Climate change and human land-use changes are exerting enormous pressures on culturally important species and ecosystems, such as the salmon watersheds of western North America. These ecosystems are being rapidly transformed by rapid climate change as well as pressured by various industrial land-uses. This talk shared three vignettes of forward-looking science on climate change impacts and corresponding industry pressures. Sea-level rise is forecasted to inundate estuaries that are important nursery habitat for juvenile salmon with relevance to coastal development and restoration. Changing climates and forestry practices are warming stream temperatures and altering flow regimes that control salmon productivity and survival. On the other hand, glacier retreat is creating new rivers and lakes for salmon, but these nascent habitats are also the target of active mining exploration and development. Collectively, these examples showcase that there is an urgent need for climate change action, but also that forward-looking science such as this can inform proactive conservation and management actions that will increase the ability of these ecosystems to support salmon into the future. The talk showcased local opportunities to increase climate resilience, with potential broader relevance to global challenges of climate change.

Worldwide stream and watershed restoration efforts cost billions annually. These projects are typically local-scale activities that do not have a measurable effect on ecosystem function or services. One ecosystem restoration technique that can have a large-scale effect is dam removal. This single action allows for the re-connection of ecosystem processes such as upstream and downstream organism movement, the rapid transformation from lentic to lotic conditions in former reservoirs, rapid shifts in community structure and food webs, and accelerated habitat creation through sediment deposition. Results were presented from the Elwha River, where the largest dam removal ever undertaken resulted in measurable ecosystem changes. The release and subsequent downstream transport of tens of millions of metric tonnes of sediment from former reservoirs has resulted in the transformation and rebuilding of estuarine and riverine habitats. The resumption of free passage for aquatic organisms has re-established anadromous fishes to areas that have been void of such species for 100 years, prompting rapid increase in salmonid life history diversity. Short-term changes due to large changes in sediment supply resulted in reductions in Chinook salmon productivity but has recently rebounded. Following dam removal, marine derived nutrients increased, entered food webs and altered the migration patterns and fecundity of an aquatic song bird. Results demonstrate the critical importance of maintaining longitudinal connectivity for maintaining watershed processes and ecosystem services, and linking management such as habitat restoration, hatchery operations, and harvest into an integrated set of actions.

The Habitat Assessment and Restoration Planning (HARP) Model is a process-based model that links land use, climate change, and habitat restoration to riverine habitat quantity and quality, which are then linked to salmon life-cycle models to compare the potential effects of alternative habitat futures on salmon and steelhead populations. The model was used to estimate changes in spawner abundance from historical to current habitat conditions, as well as for future conditions including climate change and habitat restoration. The model has three main components: a spatial analysis that processes geospatial inputs to create habitat data layers, a habitat analysis that translates habitat data into input parameters for life-cycle models, and the life-cycle models that estimate changes in salmon abundance and productivity for all species and run types included for a given location. To date the model has been run in the Chehalis, Snohomish, and Stillaguamish River basins, evaluating effects of climate change and habitat restoration scenarios on Chinook salmon, coho salmon, and steelhead. Results suggest that floodplain reconnection and restoration of wood and shade often benefit multiple species, whereas beaver ponds, barrier removal, and bank armor removal mainly benefit individual species or subpopulations. More generally, the model suggests that vulnerability to climate change varies among species and run types, and that habitat restoration will produce larger increases in spawner abundance for less vulnerable species. Moreover, populations with very low ocean survival may have limited responses to habitat restoration because the external constraint limits potential abundance increases.

Pacific salmonids in the Canadian province of British Columbia (BC) face an existential crisis from cumulative effects of human activities and climate change. Indigenous peoples need to be central to the collective response to the crisis, yet Canadian government salmon risk assessments in Nuu-chah-nulth First Nation territories on the west coast of Vancouver Island have struggled to integrate Nuu-chah-nulth knowledge and worldview. Through research co-produced by Uu-a-thluk (Nuu-chah-nulth Tribal Council) and the salmon Watersheds Lab (SFU), efforts were made to elevate Nuu-chah-nulth perspectives on risks to salmon. A decolonized approach was taken founded in Nuu-chah-nulth worldview and values that upheld hereditary leadership and respected Indigenous data sovereignty. A qualitative expert elicitation was employed based on semi-structured interviews and a focus group. The conversations were unconstrained such that participants defined the scope of risk and related connections. Nuu-chah-nulth knowledge holders emphasized colonial greed and governance as drivers and enablers of harm to salmon. Knowledge holders also described pathways over time by which a range of human activities and climate change have degraded the resilience and abundance of many individual stream and river salmon populations. Finally, knowledge holders explained ways in which salmon declines have impacted Nuu-chah-nulth ways of life at individual, family, and community scales. The research demonstrates the importance of Nuu-chah-nulth knowledge to salmon stewardship and the criticality of co-governance to sustainable futures for salmon and people. The presenters described the research results and implications, including a discussion of the Mowachaht/Muchalaht First Nation’s Salmon Parks Indigenous Protected and Conserved Area (IPCA).

For millennia First Nations in British Columbia have employed sophisticated technology and governance systems fostering the long-term sustainability of salmon fisheries. Indigenous governance authority was usurped by colonial governments in the late-19th century, and fisheries were transformed from local in-river fisheries managed with place-based knowledge to marine mixed-stock fisheries. Following more than a century of legal and political struggle, First Nations are reasserting their inherent rights as fishery managers, revitalizing Indigenous management systems, and working with partners to braid ancient harvest tools with cutting edge technology to advance sustainability and equity in salmon fisheries. In the face of increasing climate variability and changes there is a heightened need for adaptive fishery management using high-quality in-season information. Artificial Intelligence (AI) is transforming society at an accelerating pace, including in fishery management. Computer-vision models, a class of AI that performs automated object detection and classification, holds promise for fishery monitoring, however these tools have rarely been co-developed to address the needs and concerns of local and Indigenous communities. This presentation detailed the development of computer-vision models for automated salmon enumeration, revitalizing the building of in-river weirs for harvest and real-time monitoring, and the evaluation of the benefits of in-season data for salmon populations and fisheries. Computer-vision tools leverage limited funding and capacity through a novel application of AI to produce real-time information on salmon returns, reducing conservation risks and increasing long-term harvest opportunity across a range of future climate scenarios. These tools support re-emerging in-river fisheries and enable in-season management supporting long-term resilience of wild salmon.

Cumulative effects assessment frameworks at ecosystem scales that incorporate local knowledge and values are needed to achieve better outcomes for biodiversity and people. However, predicting the cumulative effects of multiple pressures is challenging and fraught with uncertainties, but necessary to achieve sustainable economies and resilient ecosystems. This presentation provided an overview of the mapping of cumulative impacts of over 30 pressures for salmon and other connected species in the Great Bear Rainforest, British Columbia Canada, a region famous for implementation of principles of ecosystem-based management. Informed by the interests and knowledge of three First Nations in the Central Coasts region of British Columbia, these pressure maps were incorporated in a spatial future-focused Bayesian model to predict regional cumulative effects of alternative development pathways for four sectors (forestry, energy/mining, tourism, and salmon aquaculture) on ecosystem health across the land and sea. Future outcomes for overall ecosystem health were predicted to be worst in development scenarios with high future forestry activities (> 60% decline in some areas). Continuation or development of all four industries resulted in an 8% decline overall in ecosystem health across the Central Coast. In contrast, predicted ecosystem health in the tourism economy scenario increased up to 15% in some marine areas, primarily driven by the removal of salmon aquaculture and forestry activities. Researchers worked directly with local Indigenous decision makers to build this regional approach to assessing the cumulative effects of current and future human activities, with outputs directly informing ecosystem-based management of lands and waters in the region.

Many salmon populations in the Pacific Northwest are struggling despite widespread management intervention. Cumulative effects may be contributing to depressed population growth. Recently, Fisheries and Oceans Canada amended the Fisheries Act to consider cumulative effects in the protection of fish habitat, but the diffuse nature of studies connecting multiple stressors and salmon productivity has limited the development of a cohesive understanding of cumulative effects in Canada. This presentation provided an overview of efforts to outline pathways of effects (POE) between activities (e.g. forestry, agriculture), stressors (e.g. increased sedimentation), and Pacific salmon productivity (e.g. survival, fecundity) in British Columbia, Canada. Researchers completed a comprehensive review of peer-reviewed literature to build POE, identified research gaps, and outlined future research priorities. Focus was on activities and stressors that could impact the freshwater phase of the Pacific salmon life cycle in British Columbia, Canada. Over 30,000 abstracts were reviewed, data was extracted from ~850 articles and >6000 stressor-response pairs were identified. POE diagrams were developed between six main activities (i.e. mining, forestry, hydropower, urban development, rural development and agriculture), their associated sub-activities, stressors, and life-stage specific salmon productivity. It was found that while certain stressors and life stages (e.g. forestry and juvenile salmon abundance) were well represented, other stressors and life stages had limited information. Few studies examined how multiple stressors could contribute to carryover effects on marine survival or to overall salmon population productivity. Future studies should examine cumulative impacts across the salmon life-cycle at a scale relevant to population productivity (e.g. watersheds).

Following the NACCB Symposium, Watershed Futures Initiative hosted a networking gathering, Talking BC Salmon and Cumulative Effects, on June 26, 2024. It was an opportunity to connect with others who are working on and thinking about the multiple stressors facing BC's salmon and watersheds and the urgent need for effective solutions. Advancing a positive and more resilient future for salmon and people in BC requires diverse perspectives and improvement in the science and governance of cumulative effects.