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Throughout human history, Indigenous and local communities have stewarded nature. In the present article, we revisit the ancestral principle of reciprocity between people and nature and consider it as a conceptual intervention to the current notion of ecosystem services commonly used to inform sustainability transformation. We propose the concept of reciprocal contributions to encompass actions, interactions, and experiences between people and other components of nature that result in positive contributions and feedback loops that accrue to both, directly or indirectly, across different dimensions and levels. We identify reciprocal contributions and showcase examples that denote the importance of reciprocity for our ecological legacy and its relevance for biocultural continuity. We suggest that the concept of reciprocal contribution can support transformation pathways by resituating people as active components of nature and restructuring institutions so that ethical principles and practices from Indigenous and local communities can redirect policy approaches and interventions worldwide.

Climate change is altering the distribution and composition of marine fish populations globally, which presents substantial risks to the social and economic well-being of humanity. While deriving long-term climatic baselines is an essential step for detecting and attributing the magnitude of climate change and its impacts, these baselines tend to be limited to historical datasets and palaeoecological sediment records. Here, we develop a method for estimating the 'ancient Mean Temperature of the Catch' (aMTC) using Indigenous fisheries catch records from two archaeological sites in the northeast Pacific. Despite different catch compositions, we observe an increase in aMTC over a 5,000-year period at two contemporaneously occupied archaeological sites in southwestern British Columbia, Canada. We document cooler catches from 5,000 to 3,000 cal yr BP and comparatively warmer catches from 1,800 to 250 cal yr BP. These warmer temperatures are broadly consistent with palaeoceanographic sea surface temperature proxies from British Columbia and Alaska. Because this method requires converting measures of fish bones into estimates of fish size structure, abundance, biomass, and finally aMTC, opportunities exist to account for both variation and uncertainty at every step. Nevertheless, given that preindustrial fisheries data are ubiquitous in coastal archaeological sites, this method has the potential to be applied globally to broaden the temporal and geographic scale of ocean temperature baselines.The online version contains supplementary material available at 10.1007/s10641-022-01243-7.

With climate, biodiversity and inequity crises squarely upon us, never has there been a more pressing time to rethink how we conceptualize, understand and manage our relationship with Earth's biodiversity. Here, we describe governance principles of 17 Indigenous Nations from the Northwest Coast of North America used to understand and steward relationships among all components of nature, including humans. We then chart the colonial origins of biodiversity science and use the complex case of sea otter recovery to illuminate how ancestral governance principles can be mobilized to characterize, manage and restore biodiversity in more inclusive, integrative and equitable ways. To enhance environmental sustainability, resilience and social justice amid today's crises, we need to broaden who benefits from and participates in the sciences of biodiversity by expanding the values and methodologies that shape such initiatives. In practice, biodiversity conservation and natural resource management need to shift from centralized, siloed approaches to those that can accommodate plurality in values, objectives, governance systems, legal traditions and ways of knowing. In doing so, developing solutions to our planetary crises becomes a shared responsibility. This article is part of the theme issue ‘Detecting and attributing the causes of biodiversity change: needs, gaps and solutions’.

Feedbacks between social and ecological processes can lead to sustainable stewardship practices that support ecological resilience among harvested populations. This is evident along the world's coast lines, where Indigenous knowledge systems have facilitated millennia of human–nature coexistence. However, social–ecological conditions globally are quickly shifting, posing challenges for coastal Indigenous communities where customary harvest of ocean resources, such as kelps, needs to adapt to growing markets, novel climates and changing governance regimes. Consequently, a pressing need exists to determine how specific ecological and social variables drive key dynamics within coupled human–ocean systems. Motivated by the information needs of an Indigenous community on Canada's Pacific Coast, we co‐designed a traditional harvest experiment, field surveys and semi‐directed interviews with Indigenous resource users and managers to measure the ecological resilience of the feather boa kelp Egregia menziesii to harvest and determine what environmental variables most affected its recovery. We wove these results with information on current stewardship practices to inform future management of this slow‐growing perennial kelp based on Indigenous knowledge and western science. We found that Egregia recovered from traditional harvest levels faster than expected with minimal impact on its productivity because plants sprouted new fronds. In fact, traditional harvest levels of Egregia mimicked natural frond loss. Indigenous knowledge and empirical ecological evidence revealed the importance of individual plant size, site‐specific seawater temperature and wave exposure in driving Egregia recovery. Indigenous stewardship practices reflected these ecological relationships in the practice of selecting large plants from sites with healthy patches of Egregia. While we documented key social controls of harvest, current self‐reported harvest levels of kelp fronds were two times greater than the stated social norm, but only 1.2 times greater in terms of kelp biomass. Consequently, traditional harvest protocols facilitate Egregia recovery and promote its sustained use. However, its ecological resilience is susceptible to the erosion of customary practices and warming ocean temperatures. Co‐produced research that mobilizes multiple bodies of knowledge can enhance our understanding of social–ecological resilience, empower local decision makers and democratize the science and practice of natural resource management. ​ A free Plain Language Summary can be found within the Supporting Information of this article.

This essay explores shifting scientific understandings of fish and the evolution of fisheries science, and it grapples with colonialism as a system of power. We trace the rise of fisheries science to a time when Western nation-states were industrializing fishing fleets and competing for access to distant fishing grounds. A theory of fishing called "maximum sustainable yield" (MSY) that understands fish species in aggregate was espoused. Although alternatives to MSY have been developed, decision-making continues to be informed by statistical models developed within fisheries science. A challenge for structured management systems now rests in attending to different systems of knowledge and addressing local objectives, values, and circumstances. To deepen and illustrate key points, we examine Pacific herring (

A major challenge in sustainability science is identifying targets that maximize ecosystem benefits to humanity while minimizing the risk of crossing critical system thresholds. One critical threshold is the biomass at which populations become so depleted that their population growth rates become negative—depensation. Here, we evaluate how the value of monitoring information increases as a natural resource spends more time near the critical threshold. This benefit emerges because higher monitoring precision promotes higher yield and a greater capacity to recover from overharvest. We show that precautionary buffers that trigger increased monitoring precision as resource levels decline may offer a way to minimize monitoring costs and maximize profits. In a world of finite resources, improving our understanding of the trade-off between precision in estimates of population status and the costs of mismanagement will benefit stakeholders that shoulder the burden of these economic and social costs.

The importance of disturbance Work in sea otters over the last few decades has transformed our understanding of the importance of specific species, or keystones, as drivers of community structure and stability. Foster et al . took the next step and tested whether otter foraging might influence genetic diversity in an eelgrass ecosystem (see the Perspective by Roman). The authors found that eelgrass genetic diversity was significantly higher where otters were present and that the impact was related to time: Longer otter presence was associated with higher genetic diversity. These results illustrate how the actions of a predator can affect the diversity of a producer in a tropic system. —SNV

Significance Climate change, habitat loss, and overharvesting are threatening coastal ecosystems worldwide. A less widely recognized threat is the decline in Indigenous mariculture practices. These practices, such as building of clam gardens, structured coastal ecosystems for millennia. Teasing out the dynamic and intertwined relationships between humans and culturally valued species, such as clams, requires long-term paleoecological and archaeological records. These records are requisite for creating meaningful management targets and for applying traditional mariculture practices, such as the tending of clam gardens, to increase the productivity and sustainability of our foods today. Documenting these interactions between humans and coastal ecosystems, such as we have done here, also counteracts the erasure of the long-term connections of Indigenous peoples to their lands and seas., Historical ecology can provide insights into the long-term and complex relationships between humans and culturally important species and ecosystems, thereby extending baselines for modern management. We bring together paleoecological, archaeological, and modern clam records to explore the relationship between humans and butter clams (Saxidomus gigantea) throughout the Holocene in the northern Salish Sea of British Columbia, Canada. We compare butter clam size and growth patterns from different temporal, environmental, and cultural contexts spanning 11,500 y to present. Butter clam size and growth were restricted in early postglacial times but increased over the next few millennia. During the early-Late Holocene, humans took increasing advantage of robust clam populations and after 3.5 ka, began constructing clam gardens (intertidal rock-walled terraces). Environmental and cultural variables, including coarse substrate, stabilized sea surface temperature, and the presence of a clam garden wall, increased clam growth throughout the Holocene. Measurements of clams collected in active clam gardens and deposited in middens suggest that clam gardens as well as other mariculture activities enhanced clam production despite increased harvesting pressure. Since European contact, decline of traditional management practices and increases in industrial activities are associated with reduced clam size and growth similar to those of the early postglacial clams. Deeper-time baselines that more accurately represent clam population variability and allow us to assess magnitudes of change throughout time as well as the complex interactions among humans and clams are useful for modern marine resource management.

Understanding how trophic dynamics drive variation in biodiversity is essential for predicting the outcomes of trophic downgrading across the world’s ecosystems. However, assessing the biodiversity of morphologically cryptic lineages can be problematic, yet may be crucial to understanding ecological patterns. Shifts in keystone predation that favor increases in herbivore abundance tend to have negative consequences for the biodiversity of primary producers. However, in nearshore ecosystems, coralline algal cover increases when herbivory is intense, suggesting that corallines may uniquely benefit from trophic downgrading. Because many coralline algal species are morphologically cryptic and their diversity has been globally underestimated, increasing the resolution at which we distinguish species could dramatically alter our conclusions about the consequences of trophic dynamics for this group. In this study, we used DNA barcoding to compare the diversity and composition of cryptic coralline algal assemblages at sites that differ in urchin biomass and keystone predation by sea otters. We show that while coralline cover is greater in urchin-dominated sites (or “barrens”), which are subject to intense grazing, coralline assemblages in these urchin barrens are significantly less diverse than in kelp forests and are dominated by only 1 or 2 species. These findings clarify how food web structure relates to coralline community composition and reconcile patterns of total coralline cover with the widely documented pattern that keystone predation promotes biodiversity. Shifts in coralline diversity and distribution associated with transitions from kelp forests to urchin barrens could have ecosystem-level effects that would be missed by ignoring cryptic species’ identities.

The reintroduction of a previously extirpated predator can engender conflict when the reintroduced species depletes customary fisheries to which indigenous communities have constitutionally protected rights. In the case of sea otter (Enhydra lutris) recovery on the west coast of North America, not only is Canada’s Species at Risk Act in conflict with Indigenous rights, but it also illuminates gaps in the principles of ecosystem-based management (EBM), such as equity and social justice. Broadly, we ask in this paper how EBM might be advanced if Indigenous communities were viewed as components of ecosystems having rights to a sustainable future equal to other components. Specifically, we explore evidence of sea otter management among precontact Northwest Coast societies and a contemporary co-managed system proposed by the Nuu-chah-nulth First Nations that would combine research with refinement of traditional hunting practices. We show that barriers persist through lack of knowledge of past controlled hunts, ignorance of recent experiences of successful community-based clam management, distrust of Indigenous capacity to self-manage or co-manage a hunt, and divergent values among actors.

The prevalence of disease-driven mass mortality events is increasing, but our understanding of spatial variation in their magnitude, timing and triggers are often poorly resolved. Here, we use a novel range-wide dataset comprised 48 810 surveys to quantify how sea star wasting disease affected Pycnopodia helianthoides , the sunflower sea star, across its range from Baja California, Mexico to the Aleutian Islands, USA. We found that the outbreak occurred more rapidly, killed a greater percentage of the population and left fewer survivors in the southern half of the species's range. Pycnopodia now appears to be functionally extinct (greater than 99.2% declines) from Baja California, Mexico to Cape Flattery, Washington, USA and exhibited severe declines (greater than 87.8%) from the Salish Sea to the Gulf of Alaska. The importance of temperature in predicting Pycnopodia distribution rose more than fourfold after the outbreak, suggesting latitudinal variation in outbreak severity may stem from an interaction between disease severity and warmer waters. We found no evidence of population recovery in the years since the outbreak. Natural recovery in the southern half of the range is unlikely over the short term. Thus, assisted recovery will probably be required to restore the functional role of this predator on ecologically relevant time scales.

Compelling new evidence shows that kelp production contributes an important and underappreciated flux of carbon in the ocean. Major questions remain, however, about the controls on the cycling of this organic carbon in the coastal zone, and their implications for future carbon sequestration. Here we used field experiments distributed across 28° latitude, and the entire range of two dominant kelps in the northern hemisphere, to measure decomposition rates of kelp detritus on the seafloor in relation to environmental factors. Ocean temperature was the strongest control on detritus decomposition in both species, and it was positively related to decomposition. This suggests that decomposition could accelerate with ocean warming under climate change, increasing remineralization and reducing overall kelp carbon sequestration. However, we also demonstrate the potential for high kelp-carbon storage in cooler (northern) regions, which could be targeted by climate mitigation strategies to expand blue carbon sinks.

The historic extirpation and subsequent recovery of sea otters (Enhydra lutris) have profoundly changed coastal social-ecological systems across the northeastern Pacific. Today, the conservation status of sea otters is informed by estimates of population carrying capacity or growth rates independent of human impacts. However, archaeological and ethnographic evidence suggests that for millennia, complex hunting and management protocols by Indigenous communities limited sea otter abundance near human settlements to reduce the negative impacts of this keystone predator on shared shellfish prey. To assess relative sea otter prevalence in the Holocene, we compared the size structure of ancient California mussels (Mytilus californianus) from six archaeological sites in two regions on the Pacific Northwest Coast, to modern California mussels at locations with and without sea otters. We also quantified modern mussel size distributions from eight locations on the Central Coast of British Columbia, Canada, varying in sea otter occupation time. Comparisons of mussel size spectra revealed that ancient mussel size distributions are consistently more similar to modern size distributions at locations with a prolonged absence of sea otters. This indicates that late Holocene sea otters were maintained well below carrying capacity near human settlements as a result of human intervention. These findings illuminate the conditions under which sea otters and humans persisted over millennia prior to the Pacific maritime fur trade and raise important questions about contemporary conservation objectives for an iconic marine mammal and the social-ecological system in which it is embedded.

Rapid system‐wide changes triggered by predators can pose considerable challenges to people. In the Northeast Pacific, the recovery of sea otters Enhydra lutris following their extirpation due to the 18th and 19th century fur trade is driving a social‐ecological regime shift with profound implications. While the ecological consequences of this shift are well documented, very little research has examined the conditions that enable or constrain people's ability to adapt to the social, economic and cultural changes that transpire. Through a collaborative partnership and workshops with Indigenous knowledge holders spanning Alaska to British Columbia, along with quantitative and qualitative interviews in two Indigenous communities among the first to experience sea otter recovery, we examined people's perceptions of the social‐ecological conditions that affect their ability to adapt to these changes. We found that communities differed in their relative rankings of adaptation‐enabling conditions; however, the following four broad strategies were perceived as critical to improving coexistence with sea otters: (a) strengthening Indigenous governance and decision‐making authority; (b) promoting adaptive co‐management; (c) weaving Indigenous knowledge and Western science into management plans and (d) establishing learning platforms. Both communities also identified that increased livelihood options and financial assistance would not compensate for lost food security. Differences in enabling conditions and attitudes towards sea otters within and between communities can be attributed to the social‐ecological and political context in which sea otter recovery occurs. Our study suggests that enhancing Indigenous peoples' ability to adapt to predator‐induced regime shifts will require a transformation in current resource governance systems if we are to navigate towards an ecologically sustainable and socially just operating space. Overall, this work highlights the need for more Indigenous authority, knowledge and leadership in addressing predator‐induced regime shifts in coupled human‐ocean systems. A free Plain Language Summary can be found within the Supporting Information of this article.

While the agency of individuals has been identified as a key factor in triggering governance transformations in social-ecological systems, more research attention is needed on how the social position of the actors involved influences these processes of change. Here, we highlight how the unique position of Indigenous women in a recent fishery conflict brought strength to this resource struggle and led to changes in the management of Pacific herring (Clupea pallasii) on the Central Coast of British Columbia, Canada. Through 18 semi-structured interviews with Heiltsuk women and men involved in this fishery conflict, we identified important actions taken by women in the community, which contributed to advancing the preconditions for transformation of the existing governance system. Heiltsuk women took on key leadership roles, increasing social cohesion, facilitating the flow of information, and negotiating among those holding power and conflicting objectives. Viewed through the framework of transformative change in social-ecological systems, women demonstrated strategic agency in challenging colonial governance regimes and catalyzing change. We relate these findings to theoretical understandings of women in environmental justice movements and activism and underscore the importance of Indigenous women as agents of change in their communities and as important actors in fisheries governance transformations. These leadership roles must be recognized and supported to navigate towards natural resource sustainability and social justice, globally, as well as reconciliation for past injustices, nationally.

The roles of dispersal and recruitment have long been a focal point in ecology and conservation. The adopted migrant hypothesis proposes a life history in which social learning transmits migratory knowledge between generations of iteroparous fish. Specifically, juveniles disperse from the parental spawning site, encounter and recruit to a local adult population, and learn migration routes between spawning and foraging habitats by following older, experienced fish. Although the adopted migrant life history may apply to many species of pelagic marine fishes, there is scant theoretical or empirical work on the consequent population dynamics. We developed and analyzed a mathematical model of this life history in which the recruitment of juveniles depends on the relative abundance of the local populations and recruitment overlap, which measures the ease with which juveniles are recruited by a nonparental population. We demonstrate that the adopted migrant life history can maintain spatial demographic structure among local populations, that it can also predispose local populations to collapse when a tipping point is crossed, and that recovery after collapse is impaired by reduced recruitment at small local population sizes.

The early stages of ovarian folliculogenesis generally progress independent of gonadotropins, whereas later stages require signaling initiated by FSH. In Siberian hamsters, cycles of folliculogenesis are mediated by changes in photoperiod which depress the hypothalamic pituitary gonadal axis. Reduced gonadotropins lead to decreases in mature follicle development and ovulation; however, early stages of folliculogenesis have not been explored in regressed ovaries. We hypothesized that intraovarian factors that contribute predominantly to later stages of folliculogenesis would react to changes in photoperiod, whereas factors contributing to earlier stages would not change. To probe if the early stages of folliculogenesis continue in the photoinhibited ovary while late stages decline, we measured the mRNA abundance of factors that interact with FSH signaling (Fshr, Igf1, Cox2) and factors that can function independently of FSH (c-Kit, Kitl, Foxo3, Figla, Nobox, Sohlh1, Lhx8). While plasma FSH, antral follicles, and corpora lutea numbers declined with exposure to inhibitory photoperiod, the numbers of primordial, primary, and secondary follicles did not change. Expression of factors that interact with FSH signaling changed with changes in photoperiod; however, expression of factors that do not interact with FSH were not significantly altered. These results suggest that the photoinhibited ovary is not completely quiescent, as factors important for follicle selection and early follicle growth are still expressed in regressed ovaries. Instead, the lack of gonadotropin support that characterizes the non-breeding season appears to inhibit only final stages of folliculogenesis in Siberian hamsters.

Low trophic‐level forage fish are experiencing global declines, influencing coupled human–ocean systems worldwide. Along the northwest coast of North America, declining trajectories of Pacific herring (Clupea pallasii) have prompted interest in improving the understanding of its population and community dynamics to better guide future conservation and management strategies. To improve future population estimates and understanding of the ecological factors governing herring egg survival, the magnitude, spatial variation and mechanisms driving herring egg loss rates were quantified. This was achieved by way of repeated observational field surveys and a predator exclusion experiment. Observational surveys revealed that regional egg loss rates (Z) were substantial and ranged from 0.101 ± 0.019 to 0.134 ± 0.028, the equivalent of 88–94% egg loss over a 21 day incubation period, or 50–60% egg loss over 6.8 days, the average time lag between spawn deposition and annual egg surveys. Furthermore, spatial variation was high, with egg loss rates varying 5‐fold among study sites. Depth, time since spawn, and spawn area were primary spatial drivers of egg loss, but predator abundance and exposure were secondarily important. Experimental evidence showed that benthic predation and habitat type were strong drivers of egg loss, suggesting that a high proportion of eggs, particularly those spawned on benthic substrates, are consumed by predators. These results have important conservation implications for managers and ecologists seeking to estimate herring biomass and to understand the environmental influences on predator–prey interactions that affect herring dynamics.

Coastal communities worldwide rely on small-scale artisanal fisheries as a means of increasing food security and alleviating poverty. Even small-scale fishing activities, however, are prone to resource depletion and environmental degradation, which can erode livelihoods in the long run. Thus, there is a pressing need to identify viable and resilient artisanal fisheries, and generate knowledge to support management within the context of a rapidly changing climate. We examined the ecosystem-level consequences of an artisanal kelp fishery (Macrocystis pyrifera), finding small-scale harvest of this highly productive species poses minimal impacts on kelp recovery rates, survival, and biomass dynamics, and abundances of associated commercial and culturally important fish species. These results suggest that small-scale harvest poses minimal trade-offs for the other economic benefits provided by these ecosystems, and their inherent, spiritual, and cultural value to humans. However, we detected a negative impact of warmer seawater temperatures on kelp recovery rates following harvest, indicating that the viability of harvest, even at small scales, may be threatened by future increases in global ocean temperature. This suggests that negative impacts of artisanal fisheries may be more likely to arise in the context of a warming climate, further highlighting the widespread effects of global climate change on coastal fisheries and livelihoods.

Marine management interventions are increasingly being implemented with the explicit goal of rebuilding ocean ecosystems, but early responses may begin with alterations in ecological interactions preceding detectable changes in population-level characteristics. To establish a baseline from which to monitor the effects of spatial protection on reef fish trophic ecology and track future ecosystem-level changes, we quantified temperate reef fish densities, size, biomass, diets and isotopic signatures at nine sites nested within two fished and one five-year old marine protected area (MPA) on the northwest coast of Canada. We calculated rockfish (Sebastes spp.) community and species-specific niche breadth for fished and protected areas based on δ13C and δ15N values. We found that rockfish community niche width was greater inside the MPA relative to adjacent fished reefs due to an expanded nitrogen range, possibly reflecting early changes in trophic interactions following five years of spatial protection. Our data also demonstrated that the MPA had a positive effect on the δ15N signature of rockfish (i.e., trophic position), but the effect of rockfish length on its own was not well-supported. In addition, we found a positive interaction between rockfish length and δ15N signature, such that δ15N signatures of rockfish caught within the MPA increased more rapidly with body size than those caught in fished areas. Differences in rockfish size structure and biomass among fished and unfished areas were not clearly evident. Species of rockfish and lingcod varied in trophic and size responses, indicating that life-history traits play an important role in predicting MPA effects. These results may suggest early changes in trophic behavior of slow-growing rockfish due to predation risk by faster growing higher trophic level predators such as lingcod inside MPAs established on temperate reefs. Consequently, spatial protection may restore both the trophic and behavioral roles of previously fished consumers earlier and in measurable ways sooner than observable changes in abundance and size.

Ecosystems often shift abruptly and dramatically between different regimes in response to human or natural disturbances. When ecosystems tip from one regime to another, the suite of available ecosystem benefits changes, impacting the stakeholders who rely on these benefits. These changes often create some groups who stand to incur large losses if an ecosystem returns to a previous regime. When the participation cost in the decision-making process is extremely high, this can “lock in” ecosystem regimes, making it harder for policy and management to shift ecosystems out of what the majority of society views as the undesirable regime. Public stakeholder meetings often have high costs of participation, thus economic theory predicts they will be dominated by extreme views and often lead to decisions that do not represent the majority viewpoint. Such extreme viewpoints can create strong inertia even when there is broad consensus to manage an ecosystem towards a different regime. In the same manner that reinforcing ecological feedback loops make it harder to exit an ecosystem regime, there are decision-making feedback loops that contribute additional inertia.

The environmental consequences of bitumen extraction from oil sands deposits are at the center of North American natural resource and energy policy debate, yet impacts on ocean environments have received little attention. Using a quantitative framework, we identify knowledge gaps and research needs related to the effects of oil sands development on marine biota. Fifteen sources of stress and disturbance – varying greatly in spatial and temporal scale – are generated via two pathways: (1) the coastal storage and oceanic transport of bitumen products, and (2) the contribution of industry-derived greenhouse gases to climate change in the ocean. Of highest research priority are the fate, behavior, and biological effects of bitumen in the ocean. By contrast, climate-change impacts are scientifically well established but not considered in key regulatory processes. Most stressors co-occur and are generated by other industries, yet cumulative effects are so far unaccounted for in decision making associated with new projects. Our synthesis highlights priority research needed to inform future energy development decisions, and opportunities for policy processes to acknowledge the full scope of potential and realized environmental consequences.

Multihost infectious disease outbreaks have endangered wildlife, causing extinction of frogs and endemic birds, and widespread declines of bats, corals, and abalone. Since 2013, a sea star wasting disease has affected >20 sea star species from Mexico to Alaska. The common, predatory sunflower star (Pycnopodia helianthoides), shown to be highly susceptible to sea star wasting disease, has been extirpated across most of its range. Diver surveys conducted in shallow nearshore waters (n = 10,956; 2006–2017) from California to Alaska and deep offshore (55 to 1280 m) trawl surveys from California to Washington (n = 8968; 2004–2016) reveal 80 to 100% declines across a ~3000-km range. Furthermore, timing of peak declines in nearshore waters coincided with anomalously warm sea surface temperatures. The rapid, widespread decline of this pivotal subtidal predator threatens its persistence and may have large ecosystem-level consequences.

Background Traditional food systems are under pressure from various stressors, including climate change which is projected to negatively alter the abundance of marine species harvested by coastal First Nations (FNs) in British Columbia (BC). Objective To model the potential impacts of the climate-related declines in seafood production on the nutritional status of coastal BC FNs. In addition, we projected potential changes in nutrient intakes, under different scenarios of substitution where traditional seafood is replaced with alternative non-traditional foods. Methods The study design is a mixed-method approach that combines two datasets: projected scenarios of climate-related change on seafood catch potential for coastal BC FNs and data derived from the cross-sectional First Nations Food, Nutrition, and Environment Study. The consumption of seafood was estimated using a food frequency questionnaire among 356 FNs. The contribution of seafood consumption to protein, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), vitamins (A, B12, D, niacin), and minerals (zinc, selenium and iron) requirements was assessed using Dietary Reference Intakes (DRIs). Results Traditional seafood consumption provided daily recommendations of EPA+DHA (74-184%) and vitamin B12 (84-152%) and substantial levels of niacin (28-55%), selenium (29-55%), vitamin D (15-30%) and protein (14-30%). Projected climate change was estimated to reduce the intakes of essential nutrients by 21% and 31% under 'strong mitigation' (Representative Concentration Pathway, RCP2.6) and 'business-as-usual' (RCP8.5) climate change scenarios, respectively, by the year 2050 relative to 2000. The hypothetical substitution of seafood with selected alternative non-traditional foods does not provide adequate amounts of nutrients. Conclusion Traditionally-harvested seafood remains fundamental to the contemporary diet and health of coastal BC FNs. Potential dietary shifts aggravated by climate-related declines in seafood consumption may have significant nutritional and health implications for BC FN. Strategies to improve access to seafood harvest potential in coastal communities are needed to ensure nutritional health and overall well-being and to promote food security and food sovereignty in coastal FNs.

Unanticipated declines among exploited species have commonly occurred despite harvests that appeared sustainable prior to collapse. This is particularly true in the oceans where spatial scales of management are often mismatched with spatially complex metapopulations. We explore causes, consequences, and potential solutions for spatial mismatches in harvested metapopulations in three ways. First, we generate novel theory illustrating when and how harvesting metapopulations increases spatial variability and in turn masks local-scale volatility. Second, we illustrate why spatial variability in harvested metapopulations leads to negative consequences using an empirical example of a Pacific herring metapopulation. Finally, we construct a numerical management strategy evaluation model to identify and highlight potential solutions for mismatches in spatial scale and spatial variability. Our results highlight that spatial complexity can promote stability at large scales, however, ignoring spatial complexity produces cryptic and negative consequences for people and animals that interact with resources at small scales. Harvesting metapopulations magnifies spatial variability, which creates discrepancies between regional and local trends while increasing risk of local population collapses. Such effects asymmetrically impact locally constrained fishers and predators, which are more exposed to risks of localized collapses. Importantly, we show that dynamically optimizing harvest can minimize local risk without sacrificing yield. Thus, multiple nested scales of management may be necessary to avoid cryptic collapses in metapopulations and the ensuing ecological, social, and economic consequences.