Southwest Alaska Research Articles

Hydrokinetic Assessment of the Kvichak River near Igiugig, Alaska, Using a Two-Dimensional Hydrodynamic Model

Two-dimensional hydrodynamic simulations were performed on a monthly basis along 2.5 km of the Kvichak River near Igiugig in southwest Alaska, USA, to estimate flow conditions and to assess the hydrokinetic potential of the river reach. Instantaneous power density function along the computational domain was calculated. Study results indicate that two areas may be suitable for deploying turbines. The best option is located near the town, where the channel is relatively straight. A second possible site is located near the end of the study reach (approximately 2.3 km, along the river, from Lake Illiamna). Monthly-averaged velocities along the thalweg ranged from 1.7 to 2.7 m/s; and from 1.1 to 2 m/s at the upstream and downstream sites, respectively. Similarly, averaged values for the instantaneous power density, reduced by an extraction coefficient, were approximately 1500 and 5500 W/m2 during April and September, respectively, at the upstream site, as well as 400 and 2500 W/m2 for the same months at the downstream site. It was found that a previous resource assessment, which considered cross-sectionally averaged velocities, substantially underestimated the available power density along the river reach. Finally, the importance of having adequate bathymetric data is demonstrated by comparing field measurements with model simulations.

Water: The Gift of a Good Question

Ann Fienup-Riordan Ann Fienup-Riordan, Calista Elders Council, 9951 Prospect Dr., Anchorage AK 99507; riordan{at}alaska.net

Stable Nitrogen and Carbon Isotope Ratios Indicate Traditional and Market Food Intake in an Indigenous Circumpolar Population 3

The transition of a society from traditional to market-based diets (termed the nutrition transition) has been associated with profound changes in culture and health. We are developing biomarkers to track the nutrition transition in the Yup'ik Eskimo population of Southwest Alaska based on naturally occurring variations in the relative abundances of carbon and nitrogen stable isotopes (δ15N and δ13C values). Here, we provide three pieces of evidence toward the validation of these biomarkers. First, we analyzed the δ15N and δ13C values of a comprehensive sample of Yup'ik foods. We found that δ15N values were elevated in fish and marine mammals and that δ13C values were elevated in market foods containing corn or sugar cane carbon. Second, we evaluated the associations between RBC δ15N and δ13C values and self-reported measures of traditional and market food intake (n = 230). RBC δ15N values were correlated with intake of fish and marine mammals (r = 0.52; P < 0.0001). RBC δ13C values were correlated with intake of market foods made from corn and sugar cane (r = 0.46; P < 0.0001) and total market food intake (r = 0.46; P < 0.0001). Finally, we assessed whether stable isotope ratios captured population-level patterns of traditional and market intake (n = 1003). Isotopic biomarkers of traditional and market intake were associated with age, community location, sex, and cultural identity. Self-report methods showed variations by age and cultural identity only. Thus, stable isotopes show potential as biomarkers for monitoring dietary change in indigenous circumpolar populations.

Climate variability and spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska

We used tree ring data (AD 1601-2007) to examine the occurrence of and climatic influences on spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska and found evidence of regional-scale outbreaks dating from the mid-1700s, related to climate variability at multiple temporal scales. Over interannual time scales (approximately 1-3 years), El Niño years, combined with severe late-summer drought, appeared to contribute significantly to spruce beetle outbreaks in the study area. Over multidecadal time scales (up to approximately 40 years), cool-phase Pacific Decadal Oscillation (PDO) conditions tended to precede beetle outbreaks, regardless of the phase of El Niño-Southern Oscillation (ENSO). All sites showed low-severity disturbances attributed to spruce beetle damage, most notably during the 1810s. During other major periods of disturbance (i.e., 1870s, 1910s, 1970s), the effects of spruce beetle outbreaks were of moderate or higher severity. The highly synchronized timing of spruce beetle outbreaks at interannual to multidecadal scales, and particularly the association between cool-phase PDO conditions and beetle disturbance, suggests that climate (i.e., temperature, precipitation) is a primary driver of outbreaks in the study area. Our disturbance chronologies (mid-1700s to present) suggest that recent irruptions (1990s to present) in south-central and southwest Alaska are within the historical geographic range, but that outbreaks since the 1990s show greater spatiotemporal synchrony (i.e., more sites record high-severity infestations) than at any other time in the past approximatly 250 years.

Long-term river discharge and multidecadal climate variability inferred from varved sediments, southwest Alaska

Sedimentological analyses of 289 years (AD 1718–2006) of varved sediment from Shadow Bay, southwest Alaska, were used to investigate hydroclimate variability during and prior to the instrumental period. Varve thicknesses relate most strongly to total annual discharge (r 2 = 0.75, n = 43, p < 0.0001). Maximum annual grain size depends most strongly on maximum spring daily discharge (r 2 = 0.63, n = 43, p < 0.0001) and maximum annual daily discharge (r 2 = 0.61, n = 43, p < 0.0001), while varve thickness is poorly correlated with maximum annual grain size (r 2 = 0.004, n = 287, p = 0.33). Relations between varve thickness and annual climate variables (temperature, precipitation, North Pacific (NP) and Pacific Decadal Oscillation (PDO) indices) are insignificant. On multidecadal timescales, however, regime shifts in varve thickness and total annual discharge coincide with shifts in NP and PDO indices. Periods with increased varve thickness and total annual discharge were associated with warm PDO phases and a strengthened Aleutian Low. The varve-inferred record of PDO suggests that any periodicity in the PDO varied over time, and that the early 19th century marked a transition to a more frequent or detectable shifts.

An assessment of parasite infestation rates of juvenile sockeye salmon after 50 years of climate warming in southwest Alaska

Climate change has produced disproportionate levels of warming in high latitude ecosystems. A critical challenge is to understand how changes in temperature will mediate ecological processes, such as disease. Several authors have suggested that warming will increase prevalence of diseases at high latitudes, yet long-term studies are lacking. We evaluated how parasite abundance and prevalence in an ecologically and economically important species (juvenile sockeye salmon Oncorhynchus nerka) has changed in an Alaskan watershed that has experienced substantial climatic change over the past half-century. We hypothesized that the average increase in summer water temperature of 1.9°C over the past 46 years in our study system would have resulted in a corresponding increase in fish metabolism, and thus potential consumption rates, that would increase infestation rates of the tapeworm Triaenophorus crassus. However, our comparison of data from 1948–1960 to 2008–2009 provided no evidence that the parasite load in juvenile sockeye salmon has significantly changed and that there is no significant relationship between summer temperature and average infestation rates. Climatic projections for southwest Alaska forecast a continuation of the current warming trend, which could potentially have effects on our studied parasite-host interaction, but thus far we found no change in infestation rates over the last 60 years.

Found in translation: Decoding local understandings of genetics and heredity in a Yup’ik Eskimo community

The Center for Alaska Native Health Research is a community-based participatory research center that conducts studies involving genetic research with Yup'ik Eskimo community members in Southwest Alaska, where Yup'ik remains the first language for most residents. Cultural equivalents are needed to communicate results of these studies among all partners and members of the participating communities, since many scientific terms have no direct translation in Yup'ik. To inform that effort, we examined local understandings of genetics and heredity in one community. Here, we report results from back-translated Yup'ik interviews, and identify working genetic concepts shared by participants from interviews and focus groups. We suggest issues involved in, and some potential steps toward, developing a concise, scientifically accurate and culturally relevant term for "genetics" and other health concepts.

A 16 000‐year record of vegetational change in south‐western Alaska as inferred from plant macrofossils and pollen

AbstractPollen and macrofossil analyses of a sediment core from Beaver Pond (60° 37′ 14″ N, 154° 19′ W, 579 m a.s.l.) reveal a record of regional and local postglacial vegetation change in south‐western Alaska. The chronology is based on five AMS (accelerator mass spectrometry) 14C ages obtained from terrestrial plant macrofossils. Pollen and macrofossil records suggest that open herb and shrub tundra with e.g. Poaceae, Cyperaceae, Artemisia, Vaccinium and Salix prevailed on the landscape before ca. 14 000 cal a BP. The shift from herb‐ to shrub‐dominated tundra (Salix, subsequent Betula expansion) possibly reflects climatic warming at the beginning of the Bølling period at ca. 14 700–14 500 and around 13 500 cal a BP. Vegetation (Betula shrub tundra) remained relatively stable until the early Holocene. Macrofossil influx estimates provide evidence for greater biomass in Betula shrub tundra during the early postglacial period than today. Charcoal accumulation rates suggest tundra fire activity was probably greater from ca. 12 500 to 10 500 cal a BP, similar to results from elsewhere in Alaska. The pollen and macrofossil records of Beaver Pond suggest the prevalence of low shrub tundra (shrub Betula, Betula nana, Vaccinium, Ledum palustre, Ericaceae) and tall shrub tundra (Alnus viridis ssp. crispa, Salix) between 10 000 and 4000 cal a BP. This Holocene vegetation type is comparable with that of the modern treeless wet and moist tundra in south‐western Alaska. The expansion of Picea glauca occurred ∼4000 cal a BP, much later than that of A. viridis (ssp. crispa), whereas in central and eastern Alaska Picea glauca expanded prior to or coincident with Alnus (viridis). At sites located only 200–400 km north‐east of Beaver Pond (Farewell and Wien lakes), Picea glauca and Betula forests expanded 8000–6000 cal a BP. Unfavourable climatic conditions and soil properties may have inhibited the expansion and establishment of Picea across south‐west Alaska during the mid and late Holocene. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Successful aging through the eyes of Alaska Native elders. What it means to be an elder in Bristol Bay, AK.

Alaska Natives (ANs) view aging from a holistic perspective, which is not typical of the existing successful aging literature. One of the challenges of conducting research with cultural groups (e.g., ANs) is the lack of data, or research, on culture and aging and its impact on how we view successful aging. This research explores successful aging from an AN perspective or what it means to reach "Eldership" in rural Alaskan communities, which is an area of successful aging where there is very little research. Data were gathered from 26 elders aged 61-93 years in 6 Bristol Bay communities in Southwest Alaska. An Explanatory Model approach was used and adapted to gain a sense of the beliefs about aging and establish an indigenous understanding of successful aging or what it means to attain "Eldership." Rather than establishing a definition of successful aging for AN Elders, this study highlights the four elements of "Eldership" or what AN Elders believe are important characteristics to becoming a respected elder. The four elements of "Eldership" are emotional well-being, community engagement, spirituality, and physical health, which are the characteristics of ANs who have reached "Eldership" and become a respected Elder in their community. This research seeks to inform studies on indigenous aging that prioritizes the perspectives of elders to affect positively on the delivery of health care services in rural Alaska.

ASSESSMENT OF CLINICAL PATHOLOGY AND PATHOGEN EXPOSURE IN SEA OTTERS (ENHYDRA LUTRIS) BORDERING THE THREATENED POPULATION IN ALASKA

Northern sea otter (Enhydra lutris kenyoni) abundance has decreased dramatically over portions of southwest Alaska, USA, since the mid-1980s, and this stock is currently listed as threatened under the Endangered Species Act. In contrast, adjacent populations in south central Alaska, USA, and Russia have been stable to increasing during the same period. Sea otters bordering the area classified in the recent decline were live-captured during 2004-2006 at Bering Island, Russia, and the Kodiak Archipelago, Alaska, USA, to evaluate differences in general health and current exposure status to marine and terrestrial pathogens. Although body condition was lower in animals captured at Bering Island, Russia, than it was at Kodiak, USA, clinical pathology values did not reveal differences in general health between the two regions. Low prevalences of antibodies (<5%) were found in Kodiak, USA, and on Bering Island, Russia, to Toxoplasma gondii, Sarcocystis neurona, and Leptospira interrogans. Exposure to phocine herpesvirus-1 was found in both Kodiak, USA (15.2%), and Bering Island, Russia (2.3%). Antibodies to Brucella spp. were found in 28% of the otters tested on Bering Island, Russia, compared with only 2.7% of the samples from Kodiak, USA. Prevalence of exposure to Phocine distemper virus (PDV) was 41% in Kodiak, USA, but 0% on Bering Island, Russia. Archived sera from southwest and south-central Alaska dating back to 1989 were negative for PDV, indicating exposure occurred in sea otters in Kodiak, USA, in recent years. Because PDV can be highly pathogenic in naïve and susceptible marine mammal populations, tissues should be examined to explore the contribution of this virus to otter deaths. Our results reveal an increase in exposure to pathogens in sea otters in Kodiak, Alaska, USA, since the 1990 s.

In Pursuit of Singular Salmon: Paradoxes of Sustainability and the Quality Commodity

New ways of accounting for natural resources, as well as for their producers and consumers, inform efforts by Alaskan salmon fishers to service emerging markets in sustainable goods. For much of the twentieth century, commercial fishers in the rural Bristol Bay region of southwest Alaska harvested salmon as ‘poundage’, an undifferentiated mass destined for transformation into relatively uniform products. In more recent years, Alaska's fishers and policymakers have sought to produce ‘quality’ salmon for new sectors as a way to boost its wild salmon industry, which is strong biologically but has struggled economically with the proliferation of cheaper farmed salmon. Quality salmon is not caught and canned for mass consumption, but ‘babied’ for upscale market segments through fish harvesting and processing practices like gentle handling, bleeding, and chilling. Such standards present practical and conceptual challenges for Bristol Bay producers given the ecology and longtime ethos of the fishery, and expose a deeper paradox: In order for wild salmon to be made distinctive, it must be remade to meet aesthetic and technical norms largely established by the farmed salmon industry. This paradox reflects tensions within processes of commodification, which are heightened as commodity-making, to draw on Michel Callon's analysis, comes to rely ever more saliently on generating singularity, the unique or personal. In critical respects, singular salmon replicates the very economic forms to which it is positioned as an alternative, and materializes novel social distinctions in sites of production. The pursuit of new industry paradigms in Bristol Bay thus reveals the predicaments of sustaining the fishery by making and marketing nature as a commodity.

Developing effective sampling designs for monitoring natural resources in Alaskan national parks: An example using simulations and vegetation data

Monitoring natural resources in Alaskan national parks is challenging because of their remoteness, limited accessibility, and high sampling costs. We describe an iterative, three-phased process for developing sampling designs based on our efforts to establish a vegetation monitoring program in southwest Alaska. In the first phase, we defined a sampling frame based on land ownership and specific vegetated habitats within the park boundaries and used Path Distance analysis tools to create a GIS layer that delineated portions of each park that could be feasibly accessed for ground sampling. In the second phase, we used simulations based on landcover maps to identify size and configuration of the ground sampling units (single plots or grids of plots) and to refine areas to be potentially sampled. In the third phase, we used a second set of simulations to estimate sample size and sampling frequency required to have a reasonable chance of detecting a minimum trend in vegetation cover for a specified time period and level of statistical confidence. Results of the first set of simulations indicated that a spatially balanced random sample of single plots from the most common landcover types yielded the most efficient sampling scheme. Results of the second set of simulations were compared with field data and indicated that we should be able to detect at least a 25% change in vegetation attributes over 31 years by sampling 8 or more plots per year every five years in focal landcover types. This approach would be especially useful in situations where ground sampling is restricted by access.

An Ex-Ante Cost-Benefit Analysis of All-Terrain Vehicle Transportation Corridor in Southwest Alaska

This research explores the construction of a geotextile ATV corridor connecting two separate village subsets, Oscarville-Napakiak and Akiak-Akiachak, in the Kuskokwim River delta. Cost-benefit analysis was used to compare the costs of constructing a geotextile trail to the benefits derived from the reduction of injuries, fatalities, and fuel consumption observed on the existing river transportation corridor during a 20-year period. Secondary data was collected for population estimates, fatality and injury rates, while the rapid rural appraisal approach was used to access the traffic rates between each village subset. The results reveal that the construction of a geotextile ATV corridor in the Alaskan bush would prove to be an economically feasible transportation alternative.

Contrasting Ecology Shapes Juvenile Lake‐Type and Riverine Sockeye Salmon

AbstractHere we compare the body shape of juvenile (age‐0) sockeye salmon Oncorhynchus nerka that rear in lakes (lake type) with that of those that rear in rivers (riverine) and relate rearing habitat to morphology and ecology. The two habitats present different swimming challenges with respect to water flow, foraging strategy, habitat complexity, and predation level. We present morphological data from three riverine and three lake‐type populations in southwest Alaska. Using multivariate analyses conducted via geometric morphometrics, we determine population‐ and habitat‐specific body shape. As predicted, riverine sockeye salmon have a more robust body shape, whereas lake‐type sockeye salmon have a more streamlined body shape. In particular, we found differences in caudal peduncle depth (riverine deeper), eye size (riverine larger), and overall body depth (riverine deeper). One lake‐type population did not follow the predicted pattern, exhibiting an overall exaggerated riverine body shape. Differences between the habitats in terms of predation, complexity, and foraging ecology are probably drivers of these differences. Allometry differed between life history types, suggesting that there are habitat‐specific developmental differences.

Stream geomorphology regulates the effects on periphyton of ecosystem engineering and nutrient enrichment by Pacific salmon

Summary1. Pacific salmon (Oncorhynchus spp.) returning to streams deliver substantial quantities of nutrients (nitrogen and phosphorus) that may stimulate primary production. Salmon can also affect the phytobenthos negatively via physical disturbance during nest excavation, a process that may counteract the positive effects of salmon‐derived nutrients on benthic algae. The ability of salmon to disturb benthic habitats may be a function of substratum particle size, and therefore, the geomorphology of streams could determine the net effect of salmon on benthic communities.2. Based on surveys of 17 streams in southwest Alaska before the salmon run and during peak salmon density, we identified size thresholds for the disturbance of substratum particles by salmon and classified particles as vulnerable (&lt;60 mm B‐axis), invulnerable (&gt;110 mm) or transitional (61–110 mm). At the scale of individual rocks, algal biomass on vulnerable substrata decreased at peak spawning (relative to values before the run) as a power function of salmon density; transitional and invulnerable substrata showed no quantifiable pattern. However, invulnerable substrata in streams with more than 0.11 salmon m−2 showed net algal accrual, or relatively smaller declines in algal biomass, than vulnerable substrata, indicating that large rocks provide refuge for benthic algae from salmon disturbance.3. We expected that streams with proportionally larger rocks would respond positively to salmon at the whole‐stream scale, after accounting for the relative abundance of rocks of different sizes within streams. Invulnerable rocks made up only 0–12% of the total substratum particle size distribution in salmon‐bearing streams, however, and algal accrual on invulnerable substrata did not outweigh the strong disturbance effects on the more spatially extensive vulnerable substrata. The change in whole‐stream benthic algal biomass among streams was negatively related to salmon density.4. Stable isotopes of nitrogen (δ15N) were used to track nutrients from salmon into benthic biota. Periphyton δ15N on rocks of all size classes was higher at peak salmon spawning than before the salmon run, indicating the uptake of salmon‐derived nitrogen. Peak δ15N values were positively related to salmon abundance and followed a two‐isotope mixing relationship. The per cent of N from salmon in periphyton was also related to salmon density and was best explained by a saturating relationship. Spring δ15N was unrelated to salmon returns in the previous year, suggesting little annual carryover of salmon nutrients.

Application of a Double-Observer Aerial Line-Transect Method to Estimate Brown Bear Population Density in Southwestern Alaska

Abstract Brown bear Ursus arctos population density was estimated for a 21,178-km2 study area in southwest Alaska. Estimates were obtained using an aerial line-transect method that allows for peak detection to be both off the transect line and less than 100%. Data collection required five small aircraft with 2-person crews. Surveys were flown in 10-d windows to capture the period after den emergence but prior to full green-up. Surveys were flown in two consecutive years in order to detect sufficient bear groups to support the estimation. The study detected 197 bear groups (330 bears) in 969 aerial transects averaging 24.8 km long and with a strip width of 728 m. Estimated population density in the study area was 40.4 bears/1,000 km2 (95% CI = 31.4–54.5); estimated density of independent bears was 27.3 bears/1,000 km2 (95% CI = 21.4–34.4). Assuming similar estimate precision, repeating the survey could detect population changes of approximately 38% or larger with a power of 80%. We find the method described here suitable for regions of relatively high bear population densities or detection rates.

A Resilient Subsistence Salmon Fishery in Southwest Alaska

Harvesting and processing salmon is a significant subsistence activity for the residents of Nondalton, a predominantly Dena’ina Athabaskan community in Southwest Alaska. The Nondalton fishery, as a resilient social-ecological system, has had to adapt to change in order to maintain continuity over time. This paper will explore adaptation in a resilient salmon fishery through an ethnographic research project that documents the socio-cultural, economic, and environmental circumstances of fishing, mainly sockeye salmon (Oncorhynchus nerka), in the Kvichak Watershed of Southwest Alaska.

The dynamic context of cultural and social sustainability of communities in Southwest Alaska

PurposeCommercial fishing in Southwest Alaska provides for an opportunity to engage in wage labor jobs while still allowing for time to participate in subsistence hunting and fishing. Salmon therefore is an important part of both the wage labor economy and the subsistence economy. In Southwest Alaska recent studies documenting the subsistence economy and traditional ecological knowledge have centered on the communities that inhabit the Kvichak Watershed. This watershed comprising Iliamna Lake and Lake Clark along with other numerous feeder streams, rivers, and lakes is an important spawning habitat for the Bristol Bay fishery, one of the largest salmon fisheries in the world. Some of these studies are partially due to a proposed copper and gold mine. This paper aims to address these issues.Design/methodology/approachInterviews for these studies are structured household surveys that document household demographics, subsistence harvest for one study year, and household economics. In addition at the completion of each survey residents are asked to include comments and concerns regarding local subsistence patterns and trends.FindingsResidents during these studies have expressed concern that social and cultural changes are also happening in an environment where they are also seeing rapid ecological changes. These changes included climate variability and unpredictable weather. This creates an environment that is difficult to plan for subsistence hunting and fishing while continuing to take into consideration a work schedule, the money from which provides the means and materials for engaging in subsistence.Originality/valueThis paper will examine factors of change and ask the question of whether it can assess the impacts of climate variability and change on rural communities in Southwest Alaska without also trying to understand cultural and social sustainability within the larger dynamic context in which these changes are occurring.

Trend data do support the sequential nature of pinniped and sea otter declines in the North Pacific Ocean, but does it really matter?

TheSequentialMegafaunalCollapseHypothesis(SMCH)positsthatdecimationofgreat whales in the North Pacific Ocean in the 1950s and 1960s, by Russia and Japanfollowing the end of World War II, removed an important source of prey for marinemammal eating killer whales in southwest Alaska (the Aleutian Islands, southernBering Sea, and western and central Gulf of Alaska). The killer whales subsequentlybroadened their diets to include a larger proportion of other, much smaller species—harbor seals, Steller sea lions, fur seals, and sea otters—driving them into steepdecline. In the preceding letter, Wade, Ver Hoef, and DeMaster present informationand analyses that purportedly refute the SMCH. But, as explained below, we takeexception to their analytical procedures, use of data, and the strong claims they haveemployed in their continuing attempts to discredit the hypothesis.

Causes and consequences of marine mammal population declines in southwest Alaska: a food-web perspective

Populations of sea otters, seals and sea lions have collapsed across much of southwest Alaska over the past several decades. The sea otter decline set off a trophic cascade in which the coastal marine ecosystem underwent a phase shift from kelp forests to deforested sea urchin barrens. This interaction in turn affected the distribution, abundance and productivity of numerous other species. Ecological consequences of the pinniped declines are largely unknown. Increased predation by transient (marine mammal-eating) killer whales probably caused the sea otter declines and may have caused the pinniped declines as well. Springer et al. proposed that killer whales, which purportedly fed extensively on great whales, expanded their diets to include a higher percentage of sea otters and pinnipeds following a sharp reduction in great whale numbers from post World War II industrial whaling. Critics of this hypothesis claim that great whales are not now and probably never were an important nutritional resource for killer whales. We used demographic/energetic analyses to evaluate whether or not a predator-prey system involving killer whales and the smaller marine mammals would be sustainable without some nutritional contribution from the great whales. Our results indicate that while such a system is possible, it could only exist under a narrow range of extreme conditions and is therefore highly unlikely.