Canada’s Wild Salmon Policy (WSP) has helped produce numerous accomplishments but its continued effectiveness may be challenged by rapidly changing ocean conditions. To illustrate how incipient ecosystem changes can affect salmon and how the WSP is situated to guide responses to these changes, here we review the emergence of thiamine deficiency complex (TDC) in Chinook salmon. TDC results from a combination of factors that allow it to emerge rapidly. Analyses completed in 2023 indicated that TDC was likely present in eight ecologically distinct Canadian Chinook salmon populations. Responding to developing threats like TDC requires ongoing monitoring, international collaboration, and an understanding of environmental drivers to apply response mechanisms to manage vulnerable populations, key components of the WSP. Still, conducting and integrating mechanistic studies into management remains challenging, especially if climate change alters underlying ecological interactions. In implementing the WSP, re-emphasizing ecosystem studies and supporting them with both a consistent funding source and a specific directive for responsive ecological research could allow Canada to strengthen its ability to safeguard salmon populations in the face of acute ocean changes.

Intertidal mudflats support microphytobenthic biofilms, which underpin coastal food webs and provide critical food for migratory shorebirds. However, seasonal changes in microphytobenthos biomass and spatial structure are poorly understood despite their potential consequences for shorebird foraging and the resilience of intertidal ecosystems to global change. The distribution, biomass, and quality of microphytobenthos fluctuate in response to tidal regimes, weather, and human impacts, yet traditional monitoring methods lack the spatial and temporal resolution to resolve these dynamics at scales relevant to shorebirds. To address this gap, we used high-resolution drone-acquired multispectral and red-green-blue optical imagery to investigate seasonal microphytobenthos biomass and spatial patterns across 380 ha of intertidal mudflats in a hemispherically significant shorebird stopover site. Seasonal analysis explained 53.2% of microphytobenthos biomass variation, with elevation and microtopography as key predictors. Contrary to expectations, microphytobenthos biomass was highest in fall and winter rather than spring coinciding with atypically cold and wet conditions. Satellite observations indicate that this seasonal pattern of low biomass in spring has been typical since at least 2019, suggesting a potential shift in seasonal microphytobenthos dynamics. The use of drone-based remote sensing for resolving fine-spatial-scale microphytobenthos distribution patterns provides high-resolution snapshots of biofilm distribution at key seasonal time points. Increasing drone-based monitoring frequency or integration with satellite observations could capture intra-seasonal microphytobenthos dynamics and help resolve how seasonal and interannual variability in microphytobenthos biofilm availability influences shorebird foraging opportunities and migration success.

Trophic connections between the food web base and zooplankton affect the structure of marine food webs and fluxes to higher predators. The food that zooplankton consume shifts in response to prey resources, but specific zooplankton trophic sources remain unresolved over the dynamic seasonal cycle for many species. We investigated the food web pathways from basal production to 10 meso- and macrozooplankton species at six times over an annual cycle at a temperate coastal site, using fatty acid and stable isotope trophic markers. In addition, we concurrently characterized the zooplankton prey field through three size fractions of particulate organic matter (POM) to relate zooplankton trophic sources to specific components of primary production. Distinct stable isotope and fatty acid signatures of POM size classes enabled the identification of different pathways that support zooplankton. Overall, we found strong ties to pico-POM based production, challenging the expectation that productive coastal regions are sustained by micro-phytoplankton like diatoms. Zooplankton displayed widespread trophic flexibility and large seasonal differences in trophic markers, including varying by up to > 1 trophic position within species, with several taxa exhibiting seasonally shifting trophic associations. Despite this, inter-specific differences were the greatest source of variability for zooplankton stable isotopes and fatty acids, which generally corresponded to established trophic roles and feeding types. Defining the seasonal trophic sources to zooplankton is the first step to mechanistically link the food web base to higher trophic levels and to understand how shifts in phytoplankton size structure under climate change will influence higher trophic levels.

Chinook salmon exhibit far-flung and disparate population-specific marine migrations that have made it difficult to assess their trophic ecology. In this study, we collected returning and resident subadult Fraser River Chinook salmon in 2018 and 2019 from population groups with different known run-timings (spring, summer, and fall) and marine distributions relative to the Fraser River (local/south, north, offshore) and processed them for carbon and nitrogen CSIA-AA. We investigated population-specific differences in trophic level using delta 15NAA, and used delta 13CAA with published taxon-specific fingerprints of phytoplankton groups to investigate differences in the primary producer base that underpinned the food web they experienced. The south/local Fraser Fall 41 population exhibited distinct delta 13CAA values from the north and offshore Summer 41, Spring 52, and Summer 52 populations, likely due to their different geographic distributions and corresponding differences in primary producer communities. Chinook salmon trophic level was variable, with evidence for more omnivory and lower trophic levels in the southern distributing populations (TL = 3.7 +/- 0.2) relative to the northern ones (TL = 3.9 +/- 0.1), although there was interannual variability in the trophic level of the southern distributing population. This analysis builds on previous investigations of Chinook salmon marine ecology, linking distribution to basal food web resources to trophic level, and highlights the importance of population-specific marine distributions in structuring Chinook salmon trophic ecology. Knowledge of their food web ecology is necessary to understand how this species is and will respond to changing climate and ocean conditions and support management and conservation efforts.

Coastal marine ecosystems are increasingly impacted by urbanization-driven changes in land-derived organic matter (OM) and macronutrient inputs. Understanding these impacts requires quantification of inputs and the ability to trace them in the environment. This study quantified stormwater and urban river biogeochemistry in Vancouver, British Columbia (Canada). Nitrate and silicate concentrations were an order of magnitude higher in urban rivers (38.52 ± 31.95 and 8.81 ± 6.46 µmol L-1) than stormwater (114.98 ± 168.91 and 8.88 ± 12.29 µmol L-1), while the opposite was true for phosphate (0.40 ± 0.70 and 1.36 ± 2.53 µmol L-1). Dissolved and particulate organic carbon (DOC and POC) and particulate nitrogen (PN) were lower in rivers than in stormwater (river vs stormwater DOC: 4.57 ± 4.37 vs 10.26 ± 13.55 mg L-1; POC: 0.97 ± 3.37 vs 15.92 ± 21.46 mg L-1; PN: 0.06 ± 0.08 vs 0.81 ± 0.84 mg L-1), while total dissolved nitrogen (TDN) was higher in rivers (river vs stormwater TDN: 3.43 ± 2.94 vs 2.41 ± 1.71 mg L-1). Surprisingly, fatty acid concentrations were 1-2 orders of magnitude lower in river than in stormwater (mean Total fatty acids = 17.92 ± 14.53 and 464.81 ± 463.74 µg L-1). Metro Vancouver’s annual stormwater flux of nitrate, DOC, POC, and PN to the marine environment was estimated to exceed that from combined wastewater treatment plants. In combination, fatty acids and C and N stable isotopes distinguished river, stormwater, and wastewater OM, providing a tool for tracing urban-derived OM in receiving ecosystems.

Fjords are deep-water estuaries that support a wide range of marine habitats for pelagic fish. Yet, knowledge gaps in fish distribution and habitat use limit the implementation of efficient marine conservation strategies within fjords. Using five British Columbia fjords as a case study, we demonstrated that eDNA metabarcoding combined with species traits can enhance the detection and monitoring of conservation priority species (CPS) within systematic conservation planning frameworks. Spatiotemporal eDNA patterns confirmed the presence of endangered eulachon (Thaleichthys pacificus) across three fjords and identified deep fjord habitats as conservation priorities for mesopelagic species, including sensitive elasmobranchs and diel vertical migrators such as northern lampfish (Stenobrachius leucopsarus). eDNA peaks for several CPS during winter and spring matched documented spawning windows, underscoring the importance of fjords as seasonal spawning habitat. This globally transferable approach can supplement local stewardship initiatives and long-term monitoring efforts, contributing to more effective marine conservation area design and management.

Twenty years after its adoption, Canada’s Wild Salmon Policy remains a globally significant framework intended to conserve Pacific salmon biodiversity, yet implementation has lagged behind its ambition. Drawing on ten papers in this Special Collection and discussions at a 2026 workshop of researchers and policy practitioners from Indigenous and federal governments, academia, and the non-profit sector, we synthesize five major themes that define the current state of Policy implementation. These themes highlight the need to invest in monitoring and assessment capacity, modernize decision frameworks for a changing climate, strengthen governance and accountability, integrate ecosystem processes, and advance rights-based co-governance with Indigenous Peoples. Building on these themes, we present 20 consensus recommendations intended to strengthen implementation of the Wild Salmon Policy and improve the long-term conservation and recovery of wild Pacific salmon.

The movement of water from land to the ocean serves as a major biogeochemical link between terrestrial and marine systems, through which terrestrial disturbances can impact freshwater quality and coastal oceans. Wildfire is a major terrestrial disturbance, however its influence on water quality in large freshwater systems and the ocean is understudied. As anthropogenic pressures change fire regimes globally, it is important that this connection is better understood. The Fraser River's basin has significant wildfire history, and the Fraser River has major influence on its receiving waters of the Salish Sea, making this an ideal system in which to investigate the influence of fire on water quality from freshwater to the ocean. This study assessed cumulative impacts of wildfire on Fraser River water quality using historical water quality and fire data. Wildfire in the Fraser River basin explained up to 16.3 % of variance in water quality, and fires burning closer to major waterways had immediate influence on water quality, while farther away wildfires had a delayed influence on water quality. For water quality variables of particular importance in the Salish Sea, wildfire was linked to short term decreases in the riverine concentrations of some constituents, and delayed increases in the concentrations of nearly all assessed water quality variables. These findings have implications for coastal ocean productivity and contamination, and identify fire as an important agent of biogeochemical cycling between land and ocean.

The subarctic northeast Pacific (SNEP) is a high-nutrient, low-chlorophyll region where primary productivity is limited by bioavailable iron during the spring through autumn, and by light limitation during winter. Here, we investigate the spatio-temporal distribution and drivers of SNEP surface phytoplankton biomass and community composition in the winters of 2019 and 2020 using in situ environmental data, chemotaxonomic analysis of phytoplankton pigment samples, and Sentinel-3A Ocean Land Color Instrument imagery. The utilized satellite-based algorithm showed promise replicating the expected trends of: (a) homogenous phytoplankton communities dominated by haptophytes, green algae, and pelagophytes in highly mixed light-limited oceanic waters and; (b) increased diatoms in coastal Haida Gwaii waters with reduced mixed-layer depth (MLD) and salinity. Unexpectedly, increases in cryptophytes were observed in the northern extents of the SNEP, which coincided with winter marine heatwave driven reductions in MLDs and also the presence of a mesoscale eddy. This finding highlights a deviation from expected homogeneous phytoplankton conditions, which may be systematically missed by spatially and temporally constrained in situ sampling. The further advancement and deployment of the satellite-based algorithm could significantly expand the understanding of winter phytoplankton dynamics in the SNEP, a critical period for Pacific salmon survival, improving the understanding of trophic linkages and match/mismatch dynamics, and contributing to improve the forecasting of salmon returns.

The use of trait-based approaches complements taxonomic community analysis by linking species distributions with organismal traits. For marine zooplankton, traits are used to identify functional similarities between species and to quantify the roles of zooplankton in the food web and biogeochemical cycles. Efforts in understanding the functional biogeography of zooplankton have generally focused on copepods and the latitudinal gradient, while investigations on the wider zooplankton community and the cross-shelf gradient are limited. The objective of this study was to test whether taxonomically distinct zooplankton communities along the cross-shelf gradient are functionally distinct based on multiple functional characteristics. Two decades of zooplankton monitoring data from the Northeast subarctic Pacific Ocean were synthesized with a zooplankton trait database that provides a more extensive set of traits compared to previous functional biogeography studies. The 163 species of crustacean and soft-bodied zooplankton were first categorized into ten functional groups. The Offshore, Deep Shelf, Nearshore, and Deep Fjord bioregions were found to significantly differ in the relative composition of functional groups, community total trait values, community weighted means of traits, and functional diversity metrics. This study additionally explored assemblages with similar functional characteristics that are found in multiple bioregions and described the regional differences in the relationship between functional diversity and ecosystem functioning for zooplankton. The functional characterization of the bioregions provides a foundation for explaining how oceanographic drivers influence the functional characteristics of zooplankton communities and for improving predictions on how environmental changes would influence the distribution of traits and community-level functioning.

Estuarine mudflats are colonized by biofilm-forming microphytobenthos (MPB), which support primary production, stabilize sediment, and provide critical food for benthic invertebrates and shorebirds. MPB biomass fluctuates intra-daily, peaking post-emersion and declining before tidal immersion. Understanding these dynamics requires high-resolution monitoring, yet traditional methods, including sediment sampling and satellite imagery, lack the necessary spatial and temporal precision. We used unoccupied aerial vehicles (UAVs) to map MPB distribution, biomass, and mudflat morphology at shorebird-relevant scales. Hourly multispectral surveys over two 12-hour tidal emersion cycles at the Fraser River Estuary, British Columbia-an internationally significant shorebird stopover-captured diel MPB dynamics. Optical imagery was processed using a photogrammetric co-alignment approach to generate continuous chl-a maps (via the normalized vegetation index), digital surface models, and topographic position index layers. UAV-derived data were integrated with climate variables to model MPB variability and quantify diel biofilm patch dynamics. A modified Z-score normalization of pseudo-invariant features stabilized reflectance data, allowing fine-scale analysis of MPB distribution. Our diel model explained 31.6 % of MPB variation, with biomass peaking seven hours post-emersion, consistent with vertical migration of microalgae. Mudflat morphology significantly influenced MPB biomass, and spatial metrics revealed interactions between MPB dynamics, microtopography and shorebird foraging ecology. The study demonstrates the efficacy of high-temporal-resolution UAV imagery for monitoring MPB and mudflat morphology, enabling detailed examination of MPB diel vertical migration in response to emersion timing and light availability. Such new insights into estuarine ecology provide a framework for advancing conservation strategies and habitat management in intertidal environments.

Salmon populations are declining worldwide, with high mortality rates during juvenile marine migration presenting a bottleneck to recruitment. The ocean conditions along the main migratory route of juvenile salmon in British Columbia are characterized by high variability in CO2, with the amplitude, duration, and frequency of ocean acidification events exacerbated by climate change. Similarly, the variability in ocean conditions affects the abundance and diversity of plankton prey, leading to areas of food paucity for juvenile salmon. We investigated the combined effects of ocean acidification (control and 3200 μatm CO2) and food limitation (ad libitum, ½ ration, and food deprived) on the survival, condition, and gene expression profiles of juvenile Chum salmon (Oncorhynchus keta) to develop predictive biomarkers for CO2 exposure and food deprivation. Ocean acidification caused a direct 3-fold increase in mortality over 25 days of exposure, which was unaffected by food availability but differentially affected smaller fish. CO2 exposure induced transcriptomic changes in a suite of genes associated with ion regulation, while food deprivation was associated with a differential expression of stress, immune, and mortality markers, as well as reduced condition factor. Our data indicate that CO2 directly impairs ionoregulatory capacity to the point of failure in juvenile Chum salmon and that these effects cannot be compensated through increased energy from food. Applying our gene panels as biomarkers to a subset of fish with known exposure, we were able to accurately predict exposure to CO2 and food deprivation (74% and 90%, respectively). By combining these gene panels with previously established biomarkers for other environmental stressors, the recent environmental stress history of wild fish can be determined and can be used in models to predict salmon returns, informing fisheries management and conservation efforts.

North Pacific humpback whales (Megaptera novaeangliae) have recovered rapidly following their depletion by commercial whaling. Diet studies are necessary to assess food web implications of their recovery. This study investigates the diet composition of humpback whales foraging in the northern Strait of Georgia, British Columbia, Canada, an area experiencing a recent return of humpback whales. Humpback whale skin samples (n = 108), juvenile herring (n = 202), adult herring (n = 23), euphausiids (n = 63), and amphipods (n = 6) were collected in the summer months of 2022 and 2023 and analyzed for carbon (delta 13C) and nitrogen (delta 15N) stable isotopes. Applying these isotope data, the Bayesian mixing model MixSIAR was used to estimate the contribution of each prey type to humpback whale diet. We found that, during the summer months, humpback whales primarily consumed euphausiids (85.3%, range: 76.4%-94.0%) and juvenile herring (10.2%, range: 0.8%-21.0%), with minimal contributions from adult herring and amphipods. Diet composition was consistent across months and years. These findings provide critical insights into humpback whale foraging ecology, informing conservation efforts for both predator and prey species in the region.

In this study, we evaluated how well DNA metabarcoding of environmental samples captures changes in marine mesozooplankton community composition to optimize the use of sequencing data for studying seasonal dynamics. Although DNA metabarcoding is increasingly used to monitor the distribution of marine communities, there is a lack of standardized methods, and it remains uncertain to what extent the DNA data reflects patterns of community dynamics observed by other methods. Zooplankton net samples were collected every second week throughout 2017 in the northern Salish Sea, British Columbia. We compared metabarcoding of two genetic markers (18S targeting eukaryotes and cytochrome oxidase I targeting invertebrates) with microscopic assessments of the zooplankton collected. We also evaluated how data transformation using relative abundance, presence/absence, and the eDNA-index, affects the linearity between the morphological and genetic methods. Despite low taxonomic agreement between DNA metabarcoding and microscopy, we found most biomass dominating genera to be well represented. Using the eDNA-index, we found a generally good congruence between the seasonal cycles observed with microscopy and DNA, and that discrete water samples analyzed with DNA metabarcoding can provide information on the vertical distributions of mesozooplankton genera. We conclude by presenting guidelines for future studies that aim to use DNA to study marine zooplankton community dynamics.

Fire is an important driver of carbon cycling across terrestrial and aquatic ecosystems, but global fire regimes are changing. Black carbon (BC), a product of biomass burning, is more environmentally persistent than its parent biomass carbon and cycles differently than bulk organic carbon. This study aims to refine understanding of the environmental drivers of BC flux from land to ocean through year‐long measurement of BC in the Fraser River in British Columbia, Canada. The Fraser River’s environmental context is distinct from systems that currently form the basis of understanding of BC export, characterized by highly seasonally variable hydrology, and with its basin spanning diverse ecosystems from glaciated mountainous regions to dry flatlands. We found that the Fraser River exported 18,765 ± 2,734 Mg yr −1 of BC, with dissolved black carbon (DBC) comprising 3.3 ± 0.9% of annual dissolved organic carbon (DOC) flux, both lower than previous estimates would suggest. Strong seasonal variation in the DBC content of DOC and BC aromaticity were measured in the Fraser River. This reveals the importance of seasonal hydrology in the export of different pools of BC and indicates that seasonality and hydrologic regime should be given more consideration in future estimations of global riverine BC flux. These findings bring to light the importance of seasonality, hydrology, and basin topography in BC transport, with implications for global carbon cycles in a changing climate.

Knowledge of the trophic ecology of zooplankton is essential for evaluating their functional roles in marine food webs and nutrient cycling since they represent the link between primary producers and higher trophic levels. Here we investigated the fatty acid (FA) composition of different zooplankton size classes and selected species collected in the vicinity of the sub-Antarctic Kerguelen Islands in late austral summer 2018 as part of the MOBYDICK research project. The analysis revealed that zooplankton FA composition varied significantly across size classes and species but not among stations. Larger zooplankton (>1000 mu m) generally had higher total FA (TFA) amounts per dry weight than smaller classes (22.1 +/- 3.0 vs. 61.9 +/- 11.8 mg g(-1)). Essential FAs (EFA) accounted for 40.5 +/- 0.8 % of TFA, with 22:6n-3 (DHA) and 20:5n-3 (EPA) being the most prominent. Diatom trophic markers (TM) were abundant in larger zooplankton size classes, while non-diatom TM were more prevalent in smaller size classes. The FA-based nutritional quality index (NQI) of zooplankton was positively correlated with EFA and DHA, and it was higher than the NQI of phytoplankton concurrently collected, indicating that zooplankton has a better nutritional quality than primary producers. This study highlights the importance of size and species-specific dietary preferences in determining zooplankton FA profiles and the high nutritional quality of this group collected during late austral summer, which significantly contributes to our understanding of zooplankton's ecological role in sub-Antarctic pelagic food webs.

Knowledge of zooplankton distributions in the Eastern Subarctic Pacific (ESP) is limited and hinders our ability to assess ecosystem level change. To provide baseline information and increase our understanding of zooplankton ecology in the ESP, large-scale winter to early spring epipelagic zooplankton dynamics were investigated as part of three expeditions. Bongo tows (0.6-m mouth diameter, 250 µm mesh) were collected in 2019 (19 February – 15 March) and 2020 (12 March – 4 April) north of 47.5°N and east of 147.5°W and during a third survey in 2022 (6 February – 17 April), which expanded coverage westward to 172°W. General Additive Models identified a region of low zooplankton abundance and low biomass of small zooplankton in the Alaska Gyre. Cluster analysis of genus abundances separated samples largely along a temperature gradient. Clusters were broadly grouped into cool (<7 °C) and warm (>7 °C) assemblages. Cool assemblage clusters were dominated by subarctic taxa and their composition suggested a broad coherence in zooplankton structure north of the bifurcation of the North Pacific Current (NPC), with variation driven by the circulation of the gyre and inputs from neighbouring current systems. Warm assemblage clusters were primarily associated with the NPC bifurcation and were characterized by a mix of Subarctic, California Current, and Transition Zone taxa. Differences in species composition and biomass across the Alaska Gyre and between the northern ESP and the NPC bifurcation, including increased biomass of small zooplankton associated with the bifurcation, give insight into the foraging landscape that supports planktivores in the ESP.

The use of trait-based approaches and trait data in zooplankton ecology is rapidly growing to better understand and predict the patterns of zooplankton distributions and their role in aquatic ecosystems and biogeochemical cycles. Although the number of zooplankton trait-based studies and available trait datasets is increasing, several challenges remain for the findability, accessibility, interoperability, and reusability (FAIR) in trait-based approaches that, if unaddressed, may stifle progress in this research area. Here, we review recent applications of trait-based approaches in zooplankton research and summarize the currently available trait data resources. To realize the potential of trait-based approaches to resolve ecological roles of zooplankton, datasets and approaches must adhere to FAIR principles. We provide recommendations and pathways forward to ensure FAIRness while highlighting the importance of collaborative efforts. These practical and easily implementable strategies will enhance the FAIRness of trait data, ultimately advancing zooplankton ecological research and connecting these findings to aquatic ecosystem functioning.

Ongoing climate change is expected to transform ecosystems worldwide. Time series of remotely sensed data are now of sufficient length to begin to assess change in the ocean at large spatial and temporal scales. This study focused on changes in the phytoplankton phenology and composition in the subarctic Pacific Ocean, winter residence region for Pacific salmonids. A time series of satellite phytoplankton phenology metrics and phytoplankton functional groups between 2002 and 2022 were analyzed. Additionally, potential drivers of change were determined among the essential environmental factors and climate indices. Using changepoint analysis, a decrease in the total bloom length was revealed in recent years in all bioregions except for the waters surrounding the Kamchatka Peninsula. Moreover, a decreasing trend in the diatom-to-dinoflagellate Chl-a and the diatom-to-small algae Chl-a, consisting of haptophytes, pelagophytes, green algae, and cyanobacteria, was observed in the Gulf of Alaska. A sharp decline was particularly pronounced after 2018, which probably stemmed from a combination of the weaker currents forming the North Pacific Gyre Oscillation (NPGO) and recurring marine heat waves after 2014. It is uncertain yet whether the decline of the diatom group is temporary or marks the beginning of a long-term shift in the phytoplankton community structure in the subarctic Pacific. The following years will likely bring the answers.