Sustaining the Yukon River Chinook System A Resilience Approach

Sustaining the Yukon River Chinook System A Resilience Approach

The Yukon Chinook Social-Ecological System

Commercial and subsistence harvest levels of Yukon River Chinook Salmon, 1961–2012. Source: JTC 2013 USCanada Regional Information Report A312-02

Weak runs of Chinook (King) salmon along the Yukon River have created a crisis. Increasingly, families living along the Yukon River and its tributaries are missing a valuable food and vital cultural resource; commercial fishermen are losing important income; managers are grappling with insoluble problems; and officials are repeatedly declaring regional economic and fisheries disasters. The Chinook run failed to meet US-Canada treaty obligations five of the eight years between 2007-2014, and managers are likely to continue eliminating commercial harvest and reducing subsistence harvest until the runs recover.

The Yukon River Chinook system and its problems are complex.

Sustaining the system for the long term will require innovative and comprehensive approaches. In April 2014, two dozen scientists, managers, and stakeholders met in Fairbanks at the University of Alaska campus for a workshop titled “Fostering Resilience in Yukon River Chinook.” The workshop applied a resilience framework to identify sources of long-term resilience, vulnerability, possible tipping points, and feedback mechanisms in this complex adaptive system. Their goal was to brainstorm — across disciplines — new ideas to foster both healthy salmon stocks and prospering rural communities. The workshop focused on Chinook salmon and their ecosystems as a complex adaptive social-ecological system, which includes not only the salmon and their ocean and freshwater ecosystems, but also the connections and relationships between salmon and people across their range.

Researchers and managers do not fully understand the population dynamics of Yukon River Chinook salmon, in part because of the lack of sufficient long-term data.

Accurate estimations of the entire run size do not exist prior to 2005, when a sonar installation at Eagle enabled a direct estimate of the Canadian subpopulation.

Commercial and subsistence harvest estimates (see figure at left), along with other assessment projects such as the Pilot Station sonar, only provide biased and incomplete abundance indices. Yukon harvests (commercial and subsistence) ranged between 100,000 to 150,000 fish per year in the 1970s, increased to approximately 150,000 to 200,000 fish

The “Fostering Resilience in Yukon River Chinook” workshop was held 1-3 April 2014 at the University of Alaska Fairbanks. The workshop was sponsored by the UAF College of Natural Science and Mathematics’ Sydney Chapman Chair with additional support from the North Pacific Research Board, UAF’s International Arctic Research Center, and the Institute of Marine Science in UAF’s School of Fisheries and Ocean Sciences.

For additional and related information visit: www.adfg.alaska.gov/index.cfm?adfg=chinookinitiative_yukon.main www.afsc.noaa.gov/ABL/default.php www.aykssi.org www.nprb.org www.sfos.uaf.edu

per year in the 1980s to 2000s, declined precipitously in 2008, and have remained at low levels since.

Not only has the number of fish likely declined, but size at age and age at return appear to be declining, with a smaller proportion of females observed in the run, raising questions among users and scientists about the quality of escapement: Do the fish that do make it to the spawning grounds reflect the optimum sex ratio and distribution of age classes and sizes for specific stocks? Some workshop participants expressed concern that extremely low fish numbers could tip salmon runs to a pattern of persistent low numbers, resulting in continued severe restrictions to subsistence and commercial fisheries and economic and cultural shifts in resource use. However, recent brood year returns may be within the range of historic variation and could eventually return to higher levels. Because complex and interacting environmental and biological factors in both the river and marine environments contribute to variation in annual run sizes, the ranges of future variation are difficult to predict. It follows that managing for social-ecological resilience will require focus on monitoring, process interactions across time and space scale, and exploring alternative trajectories for resource utilization.

Management agencies, researchers, and others are currently collecting observations, undertaking analyses, and implementing regulations in efforts to better understand and promote the resilience of Yukon Chinook populations. These include retrospective studies, stock assessments, modeling exercises, and both fresh water and salt water field surveys. For example, the Alaska Department of Fish and Game (ADF&G) recently conducted a stock assessment gap analysis for Alaskan Chinook and is in the midst of a $30 million research program to bolster our fundamental stock assessment program for this species using a suite of indicator stocks.

The National Oceanographic and Atmospheric Administration’s (NOAA’s) Ecosystem Monitoring and Assessment program conducts annual fisheries and oceanographic surveys on the Bering Sea shelf. Canada’s Department of Fisheries and Oceans recently convened a Southern B.C. Chinook Panel to examine productivity trends for various stock groups, including many from Alaska. Such research efforts represent one critically important facet of maintaining sustainable Chinook populations over the long-term. Other aspects of balancing the biological and social needs of the Chinook system within an effective management strategy include implementing the resilience-building and vulnerability-mitigating recommendations outlined in this document.

What is the Resilience Approach?

Although the future conditions of complex adaptive systems are almost impossible to predict, the factors determining their resilience allow us to better understand their sensitivity to change. Resilience, or flexibility, denotes the capacity of a system to absorb a variety of shocks and disruptions while sustaining its fundamental structure and function. A diversity of species, landscapes, and livelihoods increases the options that a system has to respond to uncertain changes. Resilience also depends on the balance of stabilizing feedbacks, which tend to maintain the current properties of the system, and innovation, which can move the system in new directions.

Understanding the factors that govern the resilience of the Yukon Chinook salmon system enables us to suggest interventions that might alter its vulnerability, resilience, tipping points, and feedback mechanisms.

Example time history of a complex adaptive system that exhibits changing resilience and tipping point thresholds over time. Stabilizing feedbacks keep the system fluctuating around an average level (dashed lines) within each multi-year regime. Regimes can be characterized and thresholds influenced by many factors. In a salmon system, such factors could potentially include habitat quality, availability of prey, fishing pressure, stock assessment data quality, regulations, or climate.

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Adaptability

Warming temperatures will decrease the amount of preferred ocean habitat for Chinook salmon in coming decades. The figure depicts projected changes in preferred summer habitat between the 1980s (blue) to 2080 (pink) under a medium-rate warming scenario.

Figure reproduced following Abdul-Aziz et al., 2011.

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The workshop identified several sources of potential resilience in the Yukon River Chinook, including the extensive and diverse habitats used by salmon in both the freshwater and oceanic stages of their life cycle, genetic diversity, and the presence of multiple age classes in spawning runs.

Chinook use both glacial and non-glacial rivers and spawn in small streams to large rivers; over 150 spawning sites have been identified within the Yukon Basin. Straying spawners seek out new potential spawning streams for depositing eggs. In the ocean, Chinook migrate over large areas of the Bering Sea, utilizing both coastal and deep-sea habitats.

The contribution of multiple age classes to each spawning run spreads the risk of run failure to future production across several cohorts. Recent research suggests that Chinook may even have the capacity to adapt to warming temperatures because Chinook that lay larger eggs appear to produce offspring that have greater heat tolerance.

People also have a large reservoir of potential resilience in their interactions with salmon. Chinook have been a critical food and cultural resource for Yukon River residents for thousands of years. At times of low salmon abundance, people have shifted to other subsistence foods, especially in the lower river where there are a wide variety of salmon and non-salmon fish and marine and terrestrial mammals. Sharing salmon within and among communities, customary and traditional trade, and lower-river commercial harvest all contribute to the flexibility of mixed economies along the Yukon River, as does the range of gear types and technologies used to harvest salmon.

The boards and councils that provide directives to fisheries managers, the managers themselves, and the applicable laws are also all important parts of this salmon system as they seek to sustain salmon populations, regulate harvest across the drainage and manage for sustainable escapements that conserve salmon populations and support harvest opportunity.

Vulnerability

Especially at times of low abundance, the Chinook salmon system is exposed to numerous sources of potential stress. Climate change in the Yukon River basin and adjacent seas is occurring as rapidly as any place on Earth, but its effects on salmon are difficult to predict. Some effects may be beneficial, such as greater winter streamflow or warming river and ocean waters in places presently too cold for optimal salmon growth.

However, many indirect effects of climate change could harm salmon, such as increased sediment input from thawing permafrost and melting glaciers, altered summer streamflow, changes in sea ice and ocean food webs, and short-lived catastrophic events like drainage of a lake due to permafrost melting or a landslide blocking tributary access.

Human-salmon interactions other than directed harvests in established fisheries could substantially influence the resilience of Yukon Chinook salmon populations. For example, the collateral losses of Chinook salmon that occur when human development degrades riparian zones, and losses due to blockages and impairment of migratory corridors inherent in some modes of hydroelectric energy production may produce effects as large and uncertain as climate-driven effects. Biased data can misdirect management decisions.

There are also important sources of vulnerability relevant to the human dimensions of the salmon system. If harvest is prohibited for several years because of low salmon numbers, what effects will rural residents experience at their fish camps, in teaching younger generations, and in maintaining mixed subsistence economies? In the lower river, where commercial fishing has been an important source of cash to support subsistence, how long can markets and marketing infrastructure be maintained when Chinook harvest is not allowed?

Example of system vulnerability induced by habitat degradation. Photo by Chris Stark

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Sources of vulnerability and resilience, tipping points, and feedbacks in the Yukon Chinook salmon social-ecological system, as identified by workshop participants.

Interacting time and space scales via amplifying and stabilizing feedbacks provide limits to the system within the range of normal variation. Shocks, chaos, or new and multiple stressors can push a socialecological system over a tipping point and into a new and different norm.

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Sources of vulnerability • • • • • • • • •

Disease Competition for food resources limited by ocean carrying capability Variability in migration routes into poor habitat (the Arctic?)

Perceptions that other groups are not bearing the burden equally Bottlenecks and timing match-mismatch at various life stages Riparian zone degradation Density-dependent predator pits The unknown unknowns Bycatch

Sources of resilience • • • • • • •

Ability for harvesters to adapt to changing conditions Genetic diversity in the wild stocks Pioneers that spawn in new or different watersheds Flexible management practices Diversity of fresh and salt water habitat use Variation in the number of years from egg to spawning Empowerment of local communities in management decisions

Tipping points • • • • • • •

Loss of mixed economy for river residents Thermally-induced system changes Compounding effects of multiple stressors Failure to meet treaty obligations Changing prey and predator fields Low productivity Human response to climate change

Amplifying and stabilizing feedbacks • • • • • • •

Ice, albedo, and warming temperatures changing ocean habitat Warming temperatures near the northern limit of Chinook range Uncertainty in run strength informing management harvest limits Alternate food resources for fishers in times of low abundance Hatchery fish displacing and interbreeding with wild stocks Management promoting both access to fishing and adequate escapement Management that rigidly follows a maximum sustained yield protocol

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Recommendations

Forecasting the future Yukon Chinook salmon system is difficult because there is great uncertainty in the trajectory along which the many sources of resilience and vulnerability will interact. Many of the future changes are global or international in scale and impossible to prevent through local management efforts alone. The workshop therefore focused on strategies for strengthening the resilience and reducing the vulnerability of the Yukon Chinook-human system. As additions or enhancements to the management options currently being pursued by the responsible management institutions to enable resilient Chinook salmon populations, and in addition to the laws and regulations currently in place to promote responsible human-salmon interactions, we recommend the following.

• Maintain habitat throughout the Yukon River watershed. Without

substantially negatively impacting development activities, habitat degradation due to construction, logging, and other developmentrelated activities is preventable. It may not be possible to prevent habitat loss due to climate warming effects such as permafrost degradation, sediment input, and risk of high-temperature stress during periods of low flow but the overall effect of these losses can be minimized by keeping as much habitat intact as possible.

• Maintain the diversity of spawning habitats throughout the Yukon River watershed. This promotes habitat and genetic diversity, and therefore ensures a greater range of adaptive options to salmon populations during unpredictable future changes.

• Minimize pollution, especially in habitats shared by large numbers of salmon. These include key spawning areas at the outflows of large lakes, the mainstem of the Yukon River, and the nearshore environment traversed by smolt as they enter the sea from the Yukon River plume.

• Explore strategies to foster the harvest and consumption of nonsalmon species. Maintaining a broad diversity of subsistence foods is an adaptive strength that village communities can and do employ to mitigate swings in resource abundance, while simultaneously potentially reducing predation on Chinook smolt and fry in the freshwater system.

• Continue to develop and implement ever more effective measures for reducing unintentional catches of Chinook in marine and freshwater fisheries in domestic and international waters, including measures that respond to fluctuations in Chinook abundance.

• Engage communities and managers in exploring options for maintaining both diverse salmon stocks and salmon-based mixed subsistence economies at times of low Chinook abundance. Examples

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of promising strategies include scheduling of fishing openings at times and places that minimize harvest of female Chinook, fostering use of gear that returns live female Chinook to the river when they are accidentally caught, liberalizing harvest opportunities for alternative subsistence foods, and ensuring sufficient subsistence harvest of Chinook salmon to sustain mixed subsistence economies.

• Explore management options to strengthen subsistence systems at times of high Chinook abundance, such as commercial or customary trade that allows purchase of equipment that facilitates subsistence during more difficult times.

• Maintain multiple tiers having differently assigned priorities for subsistence harvest that are responsive to variation in both Chinook abundance and subsistence needs.

• Encourage and support international dialogue among all of the nations that are engaged in harvest and production of salmon in the North Pacific by working through the existing international treaty bodies responsible for discussing ocean carrying capacity, preventing salmon harvests of salmon on the high seas (non-EEZ), and data sharing. The responsible bodies are the Yukon Panel of the Pacific Salmon Treaty and the North Pacific Anadromous Fish Commission.

N. Alstrom in St Marys. Photo by Caroline Brown

• Promote long-term, ecosystem-based management, based on improved appreciation of the multi-scale and multi-specie ecosystem that Chinook encounter during their life cycle, in order to support a healthy Yukon Chinook social-ecological system.

• Educate and engage the public on the importance of best practices to protect salmon and their habitats and the essential roles played by the laws of policies that guide federal and state regulatory agencies responsible for the human activities that impact salmon and their habitats in achieving a resilient salmon-human system.

• Maintain responsiveness in the management system such that managers can continue to adapt harvest rates in response to new observations about stock size.

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Research Imperatives for Resilience Management of Yukon River Chinook

• Undertake long-term monitoring of the number of spawning adults and their productivity (number of recruits per spawning adult) in selected monitoring sites that span the range of spawning habitats to improve understanding of potential causes of variation in recruitment.

• Improve understanding of ecosystem factors, both top-down and bottom-up, that influence survival of smolt as they leave the river and begin their first year at sea, to identify critical places and times for early marine survival.

• Identify the most productive components of the vast habitat network that comprises the Yukon River ecosystem, and explore whether this pattern of productivity is stable through time or is better represented as a shifting habitat mosaic.

• Improve understanding of the regional diversity in cultural practices and meanings related to use of Chinook salmon in the Yukon River Basin, so as to build sensitive adaptive strategies for times of low harvest.

• Identify and rank factors that determine the carrying capacity of the ocean and the nature in which wild and hatchery salmon and other fishes compete for finite oceanic resources, so as to better inform ecosystem-based management across the greater North Pacific.

Photo by Deborah Mercy, Alaska Sea Grant

• Better understand Chinook behaviors and environmental stressors that may impact survival (e.g. thermal limits, hypoxia, acidification, pollution, etc.) in both fresh and salt water and how a changing climate and global environment may alter these behaviors.

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• Continue ongoing and undertake new gap analyses spanning the entire Pacific Northwest regarding Chinook population trends and other critical information. Examine climate effects, marine production, disease, genetics, and human interactions. Population declines observed from the Yukon Basin down to Canada’s Fraser River may or may not be due to the same underlying factors.

• Further develop and apply multi-species management approaches, including population dynamics between Chinook and other salmon in the Yukon River.

• Continue to reduce and identify uncertainty present in production dynamics and run assessments to clarify and minimize risks to sustainable management and harvest of Yukon River Chinook salmon.

Fostering Resilience in the Yukon Chinook System

The ability of this remarkable complex adaptive social-ecological system to maintain function under new environmental stressors depends critically on keeping the system’s components flexible and adaptive.

There exist diverse perspectives on whether the system is inherently resilient or vulnerable. Ultimately, the Yukon Chinook and the people who harvest them will face changes wrought by an evolving climate, management decisions, and other human-derived impacts.

Informed management requires accurate data and an appreciation of the multiple and cross-scale social, economic, and ecological ramifications of regulatory action. While managers lack control over the full system, their decisions may determine the vitality of both the future returns and the cultural traditions and activities associated with Chinook salmon.

Flexible, creative, and adaptive management approaches that pursue the recommendations provided here will foster resilience in the Yukon River Chinook.

Stan Zuray’s fish wheel. Photo by Jan Conitz

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The University of Alaska Fairbanks is an affirmative action/equal opportunity employer and educational institution and is a part of the University of Alaska system. Cover photos by Deborah Mercy, Alaska Sea Grant, except Chinook salmon photos: Washington Department of Fish and Wildlife http://wdfw.wa.gov. Design: Rasmuson Library Graphics/Dixon Jones.