Collaboration and engagement with decision-makers are needed to reduce evidence complacency in wildlife management

There exists an extensive, diverse, and robust evidence base to support complex decisions that address the planetary biodiversity crisis. However, it is generally not sought or used by environmental decision-makers, who instead draw on intuition, experience, or opinion to inform important decisions. Thus, there is a need to examine evidence exchange processes in wildlife management to understand the multiple inputs to decisions. Here, we adopt a novel approach, fuzzy cognitive mapping (FCM), to examine perceptions of individuals from Indigenous and Western governments on the reliability of evidence which may influence freshwater fisheries management decisions in British Columbia, Canada. We facilitated four FCM workshops participants representing Indigenous or Western regulatory/governance groups of fisheries managers. Our results show that flows of evidence to decision-makers occur within a relatively closed governance network, constrained to the few well-connected decision-making organizations (i.e., wildlife management agencies) and their close partners. This implies that increased collaboration (i.e., knowledge co-production) and engagement (i.e., knowledge brokerage) with wildlife managers and decision-makers are needed to produce actionable evidence and increase evidence exchange.

Effects of pre-winter cortisol exposure on condition, diet, and morphology of wild juvenile brown trout (Salmo trutta)

Winter is an energetically challenging period for many animals in temperate regions because of the relatively harsh environmental conditions and reduction in food availability during this season. Moreover, stressors experienced by individuals in the fall can affect their subsequent foraging strategy and energy stores after exposure has ended, referred to as carryover effects. We used exogenous cortisol manipulation of wild juvenile brown trout (Salmo trutta) in the fall to simulate a physiological stress response and then investigated short-term (2 weeks) and long-term (4 months) effects on condition metrics (hepatosomatic index and water muscle content), diet (stomach contents and stable isotopes), and morphology during growth in freshwater. We revealed some short-term impacts, likely due to handling stress, and long-term (seasonal) changes in diet, likely reflecting prey availability. Unfortunately, we had very few recaptures of cortisol-treated fish at long-term sampling, limiting detailed analysis about cortisol effects at that time point. Nonetheless, the fish that were sampled showed elevated stable isotopes, suggestive of a cortisol effect long after exposure. This is one of few studies to investigate whether cortisol influences foraging and morphology during juvenile growth, thus extending the knowledge of proximate mechanisms influencing ecologically-relevant phenotypes.

Opportunities and challenges with transitioning to non-lethal sampling of wild fish for microbiome research

The microbial communities of fish are considered an integral part of maintaining the overall health and fitness of their host. Research has shown that resident microbes reside on various mucosal surfaces, such as the gills, skin, and gastrointestinal tract, and play a key role in various host functions, including digestion, immunity, and disease resistance. A second, more transient group of microbes reside in the digesta, or feces, and are primarily influenced by environmental factors such as the host diet. The vast majority of fish microbiome research currently uses lethal sampling to analyse any one of these mucosal and/or digesta microbial communities. The present paper discusses the various opportunities that non-lethal microbiome sampling offers, as well as some inherent challenges, with the ultimate goal of creating a sound argument for future researchers to transition to non-lethal sampling of wild fish in microbiome research. Doing so will reduce animal welfare and population impacts on fish while creating novel opportunities to link host microbial communities to an individual's behavior and survival across space and time (e.g., life-stages, seasons). Current lethal sampling efforts constrain our ability to understand the mechanistic ecological consequences of variation in microbiome communities in the wild. Transitioning to non-lethal sampling will open new frontiers in ecological and microbial research.

Animal migration in the Anthropocene: threats and mitigation options

Animal migration has fascinated scientists and the public alike for centuries, yet migratory animals are facing diverse threats that could lead to their demise. The Anthropocene is characterised by the reality that humans are the dominant force on Earth, having manifold negative effects on biodiversity and ecosystem function. Considerable research focus has been given to assessing anthropogenic impacts on the numerical abundance of species/populations, whereas relatively less attention has been devoted to animal migration. However, there are clear linkages, for example, where human-driven impacts on migration behaviour can lead to population/species declines or even extinction. Here, we explore anthropogenic threats to migratory animals (in all domains - aquatic, terrestrial, and aerial) using International Union for the Conservation of Nature (IUCN) Threat Taxonomy classifications. We reveal the diverse threats (e.g. human development, disease, invasive species, climate change, exploitation, pollution) that impact migratory wildlife in varied ways spanning taxa, life stages and type of impact (e.g. from direct mortality to changes in behaviour, health, and physiology). Notably, these threats often interact in complex and unpredictable ways to the detriment of wildlife, further complicating management. Fortunately, we are beginning to identify strategies for conserving and managing migratory animals in the Anthropocene. We provide a set of strategies that, if embraced, have the potential to ensure that migratory animals, and the important ecological functions sustained by migration, persist.

Considerations for Research Funders and Managers to Facilitate the Translation of Scientific Knowledge into Practice

Research funders and managers can play a critical role in supporting the translation of knowledge into action by facilitating the brokering of knowledge and partnerships. We use semi-structured interviews with a research funding agency, the Australian Centre for International Agricultural Research (ACIAR), to explore (i) ways that funders can facilitate knowledge brokering, the (ii) barriers to, and (iii) enablers for, facilitating knowledge brokering, and (iv) the individual skills and attributes for research program funders and managers to be effective brokers. Based on these findings, we generate three considerations for research funders elsewhere, in particular R4D funders, seeking to build capacity for knowledge brokering: (i) formalise the process and practice, (ii) develop shared language and understanding, and (iii) build individual competencies and capabilities. Our findings complement the existing literature with a context specific analysis of how research funders can facilitate knowledge brokering, and by identifying the barriers and enablers in doing so.

Patterns and Pitfalls of Short-cuts Used in Environmental Management Rapid Reviews

Environmental managers and policy-makers need reliable evidence to make effective decisions. Systematic reviews are one way to provide this information but are time-consuming and may not meet the needs of decision-makers when faced with rapidly changing management requirements or transient policy-windows. Rapid reviews are one type of knowledge synthesis that follow simplified or truncated methods compared to systematic reviews. Rapid reviews on environmentally-relevant topics are growing in prevalence, but it is unclear if rapid reviews use similar short-cuts or follow available guidelines. In this methodological review, we assess 26 rapid reviews published between 2002 and 2023. Numerous rapid review short-cuts and approaches were identified, with few consistencies among studies. Short-cuts were present in all stages of the review process, with some of the most common short-cuts including not developing an a priori review protocol, not including stakeholder involvement, or not conducting critical appraisal of study validity. Poor quality in reporting of methods was observed. Fewer than half of assessed rapid reviews reported using available guidelines when developing their methods. Future rapid reviews should aim for improved reporting and adherence to published guidelines to help increase the useability and evidence-user confidence. This will also enable readers to understand where short-cuts were made and their potential consequences for the conclusions of the review.

Evaluation of the effects of exogenous cortisol manipulation and the glucocorticoid antagonist, RU486, on the exploratory tendency of bluegill sunfish (Lepomis macrochirus)

In teleost fishes, activation of the hypothalamic-pituitary-interrenal axis leads to an elevation of circulating cortisol levels as a primary stress response. While acute elevation of cortisol is generally beneficial, long-term elevation, a common characteristic of chronic stress, may lead to detrimental effects on health and physiological performance in fishes. Some stress-mediated behavioural shifts, such as variation along the shy-boldness axis in fish, may influence individual fitness. The present study evaluated the role of cortisol and its mechanisms of action in the exploratory behaviour of the bluegill sunfish (Lepomis macrochirus). Fish were implanted with cocoa butter alone (sham treatment), or cocoa butter containing cortisol, or cortisol and the glucocorticoid receptor antagonist, RU486. A control (untreated) group was also used. Animals were held for 48 h following treatment and then were subjected to a Z-maze trial to characterize the exploratory behaviour. Cortisol treatment had no measurable effect on the exploratory behaviour of bluegill sunfish. Despite presenting a higher probability of refuge emergence, fish treated with cortisol combined with RU486 behaved similarly to cortisol-treated and control groups. While these results suggest that cortisol may not be involved in the mechanisms controlling boldness, the influence of cortisol elevation across longer time periods plus validation in different contexts will be necessary to confirm this conclusion.

Impairing cardiac oxygen supply in swimming coho salmon compromises their heart function and tolerance to acute warming

Climatic warming elevates mortality for many salmonid populations during their physically challenging up-river spawning migrations, yet, the mechanisms underlying the increased mortality remain elusive. One hypothesis posits that a cardiac oxygen insufficiency impairs the heart's capacity to pump sufficient oxygen to body tissues to sustain up-river swimming, especially in warm water when oxygen availability declines and cardiac and whole-animal oxygen demand increases. We tested this hypothesis by measuring cardiac and metabolic (cardiorespiratory) performance, and assessing the upper thermal tolerance of coho salmon (Oncorhynchus kisutch) during sustained swimming and acute warming. By surgically ligating the coronary artery, which naturally accumulates arteriosclerotic lesions in migrating salmon, we partially impaired oxygen supply to the heart. Coronary ligation caused drastic cardiac impairment during swimming, even at benign temperatures, and substantially constrained cardiorespiratory performance during swimming and progressive warming compared to sham-operated control fish. Furthermore, upper thermal tolerance during swimming was markedly reduced (by 4.4 °C) following ligation. While the cardiorespiratory capacity of female salmon was generally lower at higher temperatures compared to males, upper thermal tolerance during swimming was similar between sexes within treatment groups. Cardiac oxygen supply is a crucial determinant for the migratory capacity of salmon facing climatic environmental warming.

Maxed Out: Optimizing Accuracy, Precision, and Power for Field Measures of Maximum Metabolic Rate in Fishes

Both laboratory and field respirometry are rapidly growing techniques to determine animal performance thresholds. However, replicating protocols to estimate maximum metabolic rate (MMR) between species, populations, and individuals can be difficult, especially in the field. We therefore evaluated seven different exercise treatments-four laboratory methods involving a swim tunnel (critical swim speed [Ucrit], Ucrit postswim fatigue, maximum swim speed [Umax], and Umax postswim fatigue) and three field-based chasing methods (3-min chase with 1-min air exposure, 3-min chase with no air exposure, and chase to exhaustion)-in adult coho salmon (Oncorhynchus kisutch) as a case study to determine best general practices for measuring and quantifying MMR in fish. We found that all seven methods were highly comparable and that chase treatments represent a valuable field alternative to swim tunnels. Moreover, we caution that the type of test and duration of measurement windows used to calculate MMR can have significant effects on estimates of MMR and statistical power for each approach.

Bioenergetic consequences of repeated catch-and-release fisheries interactions on adult steelhead across a range of ecologically relevant water temperatures

The biological consequences of catch-and-release angling have been studied for decades, yet little is known about the compounding effects of repeated recreational fisheries recaptures on the physiology and behaviour of angled fish. Using heart rate biologgers and behavioural assays, this study investigated the physiological and behavioural consequences of multiple simulated angling events (i.e., repeated stressors) on female steelhead (Oncorhynchus mykiss), under current (6 °C) and future (11 °C) water temperature scenarios. While steelhead in the warmer water temperature scenario demonstrated alterations in cardiac function (e.g., increases in maximum heart rate and scope of heart rate) and evidence of behavioural impairments (e.g., decreases in chase activity and landing time) over the course of two simulated angling events, cold water treated fish had negligible change. Fish subjected to two simulated angling events under warm water temperature conditions tended to demonstrate an increase in recovery time and scope for heart rate, and a decrease in resting heart rate. A second experiment was conducted to test for sex-specific differences in the heart rate response of steelhead subjected to an increase in water temperature. Females demonstrated a higher scope for heart rate when compared to males during the event and during recovery. More work is needed to better understand the interaction between multiple angling events and recovery from these events at various water temperatures, and the biological basis for sex-specific differences in cardiac function and response to challenges. This study contributes to a growing body of evidence on the effects of repeated stressors on wild fish.

Tensile strength and knot security of five suture materials exposed to natural summer conditions of a temperate lake

OBJECTIVE

Wild fish and other aquatic ectotherms are often subjected to procedures during field research that require wound closure using sutures. A variety of absorbable sutures are available for such purposes, yet degradation processes are highly dependent on temperature, and the environments in which wild ectotherms are released are almost always colder than the conditions for which absorbable sutures are typically designed (i.e., ~37°C). We therefore studied the degradation of various suture materials under a set of biologically relevant conditions for temperate freshwater fish.

METHODS

Using a force gauge, we tested the tensile strengths and knot securities of loops tied with five different absorbable suture materials (PDS-II, dyed coated Vicryl, undyed coated Vicryl, plain gut, and chromic gut) prior to and during submersion in a temperate lake over an 8-week period.

RESULT

The naturally derived collagen-based suture materials (i.e., plain gut and chromic gut) exhibited major decreases in tensile strength within 2 weeks of submersion but maintained relatively high knot security throughout the study period. The synthetic suture loops had poorer initial knot securities that increased following submersion and showed little to no evidence of degradation after 8 weeks.

CONCLUSION

Variable rates of absorbable suture degradation, or lack thereof, were observed. We discuss the implications of these trends for fish welfare considerations such as suture retention, wound healing, inflammation, and infection under natural conditions.

Are the effects of catch-and-release angling evident in changes to mRNA abundances related to metabolism, acid-base regulation and stress in lake trout (Salvelinus namaycush) gills?

Catch-and-release (C&R) angling is a conservation-oriented practice intended to reduce the impact recreational angling has on fish populations. Even though most recreationally angled fish are released, little is known about how C&R angling impacts fish at the cellular or tissue level. As the first to explore the impacts of C&R angling on mRNA abundances, our study aimed to identify how the stress of angling influenced metabolism, acid-base regulation and cellular stress in the gills of lake trout (Salvelinus namaycush). Because gills are responsible for metabolic gas exchange, are crucial sites of acid-base homeostasis and respond to stressors quickly, we hypothesized that the relative mRNA abundance of genes related to these three physiological processes would be altered after angling. We took gill samples of live lake trout at 0, 2 or 48 h after fish were angled by rod and reel, and then used quantitative PCR (qPCR) to measure the relative abundance of nine candidate mRNA transcripts. Heat shock protein 70 (hsp70) mRNA levels significantly increased over 5-fold 2 h after angling, indicating a potential activation of a cytoprotective response. However, contrary to our hypothesis, we observed no change in the relative mRNA abundance of genes related to metabolism or acid-base regulation in response to C&R angling within a 48-h period. As C&R angling can negatively impact fish populations, further use of transcript-level studies will allow us to understand the impact C&R has on specific tissues and improve our knowledge of how C&R influences overall fish health.

A field test of the "graveyard hypothesis" reveals avoidance of chemical but not visual cues in Bahamian queen conch (Aliger gigas)

Queen conch (Aliger gigas) are large gastropod molluscs harvested for their meat, shells, and pearls and as they are generally easy to collect by hand, they are vulnerable to overfishing. In The Bahamas, fishers often clean (or "knock") their catch and dispose of the shells away from collection sites, forming midden heaps or "graveyards". Although queen conch are motile and found throughout shallow water habitats, live animals are rarely observed in the vicinity of middens, giving rise to a common belief that conch actively avoid graveyards, possibly by moving offshore. Here, we experimentally evaluated avoidance behaviours of queen conch to chemical (tissue homogenate) and visual (shells) cues indicative of harvesting activity using replicated aggregations of six size-selected small (< 14cm shell length) and large (> 14cm) conch at Eleuthera Island. Large conch were consistently more likely to move, and to move farther, than small conch, independent of treatment. Small conch, however, demonstrated greater occurrence of movement in response to chemical cues vs seawater controls, while conch of both sizes demonstrated equivocal responses to visual cues. Collectively, these observations suggest that more economically desirable large conch may be less vulnerable to capture during successive harvest events than smaller juveniles due to their greater propensity to move, and that chemical cues consistent with damage-released alarm cues may play a greater role in eliciting avoidance behaviour than the visual cues typically associated with queen conch graveyards. DATA AVAILABILITY: Data and R code are archived and freely available at Open Science Framework (https://osf.io/x8t7p/; DOI: 10.17605/OSF.IO/X8T7P).

How can physiology best contribute to wildlife conservation in a warming world?

Global warming is now predicted to exceed 1.5°C by 2033 and 2°C by the end of the 21st century. This level of warming and the associated environmental variability are already increasing pressure on natural and human systems. Here we emphasize the role of physiology in the light of the latest assessment of climate warming by the Intergovernmental Panel on Climate Change. We describe how physiology can contribute to contemporary conservation programmes. We focus on thermal responses of animals, but we acknowledge that the impacts of climate change are much broader phylogenetically and environmentally. A physiological contribution would encompass environmental monitoring, coupled with measuring individual sensitivities to temperature change and upscaling these to ecosystem level. The latest version of the widely accepted Conservation Standards designed by the Conservation Measures Partnership includes several explicit climate change considerations. We argue that physiology has a unique role to play in addressing these considerations. Moreover, physiology can be incorporated by institutions and organizations that range from international bodies to national governments and to local communities, and in doing so, it brings a mechanistic approach to conservation and the management of biological resources.

Global responses to the COVID-19 pandemic by recreational anglers: considerations for developing more resilient and sustainable fisheries

The global COVID-19 pandemic resulted in many jurisdictions implementing orders restricting the movements of people to inhibit virus transmission, with recreational angling often either not permitted or access to fisheries and/or related infrastructure being prevented. Following the lifting of restrictions, initial angler surveys and licence sales suggested increased participation and effort, and altered angler demographics, but with evidence remaining limited. Here, we overcome this evidence gap by identifying temporal changes in angling interest, licence sales, and angling effort in world regions by comparing data in the 'pre-pandemic' (up to and including 2019); 'acute pandemic' (2020) and 'COVID-acclimated' (2021) periods. We then identified how changes can inform the development of more resilient and sustainable recreational fisheries. Interest in angling (measured here as angling-related internet search term volumes) increased substantially in all regions during 2020. Patterns in licence sales revealed marked increases in some countries during 2020 but not in others. Where licence sales increased, this was rarely sustained in 2021; where there were declines, these related to fewer tourist anglers due to movement restrictions. Data from most countries indicated a younger demographic of people who participated in angling in 2020, including in urban areas, but this was not sustained in 2021. These short-lived changes in recreational angling indicate efforts to retain younger anglers could increase overall participation levels, where efforts can target education in appropriate angling practices and create more urban angling opportunities. These efforts would then provide recreational fisheries with greater resilience to cope with future global crises, including facilitating the ability of people to access angling opportunities during periods of high societal stress.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11160-023-09784-5.

Environmental evidence in action: on the science and practice of evidence synthesis and evidence-based decision-making

In civil society we expect that policy and management decisions will be made using the best available evidence. Yet, it is widely known that there are many barriers that limit the extent to which that occurs. One way to overcome these barriers is via robust, comprehensive, transparent and repeatable evidence syntheses (such as systematic reviews) that attempt to minimize various forms of bias to present a summary of existing knowledge for decision-making purposes. Relative to other disciplines (e.g., health care, education), such evidence-based decision-making remains relatively nascent for environment management despite major threats to humanity, such as the climate, pollution and biodiversity crises demonstrating that human well-being is inextricably linked to the biophysical environment. Fortunately, there are a growing number of environmental evidence syntheses being produced that can be used by decision makers. It is therefore an opportune time to reflect on the science and practice of evidence-based decision-making in environment management to understand the extent to which evidence syntheses are embraced and applied in practice. Here we outline a number of key questions related to the use of environmental evidence that need to be explored in an effort to enhance evidence-based decision-making. There is an urgent need for research involving methods from social science, behavioural sciences, and public policy to understand the basis for patterns and trends in environmental evidence use (or misuse or ignorance). There is also a need for those who commission and produce evidence syntheses, as well as the end users of these syntheses to reflect on their experiences and share them with the broader evidence-based practice community to identify needs and opportunities for advancing the entire process of evidence-based practice. It is our hope that the ideas shared here will serve as a roadmap for additional scholarship that will collectively enhance evidence-based decision-making and ultimately benefit the environment and humanity.

Aerobic response to thermal stress across ontogeny and habitats in a teleost fish

Near-future climate change projections predict an increase in sea surface temperature that is expected to have significant and rapid effects on marine ectotherms, potentially affecting a number of critical life processes. Also, some habitats undergo more thermal variability than others and the inhabitants thereof must be more tolerant to acute periods of extreme temperatures. Mitigation of these outcomes may occur through acclimation, plasticity, or adaptation, although the rate and extent of a species' ability to adjust to warmer temperatures is largely unknown, specifically as it pertains to effects on various performance metrics in fishes that inhabit multiple habitats throughout ontogenetic stages. Here, the thermal tolerance and aerobic performance of schoolmaster snapper (Lutjanus apodus Walbaum, 1792) collected from two different habitats were experimentally assessed under different warming scenarios (temperature treatments = 30, 33, 35, 36° C) to assess vulnerability to an imminently changing thermal habitat. Larger subadult and adult fish collected from a 12 m deep coral reef exhibited a lower critical thermal maximum (CT_max ) compared to smaller juvenile fish collected from a 1 m deep mangrove creek. However, CT_max of the creek-sampled fish was only 2° C above the maximum water temperature measured in the habitat from which they were collected, compared to a CT_max that was 8° C higher in the reef-sampled fish, resulting in a wider thermal safety margin at the reef site. A GLM showed a marginally significant effect of temperature treatment on resting metabolic rate (RMR) but there were no effects on any of the tested factors on maximum metabolic rate (MMR) or absolute aerobic scope (AAS). Post-hoc tests revealed that RMR was significantly higher for creek-collected fish at the 36° C treatment and significantly higher for reef-collected fish at 35° C. Swimming performance (measured by critical swimming speed [U_crit ]) was significantly lower at the highest temperature treatment for creek-collected fish and trended down with each successive increase in temperature treatment for reef-collected fish. These results show that metabolic rate and swimming performance responses to thermal challenges are somewhat consistent across collection habitats, and this species may be susceptible to unique types of thermal risk depending on its habitat. We show the importance of intraspecific studies that couple habitat profiles and performance metrics to better understand possible outcomes under thermal stress. This article is protected by copyright. All rights reserved.

Applied winter biology: threats, conservation and management of biological resources during winter in cold climate regions

Winter at high latitudes is characterized by low temperatures, dampened light levels and short photoperiods which shape ecological and evolutionary outcomes from cells to populations to ecosystems. Advances in our understanding of winter biological processes (spanning physiology, behaviour and ecology) highlight that biodiversity threats (e.g. climate change driven shifts in reproductive windows) may interact with winter conditions, leading to greater ecological impacts. As such, conservation and management strategies that consider winter processes and their consequences on biological mechanisms may lead to greater resilience of high altitude and latitude ecosystems. Here, we use well-established threat and action taxonomies produced by the International Union of Conservation of Nature-Conservation Measures Partnership (IUCN-CMP) to synthesize current threats to biota that emerge during, or as the result of, winter processes then discuss targeted management approaches for winter-based conservation. We demonstrate the importance of considering winter when identifying threats to biodiversity and deciding on appropriate management strategies across species and ecosystems. We confirm our expectation that threats are prevalent during the winter and are especially important considering the physiologically challenging conditions that winter presents. Moreover, our findings emphasize that climate change and winter-related constraints on organisms will intersect with other stressors to potentially magnify threats and further complicate management. Though conservation and management practices are less commonly considered during the winter season, we identified several potential or already realized applications relevant to winter that could be beneficial. Many of the examples are quite recent, suggesting a potential turning point for applied winter biology. This growing body of literature is promising but we submit that more research is needed to identify and address threats to wintering biota for targeted and proactive conservation. We suggest that management decisions consider the importance of winter and incorporate winter specific strategies for holistic and mechanistic conservation and resource management.

The ecological relevance of critical thermal maxima methodology for fishes

Critical thermal maxima methodology (CTM) has been used to infer acute upper thermal tolerance in fishes since the 1950s, yet its ecological relevance remains debated. In this study, the authors synthesize evidence to identify methodological concerns and common misconceptions that have limited the interpretation of critical thermal maximum (CT_max ; value for an individual fish during one trial) in ecological and evolutionary studies of fishes. They identified limitations of, and opportunities for, using CT_max as a metric in experiments, focusing on rates of thermal ramping, acclimation regimes, thermal safety margins, methodological endpoints, links to performance traits and repeatability. Care must be taken when interpreting CTM in ecological contexts, because the protocol was originally designed for ecotoxicological research with standardized methods to facilitate comparisons within study individuals, across species and contexts. CTM can, however, be used in ecological contexts to predict impacts of environmental warming, but only if parameters influencing thermal limits, such as acclimation temperature or rate of thermal ramping, are taken into account. Applications can include mitigating the effects of climate change, informing infrastructure planning or modelling species distribution, adaptation and/or performance in response to climate-related temperature change. The authors' synthesis points to several key directions for future research that will further aid the application and interpretation of CTM data in ecological contexts.

Metabolic constraints and individual variation shape the trade-off between physiological recovery and anti-predator responses in adult sockeye salmon

Metabolic scope represents the aerobic energy budget available to an organism to perform non-maintenance activities (e.g., escape a predator, recover from a fisheries interaction, compete for a mate). Conflicting energetic requirements can give rise to ecologically relevant metabolic trade-offs when energy budgeting is constrained. The objective of this study was to investigate how aerobic energy is utilized when individual sockeye salmon (Oncorhynchus nerka) are exposed to multiple acute stressors. To indirectly assess metabolic changes in free-swimming individuals, salmon were implanted with heart rate biologgers. The animals were then exercised to exhaustion or briefly handled as a control, and allowed to recover from this stressor for 48 h. During the first 2 h of the recovery period, individual salmon were exposed to 90 ml of conspecific alarm cues or water as a control. Heart rate was recorded throughout the recovery period. Recovery effort and time was higher in exercised fish, relative to control fish, whereas exposure to an alarm cue had no effect on either of these metrics. Individual routine heart rate was negatively correlated with recovery time and effort. Together, these findings suggest that metabolic energy allocation towards exercise recovery (i.e., an acute stressor; handling, chase, etc.) trumps anti-predator responses in salmon, although individual variation may mediate this effect at the population level.

Biological mechanisms matter in contemporary wildlife conservation

Given limited resources for wildlife conservation paired with an urgency to halt declines and rebuild populations, it is imperative that management actions are tactical and effective. Mechanisms are about how a system works and can inform threat identification and mitigation such that conservation actions that work can be identified. Here, we call for a more mechanistic approach to wildlife conservation and management where behavioral and physiological tools and knowledge are used to characterize drivers of decline, identify environmental thresholds, reveal strategies that would restore populations, and prioritize conservation actions. With a growing toolbox for doing mechanistic conservation research as well as a suite of decision-support tools (e.g., mechanistic models), the time is now to fully embrace the concept that mechanisms matter in conservation ensuring that management actions are tactical and focus on actions that have the potential to directly benefit and restore wildlife populations.

Telemetry-based spatial-temporal fish habitat models for fishes in an urban freshwater harbour

Fish habitat associations are important measures for effective aquatic habitat management, but often vary over broad spatial and temporal scales, and are therefore challenging to measure comprehensively. We used a 9-year acoustic telemetry dataset to generate spatial-temporal habitat suitability models for seven fish species in an urban freshwater harbour, Toronto Harbour, Lake Ontario. Fishes generally occupied the more natural regions of Toronto Harbour most frequently. However, each species exhibited unique habitat associations and spatial-temporal interactions in their habitat use. For example, largemouth bass exhibited the most consistent seasonal habitat use, mainly associating with shallow, sheltered embayments with high aquatic vegetation (SAV) cover. Conversely, walleye seldom occupied Toronto Harbour in summer, with the highest occupancy of shallow, low-SAV habitats in the spring, which corresponds to their spawning period. Others, such as common carp, shifted between shallow summer and deeper winter habitats. Community level spatial-temporal habitat importance estimates were also generated, which can serve as an aggregate measure for habitat management. Acoustic telemetry provides novel opportunities to generate robust spatial-temporal fish habitat models based on wild fish behaviour, which are useful for the management of fish habitat from a fish species and community perspective.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10750-023-05180-z.

Freshwater protected areas can preserve high-performance phenotypes in populations of a popular sportfish

Recreational fishing has the potential to cause evolutionary change in fish populations; a phenomenon referred to as fisheries-induced evolution. However, detecting and quantifying the magnitude of recreational fisheries selection in the wild is inherently difficult, largely owing to the challenges associated with variation in environmental factors and, in most cases, the absence of pre-selection or baseline data against which comparisons can be made. However, exploration of recreational fisheries selection in wild populations may be possible in systems where fisheries exclusion zones exist. Lakes that possess intra-lake freshwater protected areas (FPAs) can provide investigative opportunities to evaluate the evolutionary impact(s) of differing fisheries management strategies within the same waterbody. To address this possibility, we evaluated how two physiological characteristics (metabolic phenotype and stress responsiveness) as well as a proxy for angling vulnerability, catch-per-unit-effort (CPUE), differed between populations of largemouth bass (Micropterus salmoides) inhabiting long-standing (>70 years active) intra-lake FPAs and adjacent, open access, main-lake areas. Fish from FPA populations had significantly higher aerobic scope (AS) capacity (13%) and CPUE rates compared with fish inhabiting the adjacent main-lake areas. These findings are consistent with theory and empirical evidence linking exploitation with reduced metabolic performance, supporting the hypothesis that recreational fishing may be altering the metabolic phenotype of wild fish populations. Reductions in AS are concerning because they suggest a reduced scope for carrying out essential life-history activities, which may result in fitness level implications. Furthermore, these results highlight the potential for unexploited FPA populations to serve as benchmarks to further investigate the evolutionary consequences of recreational fishing on wild fish and to preserve high-performance phenotypes.

Confronting a post-pandemic new-normal-threats and opportunities to trust-based relationships in natural resource science and management

Natural resource governance is inherently complex owing to the socio-ecological systems in which it is embedded. Working arrangements have been fundamentally transformed throughout the COVID-19 pandemic with potential negative impacts on trust-based social networks foundational to resource management and transboundary governance. To inform development of a post-pandemic new-normal in resource management, we examined trust relationships using the Laurentian Great Lakes of North America as a case study. 82.9% (n = 97/117) of Great Lakes fishery managers and scientists surveyed indicated that virtual engagement was effective for maintaining well-established relationships during the pandemic; however, 76.7% (n = 89/116) of respondents indicated in-person engagement to be more effective than virtual engagement for building and maintaining trust. Despite some shortcomings, virtual or remote engagement presents opportunities, such as: (1) care and nurturing of well-established long-term relationships; (2) short-term (1-3 years) trust maintenance; (3) peer-peer or mentor-mentee coordination; (4) supplemental communications; (5) producer-push knowledge dissemination; and, if done thoughtfully, (6) enhancing diversity, equity, and inclusion. Without change, pre-pandemic trust-based relationships foundational to cooperative, multinational, resource management are under threat.

Towards vibrant fish populations and sustainable fisheries that benefit all: learning from the last 30 years to inform the next 30 years

A common goal among fisheries science professionals, stakeholders, and rights holders is to ensure the persistence and resilience of vibrant fish populations and sustainable, equitable fisheries in diverse aquatic ecosystems, from small headwater streams to offshore pelagic waters. Achieving this goal requires a complex intersection of science and management, and a recognition of the interconnections among people, place, and fish that govern these tightly coupled socioecological and sociotechnical systems. The World Fisheries Congress (WFC) convenes every four years and provides a unique global forum to debate and discuss threats, issues, and opportunities facing fish populations and fisheries. The 2021 WFC meeting, hosted remotely in Adelaide, Australia, marked the 30th year since the first meeting was held in Athens, Greece, and provided an opportunity to reflect on progress made in the past 30 years and provide guidance for the future. We assembled a diverse team of individuals involved with the Adelaide WFC and reflected on the major challenges that faced fish and fisheries over the past 30 years, discussed progress toward overcoming those challenges, and then used themes that emerged during the Congress to identify issues and opportunities to improve sustainability in the world's fisheries for the next 30 years. Key future needs and opportunities identified include: rethinking fisheries management systems and modelling approaches, modernizing and integrating assessment and information systems, being responsive and flexible in addressing persistent and emerging threats to fish and fisheries, mainstreaming the human dimension of fisheries, rethinking governance, policy and compliance, and achieving equity and inclusion in fisheries. We also identified a number of cross-cutting themes including better understanding the role of fish as nutrition in a hungry world, adapting to climate change, embracing transdisciplinarity, respecting Indigenous knowledge systems, thinking ahead with foresight science, and working together across scales. By reflecting on the past and thinking about the future, we aim to provide guidance for achieving our mutual goal of sustaining vibrant fish populations and sustainable fisheries that benefit all. We hope that this prospective thinking can serve as a guide to (i) assess progress towards achieving this lofty goal and (ii) refine our path with input from new and emerging voices and approaches in fisheries science, management, and stewardship.

The Role of Metabolic Phenotype in the Capacity to Balance Competing Energetic Demands

AbstractGiven the critical role of metabolism in the life history of all organisms, there is particular interest in understanding the relationship between individual metabolic phenotypes and the capacity to partition energy into competing life history traits. Such relationships could be predictive of individual phenotypic performances throughout life. Here, we were specifically interested in whether an individual fish's metabolic phenotype can shape its propensity to feed following a significant stressor (2-min exhaustive exercise challenge). Such a relationship would provide insight into previous intraspecific observations linking high metabolism with faster growth. Using a teleost fish, the barramundi (Lates calcarifer), we predicted that individuals with high standard metabolic rates (SMRs) and maximal metabolic rates (MMRs) would be faster to recover and resume feeding after exercise. Contrary to our prediction, neither SMR nor MMR was correlated with latency to feed after exercise (food was offered at 0.5, 1.5, 3, and 18 h after exercise). Only time after exercise and individual fish ID were significant predictors of latency to feed. Measurements of MMR from the same individuals (three measurements spaced 8-12 d apart) revealed a moderate degree of repeatability (R=0.319). We propose that interindividual differences in biochemical and endocrine processes may be more influential than whole-organism metabolic phenotype in mediating feeding latency after exercise.

Foresight science in conservation: Tools, barriers, and mainstreaming opportunities

Foresight science is a systematic approach to generate future predictions for planning and management by drawing upon analytical and predictive tools to understand the past and present, while providing insights about the future. To illustrate the application of foresight science in conservation, we present three case studies: identification of emerging risks to conservation, conservation of at-risk species, and aid in the development of management strategies for multiple stressors. We highlight barriers to mainstreaming foresight science in conservation including knowledge accessibility/organization, communication across diverse stakeholders/decision makers, and organizational capacity. Finally, we investigate opportunities for mainstreaming foresight science including continued advocacy to showcase its application, incorporating emerging technologies (i.e., artificial intelligence) to increase capacity/decrease costs, and increasing education/training in foresight science via specialized courses and curricula for trainees and practicing professionals. We argue that failure to mainstream foresight science will hinder the ability to achieve future conservation objectives in the Anthropocene.

Conservation connections: incorporating connectivity into management and conservation of flats fishes and their habitats in a multi-stressor world

Coastal marine fisheries and the habitats that support them are under extensive and increasing pressures from numerous anthropogenic stressors that occur at multiple spatial and temporal scales and often intersect in unexpected ways. Frequently, the scales at which these fisheries are managed do not match the scales of the stressors, much less the geographic scale of species biology. In general, fishery management is ill prepared to address these stressors, as underscored by the continuing lack of integration of fisheries and habitat management. However, research of these fisheries is increasingly being conducted at spatial and temporal scales that incorporate biology and ecological connectivity of target species, with growing attention to the foundational role of habitat. These efforts are also increasingly engaging stakeholders and rights holders in research, education, and conservation. This multi-method approach is essential for addressing pressing conservation challenges that are common to flats ecosystems. Flats fisheries occur in the shallow, coastal habitat mosaic that supports fish species that are accessible to and desirable to target by recreational fishers. Because these species rely upon coastal habitats, the anthropogenic stressors can be especially intense-habitat alteration (loss and degradation) and water quality declines are being exacerbated by climate change and increasing direct human impacts (e.g., fishing effort, boat traffic, depredation, pollution). The connections necessary for effective flats conservation are of many modes and include ontogenetic habitat connectivity; connections between stressors and impacts to fishes; connections between research and management, such as research informing spawning area protections; and engagement of stakeholders and rights holders in research, education, and management. The articles included in this Special Issue build upon a growing literature that is filling knowledge gaps for flats fishes and their habitats and increasingly providing the evidence to inform resource management. Indeed, numerous articles in this issue propose or summarize direct application of research findings to management with a focus on current and future conservation challenges. As with many other fisheries, a revised approach to management and conservation is needed in the Anthropocene.

Population variability in thermal performance of pre-spawning adult Chinook salmon

Climate change is causing large declines in many Pacific salmon populations. In particular, warm rivers are associated with high levels of premature mortality in migrating adults. The Fraser River watershed in British Columbia, Canada, supports some of the largest Chinook salmon (Oncorhynchus tshawytscha) runs in the world. However, the Fraser River is warming at a rate that threatens these populations at critical freshwater life stages. A growing body of literature suggests salmonids are locally adapted to their thermal migratory experience, and thus, population-specific thermal performance information can aid in management decisions. We compared the thermal performance of pre-spawning adult Chinook salmon from two populations, a coastal fall-run from the Chilliwack River (125 km cooler migration) and an interior summer-run from the Shuswap River (565 km warmer migration). We acutely exposed fish to temperatures reflecting current (12°C, 18°C) and future projected temperatures (21°C, 24°C) in the Fraser River and assessed survival, aerobic capacity (resting and maximum metabolic rates, absolute aerobic scope (AAS), muscle and ventricle citrate synthase), anaerobic capacity (muscle and ventricle lactate dehydrogenase) and recovery capacity (post-exercise metabolism, blood physiology, tissue lactate). Chilliwack Chinook salmon performed worse at high temperatures, indicated by elevated mortality, reduced breadth in AAS, enhanced plasma lactate and potassium levels and elevated tissue lactate concentrations compared with Shuswap Chinook salmon. At water temperatures exceeding the upper pejus temperatures (T_pejus, defined here as 80% of maximum AAS) of Chilliwack (18.7°C) and Shuswap (20.2°C) Chinook salmon populations, physiological performance will decline and affect migration and survival to spawn. Our results reveal population differences in pre-spawning Chinook salmon performance across scales of biological organization at ecologically relevant temperatures. Given the rapid warming of rivers, we show that it is critical to consider the intra-specific variation in thermal physiology to assist in the conservation and management of Pacific salmon.

Goals, challenges, and next steps in transdisciplinary fisheries research: perspectives and experiences from early-career researchers

Fisheries are highly complex social-ecological systems that often face 'wicked' problems from unsustainable resource management to climate change. Addressing these challenges requires transdisciplinary approaches that integrate perspectives across scientific disciplines and knowledge systems. Despite widespread calls for transdisciplinary fisheries research (TFR), there are still limitations in personal and institutional capacity to conduct and support this work to the highest potential. The viewpoints of early career researchers (ECRs) in this field can illuminate challenges and promote systemic change within fisheries research. This paper presents the perspectives of ECRs from across the globe, gathered through a virtual workshop held during the 2021 World Fisheries Congress, on goals, challenges, and future potential for TFR. Big picture goals for TFR were guided by principles of co-production and included (i) integrating transdisciplinary thinking at all stages of the research process, (ii) ensuring that research is inclusive and equitable, (iii) co-creating knowledge that is credible, relevant, actionable, and impactful, and (iv) consistently communicating with partners. Institutional inertia, lack of recognition of the extra time and labour required for TFR, and lack of skill development opportunities were identified as three key barriers in conducting TFR. Several critical actions were identified to help ECRs, established researchers, and institutions reach these goals. We encourage ECRs to form peer-mentorship networks to guide each other along the way. We suggest that established researchers ensure consistent mentorship while also giving space to ECR voices. Actions for institutions include retooling education programs, developing and implementing new metrics of impact, and critically examining individualism and privilege in academia. We suggest that the opportunities and actions identified here, if widely embraced now, can enable research that addresses complex challenges facing fishery systems contributing to a healthier future for fish and humans alike.

Allometric Scaling of Anaerobic Capacity Estimated from a Unique Field-Based Data Set of Fish Swimming

AbstractLocomotion is a defining characteristic that can dictate many aspects of an organism's life history in the pursuit of maximizing fitness, including escaping predators, capturing prey, and transitioning between habitats. Exhaustive exercise can have negative consequences for both short-term and long-term energetics and life history trade-offs, influencing fish survival and reproduction. Studies of swimming performance and exhaustive exercise in fish are often conducted on individual species, but few multispecies analyses exist and even fewer in field settings. In fish, swimming performance and exercise have historically been studied in the laboratory using swim tunnels, but an increasing body of work in recreational fisheries science provides a novel way to examine swimming capacity and exhaustion. Using fight time, the time it takes for a hooked fish to be landed on rod and reel fishing gear, as an opportunistic proxy for fish exhaustion, a multispecies meta-analysis of data from studies on recreational fisheries was conducted to elucidate the factors that most influence capacity for exhaustive exercise. Data from 39 species of freshwater and marine fish were aggregated, and negative binomial mixed effects models as well as phylogenetic least squares regression were used to identify the factors that most influenced exhaustive exercise in the field. Fish total length, aspect ratio of the caudal fin, and body form were significant factors in explaining the capacity for exhaustive exercise. Large migratory fish with high aspect ratios were able to fight, and therefore exercise, the longest. These results illustrate that body form and physiology are both deeply intertwined to inform function across fish species and point to angling fight time as a useful approximation of fish swimming capabilities that can be further developed for understanding the limits of fish exercise physiology.

Braiding Indigenous knowledge systems and Western-based sciences in the Alberta oil sands region: A systematic review

The braiding of Indigenous knowledge systems and Western-based sciences offers insights into ecology and has emerged as a way to help address complex environmental issues. We reviewed the publicly available ecological research involving the braiding of Indigenous knowledge systems and Western-based sciences to support collaborative work in the Alberta oil sands region of Canada. We conducted a systematic review, coding for 78 questions in six categories: (1) literature search and bibliographic information; (2) research themes; (3) study setting and design; (4) knowledge systems; (5) power relationships, colonization, and ethical considerations in research; and (6) benefits and challenges of braiding. We identified six articles that braided knowledge, with those articles focusing on environmental management and monitoring for impacts of industrial activity in northern Alberta. Researchers used a broad range of approaches to gather Indigenous knowledge and scientific data and identified multiple challenges (e.g., asymmetries of power, resource availability, and funding) to research. Our findings show that more support is needed to foster, promote, and disseminate interdisciplinary collaborative work involving braiding. Additional support is also required to address Indigenous community research needs related to the assessment of environmental impact and reclamation, as well as the understanding of ecological threats across the region.

A stakeholder-engaged approach to evaluating spawning aggregation management as a strategy for conserving bonefish (Albula vulpes) in Cuba

Animals that congregate in large numbers to reproduce in spatially and temporally distinct locations are particularly susceptible to overexploitation. Many fishes form spawning aggregations that are intentionally targeted given ease of capture. Bonefish (Albula spp.) species aggregate to spawn and are culturally and economically important, but generally lack management such as spawning area protections to ensure that fisheries are sustainable. Here, we use Cuba as a case study to inform the development and refinement of management strategies for bonefish. Recommendations for the management of bonefish pre-spawning aggregations were based on international experiences, which have been adapted to the Cuban context from results of surveys and interviews with Cuban fisheries professionals and fishing guides. The achievability and feasibility of recommendations were further reviewed by additional experts in the field of fisheries, management and Cuban policy. The process revealed extensive data-limitations for bonefish fisheries and underscored the importance of including fishing guides, local ecological knowledge and the context of marine protected areas in Cuba for bonefish management. Recommendations include (1) initiating information exchange between Cuban management agencies and third-party institutions related to bonefish management; (2) utilizing local ecological knowledge to gather information, formulate management strategies and enforce regulations; (3) implementing spatial and temporal management measures for bonefish spawning sites; (4) using what is already in place, by protecting spawning sites in the context of existing marine protected areas; (5) collaborating with all stakeholders to manage bonefish spawning sites; and (6) reducing the commercial harvest of the species.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10641-022-01355-0.

Identifying thresholds in air exposure, water temperature and fish size that determine reflex impairment in brook trout exposed to catch-and-release angling

Understanding the factors that contribute to fish impairment and survival from angling events is essential to guide best angling practices for catch-and-release (C&R) recreational fisheries. Complex interactions often exist between angler behaviour, environmental conditions, and fish characteristics that ultimately determine biological outcomes for fish. Yet, few studies focus on identifying biologically relevant thresholds. We therefore examined the effects of water temperature, air exposure and fish size on reflex impairment and mortality in brook trout Salvelinus fontinalis exposed to experimental and simulated angling stressors (n = 337). Using conditional inference trees, we identified interactions among these factors as well as threshold values within them that determine brook trout reflex impairment as an indicator of whole animal stress. Specifically, longer air exposure times (>30 sec) and warmer temperatures (>19.5°C) had a synergistic effect leading to higher reflex impairment scores. Further, larger fish (>328 mm) were more sensitive to air exposure durations >10 sec. Of the reflex impairment measures, loss of equilibrium and time to regain equilibrium were strongly and moderately associated with brook trout mortality (18-24 h monitoring), although mortality rates were generally low (6%). These findings support previous research that has established strong links between these reflex impairment measures and fish health outcomes in other species. They also highlight the important interactions among air exposure duration, water temperature and fish size that determine impairment in brook trout, providing specific thresholds to guide best angling practices for C&R fisheries. This approach may be widely applicable to generate similar thresholds that can be encouraged by regulators and adopted by anglers for other common C&R fishes.

Collaboration between fish passage scientists and engineers: Insights from an international questionnaire

Fish passage science and practice seeks to facilitate the movement of fish around obstacles in their habitat, primarily through the construction of fishways and culverts. Successful implementation of fish passage requires collaboration between groups with very different backgrounds and expertise, including knowledge-producers (scientists who study fish passage and related topics such as fish swimming ability) and knowledge users (engineers who apply that knowledge to design fish passage solutions). To investigate the nature of collaboration between these groups, we surveyed fish passage scientists and engineers from around the world. Respondents were asked about the importance of collaboration, mechanisms of collaboration, potential barriers to collaboration, and how collaboration can be improved. Both fish passage scientists and engineers reported high importance of collaboration and that they collaborated frequently with the other group. Respondents reported that consultation with other professionals (of their discipline and the other) was the most important means of obtaining and sharing information related to fish passage science and engineering. Both groups also tended to over-estimate their knowledge and use of the other's discipline. While respondents reported high engagement in collaboration, key themes emerged with respect to barriers to collaboration and means of improving collaboration. These included lacking a shared understanding of both disciplines, professional differences, insufficient institutional support, and inadequate sharing of knowledge (e.g., reporting and publishing). Opportunities for improving collaboration identified by respondents included 1) more interdisciplinary opportunities that facilitate interaction (particularly conferences and workshops); 2) promoting collaborative projects and interactions between fish passage scientists and engineers on project teams; and 3) ensuring that information is shared between groups (e.g., through accessible publications). Findings from this research have the potential to enhance collaboration between scientists and engineers, to the benefit of fish passage and fish populations.

The movement ecology of fishes

Movement of fishes in the aquatic realm is fundamental to their ecology and survival. Movement can be driven by a variety of biological, physiological and environmental factors occurring across all spatial and temporal scales. The intrinsic capacity of movement to impact fish individually (e.g., foraging) with potential knock-on effects throughout the ecosystem (e.g., food web dynamics) has garnered considerable interest in the field of movement ecology. The advancement of technology in recent decades, in combination with ever-growing threats to freshwater and marine systems, has further spurred empirical research and theoretical considerations. Given the rapid expansion within the field of movement ecology and its significant role in informing management and conservation efforts, a contemporary and multidisciplinary review about the various components influencing movement is outstanding. Using an established conceptual framework for movement ecology as a guide (i.e., Nathan et al., 2008: 19052), we synthesized the environmental and individual factors that affect the movement of fishes. Specifically, internal (e.g., energy acquisition, endocrinology, and homeostasis) and external (biotic and abiotic) environmental elements are discussed, as well as the different processes that influence individual-level (or population) decisions, such as navigation cues, motion capacity, propagation characteristics and group behaviours. In addition to environmental drivers and individual movement factors, we also explored how associated strategies help survival by optimizing physiological and other biological states. Next, we identified how movement ecology is increasingly being incorporated into management and conservation by highlighting the inherent benefits that spatio-temporal fish behaviour imbues into policy, regulatory, and remediation planning. Finally, we considered the future of movement ecology by evaluating ongoing technological innovations and both the challenges and opportunities that these advancements create for scientists and managers. As aquatic ecosystems continue to face alarming climate (and other human-driven) issues that impact animal movements, the comprehensive and multidisciplinary assessment of movement ecology will be instrumental in developing plans to guide research and promote sustainability measures for aquatic resources.

Cascading effects of climate change on recreational marine flats fishes and fisheries

Tropical and subtropical coastal flats are shallow regions of the marine environment at the intersection of land and sea. These regions provide myriad ecological goods and services, including recreational fisheries focused on flats-inhabiting fishes such as bonefish, tarpon, and permit. The cascading effects of climate change have the potential to negatively impact coastal flats around the globe and to reduce their ecological and economic value. In this paper, we consider how the combined effects of climate change, including extremes in temperature and precipitation regimes, sea level rise, and changes in nutrient dynamics, are causing rapid and potentially permanent changes to the structure and function of tropical and subtropical flats ecosystems. We then apply the available science on recreationally targeted fishes to reveal how these changes can cascade through layers of biological organization-from individuals, to populations, to communities-and ultimately impact the coastal systems that depend on them. We identify critical gaps in knowledge related to the extent and severity of these effects, and how such gaps influence the effectiveness of conservation, management, policy, and grassroots stewardship efforts.

Evidence of the impacts of metal mining and the effectiveness of mining mitigation measures on social-ecological systems in Arctic and boreal regions: a systematic map

BACKGROUND

Mining can directly and indirectly affect social and environmental systems in a range of positive and negative ways, and may result in societal benefits, but may also cause conflicts, not least in relation to land use. Mining always affects the environment, whilst remediation and mitigation efforts may effectively ameliorate some negative environmental impacts. Social and environmental systems in Arctic and boreal regions are particularly sensitive to impacts from development for numerous reasons, not least of which are the reliance of Indigenous peoples on subsistence livelihoods and long recovery times of fragile ecosystems. With growing metal demand, mining in the Arctic is expected to increase, demanding a better understand its social and environmental impacts. We report here the results of a systematic mapping of research evidence of the impacts of metal mining in Arctic and boreal regions.

METHODS

We searched multiple bibliographic databases and organisational websites for relevant research using tested search strategies. We also collected evidence from stakeholders and rightsholders identified in the wider 3MK project (Mapping the impacts of Mining using Multiple Knowledges, https://osf.io/cvh3u). We screened articles at three stages (title, abstract, and full text) according to a predetermined set of inclusion criteria, with consistency checks between reviewers at each level. We extracted data relating to causal linkages between actions or impacts and measured outcomes, along with descriptive information about the articles and studies. We have produced an interactive database along with interactive visualisations, and identify knowledge gaps and clusters using heat maps.

REVIEW FINDINGS

Searches identified over 32,000 potentially relevant records, which resulted in a total of 585 articles being retained in the systematic map. This corresponded to 902 lines of data on impact or mitigation pathways. The evidence was relatively evenly spread across topics, but there was a bias towards research in Canada (35% of the evidence base). Research was focused on copper (23%), gold (18%), and zinc (16%) extraction as the top three minerals, and open pit mines were most commonly studied (33%). Research most commonly focused on operation stages, followed by abandonment and post-closure, with little evidence on early stages (prospecting, exploration, construction; 2%), expansion (0.2%), or decommissioning/closure (0.3%). Mitigation measures were not frequently studied (18% articles), with groundwater mitigation most frequently investigated (54% of mitigations), followed by soil quality (12%) and flora species groups (10%). Control-impact study designs were most common (68%) with reference sites as the most frequently used comparator (43%). Only 7 articles investigated social and environmental outcomes together. the most commonly reported system was biodiversity (39%), followed by water (34%), societies (20%), and soil/geology (6%), with air the least common (1%).

CONCLUSIONS

The evidence found highlights a suite of potential knowledge gaps, namely: on early stages prior to operation; effectiveness of mitigation measures; stronger causal inference study designs; migration and demography; cumulative impacts; and impacts on local and Indigenous communities. We also tentatively suggest subtopics where the number of studies could allow systematic reviews: operation, post-closure, and abandonment stages; individual faunal species, surface water quality, water sediment quality; and, groundwater mitigation measure effectiveness.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1186/s13750-022-00282-y.

Cardiac activity in walleye (Sander vitreus) during exposure to and recovery from chemical anaesthesia, electroanaesthesia and electrostunning

Handling and conducting invasive procedures are necessary for aspects of fisheries science, invariably inducing a stress response and imposing energetic demands on fish. Anaesthesia or immobilisation techniques are often used in an attempt to mitigate stress and improve welfare, yet these also come with their own impacts on post-release recovery. Here, the authors investigated whether changes in cardiac activity (heart rates over time, heart rate maxima, and scopes) differed in adult walleye (Sander vitreus) anaesthetised with AQUI-S® 20E (eugenol), electroanaesthetised with a transcutaneous electrical nerve stimulation (TENS) unit or electrostunned with a commercially developed stunning unit. This experiment was divided into two trials. In the first trial, fish were implanted with heart rate loggers and left to recover for c. 4 days. In the second trial, fish were implanted with heart rate loggers, given 3 days to recover and re-exposed to their initial treatments (excluding surgery). Post-treatment cardiac activity was quantified for both trials. Although highly variable across individuals, the authors found no significant differences in heart rate changes over time or recovery times among treatments. Maximum heart rates were consistent among treatment groups, yet significant differences in heart rate scope provided further evidence of strong interindividual variation in the second trial. Based on these results, the authors did not identify any welfare-relevant differences or concerns associated with one treatment over another. Further investigations of the relationships between measures of cardiac function and other physiological stress markers would be beneficial towards identifying best practices for fish handling in fisheries science.

An energetics-performance framework for wild fishes

There is growing evidence that bioenergetics can explain relationships between environmental conditions and fish behaviour, distribution and fitness. Fish energetic needs increase predictably with water temperature, but metabolic performance (i.e., aerobic scope) exhibits varied relationships, and there is debate about its role in shaping fish ecology. Here we present an energetics-performance framework, which posits that ecological context determines whether energy expenditure or metabolic performance influence fish behaviour and fitness. From this framework, we present testable predictions about how temperature-driven variability in energetic demands and metabolic performance interact with ecological conditions to influence fish behaviour, distribution and fitness. Specifically, factors such as prey availability and the spatial distributions of prey and predators may alter fish temperature selection relative to metabolic and energetic optima. Furthermore, metabolic flexibility is a key determinant of how fish will respond to changing conditions, such as those predicted with climate change. With few exceptions, these predictions have rarely been tested in the wild due partly to difficulties in remotely measuring aspects of fish energetics. However, with recent advances in technology and measurement techniques, we now have a better capacity to measure bioenergetics parameters in the wild. Testing these predictions will provide a more mechanistic understanding of how ecological factors affect fish fitness and population dynamics, advancing our knowledge of how species and ecosystems will respond to rapidly changing environments.

Predator-prey landscapes of large sharks and game fishes in the Florida Keys

Interspecific interactions can play an essential role in shaping wildlife populations and communities. To date, assessments of interspecific interactions, and more specifically predator-prey dynamics, in aquatic systems over broad spatial and temporal scales (i.e., hundreds of kilometers and multiple years) are rare due to constraints on our abilities to measure effectively at those scales. We applied new methods to identify space-use overlap and potential predation risk to Atlantic tarpon (Megalops atlanticus) and permit (Trachinotus falcatus) from two known predators, great hammerhead (Sphyrna mokarran) and bull (Carcharhinus leucas) sharks, over a 3-year period using acoustic telemetry in the coastal region of the Florida Keys (USA). By examining spatiotemporal overlap, as well as the timing and order of arrival at specific locations compared to random chance, we show that potential predation risk from great hammerhead and bull sharks to Atlantic tarpon and permit are heterogeneous across the Florida Keys. Additionally, we find that predator encounter rates with these game fishes are elevated at specific locations and times, including a prespawning aggregation site in the case of Atlantic tarpon. Further, using machine learning algorithms, we identify environmental variability in overlap between predators and their potential prey, including location, habitat, time of year, lunar cycle, depth, and water temperature. These predator-prey landscapes provide insights into fundamental ecosystem function and biological conservation, especially in the context of emerging fishery-related depredation issues in coastal marine ecosystems.