Implementing Ecosystem-Based Management Principles in the Design of a Salmon Ocean Ecology Program

Abstract

Two decades have passed since the initiation of the National Oceanic and Atmospheric Administration's research program aimed at advancing the understanding of estuary and ocean ecology of United States West Coast Pacific salmon (Oncorhynchus spp.). In this review and prospectus, we summarize key findings from this program and describe a plan for transitioning it to better support Ecosystem-Based Management (EBM). While we focus on salmon research, our approach applies to research design generally. Our path forward involves increasing understanding of ecosystem processes to improve the dependability of scenario testing under novel conditions. Over the past two decades, we developed a conceptual model for how climate, predators, prey, fisheries, and human activities influence salmon. Knowledge gaps we identified from our conceptual model include limited understanding of salmon distributions, behavior, maturation dynamics, and population dynamics, and salmon interactions with predators, competitors, and prey during winter. We consider emerging risks and vulnerabilities facing salmon and propose analysis frameworks for evaluating them. Increased predator populations, coupled with climate change, pose increasing threats to West Coast salmon and will require new strategies and actions to mitigate their negative impacts. We propose research to support the development of decision-support tools to evaluate tradeoffs associated with alternative management strategies and to inform an adaptive ecosystem management system to improve the resilience of salmon populations and salmon-dependent fisheries.

Science for integrative management of a diadromous fish stock: interdependencies of fisheries, flow, and habitat restoration

“…Similar benefits to more holistically evaluating potential responses of salmon to management decisions are evident in other systems (e.g., Scheuerell et al 2006;Battin et al 2007). More broadly, integrating work like ours on ecosystem considerations in the watershed with ecosystem-based fisheries management efforts in the ocean (Wells et al 2020) and efforts like integrated ecosystem assessments (Levin et al 2009) may facilitate linkages across marine and freshwater stages. For example, water management may prioritize desirable flow conditions to increase juvenile survival in the watershed, and fisheries management may protect marine species that buffer subadult salmon from predation at sea.…”

Protecting our coast for everyone's future: Indigenous and scientific knowledge support marine spatial protections proposed by Central Coast First Nations in Pacific Canada

“…Large-scale fisheries are only one of several factors contributing to salmon declines. Ocean warming and competition with hatchery fish have lowered the productivity of wild stocks (Connors et al, 2020), and industrial impacts on freshwater and estuarine habitats reduce juvenile survival and overall productivity (Wells et al, 2020). Because adult salmon encounter diverse stressors (e.g.…”

“…Because adult salmon encounter diverse stressors (e.g. fisheries, marine heatwaves) over vast ocean areas (Wells et al, 2020), MPAs are most likely to help mitigate salmon declines by protecting estuarine habitat critical to juveniles (Sharpe et al, 2019).…”

Size‐selective predation effects on juvenile Chinook salmon cohort survival off Central California evaluated with an individual‐based model

“…In this region, krill are indicative of the juvenile salmon forage base (MacFarlane & Norton, 2002, Wells et al, 2012, 2023), and the condition of juvenile Chinook in the GoF is associated with the availability and spatial distribution of krill (Fiechter et al, 2015; Henderson et al, 2019; Wells et al, 2012). For instance, above‐average years for juvenile growth and survival at sea have been linked to early season upwelling driving high krill abundances and good prey retention in nearshore waters where juvenile Chinook salmon enter the ocean (Fiechter et al, 2015; Wells et al, 2012, 2016, 2020). In contrast, anomalous ocean conditions concomitant with weak or late upwelling can result in warmer ocean temperatures, less spatial heterogeneity of the environment (e.g., reduced upwelling shadows, eddies, and fronts), and reduced prey concentration and availability at the time of ocean entry, each of which has been associated with stock collapses and low survival years for Central California Chinook salmon (Graham & Largier, 1997; Lindley et al, 2009; MacFarlane, 2010; Sabal et al, 2020; Wells et al, 2012, 2016; Wing et al, 1998; Woodson & Litvin, 2015).…”