: Spionidae), would be significantly faster at typical spring sea ice algal concentrations compared to concurrent phytoplankton concentrations and at open water summer versus winter temperatures.  Juvenile S. squamata from fast ice off Barrow, Alaska were fed three algal concentrations at 0°C and 5°C, simulating ambient high sea ice algal concentrations, concurrent low phytoplankton concentrations and an intermediate concentration.  Growth rates, calculated using a simple linear regression equation, were significantly higher (up to 225 times) at the highest algal concentration compared to the lowest in all experiments, showing sea ice to provide more beneficial food situation compared to the under-ice water column.  Additionally, juveniles grew over five times faster at 5°C compared to those feeding at 0°C, forecasting faster juvenile growth as Arctic temperatures warm. 


Heather Riley, M.S. Marine Biology
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Sue Hills.

Abstract: In summer, Humpback whales (Megaptera novaeangliae) of the North Pacific stock feed in Alaska's nearshore waters.  My research focused on the Bering Sea between Unimak and Samalga Pass with the objectives: 1) Estimate the number of humpback whales using the study area from 2001 through 2006; 2) Determine to what extent humpback whales exhibit site fidelity; 3) Describe the distribution of humpback whales and determine if depth, slope, and chlorophyll-a can predict the humpback whale presence.  To investigate the degree to which whales return to the Eastern Aleutian summer feeding ground, 1,985 whale photographs were collected and an identity matrix was created; Humpback whales exhibited a 22 percent return rate with 181 whales out of 802 total whales seen in more than one year during the six year study.  Program MARK was used to estimate the number of humpback whales utilizing this area, resulting in an estimate of 500 to 1600 animals.  Logistic regression and random forest classification determined that depth and longitude are significant predictors of humpback whale presence.  These results support other studies in the Eastern Aleutians and North Pacific and further confirm the importance of oceanographic and biological features in concentrating prey and predicting humpback whale distribution.


Megan M. Murphy, M.S. Marine Biology
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Katrin Iken.

Abstract: This study's primary goal was to understand the oceanographic effects on larval crab transport and distribution between an estuarine inner and more oceanic outer bay in the subarctic estuary of Kachemak Bay, Alaska.  Plankton tows and hydrographic measurements (temperature and salinity) were taken along the boundary between the two bay parts from March – October on spring and neap tides.  Summer water flow and stratification in Kachemak Bay is predominantly freshwater-driven and density patterns vary inter-annually with the amount of freshwater supplied to the inner bay.  Larvae of seven crab species occurred in a seasonal sequence and the crab larval assemblage was closely correlated to temperature in the upper 20 m.  The influence of tidal forcing on larval transport was not clear even though most species exhibited peak abundances at spring tides.  Larval distribution patterns across the inner/outer boundary indicated that Oregonia gracilis larvae may be transported into inner Kachemak Bay; however, late larval stages of the two commercially relevant species, Chionoecetes bairdi and Cancer magister, were never observed and may be exported from the inner estuary.  These observations provide an important baseline for further studies to understand Kachemak Bay's role as a source or sink for larval crab.

Spring 2010 Abstracts


Scott David Ayers, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Amanda Rosenberger.

Abstract: The Arctic, known for its dynamic past, is a significant place to examine drivers of and spatial variation in diversity of life history strategies in fishes.  Diversity in heritable life history traits can lead to speciation, as may be the case for the putative Angayukaksurak charr (Salvelinus anaktuvukensis).  The goal of this study was to determine the species status of this fish, the only described freshwater species endemic to Alaska.  I examined and compared the morphology and genetics of Angayukaksurak charr and its most closely related species, the Dolly Varden (Salvelinus malma).  Meristic characters divided the specimens into three forms by major river drainage.  Morphological analysis divided the specimens into two forms along nominal species lines based on differences that could also be attributed to differences between life history forms.  Sequences from a 550 bp section of mitochondrial d-loop failed to segregate the putative Angayukaksurak charr into a separate lineage, rather placing specimens into two previously resolved lineages of holarctic Arctic charr.  In addition, analysis of microsatellite loci showed no clear differentiation between species.  Based on these results, I concluded that the Angayukaksurak charr is not a separate species, but rather a resident life history form of the Dolly Varden.


William K. Carter III, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Trent Sutton.

Abstract: Broad whitefish Coregonus nasus have long been an important subsistence resource across its Arctic and sub-Arctic range.  Despite its regional importance, little is known about the life history and ecology of this species.  This research illuminates fundamental life-history information through the use of catch-per-uniteffort (CPUE) run timing, gonadosomatic index (GSI), radio telemetry, and aging and microchemical analysis of otoliths.  From 2001 to 2006, fishwheels were used to capture individuals 1,200 km upstream from the mouth of the Yukon River.  CPUE data indicated a consistent increase in daily fish numbers through mid-September.  The GSI showed an increasing gonad weight over the sampling period, indicating preparation for spawning.  Thirty-one of 41 radio-tagged fish were tracked to a 260 km long spawning area centered 350 km upstream of the tagging site.  Thirteen of 17 fish found in the spawning area in 2003 overwintered nearby.  Ages of 79 individuals ranged from 5 to 16 years (mean age = 10; median age = 9).  Microchemical analysis showed amphidromy in 10 of 12 individuals by examining otolith strontium (Sr) concentrations.  This information indicates that the broad whitefish captured in this study were mature, migrating to a spawning/overwintering area, and have a complex amphidromous life history.


Samantha Kristin Strom Decker, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Amanda Rosenberger.

Abstract: Pacific salmon (Oncorhynchus) habitat models attempt to balance research efficiency with management effectiveness, however, model transferability between regions remains elusive.  To develop efficient habitat models, we must understand the critical elements that limit habitat.  At the northern edge of the geographic range for Chinook salmon, O. tschawytscha, water temperature is a probably a limiting habitat factor.  This study investigated the spatial and temporal correspondence between water temperature and Chinook salmon spawning on the Chena River, Alaska.  Water temperatures were monitored at 21 stations across 220 river kilometers during the 2006 and 2007 spawning seasons and compared to known thermal requirements for egg development.  While an absolute upstream thermal boundary to spawning was not discovered, we describe potential temporal limitations in thermal conditions over the spawning season.  Our results show that 98.5% of Chinook salmon selected spawning habitat in which their eggs have a 90% probability of accumulating 450 ATUs before freeze up.  This suggests not only temperature conditions limit salmon spawning habitat, but also, as expected, water temperatures temporally limit accessible Chinook salmon spawning habitat at the northern edge of their range.  This project documents new spawning habitat for the Anadromous Waters Catalog and broadens the geographical range of Chinook salmon thermal habitat research. It also contributes to the understanding of the processes that define salmon habitat, while providing a baseline for further investigations into water temperature in other thermal regimes.


Lisa M. Kamin, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Anthony Gharrett.

Abstract: We know little about the population structure of Gulf of Alaska (GOA) and Bering Sea rockfish, including Pacific ocean perch (POP, Sebastes alutus), and early life history information is sparse for many rockfish species.  Young-of-the-year (YOY) POP were collected with surface trawls during surveys of juvenile salmon in the GOA and Bering Sea.  These samples presented a unique opportunity to study POP genetics and life history.  Fourteen microsatellite loci were used to characterize the genetic variation in POP collected in a total of 45 hauls over five years.  The coincidence in timing and location of several collections between years allowed examination of both fine- and broad-scale geographic variation (within cohorts) as well as interannual (between cohorts) genetic variation.  The geographic genetic structure of these collections was also compared to geographic structure of adult POP described in a previous study (Palof, 2008).  As in the adult study, significant broad-scale geographic divergence was observed in YOY POP in the GOA.  Fine-scale geographic divergence was also observed and may be the result of variable current regimes and oceanographic features at several locations.  The limited amount of temporal variation observed seems to be the result of variable oceanography and fine-scale population structure rather than the influence of a sweepstakes effect.  The relationship between genetic divergence and geographic separation is virtually identical in YOY and adult POP, which confirms that dispersal of POP is limited in all life stages and also demonstrates that most YOY are produced by adults that are located nearby.


Trina J. Lapis, M.S. Interdisciplinary (Seafood Science & Nutrition)
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Alexandra Oliveira.

Abstract: Natural variation in the lipid content of wild-caught Pacific salmon causes inconsistency in the omega-3 fatty acid (FA) content per serving of canned product.  An increase in product value may result from advertising the DHA and EPA contents per serving in the nutritional label.  The objectives of this study were to add different levels of salmon oil (SO) to canned bright or dark pink salmon, to investigate the variability in the lipid content within and between groups, to determine nutritionally important parameters, and to evaluate the sensorial properties of the products.  Six groups of canned product were produced either using bright (0%, 1% and 2% SO) or dark (0%, 2% and 4% SO) pink salmon.  Consumer sensory tests were conducted at the UAF campus.  Proximate composition, FAME profiles, free FA content, lipid oxidation parameters, and essential amino acid and minerals were determined per serving (100 g).  Compositional analysis revealed large variability in the lipid content within groups.  The ranges of lipid content for the control groups (0%) were 4.39 to 8.13% and 2.96 to 4.91% for bright and dark pink salmon, respectively.  Sensory evaluations indicated that 4% SO imparts negative sensorial attributes to dark pink salmon.  However, 1% and 2% SO did not significantly affect the sensorial characteristics of bright and dark pink salmon, respectively.  Adding 1% SO to bright pink salmon and 2% SO to dark pink salmon resulted to quantities of 1.24 and 1.45 g of omega-3 FA per serving, respectively.


Brooke A. McFarland, M.S. Marine Biology
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Brenda Konar.

Abstract: Habitat use in birds is often related to forage resources and predation avoidance.  The large, long-lived black oystercatcher is a shorebird that defends a composite breeding territory for foraging in the intertidal zone and nesting in the immediate upland.  Predation on young is a major source of mortality for many bird species, including black oystercatcher.  As these are long-lived birds with many reproductive opportunities, adult survival, associated with forage resources, is expected to be more important in habitat use than less-predictable breeding success.  To identify which factors most influence black oystercatcher breeding territory use, logistic regression models were developed and tested in south-central Alaska and tested in southeast Alaska.  Intertidal community composition was sampled at a subset of sites.  All known breeding sites in Kenai Fjords National Park and western Prince William Sound, plus sites in southeast Alaska, were matched with available breeding sites based on substrate and exposure classifications.  Two factors related to predation avoidance, greater distance to vegetation and isolation from the mainland, were the most important variables in habitat models.  Intertidal community composition did not vary between known breeding and available breeding sites.  This suggests black oystercatchers choose breeding territories that reduce predation risk, contrary to expectations.

Fall 2009 Abstracts


Jonathon Gerken, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Joseph Margraf.

Inconnu Stenodus leucichthys are present throughout much of the Yukon River drainage in Alaska, but only five spawning areas have been identified.  Spawning habitat requirements are therefore thought to be very specific; however, the physical qualities of these habitats have only been characterized in general terms.  The Sulukna River is one of five identified inconnu spawning areas within the Yukon River drainage.  A systematic sampling design was used in September and October of 2007-2008 to define Sulukna River spawning locations.  Presence of inconnu was identified using hook and line sampling methods and spawning was verified by catching broadcast eggs in plankton nets.  Small-scale, large-scale, and chemical habitat variables were sampled at transects located every 1.8 river kilometer (rkm).  Project results indicate that spawning habitat was confined to a narrow reach of approximately 20 rkm.  Spawning habitat occurred significantly more often in transects characterized with substrate between 6 and 12 cm, a width to depth ratio between 15 - 36, and water conductivity between 266 - 298 µS/cm.  Similar studies on other known spawning habitats would reveal whether these qualities are common to all inconnu spawning populations or unique to the Sulukna River.


Elizabeth B. Benolkin, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Joseph Margraf.

Salmon returning to Lake Clark, Alaska are a valuable subsistence, commercial and ecological resource, and are an important component of the larger Kvichak River escapement.  Average escapement to the Kvichak River declined sharply during 1996-2005, prompting studies to investigate age and size at maturity, key life history traits of salmon linked to reproductive success and survival.  We examined potential factors which may influence sockeye salmon Oncorhynchus nerka age and size at maturity: spawning habitat and ocean environment, and examined variation in both traits over time.  Sockeye salmon age and length at maturity differed among spawning locations and between brood years, but no consistent patterns were observed among habitat types.  Age and length at maturity differed over time; the proportion of older marine age 3 fish was larger in recent brood years, while fish were smaller during 1997-2001 compared to 1976-1980.  Sea surface temperatures and coastal upwelling appeared to be important indicators of fish length, highlighting the importance of the ocean environment in salmon growth.  These results demonstrate the complexity and importance of both the freshwater and ocean ecosystems in variation in age and size at maturity, and indicate that trends may not necessarily be similar among systems or years.


Lorena Elaine Edenfield, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Trent Sutton.

Declines of humpback whitefish Coregonus pidschian and least cisco C. sardinella in the Chatanika River, Alaska, have led to a restricted fall spear fishery.  However, current population characteristics and the level of exploitation that will allow long-term sustainability are unknown.  My objectives were to evaluate the current stock characteristics and examine the effects of harvest on the population structure of both species.  FAST 2.0 was used to model the effects of various levels of harvest on abundance, biomass, and yield for humpback whitefish and least cisco.  Humpback whitefish ranged from 188-583 mm fork length (FL), 154-2,748 g, and encompassed ages 5-29, while least cisco ranged from 215-425 mm FL, 100-1,400 g, and were ages 3-14.  Growth of both species was highly variable.  Annual mortality estimates were 31% (SE=1.1) for humpback whitefish and 44% (SE=1.1) for least cisco.  Overall, population characteristics were within the ranges described for other stocks in North America.  Simulations indicated that harvest negatively impacted abundance and biomass, while yield was positively impacted for both species.  Exploitation allowing 3,000-4,000 total whitefish harvested annually, at the current population estimates, was determined to be sustainable.  Further research is needed to provide accurate information regarding recruitment and mortality of these species.


Jenefer Bell, M.S. Marine Biology
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Russell Hopcroft.

Understanding the feeding environment of juvenile pink salmon when they first enter the ocean may allow hatchery-reared pink salmon to be released coincident with favorable zooplankton conditions.  ZooImage, a computer-assisted image analysis system, was evaluated to determine its ability to differentiate zooplankton groups in preserved samples collected in Prince William Sound (PWS), Alaska.  ZooImage identified particles in the training set with less than 13% error.  However, accuracy went down in field collected samples to 81.7% and dropped further to 63.3% when discard particles were removed.  Copepods, the most abundant organisms in most samples, were correctly identified 67.8% of the time with medium-sized copepods correctly identified 73.3% of the time.  ZooImage was then used to process zooplankton samples from two salmon hatcheries in PWS.  Species composition, abundance and biomass of select zooplankton groups were evaluated for correlations to salmon survival.  Salmon survival was positively correlated with larval euphausiids, amphipods, larvaceans, and barnacles.  These results suggest a connection between pink salmon survival and the availability of specific zooplankton when juvenile pink salmon are released from the hatcheries.  Continued improvements to ZooImage system will further enhance automatic identification of preserved zooplankton samples.


Maryann Bozza, M.S. Marine Biology
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Tuula Hollmen.

Steller's eiders (Polysticta stelleri) and other sea duck species have undergone population declines in recent decades, and the causes for the declines remain largely unknown.  As part of a study to investigate the role of disease in sea duck population declines, I further characterized Steller's eider humoral immunity by quantifying total serum immunoglobulin Y (IgY).  Baseline values of total serum IgY were determined for a captive flock of Steller's eiders housed at the Alaska SeaLife Center using species-specific assays.  There were no significant differences in total serum IgY between males and females or between seasons (molt and winter) for captive birds.  For free-ranging Steller's eiders, mean total serum IgY was significantly higher during molt and mid-winter compared to captive baseline values, suggesting increased disease exposure.  As a further investigation of the humoral immune response, experimental inoculations (low pathogenicity avian influenza and adenovirus) were conducted in mallards (Anas platyrhyncus) as a surrogate species.  Quantification of total serum IgY from captive Steller's eiders provides a baseline for comparative studies of total serum IgY from free-ranging Steller's eiders.  This study also provided first quantitative information about circulating IgY in free-ranging Steller's eiders.


Caroline M. Jezierski, M.S. Marine Biology
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Brenda Norcross.

Increasing numbers of sea kayakers in Kenai Fjords National Park, Alaska prompted a study to evaluate human disturbance on harbor seals.  Harbor seal behavior recorded during the molt from 2004-2006 via remotely controlled cameras and direct field observations were used to evaluate effects of human activities.  Behaviors of the seals observed in the presence and absence of kayakers/walkers were contrasted by method of collection, year, presence of humans, presence of a guide, and guide training.  Results demonstrated that harbor seals abandoned the ice and were more alert when kayakers were present than when humans were absent.  Harbor seals became progressively sensitive to the presence of walkers.  Sea kayak guides were advised to observe seal behavior and minimize contact by avoiding areas with high concentrations of hauled-out seals.  Educational training provided to sea kayak guides effectively reduced the impact of human disturbance on harbor seals.


Markus A. Janout, Ph.D. Oceanography
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Tom Weingartner.

We examined conditions and processes that control the distribution of heat and freshwater on the northern Gulf of Alaska (GOA) shelf.  Cross-shelf heat gradients are weak throughout the year, while salinity gradients are substantial due to the impact of coastal freshwater runoff.  Outer shelf water properties are influenced by large anticyclonic eddies, while the inner and middle shelves may be regulated by wind and freshwater runoff dynamics around the Alaska Coastal Current (ACC).On the outer shelf, anticyc lonic eddies propagate from the eastern GOA southwestward along the continental slope, where they favor on-shelf (off-shelf) transport of saline and nutrient-rich (fresh and iron-rich) waters.  Certain along-shelf locations are identified where low-salinity coastal waters are found near the shelfbreak within reach of eddies and may be regions of enhanced cross-shelf freshwater transport.  The eddies have lifetimes of ~5 years and increase in size and sea level anomaly west of the Seward Line, which implies more vigorous eddy cross-shelf exchange in the northwestern GOA.  By comparison, on the inner shelf the heat and freshwater distribution is dominated by large coastal river runoff, which forces the ACC and controls the vertical distribution of temperatures through stratification.  In May 2007, the coastal GOA revealed some of the lowest ocean temperatures since the early 1970s, initiated by strong atmospheric cooling and reduced coastal runoff in November 2006.  Stepwise regression shows that 81% of the variability of deep temperatures is explained by salinity stratification and air-sea heat fluxes.  Weak baroclinic flow in May 2007 likely aided the cooling through reduced along-shore heat transport. A more detailed examination of heat transport indicated that along-shore heat flux convergence in the ACC may re-supply 10-35% of the heat removed by air-sea fluxes throughout the coastal GOA cooling season, while the annual mean cross-shore heat flux convergence is insignificant.  Spatial gradients show increasing heat fluxes from off- to on-shore and from east to west.  The cross-shore gradients result from wind speed gradients due to ageostrophic near-shore wind jets near coastal mountains, while the along-shore gradients result from larger-scale pressure systems.  While the ACC advects coastal freshwater around the GOA shelf its waters are subjected to disproportional heat loss west of the Seward Line.


Mayumi L. Arimitsu, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Nicola Hillgruber.

The goal of this study was to characterize Kittlitz's murrelet (Brachyramphus brevirostris) foraging habitat relative to prey availability and oceanography in Kenai Fjords National Park, a glacial-marine system.  I conducted oceanographic, hydroacoustic, trawl, beach seine, and marine bird surveys monthly from June-August in 2007 and 2008.  High sediment load from glacial river runoff shaped the marine ecosystem, and this appeared critically important to Kittlitz's murrelets at sea.  Submerged moraines influenced inner fjord habitat that was characterized by cool, fresh, stratified, and silt-laden waters.  This silty glacial runoff limited light availability to chlorophyll near tidewater glaciers, but zooplankton abundance was enhanced in the surface waters, perhaps due to the absence of a photic cue for vertical migration.  Zooplankton community structure was influenced by glacial features and varied along an increasing temperature gradient over the summer.  Acoustic measurements suggested that low density aggregations of fish and zooplankton were available in the surface waters near glacial river outflows where murrelets typically forage.  Dense fish aggregations moved into the fjords by August.  Kittlitz's murrelets were more likely to occur in areas with higher acoustic biomass near glaciers, making these birds more susceptible to climate change than the congeneric marbled murrelet (B. marmoratus), which was most associated with shallow, ice-free areas.


Lorna I. Wilson, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. William Smoker.

The growth of Seward Peninsula sockeye salmon (Oncorhynchus nerka) from Salmon and Glacial lakes is related to their physical environment.  Dermal scales collected over many years were measured to document the annual age specific growth of smolts and adults.  The effect of fertilization on fry growth was examined using the first year of growth.  The growth histories of Salmon Lake sockeye salmon were compared to Glacial Lake sockeye salmon through smolting and in the marine environment.  Annual age specific fry growth had no direct relationship to fertilization; however, there were interactions between biomass of salmon prey and fertilization, and between prey biomass and age of smolting.  Glacial Lake age-1 smolts are the same size as Salmon Lake age-1 smolts, but age-1.3 Salmon Lake juveniles after their first year in the ocean are smaller than age-1.3 Glacial Lake juveniles suggesting lower size based mortality.  The differences in growth histories show each population's response to lake production and mortality experienced by smolt between the rearing lake and the ocean.


Haixue Shen, Ph.D. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Terrance Quinn.

Walleye pollock (Theragra chalcogramma) in the eastern Bering Sea (EBS) support the largest single-species fishery in the world.  Pollock also play an important role in the EBS ecosystem as an important prey species.  The decline of the western population of Steller sea lions during the 1980s and 1990s raised concerns about the potential competition between the pollock fishery and the sea lion population.  My research focused on pollock distribution related to the fishery and physical environment at different temporal and spatial scales using fisheries acoustic data and observer data in the winter fishing season during 2002–2006.  Temperature and wind played important roles in determining the pollock distribution in winter, especially from late February to March.  The changes in spatial structure during the fishing season suggested that the fishery probably influenced pollock distribution by removing some portion of the local population and perhaps even smoothing out the aggregated distribution of pollock.  At a small scale, pollock schools became smaller and denser.  At the meso-scale, the distances between schools increased.  At a larger scale, range estimates from variography increased which indicated that the spatial correlation among pollock extended to greater distances after fishing.  Fishing behavior was also studied using Levy flight theory and its relation to pollock distribution in the EBS.  Fishing behavior was significantly correlated to the fractal dimension of fish which measures the degree of pollock clustering, rather than to pollock spatial concentration or density in the EBS.  The observer data were also included to analyze the effect of fish distribution on fishing behavior at the school scale.  The results indicated that school density rather than the school size played an important role in fishing behavior.  Finally, catch depletion analysis was used to examine the potential local depletion.  While frequentist and Bayesian methods confirmed that the fishery caused slight local depletion in some areas in the EBS, the magnitude was less than that before sea lion protection measures were put into place in 1999 to spread out the fishery in space and time.

Summer 2009 Abstracts


Deena M. Jallen, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Joe Margraf.

Chinook salmon Oncorhynchus tshawytscha are a highly valued traditional, subsistence, and commercial resource in Southwest Alaska.  Stream habitat availability is a major component influencing salmon productivity.  The objective of this study is to identify river features associated with spawning habitat, and describe upper and lower boundaries of Chinook salmon spawning on the Tuluksak River.  River distances, elevation, salmon locations, spawning sites, and habitat observations were collected along 75 rkm (river kilometers) of the Tuluksak River primarily within the Yukon Delta National Wildlife Refuge.  Habitat and salmon observations were grouped into strata along the length of the river for comparison and analysis.  Chinook salmon were observed spawning in the upper 45 rkm of the study area.  Map-based observations of elevation and channel sinuosity correlate better with Chinook salmon spawning than in stream habitat measurements along the Tuluksak River.  The upper boundary of Chinook salmon spawning in the Tuluksak River was outside of our study area.  The lower boundary for Chinook salmon spawning habitat on similar rivers might be determined by examining elevation, sinuosity, and channel features from remote images or maps prior to conducting field studies.


David C. Caroffino, Ph.D. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Trent Sutton.

Populations of lake sturgeon Acipenser fulvescens in the Laurentian Great Lakes have not recovered after dramatic declines in the late 1800s despite the implementation of numerous recovery plans.  Although extensive lake sturgeon research has and continues to occur, critical knowledge gaps remain.  Recruitment of lake sturgeon is variable, but the extent of that variation, its limiting factors, and mortality rates experienced by early life stages are unclear.  The purpose of this study was to increase our understanding of lake sturgeon early life stages by examining characteristics of a remnant population in the Peshtigo River, Wisconsin.  Specifically, this research sought to empirically estimate rates of early life stage mortality, describe the vertical distribution of drifting larvae, evaluate the impacts of predation on recruitment, and describe patterns in movement and abundance of age-0 juveniles.  Extensive sampling of lake sturgeon eggs, larvae, age-0 juveniles, and potential predators occurred during 2006 and 2007.  Although drifting lake sturgeon larvae were captured in all parts of the water column, more were found near the surface than the substrate.  After drifting to nursery areas, individuals exhibited variable movement patterns.  Some fish were never recaptured more than 10 m from the initial capture site, while other individuals moved more than 9 km.  Even though absolute abundance of juveniles differed by an order of magnitude between 2006 and 2007, a pattern of steady decline during the summer months was similar during both years.  This downstream movement may have resulted in emigration from the Peshtigo River, as there was no evidence of predation on this life stage.  Overall mortality from the egg to age-0 juvenile life stage exceeded 99.9% in both study years.  Predation on eggs was extensive by both crayfish and fish (white sucker Catostomus commersonii), but was minimal on other life stages.  These results suggest that recruitment can vary significantly, and predation is likely only limiting at the egg life stage.  These results will allow more effective monitoring and management of lake sturgeon early life stages, thereby promoting population recovery.


Rebekka Federer, M.S. Marine Biology
School of Fisheries and Ocean Sciences
Major Advisor: Tuula Hollmen.

The spectacled eider (Somateria fischeri) was listed as threatened under the Endangered Species Act in 1993, and potential threats to population recovery include changes in the marine prey abundance and availability.  Therefore, development of diet assessment techniques has been listed as an eider recovery task.  Stable isotopes have been used to evaluate foraging ecology and nutrient allocation to reproduction in birds.  Application of this technique requires knowledge of how stable isotope signatures of animal tissues differ from their diet, referred to as isotopic fractionation, and these values can be determined experimentally using captive populations.  I established stable isotopic fractionation factors for d13C and d15N from diet to egg components, down feathers, contour feathers, cellular blood, blood plasma, and fat of captive spectacled eiders.  Sensitivity analyses indicate that choice of isotopic fractionation values from eggs of different species could considerably alter model conclusions.  Therefore, I incorporated isotopic fractionation factors from spectacled eider eggs into two published sea duck nutrient allocation models that previously used these values from falcons (Falco spp.) to assess differences in model conclusions.  Results from these studies provide further resources to understand foraging and nutrient transfer in eiders and may offer more accurate estimates for sea duck models.


Kristen Dunlap, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. William Smoker.

Water overpressures and ground vibrations from blasting may injure or kill salmonid fish in streams and embryos in streambeds.  Explosives are used to remove failing structures in remote areas of the Tongass National Forest that impair watershed function.  The State of Alaska Department of Fish and Game standards limit blast induced water overpressures to 2.7 lb/in2 (18.6 kPa) and streambed vibrations to 0.5 in/s (13 mm/s) when embryos are present.  Researchers, however, have reported salmonid mortality from pressures only as low as 12.3 and 19.3 lbs/in2 (85 and 133 kPa) and embryo mortality from vibrations as low as 5.75 in/s (146 mm/s).  I recorded in-stream overpressures and streambed vibrations with hydrophones and geophones at various distances from log bridge, log culvert, and metal culvert blasts.  Peak water pressures (lb/in2) were directly related to cube-root scaled distances with an attenuation rate of -1.51.  Peak particle velocities in gravel were directly related to square-root scaled distances (SRSD, ft/lb1/2) with an attenuation rate of -0.75.  Water pressures were less than 7.1 lb/in2 (49.0 kPa) in all but one blast, and streambed vibrations did not exceed 5.5 in/s in gravel streambeds.  State standards should be revised to reflect reported mortality and these observations of blasts in streams.


Tyler H. Dann, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Anthony Gharrett.

I observed no fitness losses among F2 hybrids of three Southeast Alaska coho salmon (Oncorhynchus kisutch) populations relative to parental controls.  Marine survival did not differ among groups in one generation, but was greater for hybrids than controls in another, although the power of these tests was low.  Increases in fluctuating asymmetry, which can signal losses in fitness, were not observed.  Line cross analyses of length suggested additive and additive plus dominance gene action, and two of three analyses suggested epistasis.  In contrast, meristic characters exhibited little variability; and in most cases tests failed to reject a simple additive model.  Half- and full-sib analyses provided no evidence of quantitative genetic variation for any trait although the power to detect these effects was low.  Comparisons of population divergence measured by quantitative traits (QST) and molecular markers (FST) that length is an adaptive trait and that bilateral meristics are highly conserved.  Although we did not observe losses in fitness, the power of our tests was low, the among-population differences were unique to our experiment and so results of this study should be interpreted with caution.


Jeanette Nienaber, M.S. Marine Biology
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Jo-Ann Mellish.

Infrared thermography (IRT) was used to collect baseline information on skin surface temperatures of two species of pinnipeds, the harbor seal (Phoca vitulina; n = 6) and the Steller sea lion (Eumetopias jubatus; n = 2).  The IRT technique was validated against objects of known temperature and through post-collection software manipulation of environmental parameters that influence IRT output (emissivity, distance, relative humidity, ambient temperature and reflected temperature).  From February 2007 to February 2008, biweekly measurements were taken of skin surface temperature (FLIR P25 infrared camera) with subsequent measurements of blubber depth (SonoSite Vet180 portable imaging ultrasound system) on captive individuals at the Alaska SeaLife Center, Seward, Alaska.  Once validated, skin surface temperatures in 10 defined regions (whole body, torso, head, eye, muzzle, shoulder, axillae, hip, fore and hind flipper) were used to determine seasonal variability as well as consistent hot or cold spots, and of those spots, which may act as thermal windows (defined areas of active heat loss and/or retention).  Concurrent measurements of blubber depth were compared to skin surface temperatures at eight body sites to assess: a) the impact of insulation level on skin surface temperature on a site-specific scale, and b) the potential use of IRT as an alternative method for the non-invasive measurement of body condition.  Both species varied seasonally in skin surface temperature from winter to reproductive and molt to winter, however, harbor seals had greater regional variation.  Similar hot and cold spots were consistently recognized in both species with shoulder, axillae, fore and hind flipper identified as likely thermal windows.  While some site-specific significant relationships were found between skin surface temperature and blubber thickness, insulation level alone explained a very small portion of the variance.  Future studies to determine the factors influencing the variance on skin surface temperature (i.e., blood flow to the skin) warrant further exploration.


Daniel Kenji Okamoto, M.S. Fisheries
School of Fisheries and Ocean Sciences
Major Advisor: Dr. Ginny Eckert.

Shallow subtidal rocky reefs in the Northeast Pacific host frequent physical and biological disturbances as well as multiple competing algal species, including kelps and algal crusts.  Kelps serve a critical role in local ecosystems by generating primary productivity and essential fish habitat.  While kelp forests rank among the best understood ecosystems in the marine environment, protected and subarctic systems remain largely ignored.  Because of the importance of kelp habitat in Southeast Alaska, and the susceptibility of kelps to both disturbance and competition, I estimated the variability in kelp community structure of subtidal, kelp dominated reefs in the Lynn Canal and quantified kelp recruitment in response to both competing algae and bare space which included clearings, artificial reefs, and settlement tiles installed at different periods. Surveyed communities varied most within rather than among reefs.  Kelps exhibited strong, rapid, variable and apparent taxa specific colonization potential to clearings, artificial reefs and settlement tiles installed from summer to late fall.  Algal crusts imposed a near 100% inhibition of kelp recruits in the field and lab; however the strong colonization potential of kelps facilitated recruitment in the face of strong inhibition by algal crusts.

Spring 2009 Abstracts

Total Serum Immunoglobulin Y in Stellers Eiders and Surrogate Species as a Marker of Humoral Immune Status and Viral Response

Maryann Bozza, M.S. Marine Biology Degree Candidate
School of Fisheries and Ocean Sciences
Faculty Advisor: Dr. Tuula Hollmen.

Steller's eiders (Polysticta stelleri) and other sea duck species have undergone population declines in recent decades, and the causes for the declines remain largely unknown.  As part of a larger study to investigate the role of disease in sea duck population declines, we further characterized Steller's eider humoral immunity by quantifying total serum immunoglobulin Y (IgY).  We developed species-specific assays to quantify total serum IgY and determined baseline values for a captive flock of Steller's eiders housed at the Alaska SeaLife Center.  There were no significant differences in total serum IgY between males and females or between molt (August-September) and winter (January-March) seasons for captive birds.  For free-ranging Steller's eiders sampled from 2004-2006 at Izembek Lagoon and Unalaska Island, mean total serum IgY was significantly higher during the molt (August-September) and mid-winter (January) compared to captive baseline values.  Free-ranging Steller's eiders had significantly higher levels of IgY in mid-winter in 2005, the only year sampled for this time frame, as compared to late winter (February-March, 2005-2006) or molt (2004-2005).  To investigate the humoral immune response in mallards as a surrogate species to experimental avian influenza and adenovirus isolates from sea duck and sympatric duck species, samples from three experimental inoculation studies were analyzed.  Mean total IgY levels were hypothesized to increase in response to viral infection, and although results in these studies were inconclusive, they suggest challenges to and opportunities for further research on the humoral immune response to viruses.  By quantifying total serum IgY from captive Steller's eiders, we have created a relevant context for total serum IgY data from free-ranging Steller's eiders that will contribute to our further understanding of population-level immune status in Alaska's sea ducks throughout their annual cycle.

Abundance, Recruitment, and Environmental Forcing of Kodiak Red King Crab

William Bechtol, Ph.D. Fisheries Candidate
School of Fisheries and Ocean Sciences, Fisheries Division
Faculty Advisor: Dr. Gordon Kruse.

Commercial harvests of red king crab Paralithodes camtschaticus around Kodiak Island, Alaska increased rapidly in the 1960s to a peak of 42,800 mt in 1965.  Stock abundance declined sharply in the late 1960s, moderated in the 1970s, and crashed in the early 1980s.  The stock has not recovered despite a commercial fishery closure since 1983.  To better understand the rise, collapse, and continued depleted status of the red king crab stock around Kodiak Island, I conducted a retrospective analysis with three primary objectives: (l) reconstruct spawning stock abundance and recruitment during 1960-2004; (2) explore stock-recruit relationships; and (3) examine ecological influences on crab recruitment.  A population dynamics model was used to estimate abundance, recruitment, and fishing and natural mortalities.  Three male and four female "stages" were estimated using catch composition data from the fishery (1960-1982) and pot (1972-1986) and trawl (19862004) surveys.  Male abundance was estimated for 1960-2004, but limited data constrained female estimates to 1972-2004.  Strong crab recruitment facilitated increased fishery capitalization during the 1960s, but the high harvest rates were not sustainable, likely due to reproductive failure associated with sex ratios skewed toward females.  To examine spawner-recruitment (S-R) relationships for the Kodiak stock, I considered lags of 5-8 years between reproduction and recruitment and, due to limited female data, two currencies of male abundance as a proxy for spawners: (I) all males = 125 mm carapace length (CL); and (2) legal males (= 145 mm CL).  Model selection involved AICc, the Akaike Information Criterion corrected for small sample size.  An autocorrelated Ricker model using all males and a 5-year lag, with the time series separated into three productivity periods corresponding to different ecological regimes, minimized AlCc values.  Depensation at low stock sizes was not detected.  Potential effects of selected biotic and abiotic factors on early life survival by Kodiak red king crab were examined by extending the S-R relationship.  Results suggested a strong negative influence of Pacific cod Gadus macrocephalus on crab recruitment.  Thus, increased cod abundance and a nearshore shift in cod distribution likely impeded crab stock rebuilding.

Nutrition and Technique for Large Scale Larval Culture of the Red King Crab (Paralithodes Camtschaticus) and Blue King Crab (Paralithodes Platypus)

Celeste Leroux, M.S. Marine Biology Degree Candidate
School of Fisheries and Ocean Sciences
Faculty Advisor: Dr. Ginny Eckert.

This presentation will outline a progression of knowledge in large-scale king crab culture through the first two years of the Alaska King Crab Research, Rehabilitation and Biology Program, a collaborative research initiative designed to develop and investigate the feasibility of this technology for the purpose of stock rehabilitation.  We collected red king crab (Paralithodes camtschaticus) and blue king crab (Paralithodes platypus) ovigerous females from the wild and reared their larvae in a series of experiments designed to addresses the fundamental role of diet in larval health, growth, and survival.  Paralithodes camtschaticus larvae were fed newly hatched Great Salt Lake strain Artemia sp. alone or in conjunction with one of three algae species commonly used in aquaculture which yielded low survival (0.35% [plus or minus] 0.33) to the glaucothoe stage.  Mass culture of P. platypus larvae fed newly hatched Great Salt Lake strain Artemia sp. and the algae Isochrysis galbana yielded low survival overall (3.27% [plus or minus] 3.86) with or without the imposed stress of handling for survival assessments.  Investigation of the low survival observed in 2007 larval rearing experiments led to biochemical analyses of crab larvae.  These results provided baseline data on the proximate composition and fatty acid profiles of newly hatched P. camtschaticus and P. platypus zoeae.  Additionally, P. platypus in later larval stages were analyzed for fatty acid composition which elucidated potential concerns regarding the effectiveness of using Great Salt Lake strain Artemia sp. nauplii as a diet, namely low values of EPA and DHA.  In 2008, we tested a revised method of enriching San Francisco Bay strain Artemia sp. with DC DCHA SELCO.  We observed higher survival for larvae fed enriched (62.19% [plus or minus] 19.4) versus newly-hatched Artemia sp. (1.18 [plus or minus] 0.89).  Feeding I. galbana algae did not present a significant effect in zoeal survival.  Along the way, many lessons were learned in the mechanical setup of a king crab hatchery and how to effectively conduct scientific research on this scale.

River Features Associated with Chinook Salmon Spawning Habitat in Southwest Alaska

Deena Jallen, MS Fisheries Degree Candidate
School of Fisheries and Ocean Sciences
Faculty Advisor: Dr. Joe Margraf.

Chinook salmon are a highly valued traditional, subsistence, and commercial resource in Southwest Alaska.  Stream habitat availability is a major component of salmon productivity.  The objective of this study was to identify river features associated with spawning habitat, and describe upper and lower boundaries of Chinook salmon spawning on the Tuluksak River.  River distances, elevation, salmon locations, spawning sites, and habitat observations, were collected along 75 rkm of the Tuluksak River primarily within the Yukon Delta National Wildlife Refuge.  Habitat and salmon observations were grouped into strata along the length of the river for comparison and analysis.  Chinook salmon were observed spawning in the upper 45 rkm of the study area.  Map based observations of elevation and channel sinuosity were found to correlate better to Chinook salmon spawning than in stream habitat measurements along the Tuluksak River.  This project indicates that the upper boundary of Chinook salmon spawning in the Tuluksak River was outside of our study area.  The lower boundary for Chinook salmon spawning habitat on similar rivers might be determined by examining elevation, sinuosity, and channel features from remote images or maps prior to conducting field studies.

Quantifying diet to tissue stable carbon and nitrogen isotope fractionation factors in captive spectacled eiders (Somateria fischeri): Creating a resource for nutrient allocation and foraging ecology studies

Rebekka Federer, SFOS M.S. Marine Biology Candidate
School of Fisheries and Ocean Sciences
Faculty Advisor: Dr. Tuula Hollmen.

Stable isotopes can be used to evaluate foraging ecology and nutrient allocation to reproduction in migratory birds that travel between isotopically distinct habitats (e.g., marine and freshwater).  Many sea ducks, including spectacled eiders (Somateria fischeri), spend much of their annual cycle at-sea and travel to freshwater habitats for the breeding period.  Spectacled eiders were listed as threatened on the Endangered Species List in 1993, and potential threats affecting their reproductive success and population recovery include changes in the marine prey abundance and availability.  Little is known about sources of nutrients and energy required during reproduction, and therefore the development of diet assessment techniques has been listed as a recovery task by the spectacled eider recovery team.  Stable isotope analyses of diet and tissues can be incorporated into mixing models to estimate the contribution of different nutrient resources to animal tissues.  However, application of stable isotope analyses in dietary or reproductive nutrient allocation models requires knowledge of how the stable isotope signatures of animal tissues differ from their diet, referred to as isotopic fractionation.  Captive populations offer an important contribution to these types of models by determining isotopic fractionation factors experimentally.  In this thesis, I established the isotopic fractionation factors for diet to egg components using captive spectacled eiders, which had not been previously determined for any sea duck species.  Sensitivity analyses indicated that using isotopic fractionation values from different species can considerably alter the results and conclusions.  I also determined the isotopic fractionation values for down feathers.  These values have not been previously reported for any avian species and could provide an alternate tissue to consider in future studies of nutrient allocation to reproduction.  Additionally, I established the isotopic fractionation factors for diet to adult tissues (i.e., cellular blood, blood plasma, adult contour feathers, and subcutaneous fat) in captive spectacled eiders, which will enable researchers to evaluate diet sources/variability and movement patterns across biomes.  Finally, I evaluated the effects of incorporating the newly derived diet to egg isotopic fractionation factors into two published sea duck nutrient allocation models that previously used isotopic fractionation values from falcons (Falco spp.).  Results from these studies provide further resources to understand foraging ecology and reproductive nutrient allocation modeling in threatened spectacled eiders and may offer more accurate estimates for other sea duck models.

Analysis of Adult Lesson Choices and their Application to Outdoor Education Program Development

Shann Jones, M.S. Interdisciplinary Program Degree Candidate
School of Fisheries and Ocean Sciences
Faculty Advisor: Dr. Terry Johnson.

The physical benefits of recreation across the life span are well documented.  Other related research indicates adults also desire to learn throughout life.  Such has been the demonstrated by the growth of innovative post-secondary weekend outdoor education events throughout North America that meet both of these human development needs.  More specifically, adult fly-fishing programs experience enrollment fluctuations largely due to popular culture.  I noticed vast variations in North American fly-fishing curriculum as I developed my own collegiate program the University of Alaska Fairbanks (UAF).  Therefore, I asked, "am I teaching adults the fly-fishing topics they want or think they should learn in the post-secondary environment?"  I distributed a comprehensive questionnaire distributed to the public to gauge their fly-fishing educational wants and requirements.  By analyzing the surveys' results, I created a science-based fly-fishing program that includes these components.  This thesis reviews that data analysis and program development.  To gauge, whether or not my course offerings met my students' expectations, pre-and post angler/aquatic education questionnaires were distributed, filled out by my class participants and qualitatively analyzed.  These questionnaires were distributed to my UAF fly fishing-related program participants from Fall 2005 through Summer 2007 and subsequently analyzed.

An Exploration of the Life History of Broad Whitefish (Coregonus nasus) in Alaska Yukon River

William Carter III, MS Fisheries Degree Candidate
School of Fisheries and Ocean Sciences
Faculty Advisor: Dr. Trent Sutton.

Broad whitefish Coregonus nasus have long been an important subsistence resource for people across its Arctic and sub-Arctic range.  Despite its regional importance, little is known about the life history and ecology of this species.  This research tries to illuminate fundamental life history information through the use of catch-per-unit-effort (CPUE) run timing, gonadosomatic index (GSI), radio telemetry, and aging and microchemical analysis of otoliths.  Fishwheels were used to capture individuals at a site 1200 km from the mouth of the Yukon River.  The CPUE data covers six years and indicates a consistent increase in daily broad whitefish numbers through mid-September.  Our GSI showed an increasing gonad weight over the sampling period, indicating preparation for spawning.  Thirty-one of 41 radio tagged fish were tracked to a 260 km long spawning area centered 350 km upstream of the tagging site.  Thirteen of 17 fish found in the spawning area in 2003 overwintered near by.  Ages of 79 individual ranged from 5 to 16 years (mean=10, median=9).  Microchemical analysis using a wavelength-dispersive electron microprobe showed amphidromy in 10 of 12 individuals by examining otolith strontium (Sr) concentrations.  These findings provide a platform for further research into the complex life history of broad whitefish.

Fall 2008 Abstracts

The Status of Pacific Walrus (Obobenus rosmarus divergens) Foraging Habitat and Diet Around St. Lawrence Island

Tracie Merrill, M.S. Marine Biology Candidate
School of Fisheries and Ocean Sciences Graduate Program in Marine Science and Limnology
Faculty Advisor: Dr. Brenda Konar.

With ongoing climate change, reduced food resources may be negatively impacting Pacific walruses (Odobenus rosmarus divergens).  Significant changes in walrus foraging habitat (benthic communities) or diet might indicate changes in prey quality or quantity.  In this study, benthic infaunal biomass, abundance, and composition were compared between 1970-1974 and 2006 southwest of St. Lawrence Island.  Sediment grain size also was compared because it strongly determines benthic community structure.  Additionally, wet weights, counts, and composition of prey items found in walrus stomachs collected near the island were compared between the 1980s and 2007.  Contrary to other studies, benthic invertebrate biomass and abundance significantly increased (mainly due to increases in the family Nuculidae).  Silt fractions increased within the region.  However, no significant dietary changes were detected in walruses.  Walruses may have undergone population redistribution or decline in response to benthic community changes that would not be expressed in stomach content analyses.

Characterization of Annual Sex Steroid and Behavioral Profiles in Spectacled Eiders (Somateria fischeri)

Abigail Ellsworth, M.S. Marine Biology Degree Candidate
SFOS, Seward Marine Center, and Alaska Sealife Center
Faculty Advisor: Drs. Shannon Atkinson and Tuula Hollmen.

The spectacled eider (Somateria fischeri) population in western Alaska declined by 96% from the 1970s though the 1990s, which led to their listing as threatened under the Endangered Species Act in 1993.  Since listing, the breeding population in western Alaska has stabilized, but has not recovered to pre-decline numbers.  Little is known about reproductive endocrinology and, more specifically, how sex steroids initiate and modulate reproductive efforts in spectacled eiders.  Furthermore, longitudinal assessment of sex steroid profiles in this, and any species, is inevitably difficult using traditional blood sampling methods.  In recent studies, measurements of sex steroids in excrement have been shown to reflect circulating hormone levels and provide a non-invasive method to frequently sample and monitor endocrine patterns in avian species.  Samples from captive spectacled eiders were used to validate the use of excrement to longitudinally monitor sex steroids in this species.  Additionally, fluctuations in annual endocrine profiles were compared to major breeding events and behavioral patterns in order to characterize the breeding season and explore the synchrony of physiology and behavior in these animals.  Radioimmunoassay (RIA) techniques measured excreted male testosterone and female total estrogens accurately.  The female total estrogen profile indicated that defining the breeding season solely by behavioral landmarks artificially truncated the season, leaving out an important ramp up (i.e. physiological preparation for breeding).  The profile also revealed peak total estrogen levels that correspond with the laying period, as well as a non-breeding season peak in mid September.  The male testosterone profile revealed peak values only occurring during the breeding season, with elevated levels beginning in mid February and continuing through the end of the laying period in early July.  Male courtship and aggressive behaviors were higher during the breeding season than the non-breeding season, indicating a behavioral shift post-lay, however only courtship and male testosterone during post lay were related.  These data suggest that excreted sex steroid levels correspond to major breeding landmarks within the annual cycle and this noninvasive method is a valuable research tool for future investigations of hormonal and behavioral correlates in threatened spectacled eiders.

Thermal limitations on Chinook salmon spawning habitat in the northern extent of their range

Samantha Decker, M.S. Fisheries Degree Candidate
School of Fisheries and Ocean Sciences
Faculty Advisor: Dr. Joe Margraf.

Salmon are highly valued ecologically, economically, and culturally; yet some populations are threatened due to habitat alteration and management priorities.  Simplifications inherent in many harvest management models often overlook regional habitat influences and typically require long and expensive time series of stock abundance data.  Additionally, most salmon habitat modeling research has been conducted in the southern end of the species range; therefore, transferability of this research may be compromised at the northern edge of their distribution.  This study investigated the importance of water temperature on the spatial and temporal limits of Chinook salmon spawning on the Chena River, Alaska.  While an absolute upstream thermal boundary to spawning was not discovered, thermal limitations in the habitat range during the spawning season were documented.  These limitations suggest not only that a thermal boundary exists, but also that thermal limitations influence the overall size of Chinook salmon spawning habitat a the northern edge of their range.  This project broadens the geographical range of Chinook salmon habitat research and contributes to the understanding of the geomorphological processes behind salmon habitat.  It also provides a baseline for further investigations into water temperature for other species and in other thermal regimes.