• Factors affecting estuarine populations of Nereocystis luetkeana in Kachemak Bay, Alaska

      Chenelot, Héloïse Anne Claude (2003-12)
      Nereocystis luetkeana forms extensive kelp beds in Kachemak Bay, Alaska. Salinity and turbidity gradients apparently regulate kelp bed distribution throughout this estuary. The beds are large at the entrance of the bay, only solitary stands occur in the inner bay, and no kelp is found at the head of the bay. The role of salinity and turbidity on Nereocystis sporophyte growth was investigated by performing reciprocal transplants among three beds along the bay axis and regularly measuring stipe growth. The effects of salinity and light on spores were studied in the laboratory by recording sinking tendency, settlement success, germination success, and germ tube length under different salinity and light levels. Grazing effects of Lacuna vincta impacted the survival of Nereocystis transplants in-situ and on plants of different age classes in the laboratory. Overall, this study suggests a possible negative estuarine effect on sporophytes transplanted from the outer to the inner bay and on certain aspects of spore development. Herbivory pressure had significant localized effects on Nereocystis survival and was most pronounced on juvenile plants. The dynamics of Nereocystis kelp beds in Kachemak Bay results from large-scale environmental factors and local-scale biological processes.
    • Factors affecting marine growth and survival of Auke Creek, Alaska coho salmon (Oncorhynchus kisutch)

      Briscoe, Ryan Jordan (2004-05)
      Correlation analyses and stepwise regression models were run to examine relationships between Auke Creek coho salmon marine survival, scale growth, and a number of physical and biological covariates: local sea surface and air temperatures, local precipitation, the Pacific Decadal Oscillation, local hatchery release numbers, size at return, and regional and state salmon catch numbers. Jack survival and adult survival covaried strongly, suggesting the primary cause of mortality is encountered in the first four or five months of marine life. The number of hatchery fish had the strongest correlation with marine survival (r = 0.71), which could indicate that hatchery releases are prey for Auke Creek coho smolts or buffering these smolts from predators. Sea surface temperature was not significantly associated with adult survival, but was with jack survival. Surprisingly, scale growth was not correlated with marine survival. Adult size appears to be determined in the last year of marine life when the fish are in the Gulf of Alaska. Regional survival trends followed closely with Auke Creek marine survival, indicating factors affecting survival are regional in scope. Specific mechanisms were not defined, but the results indicate biological covariates were more associated with Auke Creek coho survival than were physical covariates.
    • Factors influencing chinook salmon spawning distribution in the Togiak River, Alaska

      Meggers, Stephanie L.; Seitz, Andrew; Prakash, Anupma; Lopez, Andres; Tanner, Theresa (2018-12)
      Salmonids are heavily dependent on specific habitat characteristics for survival, yet few studies in Alaska have examined the relationship between habitat and spawning distribution, using remote sensing approaches. To better understand the relationship between Chinook Salmon Oncorhynchus tshawytscha spawning distribution and environmental variables like habitat type (e.g., run, riffle, pool), temperature, and proximity to channel islands, optical and thermal imagery were collected on the Togiak and Ongivinuk rivers in southwest Alaska. Object-based image analysis was used to classify and quantify habitat types, while thermal characteristics and the proximity of spawning locations to channel islands were determined in a GIS framework. Object-based image analysis was useful for classifying habitat and may provide a better alternative to pixel-based image analysis. However, rule sets were nontransferable and inconsistent among river reaches, and caution should be taken when these methods are used on large river sections. Chinook Salmon showed a preference for spawning in river runs, 80% of fish spawned in water temperatures between 8.6° and 9.4°C, and nearly 61% of Chinook Salmon spawned within 100 m of a channel island. This study provided a baseline understanding of environmental correlates of spawning for Chinook Salmon at the northern extent of their range.
    • Factors influencing zooplankton populations in Alaskan sockeye salmon (Oncorhynchus nerka) nursery lakes: insights from limnological and paleolimnological analyses

      Sweetman, Jon N.; Finney, Bruce; Barry, Ronald; Hughes, Nicholas (2001-08)
      The relative importance of sockeye salmon, invertebrate predators, and other environmental factors in structuring the size and abundance of zooplankton populations was examined in a series of 23 lakes from southern Alaska. Zooplankton abundance was strongly related to sockeye density, along with nutrient availability and alkalinity. The mean size of Bosmina longirostris, the dominant herbivorous cladoceran, was positively correlated with the abundance of the predatory copepod, Cyclops columbianus. Changes in the size and abundance of Bosmina remains over the past 300-500 years were then determined for sediments from two lakes on Kodiak Island, Alaska. The zooplankton communities showed varying responses to past changes in salmon populations, resulting from relative changes in the magnitude of adult salmon-derived nutrient loading and in predation pressure from juvenile sockeye and cyclopoid copepods. Knowledge of how various factors impact zooplankton can have important implications for the effective management of sockeye within these lake systems.
    • Fatty acid profiles of Alaskan Arctic forage fishes: evidence of regional and temporal variation

      Dissen, Julia; Hardy, Sarah; Horstmann-Dehn, Lara; Oliveira, Alexandra (2015-08)
      Fatty acids, the main components of lipids, are crucial for energy storage and other physiological functions in animals and plants. Dietary fatty acids are incorporated and conserved in consumer tissues in predictable patterns and can be analyzed in animal tissues to determine the composition of an individual's diet. This study measured the variation in fatty acid profiles of three abundant Arctic forage fish species, Arctic Cod (Boreogadus saida), Canadian Eelpout (Lycodes polaris), and Longear Eelpout (Lycodes seminudus) across multiple years (2010-2013) and geographic locations (Beaufort and Chukchi seas). These fishes are important prey items of marine mammals, sea birds, and predatory fishes, and as such they serve as a critical trophic step connecting lower trophic-level production to higher level predators. Analyzing forage fish fatty acid profiles across multiple years and geographic locations can provide insight into system-level trends in lipid transfer through the Arctic ecosystem. Fatty acid profiles differed among species, with Arctic Cod having higher concentrations of pelagic zooplankton indicator fatty acids, and Eelpout species containing higher concentrations of indicators for benthic prey. While the two Eelpout species displayed major overlap in fatty acid profiles, differences in individual fatty acids may represent niche separation between Canadian and Longear Eelpout in the Beaufort Sea. In addition to variation between species, fatty acid profiles also differed in Arctic Cod between the Beaufort and Chukchi seas, and among collection years. High lipid content and energy-rich fatty acid classes observed in Chukchi Sea Arctic Cod relative to the Beaufort Sea Arctic Cod may indicate favorable feeding conditions in this region over the years sampled, and high energy density of Arctic Cod as prey. Despite the within-species variation observed, the results of this study suggest that Alaskan Arctic forage fish with different foraging ecology can be distinguished based on fatty acid profile, which could be useful in studies that use fatty acid data to characterize diets of top predators.
    • Feasibility of using standard targets to measure sound attenuation in rivers with varying suspended sediment loads

      Pfisterer, Carl T. (2002-12)
      In this study I examined the feasibility of using standard targets to measure sound attenuation in water due to suspended sediment. I determined that the variability of the target strength measurements was sufficiently high to prevent the use of this measure in obtaining accurate attenuation estimates. Average target strength values for a 1.5 inch tungsten carbide sphere differed by as much as 11.4 dB with spreads of the upper and lower 90% values as high as 18 dB. This high variability was likely due to a combination of factors that include multipath signal returns (exacerbated by relatively high transducer side lobes) and inaccuracies in the off-axis correction calculation. Although the goal to determine a relationship between suspended sediment and attenuation was not achieved, theoretical models suggest the contribution of suspended sediment to overall sound attenuation can be significant and, in certain circumstances, the main contributor to overall signal loss.
    • Feeding ecology and energy density of juvenile chum salmon, Oncorhynchus keta, from Kuskokwim Bay, western Alaska

      Burril, Sean Eugene (2007-12)
      Juvenile chum salmon from Kuskokwim Bay were sampled for patterns in diet and energy density in 2003 and 2004. Comparisons were made interannually, seasonally, between juvenile size classes, and between sailinity ranges. Sampling was conducted using a modified Kvichak Trawl. Bomb calorimetry was used to obtain energy density values. Feeding success and feeding intensity increased with fish size and season, and was highest in waters with moderate salinity. Feeding success and intensity were lowest for smaller juvenile chum salmon collected early in the season in water with low salinity. Prey composition was similar in both years, but varied with fish size, salinity ranges, and sampling weeks. Calanoid copepods and insects combined made up>50% of all prey items consumed and>80% of the overall prey biomass for all size classes, salinity ranges, and weeks. Feeding by juvenile chum salmon in Kuskokwim Bay appeared to be opportunistic. In 2003, no significant differences in energy density were found. In 2004, energy density decreased significantly from mid-May to mid-June and with increasing fish size. Decreasing energy density with season and size suggests that juvenile chum salmon were allocating the majority of their energy towards growth and smoltification, rather than lipid storage. Results from this study indicate that Kuskokwim bay may provide a suboptimal estuarine rearing habitat for juvenile chum salmon. If seasonally increasing energy demands are not balanced by an increasing food supply, the severe implications potentially include declines in growth rates and possibly overall survival probability of chum salmon juveniles in Kuskokwim Bay.
    • Feeding ecology and movement patterns of juvenile sablefish in coastal Southeast Alaska

      Coutré, Karson Marie; Beaudreau, Anne; Mueter, Franz; Malecha, Patrick (2014-12)
      Sablefish, Anoplopoma fimbria, is a commercially valuable groundfish species undergoing population declines in the Gulf of Alaska and Bering Sea. This study assessed the role of juvenile sablefish as consumers in coastal Southeast Alaska (St. John Baptist Bay, Baranof Island, Alaska; SJBB) to better understand their use of habitat and food resources during their early life history. Specifically, the diet of juvenile sablefish was described for multiple seasons (summer and fall) and years (2012 and 2013) from analysis of stomach contents recovered using gastric lavage. Sablefish ate a wide variety of prey taxa, and the most important prey groups were Pacific herring, smelts, and scavenged salmon remains. Diet differed between seasons and years, and scavenging of salmon carcasses occurred during fall sampling periods, revealing the ability of sablefish to capitalize on pulsed, high energy prey. We further explored habitat use by juvenile sablefish within SJBB by analyzing their vertical movement patterns using acoustic telemetry data. Sablefish that were frequently detected remained predominately near the bottom, but all fish remaining in range of the acoustic receivers made short excursions into shallower water. Generalized linear mixed models were used to determine the relationship between excursion frequency and daylight and tidal cycles. The excursion frequency was highest during slack and flood stages and at dawn and may be linked to foraging. Together, these findings suggest that juvenile sablefish may maximize their growth by accessing high energy pelagic and benthic prey while remaining on the bottom for the majority of time, potentially decreasing risk of predation.
    • Feeding ecology of juvenile sockeye salmon in Afognak Lake, Alaska

      Richardson, Natura; Beaudreau, Anne; Wipfli, Mark; Finkle, Heather (2016-05)
      Much attention has been given to juvenile Sockeye Salmon (Oncorhynchus nerka) ecology with particular focus on pelagic food webs in deep nursery lakes. In contrast, this study took place at Afognak Lake, Alaska, to better understand juvenile Sockeye Salmon foraging ecology, potential consumer interactions, and metabolic opportunities and constraints in a shallow nursery lake. I collected fish every two weeks from Afognak Lake from May through August, 2013. I described ontogenetic and temporal variation in the diets of juvenile Sockeye Salmon and a potential competitor, adult Threespine Stickleback (Gasterosteus aculeatus). Notably, this study revealed that adult aquatic insects are an important prey item for lake rearing juveniles. Threespine Stickleback diets showed some overlap with diets of juvenile Sockeye Salmon; however, significant differences in diet composition suggest that Sockeye Salmon and Threespine Stickleback partition prey and habitat resources. I then used my field-derived temperature, demographic, and diet data as inputs to a bioenergetics model to estimate summer consumption rate and growth efficiency of juvenile Sockeye Salmon from Afognak Lake across a range of foraging scenarios. Consumption rate was greater and mean growth efficiency was lower for all littoral-use scenarios relative to pelagic-use scenarios. Further, daily consumption was lowest and mean growth efficiency was highest for model scenarios in which insects were a dominant component of the diet relative to scenarios in which zooplankton were the dominant prey. My findings highlight the importance of benthic-pelagic coupling in Sockeye Salmon nursery lakes and the potential for juveniles to navigate trade-offs between energy acquisition and thermal conditions across lake habitats.
    • Feeding ecology of larval and juvenile walleye pollock (Theragra chalcogramma) and Pacific cod (Gadus macrocephalus) in the Southeastern Bering Sea

      Strasburger, Wesley Wayne; Hillgruber, Nicola; Pinchuk, Alexei; Mueter, Franz (2012-08)
      Poor recruitment success during warm years (e.g., 2001-2005) was hypothesized to lead to reduced gadid recruitment in the southeastern Bering Sea. These groundfishes are of particular importance, both commercially and ecologically in the southeastern Bering Sea. The spatial and temporal overlap of early life stages of walleye pollock and Pacific cod may explain their strongly correlated recruitment trends in the southeastern Bering Sea. The goal of this study was to compare feeding patterns of larval and juvenile walleye pollock (Theragra chalcogramma) and Pacific cod (Gadus macrocephalus) in the southeastern Bering Sea, and to assess the possibility of prey resource competition. Larvae and juveniles from both species collected between May and September 2008, an exceptionally cold year, were used to analyze stomach contents. Fish body size was most consistently related to diet composition within species, however, spatial and depth factors also had an influence. Feeding success and diet composition of these two gadid species were consistently different throughout the spring, summer, and especially fall seasons. Pacific cod larvae and juveniles consistently consumed larger prey items in every season and progressively fewer prey items, especially in the fall. This data suggests that competition for prey resources was unlikely during cold 2008.
    • Feeding ecology of maturing sockeye salmon (Oncorhynchus nerka) in nearshore waters of the Kodiak archipelago

      McIntosh, Bruce Charles (2001-08)
      The diet and feeding behavior of maturing sockeye salmon (Oncorhynchus nerka) were investigated during the final marine phase of the spawning migration, prior to reentering natal streams. The stomach contents of commercially caught sockeye salmon, migrating within the nearshore waters of the Kodiak Archipelago during 1998 and 1999, were examined to determine the level of feeding activity and taxa of dominant prey items. Samples were collected throughout the majority of the migration (early June to late August) from areas known to be used principally as migration corridors, and from areas proximate to several natal streams. Dominant prey of sockeye salmon were decapod larvae, Pacific sandlance (Ammodytes hexapterus), and the pteropod Limacina helicina. Feeding activity levels and dominant prey taxa varied both between areas and within areas over time. Feeding activity levels for the population appear to gradually diminish, rather than abruptly ceasing, as sockeye approach their natal streams to spawn.
    • The feeding, movement, and growth of pink salmon, Oncorhynchus gorbuscha, fry released from a hatchery in Prince William Sound, Alaska

      Urquhart, David Lindsay (1979-12)
      As part of a study that investigated the ability of Prince William Sound to support large numbers of juvenile salmon, the movements, feeding, and growth of pink salmon, Oncorhynchus gorbuscha, fry released in the springs of 1977 and 1978 from the Port San Juan hatchery, are described. Fry were released in Sawmill Bay but preferred the waters of adjacent Elrington Passage where they remained for up to two months. Nursery areas in the Passage established by the fry in 1977 were not occupied to the same degree in 1978. Fry fed initially on epibenthic harpacticoid copepods but soon switched to feeding on calanoid copepods. Fry growth rates and diet are comparable with results of other studies. Fry behavior affected sampling and may account for between-year differences detected in growth. Weather, food abundance, and the condition of out-migrants may also account for between-year differences in fry behavior and growth.
    • Fifty years of Cook Inlet beluga whale ecology recorded as isotopes in bone and teeth

      Nelson, Mark A.; Wooller, Matthew J.; Iken, Katrin; Quakenbush, Lori T. (2017-12)
      Beluga whales (Delphinapterus leucas) are found across the Arctic and Subarctic in seasonally ice covered waters. Five stocks of beluga whales are associated with the waters near Alaska for at least part of the year and four of those five stocks are abundant and commonly hunted by Alaskan Natives. The belugas resident in Cook Inlet are also an important cultural and subsistence resource to Alaskan Natives in the area, but a ~50% decline in abundance in the 1990's led to the stock being designated as depleted under the Marine Mammal Protection Act in 2000 and listed as endangered under the Endangered Species Act in 2008. Numerous studies of beluga whales in relation to stranding events, predation (killer whales), parasitism, disease, contaminants, and other potential population threats have not identified the reason for their inability to recover. Changes in diet have been considered, but are difficult to study because observations of feeding in muddy water and beluga stomachs are difficult to obtain. To investigate the past feeding ecology of beluga whales from Cook Inlet I sampled bone and teeth for isotopic analyses. I sampled bone from 20 individuals that died between 1964 and 2007 for stable carbon and nitrogen isotope analysis (values expressed as δ¹³C and δ¹⁵N values). I also micro-sampled annual growth layer groups in the teeth of 26 individuals representing the years from 1962 to 2007. Bone and tooth data showed a general decrease in δ¹³C and δ¹⁵N values over time. The δ¹³C values from analyses of growth layer groups declined from -13.4‰ to -16.2‰ and δ¹⁵N values declined from 17.2‰ to 15.4‰. Although these values are consistent with a change in feeding ecology over time, the magnitude of the decrease in δ¹⁵N values (~2‰) is insufficient for a full trophic level shift (~3‰).The relatively large decrease in the δ¹³C values over the same time period (~3‰), however, is much greater than a full trophic level shift (~1‰) and suggests an increase in prey associated with freshwater, which typically have lower δ¹³C values than prey associated with marine water. To test this hypothesis I analyzed the strontium isotope composition (⁸⁷Sr/⁸⁶Sr ratios) of growth layer groups in teeth from a sub-set of individuals. The resulting ⁸⁷Sr/⁸⁶Sr ratios trended away from the global marine signature (0.70918) over time and toward the more freshwater signatures measured in rivers flowing into the upper reaches of Cook Inlet. These results indicate that the diet of Cook Inlet beluga whales has changed over time. This could be from feeding on different, more freshwater derived prey species, or from feeding on the same species, but on individuals from locations with a more freshwater influence. Both of these interpretations are consistent with population survey data indicating a retraction in beluga range into the upper reaches of Cook Inlet. This study presents the first evidence of a long term (~50 years) change in Cook Inlet beluga whale feeding ecology. The consequences of this change toward more freshwater-influenced prey, and how this change relates to Cook Inlet beluga whales' decline or recovery remains unknown. However, to better examine this change in feeding ecology a follow-up study will; 1) develop a strontium isoscape for the Cook Inlet watershed; 2) analyze more teeth to better analyze changes in feeding ecology by demographic group (sex, age); and 3) analyze growth layer groups from Bristol Bay beluga teeth for a comparison with Cook Inlet belugas to determine if the changes represent an ecosystem change within Cook Inlet or a broader scale change affecting another region. This study builds towards a better understanding of the changes in Cook Inlet beluga feeding ecology and will help to determine if changes in diet could be a factor in their recovery.
    • First-generation effects on development time of outcrossing between geographically isolated and seasonally isolated populations of pink salmon (Oncorhynchus gorbuscha)

      Echave, Jesse D.; Gharrett, Anthony; Smoker, William; Adkison, Milo (2010-12)
      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.
    • Fisheries management and fisheries livelihoods in Iceland

      Chambers, Catherine P.; Carothers, Courtney; Criddle, Keith; Seitz, Andrew; Helgadóttir, Guorun (2016-08)
      This dissertation explores the long-term implications of Iceland’s nationwide Individual Transferrable Quota (ITQ) system on rural communities and small-boat fishing livelihoods drawing on two years of ethnographic research in Northwest Iceland, a nationwide mailed survey of small-boat fishermen, and the compilation of fisheries human dimension indicator data for the lumpfish fishery. Results from ethnographic interviews and participant observation show that while there is a wide range of complex political, social, and environmental changes affecting coastal communities, the changes brought on by the ITQ system are perceived to have been particularly significant. Survey results suggest that the majority of small-boat fishermen perceive the ITQ system as serving the goal of wealth accumulation over the goal of resource conservation. Survey respondents and interview informants report high cultural connections to fishing through family history, but express concern that future generations may be precluded from fisheries livelihoods due to the prohibitory cost of entry into the ITQ system. Furthermore, survey responses, ethnographic interviews, and indicator data suggest that non-ITQ fisheries like the lumpfish fishery and the strandveiðar season do not serve as substantial platforms to support newcomers to fisheries. These non-ITQ fisheries can make individuals and communities more resilient by providing extra income and, at the same time, can offer social flexibility to access a fishery of cultural and historical value. However, survey and interview data also suggest that the strandveiðar fishery has resulted in new rifts in communities as Icelandic society struggles with differing perceptions of equitable access to marine resources. Survey and interview data show how decision-making power lies in the hands of a few dominant interest groups, leaving smallboat fishermen and rural communities at a disadvantage with little power to meaningfully influence national politics. Finally, the compilation of human indicator data in the lumpfish fishery highlights concepts of multiple (social, economic, and biological) goals in fisheries management and the benefits of participatory governance structures. Conclusions from this dissertation underscore the complexity of fisheries systems and the important role equity plays in sustainable fisheries management and governance.
    • Fishing for pollock in a sea of change: a history and analysis of the Bering Sea pollock fishery

      Strong, James; Criddle, Keith R.; Adkison, Milo D.; Kruse, Gordon H. (2011-08)
      The development and evolution of the eastern Bering Sea fishery for walleye pollock (Theragra chalcogramma) is retraced, its current economic and institutional structure is modeled, and the resiliency of that structure to substantive changes in pollock biomass and fuel costs is explored. Small variations in exvessel prices, total allowable catches, or allocation of catches between seasons and among industry sectors can lead to large changes to first wholesale revenues. Similarly, changes in fuel prices, changes in technology, changes in regulation, and changes in the spatial distribution of catches can lead to changes in harvesting or processing costs. Together, these changes affect the relative profitability of the inshore and offshore sectors, which can, in turn, affect the benefits that accrue to communities, the evolution of regulation, and create pressure to reallocate sector shares. The model indicates that first wholesale revenues are maximized when pollock harvests are maximized. However, legal barriers to the transfer of allocations between sectors can lead to under-harvests when product prices are low, fuel costs are high, or when the most productive fishing grounds are in the northwest regions of the eastern Bering Sea Exclusive Economic Zone.
    • For generations to come: exploring local fisheries access and community viability in the Kodiak Archipelago

      Ringer, Danielle J.; Carothers, Courtney; Cullenberg, Paula; Davis, Michael; Donkersloot, Rachel (2016-12)
      The sustainability of fisheries and fishing-dependent communities depends upon numerous political, cultural, economic, and ecological factors. My research explores a key threat to this sustainability in Alaska -- the graying of the commercial fishing fleet. As current fishermen approach retirement age and a decreasing number of young people obtain ownership level careers in Alaska's fisheries, succession impacts become an increasingly pressing issue. This research utilized a political ecology framework and mixed methods ethnography, including 70 semi-structured interviews and 609 student surveys, to study local fisheries access and community viability in the Kodiak Archipelago communities of Kodiak City, Old Harbor, and Ouzinkie. This research documents barriers that fishermen face at different stages in their careers and describes related implications. Findings indicate that opportunities for rural youth and fishermen are increasingly constrained by interrelated economic and cultural barriers that have created equity and sustainability concerns. Furthermore, research suggests that the privatization of fisheries access rights is a major catalyst of change that has amplified these barriers, generated social conflict, and resulted in a transformed paradigm of opportunity compared to decades past. Secondly, this research compares fishermen's identities and livelihood motivations to dominant framings in academic literature and policy realms. This comparison reveals that in-depth understandings of fishermen are not well explained by narrow economic assumptions and instead include broader social and cultural dimensions. Lastly, exploration of the entangled relationships between fisheries access and rural youth pathways demonstrates increasing pressures within coastal communities, such as globalization, outmigration, youth ambivalence, substance abuse, and overall constrained opportunities. Nonetheless, coastal communities are working towards increasing local resilience to external pressures through social network support and some youth are bucking demographic trends by moving into fishing livelihoods. Due to the suite of threats facing fishing people and communities, it is increasingly important to have a deeper understanding of natural resource management impacts and local dynamics within fishing communities in order to plan for sustainable coastal futures.
    • Foraging Ecology And Nutritional Stress Of Tufted Puffins (Fratercula Cirrhata) Inferred From Stable Isotopes, Fatty Acid Signatures, And Field Endocrinology

      Williams, Cory T.; Buck, C. Loren (2008)
      Prey availability has a major impact on the reproductive output of seabirds, yet information on seabird diets throughout the breeding season is often lacking. Although reduced prey availability is known to affect the growth and survival of nestling seabirds, few studies have demonstrated similar effects on indices of adult body condition. I used stable isotopes and fatty acid (FA) signatures to investigate seasonal and age-related variation in the foraging niches of tufted puffins (Fratercula cirrhata). I conducted captive feeding experiments to determine whether inferences based on these techniques are affected by moderate food restriction during growth. I also examined how adult puffins prioritize the competing goals of maximizing the growth rate of their offspring and maintaining their own condition, as measured by body mass and by the stress hormone, corticosterone (CORT). Food restriction during nestling growth affected adipose tissue FA signatures and resulted in blood that was depleted in 15N and 13C relative to well-fed controls. However, effects of nutritional restriction on delta 15N, delta13C, and FA signatures were small compared to variability in prey, indicating physiological effects do not preclude use of these techniques as dietary tracers. Stable isotopes and FA signatures of free-living adults indicated foraging niches changed over the course of the breeding season. Stable isotopes suggest chick-rearing adults and nestlings feed at the same trophic level while FA signatures indicate that parents feed nestlings a diet different from their own. Body mass of adult puffins declined between incubation and chick rearing periods. For females the magnitude of mass decline did not differ between years, whereas for males the decline was greater in the year where young puffins fledged at a lower mass. In a separate analysis, baseline CORT values of adults of both sexes did not differ between years, but were lower than those observed in a separate study area during two consecutive years with low rates of nestling growth and survival. Assuming elevated CORT and reduced body mass impact survival and/or future fecundity, these results suggest the cost of reproduction may be higher for those adults able to fledge young in years characterized by low productivity.