Southwest Alaska Research Articles

Alaskan children’s perspectives of environmental stewardship in a changing Arctic environment

ABSTRACT This chapter magnifies the voices of Alaskan children in considering education for sustainability in the Arctic. The collaborative research explored how children understood and enacted environmental stewardship in three distinct Alaskan locations: Interior Alaska, the Kenai peninsula, and a rural southwest Alaska Native village. Honoring children’s agency, the study involved child-centered research methods, including children’s drawings and descriptions, role-playing, class discussions, and video tours utilizing wearable cameras. Findings revealed common themes of environmental stewardship, yet the way children perceived and enacted stewardship varied according to the social, cultural, and geographical contexts. Cleaning up litter was perceived as immediate and important for children from Kenai and the southwest Alaskan village, yet it was scarcely mentioned by Interior Alaskan children. Interior Alaskan children emphasized pet care, while children from Kenai and the southwest Alaskan village discussed animal care in relation to hunting and fishing ethics. Care for plants was less common than care for snow. Children’s spatial autonomy, sense of belonging and personal connection with place, plays an important role in the development of competencies to live more sustainably on the land. Findings point towards contextualized and child-centered approaches to promote children’s agency to act in and for their environments.

The Efficiency between Markowitz Model and Single Index Model

It is important to investigate the different impact factors on the establishment of investment portfolio. In order to maximize the profit of a portfolio, this research selects six stocks: Adobe (ADBE), International Business Machines Corp (IBM), Bank of America Corporation (BAC), Citigroup (C), Southwest Airlines Co (LUV) and Alaska Air Group Inc. (ALK) as an empirical case to conduct investment decision. This research compares different results of two models (Markowitz model and Index Model) by analyzing the data of the portfolio such as minimum risk portfolio and maximum Sharpe Ratio portfolio. This research finds that the Markowitz Model is more appropriate to the portfolio establishment, which is presented by its sharper efficient frontier. Under all the conditions the study considered, the Markowitz Model always gets more returns than the Index Model when the risk increases by the same amount. Therefore, this research concludes that the Markowitz Model is more suitable for this portfolio. By analyzing the portfolio in two models, the study has found a better model for this portfolio, thus make more rational investments.

Genetic variation in sea otters (Enhydra lutris) from the North Pacific with relevance to the threatened Southwest Alaska Distinct Population Segment

AbstractFor the sea otter (Enhydra lutris), genetic population structure is an area of research that has not received significant attention, especially in Southwest Alaska where that distinct population segment has been listed as threatened since 2005 pursuant to the U.S. Endangered Species Act. In this study, 501 samples from 14 locations from Prince William Sound, Alaska to the Commander Islands in Russia were analyzed for variation at 13 microsatellite loci. Our results indicate a high degree of genetic divergence among the 14 locations (FST = 0.120) with gene flow conforming to the isolation by distance (IBD) model (r2 = 0.491, p < .05). The 14 sampling locations formed six geographic associations in clustering and ordination analyses that likely correspond to remnant population lineages: (1) Southcentral Alaska, (2) Kodiak and North Alaska Peninsula, (3) South Alaska Peninsula and Bristol Bay, (4) Eastern Aleutian, (5) Western Aleutian, and (6) the Commander Islands. Except for South Alaska Peninsula and Bristol Bay, these clusters closely agree with previously defined stock and management unit boundaries. Our results reveal significant genetic population structure and are generally congruent with current management strategies for the threatened Southwest Alaska distinct population segment.

Alutiiq Fish Skin Traditions: Connecting Communities in the COVID-19 Era

The Alutiiq, Indigenous inhabitants of the coastal regions of Southwest Alaska, created garments made from fish skins, especially salmon, expertly sewn by women from Kodiak Island. Traditionally, Alutiiq education focused on acquiring survival skills: how to navigate the seas in all weathers, hunting, fishing and tanning animal skins. Today, many Alutiiq people continue to provide for their families through subsistence fishing, honouring the ocean and navigating difficult times by listening to their collective wisdom. This paper describes the series of fish skin tanning workshops taught by June Pardue, an Alutiiq and Inupiaq artist from Kodiak Island that connected participants in Alaska Native communities during the COVID-19 isolation months. Through an online platform, June passed on expert knowledge of the endangered Arctic fish skin craft, assisting participants in coping with the pandemic crisis by tapping into their knowledge of the natural world, cultural resourcefulness, storytelling abilities and creative skills. Brought into the digital age, the fish skin workshops strengthened connections among Alutiiq and Alaskan craftspeople while establishing new connections with an expanded network of fashion designers, museum curators, conservators and tanners. Finally, the paper highlights how fish skin Indigenous practices address the United Nations Sustainable Development Goals (SDGs) regarding poverty, health and well-being, gender equality, clean water and sanitation, decent work and economic growth, social inequality, responsible consumption and production, climate change and maritime issues.

Recent changes in pan-Arctic sea ice, lake ice, and snow-on/off timing

Abstract. Arctic snow and ice cover are vital indicators of climate variability and change, yet while the Arctic shows overall warming and dramatic changes in snow and ice cover, the response of these high-latitude regions to recent climatic change varies regionally. Although previous studies have examined changing snow and ice separately, examining phenology changes across multiple components of the cryosphere together is important for understanding how these components and their response to climate forcing are interconnected. In this work, we examine recent changes in sea ice, lake ice, and snow together at the pan-Arctic scale using the Interactive Multisensor Snow and Ice Mapping System 24 km product from 1997–2019, with a more detailed regional examination from 2004–2019 using the 4 km product. We show overall that for sea ice, trends toward earlier open water (−7.7 d per decade, p<0.05) and later final freeze (10.6 d per decade, p<0.05) are evident. Trends toward earlier first snow-off (−4.9 d per decade, p<0.05), combined with trends toward earlier first snow-on (−2.8 d per decade, p<0.05), lead to almost no change in the length of the snow-free season, despite shifting earlier in the year. Sea ice-off, lake ice-off, and snow-off parameters were significantly correlated, with stronger correlations during the snow-off and ice-off season compared to the snow-on and ice-on season. Regionally, the Bering and Chukchi seas show the most pronounced response to warming, with the strongest trends identified toward earlier ice-off and later ice-on. This is consistent with earlier snow-off and lake ice-off and later snow-on and lake ice-on in west and southwest Alaska. In contrast to this, significant clustering between sea ice, lake ice, and snow-on trends in the eastern portion of the North American Arctic shows an earlier return of snow and ice. The marked regional variability in snow and ice phenology across the pan-Arctic highlights the complex relationships between snow and ice, as well as their response to climatic change, and warrants detailed monitoring to understand how different regions of the Arctic are responding to ongoing changes.

Sea otter population collapse in southwest Alaska: assessing ecological covariates, consequences, and causal factors

AbstractSea otter (Enhydra lutris) populations in southwest Alaska declined substantially between about 1990 and the most recent set of surveys in 2015. Here we report changes in the distribution and abundance of sea otters, and covarying patterns in reproduction, mortality, body size and condition, diet and foraging behavior, food availability, health profiles, and exposure to environmental contaminants over this 25‐yr period. The population decline, which resulted in densities on the order of 5% of environmental carrying capacity, ranged from Attu Island in the west to about Castle Cape (on the south side of the Alaska Peninsula) in the east. Remaining sea otters moved closer to shore and into shallow, protected habitats. Reproductive rates appeared unchanged with the decline. Although the demographic cause of the decline was clearly elevated mortality, stranded carcasses were rare or absent. The net rate of energy gain by foraging sea otters, body length and condition, and prey biomass density, all increased after the decline and varied inversely with sea otter population density beyond the area of decline. Sea otters within the area of decline showed no increases in health anomalies, disease, contaminant exposure, or abnormal gene transcription patterns as compared to animals outside the area of decline. These collective findings are inconsistent with nutritional limitation, disease, or environmental contaminants, and consistent with predation (or possibly some other density‐independent factor) as the reason for the sea otter population decline. Our approach and analyses provide a broad conceptual template for thinking about and assessing the causes of wildlife population declines.

Nuna Nalluyuituq (The Land Remembers): Remembering landscapes and refining methodologies through community‐based remote sensing in the Yukon‐Kuskokwim Delta, Southwest Alaska

AbstractThe following article outlines a collaborative, multidisciplinary approach to remote sensing in Southwest Alaska's Yukon‐Kuskokwim (Y‐K) Delta that combines ethnographic inquiry and remote sensing to monitor, detect and preserve cultural resources for Alaskan Native communities. Because distinctive vegetation differences are readily visible on cultural sites during the summer months, the analysis of multispectral imagery obtained from remote sensing is particularly useful. In turn, we demonstrate the efficacy of this protocol on pre‐contact settlement sites along the Ayakulik River system on Kodiak Island using a normalized difference vegetation index (NDVI) raster of the study area. Here, support vector machine (SVM) supervised classification was highly effective at identifying spectral patterns associated with anthropogenic activity while ethnographic data helped rule out false‐positive cases. In addition, we provide the results of a 2019 archaeological prospection survey carried out in conjunction with the ongoing Nunalleq Project in Quinhagak, Alaska, to further highlight the value of ethnographic data collection, ethnobotanical surveys and unmanned aerial vehicle (UAV)‐based spectroscopy alongside SVM supervised classification. Finally, we propose three suggestions for future research on Yup'ik landscapes in the Y‐K Delta regarding citizen science, language preservation and the use of collaborative online maps for community‐based decision making.

Community-level economic impacts of a change in TAC for Alaska fisheries: A multi-regional framework assessment

A marine heatwave caused the total biomass of Gulf of Alaska (GOA) Pacific cod to plummet by 67% from 2015 to 2018. Based on the results from GOA Pacific cod stock assessment model, the North Pacific Fishery Management Council cut the GOA Pacific cod total allowable catch (TAC) by 80% in 2018. This study uses a 10-region multi-regional social accounting matrix model to compute the economic impacts of the cod fishery disaster on the six borough and census areas (BCAs) in Southwest Alaska plus effects on the other four regions. We consider both the negative effects of the reduction in the cod harvest and the offsetting effects from an observed increase in the price of the fish to calculate the “net” economic impacts. This study found that the offsetting effects from the price increase are significant; the reduction in total regional output in the rest of the United States is 15% less severe if effects of the price changes are taken into account. Furthermore, the region suffering the largest impacts on total seafood industry output (Aleutians East Borough) from the reduced TAC is not necessarily the region where the largest total regional impact occurs (rest of the U.S.).

Climate drivers of Arctic tundra variability and change using an indicators framework

This study applies an indicators framework to investigate climate drivers of tundra vegetation trends and variability over the 1982–2019 period. Previously known indicators relevant for tundra productivity (summer warmth index (SWI), coastal spring sea-ice (SI) area, coastal summer open-water (OW)) and three additional indicators (continentality, summer precipitation, and the Arctic Dipole (AD): second mode of sea level pressure variability) are analyzed with maximum annual Normalized Difference Vegetation Index (MaxNDVI) and the sum of summer bi-weekly (time-integrated) NDVI (TI-NDVI) from the Advanced Very High Resolution Radiometer time-series. Climatological mean, trends, and correlations between variables are presented. Changes in SI continue to drive variations in the other indicators. As spring SI has decreased, summer OW, summer warmth, MaxNDVI, and TI-NDVI have increased. However, the initial very strong upward trends in previous studies for MaxNDVI and TI-NDVI are weakening and becoming spatially and temporally more variable as the ice retreats from the coastal areas. TI-NDVI has declined over the last decade particularly over High Arctic regions and southwest Alaska. The continentality index (CI) (maximum minus minimum monthly temperatures) is decreasing across the tundra, more so over North America than Eurasia. The relationship has weakened between SI and SWI and TI-NDVI, as the maritime influence of OW has increased along with total precipitation. The winter AD is correlated in Eurasia with spring SI, summer OW, MaxNDVI, TI-NDVI, the CI and total summer precipitation. This winter connection to tundra emphasizes the role of SI in driving the summer indicators. The winter (DJF) AD drives SI variations which in turn shape summer OW, the atmospheric SWI and NDVI anomalies. The winter and spring indicators represent potential predictors of tundra vegetation productivity a season or two in advance of the growing season.

Autumn migratory orientation and route choice in early and late dunlins Calidris alpina captured at a stopover site in Alaska.

ABSTRACTWe investigated the migratory orientation of early and late captured dunlins, Calidris alpina, by recording their migratory activity in circular orientation cages during autumn at a staging site in southwest Alaska and performed route simulations to the wintering areas. Two races of dunlins breeding in Alaska have different wintering grounds in North America (Pacific Northwest), and East Asia. Dunlins caught early in autumn (presumably Calidris alpina pacifica) oriented towards their wintering areas (east-southeast; ESE) supporting the idea that they migrate nonstop over the Gulf of Alaska to the Pacific Northwest. We found no difference in orientation between adult and juveniles, nor between fat and lean birds or under clear and overcast skies demonstrating that age, energetic status and cloud cover did not affect the dunlins’ migratory orientation. Later in autumn, we recorded orientation responses towards south-southwest suggesting arrival of the northern subspecies Calidris alpina arcticola at our site. Route simulations revealed multiple compass mechanisms were compatible with the initial direction of early dunlins wintering in the Pacific Northwest, and for late dunlins migrating to East Asia. Future high-resolution tracking would reveal routes, stopover use including local movements and possible course shifts during migration from Alaska to wintering sites on both sides of the north Pacific Ocean.

Evaluating the current condition of a threatened marine mammal population: Estimating northern sea otter (Enhydra lutris kenyoni) abundance in southwest Alaska

AbstractWe estimated density and abundance of the threatened southwest Alaska distinct population segment of northern sea otters (Enhydra lutris kenyoni) in two management units. We conducted aerial surveys in Bristol Bay and South Alaska Peninsula management units in 2016, and modeled sea otter density and abundance with Bayesian hierarchical distance sampling models and spatial environmental covariates (depth, distance to shore, depth × distance to shore). Spatial environmental covariates substantially impacted sea otter group density in both management units, but effects sizes differed between the two management units. Abundance (9,733 otters, 95% CrI 6,412–17,819) and density (0.82 otters/km2, 95% CrI 0.54–1.49) estimates for Bristol Bay indicated a moderate population size. In contrast, abundance (546 otters, 95% CrI 322–879) and density (0.06 otters/km2, 95% CrI 0.03–0.09) estimates indicated a relatively low population size in South Alaska Peninsula. Overall, our results highlight the importance of accounting for the detection process in monitoring at‐risk species to reduce the uncertainty associated with making conclusions about population declines.

Predicting impacts of food competition, climate, and disturbance on a long‐distance migratory herbivore

AbstractClimate change is driving worldwide shifts in the distribution of biodiversity, and fundamental changes to global avian migrations. Some arctic‐nesting species may shorten their migration distance as warmer temperatures allow them to winter closer to their high‐latitude breeding grounds. However, such decisions are not without risks, since this intensifies pressure on resources when they are used for greater periods of time. In this study, we used an individual‐based model to predict how future changes in food abundance, winter ice coverage, and human disturbance could impact an Arctic/sub‐Arctic breeding goose species, black brant (Branta bernicla nigricans, Lawrence 1846), and their primary food source, common eelgrass (Zostera marina L.), at the Izembek Lagoon complex in southwest Alaska. Brant use the site during fall and spring migrations, and increasingly, for the duration of winter. The model was validated by comparing predictions to empirical observations of proportion of geese surviving, proportion of geese emigrating, mean duration of stay, mean rate of mass gain/loss, percentage of time spent feeding, number of bird days, peak population numbers, and distribution across the complex. The model predicted that reductions >50% of the current decadal (2007–2015) mean of eelgrass biomass, which have been observed in some years, or increases in the number of brant, could lead to a reduction in the proportion of birds that successfully migrate to their breeding grounds from the site. The model also predicted that access to eelgrass in lagoons other than Izembek was critical for overwinter survival and spring migration of brant, if overall eelgrass biomass was 50% of the decadal mean biomass. Geese were typically predicted to be more vulnerable to environmental change during winter and spring, when eelgrass biomass is lower, and thermoregulatory costs for the geese are higher than in fall. We discuss the consequences of these predictions for goose population trends in the face of natural and human drivers of change.

New Constraints on Slip Deficit on the Aleutian Megathrust and Inflation at Mt. Veniaminof, Alaska From Repeat GPS Measurements

AbstractWe employ an enhanced data set of Global Positioning System (GPS) velocities to reassess the slip deficit along the plate interface of the Alaska‐Aleutian subduction zone. An examination of velocities of sites near Mt Veniaminof, located in the southwest Alaska Peninsula, shows that existing models for tectonic deformation do not accurately predict the local velocity field along this section of the peninsula. In a combined model, we solve for the volcanic inflation signal on the edifice of Mt. Veniaminof and reassess the variations in trench coupling outboard of the volcano. The interseismic deformation near Veniaminof and the eastern Shumagin islands requires an additional model segment with higher slip deficit than the western Shumagin islands. This segment appears to have been the main rupture patch of the 2020 M 7.9 Simeonof earthquake. The volcano inflated over the time period of 2005–2017, although at a lower rate than in 2002–2005.

Effects of variability and synchrony in assessing contributions of individual streams to habitat portfolios of river basins

Despite growing recognition that complex population portfolios are important sources of ecosystem stability and resilience, the structure of such stock complexes is often not considered in monitoring schemes to inform environmental impact assessments. The use of “index” or “indicator” sites, and of short assessment windows, to make broad claims about the relative importance of specific habitats or populations within a portfolio, assume that regional populations are highly synchronous and that abundance is stable through time. Asynchrony among populations and changes in population productivity over time render these assumptions fundamentally flawed. We used 57 years of abundance data for sockeye salmon (Oncorhynchus nerka) spawning in a set of eight streams in the Wood River watershed, southwest Alaska, to demonstrate how natural patterns of variability affect the ability of fixed assessment windows to characterize the contribution of individual populations to the entire portfolio. Additionally, simulations were used to demonstrate how different levels of synchrony and autocorrelation affect the ability of monitoring schemes to estimate the contributions of individual populations to a portfolio over the long-term. We found that fixed assessment windows were distinctly limited in their ability to characterize a population’s contribution to a portfolio over the long-tem. Asynchronous dynamics among populations, and the presence of autocorrelation that creates slow changes in populations, weaken the ability to characterize a stream's potential contribution to a portfolio from short-term assessments. These results suggest that the structure of population portfolios, and the presence of directional changes in productivity within individual populations, need to be taken into account when carrying out environmental risk assessments that aim to measure the contribution of an individual population or habitat to system wide dynamics. Typical risk assessments that depend on short monitoring periods are likely to vastly underestimate the potential long-term value of any specific habitat, and the population it supports, as a component of a multi-population portfolio.

Characterization of CYP3A pharmacogenetic variation in American Indian and Alaska Native communities, targeting CYP3A4*1G allele function.

The frequencies of genetic variants in the CYP3A4 and CYP3A5 genes differ greatly across global populations, leading to profound differences in the metabolic activity of these enzymes and resulting drug metabolism rates, with important consequences for therapeutic safety and efficacy. Yet, the impact of genetic variants on enzyme activity are incompletely described, particularly in American Indian and Alaska Native (AIAN) populations. To characterize genetic variation in CYP3A4 and CYP3A5 and its effect on enzyme activity, we partnered with AIAN people living in two regions of Alaska: Yup’ik Alaska Native people living in the Yukon‐Kuskokwim Delta region of rural southwest Alaska and AIAN people receiving care at the Southcentral Foundation in Anchorage, Alaska. We identified low frequencies of novel and known variation in CYP3A4 and CYP3A5, including low frequencies of the CYP3A4*1G and CYP3A5*1 variants, and linkage disequilibrium patterns that differed from those we previously identified in an American Indian population in western Montana. We also identified increased activity of the CYP3A4*1G allele in vitro and in vivo. We demonstrated that the CYP3A4*1G allele confers increased protein content in human lymphoblastoid cells and both increased protein content and increased activity in human liver microsomes. We confirmed enhanced CYP3A4‐mediated 4β‐vitamin D hydroxylation activity in Yup’ik people with the CYP3A4*1G allele. AIAN people in Alaska and Montana who carry the CYP3A4*1G allele—coupled with low frequency of the functional CYP3A5*1 variant—may metabolize CYP3A substrates more rapidly than people with the reference CYP3A4 allele.

Innovation and Healing in Contemporary Yup’ik Mask Making

This ethnographic study, conducted with seven contemporary Yup’ik carvers examines one of the oldest, but long suppressed, art forms in southwest Alaska – mask making. In-depth individual interviews captured the voices of artists of different ages, backgrounds and experiences, who, as they branch out and push the boundaries of traditional media, keep re-exploring and forging their cultural identity by bringing the forgotten symbols, values and worldviews associated with masks back to life. This article demonstrates how innovation unfolds the healing potential of masks and can help individuals and communities recuperate from a colonial past, and assert positive self-identification as Alaska Indigenous peoples today.

Lake trout growth is sensitive to spring temperature in southwest Alaska lakes

AbstractIn high‐latitude lakes, air temperature is an important driver of ice cover thickness and duration, which in turn influence water temperature and primary production supporting lake consumers and predators. In lieu of multidecadal observational records necessary to assess the response of lakes to long‐term warming, we used otolith‐based growth records from a long‐lived resident lake fish, lake trout (Salvelinus namaycush), as a proxy for production. Lake trout were collected from seven deep, oligotrophic lakes in Lake Clark National Park and Preserve on in southwest Alaska that varied in the presence of marine‐derived nutrients (MDN) from anadromous sockeye salmon (Oncorhynchus nerka). Linear mixed‐effects models were used to partition variation in lake trout growth by age and calendar‐year and model comparisons tested for a mean increase in lake trout growth with sockeye salmon presence. Year effects from the best mixed‐effects model were subsequently compared to indices of temperature, lake ice, and regional indices of sockeye salmon escapement. A strong positive correlation between annual lake trout growth and temperature suggested that warmer springs, earlier lake ice break‐up, and a longer ice‐free growing season increase lake trout growth via previously identified bottom‐up increases in production with warming. Accounting for differences in the presence or annual escapement of sockeye salmon with available data did not improve model fit. Collectively with other studies, the results suggest that productivity of subarctic lakes has benefitted from warming spring temperatures and that temperature can synchronise otolith growth across lakes with and without sockeye salmon MDN.

Using a structured decision analysis to evaluate bald eagle vital signs monitoring in Southwest Alaska National Parks.

Monitoring programs can benefit from an adaptive monitoring approach, where key decisions about why, where, what, and how to monitor are revisited periodically in order to ensure programmatic relevancy.The National Park Service (NPS) monitors status and trends of vital signs to evaluate compliance with the NPS mission. Although abundant, The Southwest Alaska Network (SWAN) monitors bald eagles because of their inherent importance to park visitors and role as an important ecological indicator. Our goal is to identify an optimal monitoring program that may be standardized among participating parks.We gathered an expert panel of scientists and managers, and implemented a Delphi Process to gather information about the bald eagle monitoring program. Panelists generated a list of means objectives for the monitoring program: minimizing cost, minimizing effort, maximizing the ability to detect change in bald eagle populations, and maximizing the amount of accurate information collected about bald eagles.We used a swing‐weighting technique to assign importance to each objective. Collecting accurate information about bald eagles was considered the most important means objective.Combining panelist‐generated information with objective importance, we analyzed the scenarios and defined the optimal decision using linear value modeling. Through our analysis, we found that a “Comprehensive” monitoring scenario, comprised of all feasible monitoring metrics, is the optimal monitoring scenario. Even with greatly increased cost, the Comprehensive monitoring scenario remains the best solution.We suggest further exploration of the cost and effort required for the Comprehensive scenario, to determine whether it is in the parks’ best interest to begin monitoring additional metrics.

Kin, community, and diverse rural economies: Rethinking resource governance for Alaska rural fisheries

The challenge of designing institutions and resource policy for ecosystem and social resilience in rural and small-scale fisheries is receiving renewed attention in Alaska and elsewhere. Many rural and Indigenous fishing communities have been negatively impacted by modern resource allocation and management regimes that restrict and privatize fishery access through the creation of individual property rights. This article draws on ethnographic and interview data from a multi-sited study to improve policy considerations for rural and small-scale fisheries access. The Bristol Bay region of southwest Alaska is a site of concerning social trends including the ‘graying of the fleet’ and a rise in nonlocal ownership of fishing rights. Since the state began limiting entry into salmon fisheries in 1975, local permit holdings in Bristol Bay communities have declined by roughly 50%. This paper examines the ways in which assumptions and norms operating within state, regional, and local institutions support and/or constrain local fishing practices and participation in the region. A central objective is to challenge dominant and universalist assumptions of fishermen as dis-embedded, profit-maximizing, self-interested actors that do not fit well with small-scale, rural, and Indigenous fisheries. This paper identifies social relationships and interdependencies as central to rural fishing communities and livelihoods and absent from the rational choice/individual economic actor assumptions of modern resource allocation and management regimes. Findings presented here offer new framings for environmental analyses and help to inform solutions to ecological and social sustainability concerns marking global fisheries today.

Late Pliocene Cordilleran Ice Sheet development with warm northeast Pacific sea surface temperatures

Abstract. The initiation and evolution of the Cordilleran Ice Sheet are relatively poorly constrained. International Ocean Discovery Program (IODP) Expedition 341 recovered marine sediments at Site U1417 in the Gulf of Alaska (GOA). Here we present alkenone-derived sea surface temperature (SST) analyses alongside ice-rafted debris (IRD), terrigenous, and marine organic matter inputs to the GOA through the late Pliocene and early Pleistocene. The first IRD contribution from tidewater glaciers in southwest Alaska is recorded at 2.9 Ma, indicating that the Cordilleran Ice Sheet extent increased in the late Pliocene. A higher occurrence of IRD and higher sedimentation rates in the GOA during the early Pleistocene, at 2.5 Ma, occur in synchrony with SSTs warming on the order of 1 ∘C relative to the Pliocene. All records show a high degree of variability in the early Pleistocene, indicating highly efficient ocean–climate–ice interactions through warm SST–ocean evaporation–orographic precipitation–ice growth mechanisms. A climatic shift towards ocean circulation in the subarctic Pacific similar to the pattern observed during negative Pacific Decadal Oscillation (PDO) conditions today occurs with the development of more extensive Cordilleran glaciation and may have played a role through increased moisture supply to the subarctic Pacific. The drop in atmospheric CO2 concentrations since 2.8 Ma is suggested as one of the main forcing mechanisms driving the Cordilleran glaciation.