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Recreational angling of nesting largemouth bass (Micropterus nigricans) and smallmouth bass (M. dolomieu) can greatly increase nest abandonment, and in the northern clines of their range, decrease recruitment. This is the case in eastern Ontario, where high levels of non-compliance and difficult to enforce regulations have impacted black bass (Micropterus spp.) conservation and management. Effective January 1, 2024 until December 31st, 2025, novel and experimental fishing sanctuaries were imposed on portions of Charleston Lake and Opinicon Lake that prohibit recreational fishing of all types from April 15th to the Friday before the first Saturday in July (encompassing the full bass reproductive season). As part of the formal process to institute these experimental regulations, public comments were collected on the Environmental Registry of Ontario. We examined those comments and identified supportive and non-supportive themes related to these experimental regulations. While a majority of stakeholders were in support of the new regulations, we also noted sub-themes that may hinder regulation acceptance. Those sub-themes include: a perceived lack of enforcement negating the potential benefits of the sanctuaries, under-estimation of the extent of non-compliance with existing regulations such that new regulations are unnecessary, misunderstanding and misinformation, as well as distrust of government and the academic research community. Understanding and addressing these stakeholder perspectives will help researchers studying the new sanctuary areas and managers understand any lack of compliance while informing future decisions about bass management in eastern Ontario and beyond.
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Lubina , Conservación de los Recursos Naturales , Explotaciones Pesqueras , Reproducción , Animales , Ontario , Conservación de los Recursos Naturales/legislación & jurisprudencia , Conservación de los Recursos Naturales/métodos , Explotaciones Pesqueras/legislación & jurisprudencia , Opinión PúblicaRESUMEN
Estimating the survival probability of animals released from fisheries can improve the overall understanding of animal biology with implications for fisheries management, conservation and animal welfare. Vitality indicators are simple visual measures of animal condition that change in response to stressors (like fisheries capture) and can be assessed to predict post-release survival. These indicators typically include immediate reflex responses which are typically combined into a score. Vitality indicators are straight-forward and non-invasive metrics that allow users to quantify how close (or far) an animal is from a normal, 'healthy' or baseline state, which in turn can be correlated with outcomes such as survival probability, given appropriate calibration. The literature on using vitality indicators to predict post-release survival of animals has grown rapidly over the past decade. We identified 136 papers that used vitality indicators in a fisheries context. These studies were primarily focused on marine and freshwater fishes, with a few examples using herptiles and crustaceans. The types of vitality indicators are diverse and sometimes taxa-specific (e.g. pinching leg of turtles, spraying water at nictitating membrane of sharks) with the most commonly used indicators being those that assess escape response or righting response given the vulnerability of animals when those reflexes are impaired. By presenting Pacific salmon fisheries as a case study, we propose a framework for using vitality indicators to predict survival across taxa and fisheries.
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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.
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Conocimiento , Investigación Biomédica Traslacional , AustraliaRESUMEN
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.
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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.
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COVID-19 , Humanos , COVID-19/epidemiología , Pandemias , Confianza , Recursos Naturales , Conservación de los Recursos NaturalesRESUMEN
Common carp, Cyprinus carpio, are a non-native species that established within the Laurentian Great Lakes more than a century ago and are abundant in some locations. Common carp have negatively impacted freshwater ecosystems, including in the Great Lakes, by increasing turbidity and uprooting vegetation through foraging and/or spawning activities. Knowledge of spatial ecology is necessary to effectively manage non-native species and aid in the development of remediation strategies. The aim of this study was to examine the spatial ecology of common carp across multiple spatial scales within Lake Ontario using passive acoustic telemetry. First, Residency Index (RI), as a metric for habitat preference, was calculated for common carp in Toronto Harbour (TH) and Hamilton Harbour (HH). Linear mixed modelling revealed that season, as well as the interaction between season and physical habitat conditions significantly affected RI. Specifically, during spring and summer common carp had significantly higher RI at sites with increased submerged aquatic vegetation, which could be associated with spawning activities. All common carp tagged in HH were resident, compared to half of individuals tagged in TH. Larger individuals tagged in TH were more likely to be absent from the array during summer. Non-resident common carp tagged at TH made extensive movements in spring and summer along the nearshore of Lake Ontario and were detected throughout the entire basin. Knowledge of spawning habitat could inform efforts to exclude common carp from these specific locations. Based on our findings, common carp should be managed at a regional level, as opposed to single sites, owing to their extensive movements. Supplementary Information: The online version contains supplementary material available at 10.1007/s00027-022-00917-9.
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[This corrects the article DOI: 10.1093/conphys/coab016.].
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Adult female Pacific salmon can have higher migration mortality rates than males, particularly at warm temperatures. However, the mechanisms underlying this phenomenon remain a mystery. Given the importance of swimming energetics on fitness, we measured critical swim speed, swimming metabolism, cost of transport, aerobic scope (absolute and factorial) and exercise recovery in adult female and male coho salmon (Oncorhynchus kisutch) held for 2 days at 3 environmentally relevant temperatures (9°C, 14°C, 18°C) in fresh water. Critical swimming performance (U crit) was equivalent between sexes and maximal at 14°C. Absolute aerobic scope was sex- and temperature-independent, whereas factorial aerobic scope decreased with increasing temperature in both sexes. The full cost of recovery from exhaustive exercise (excess post-exercise oxygen consumption) was higher in males compared to females. Immediately following exhaustive exercise (i.e. 1 h), recovery was impaired at 18°C for both sexes. At an intermediate time scale (i.e. 5 h), recovery in males was compromised at 14°C and 18°C compared to females. Overall, swimming, aerobic metabolism, and recovery energetics do not appear to explain the phenomenon of increased mortality rates in female coho salmon. However, our results suggest that warming temperatures compromise recovery following exhaustive exercise in both male and female salmon, which may delay migration progression and could contribute to en route mortality.
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During spawning, adult Pacific salmonids (Oncorhynchus spp.) complete challenging upriver migrations during which energy and oxygen delivery must be partitioned into activities such as locomotion, maturation and spawning behaviours under the constraints of an individual's cardiac capacity. To advance our understanding of cardiac function in free-swimming fishes, we implanted migrating adult Chinook salmon (Oncorhynchus tshawytscha) collected near the mouth of the Sydenham River, Ontario, with heart rate (fH) biologgers that recorded fH every 3 min until these semelparous fish expired on spawning grounds several days later. Fundamental aspects of cardiac function were quantified, including resting, routine and maximum fH, as well as scope for fH (maximum-resting fH). Predictors of fH were explored using generalized least-squares regression, including water temperature, discharge, fish size and fish origin (wild versus hatchery). Heart rate was positively correlated with water temperature, which aligned closely with daily and seasonal shifts. Wild fish had slower resting heart rates than hatchery fish, which led to significantly higher scope for fH. Our findings suggest that wild salmon may have better cardiac capacity during migration than hatchery fish, potentially promoting migration success in wild fish. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.
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Migración Animal/fisiología , Frecuencia Cardíaca/fisiología , Reproducción/fisiología , Salmón/fisiología , Conducta Sexual Animal/fisiología , Animales , Acuicultura , Masculino , OntarioRESUMEN
AbstractPartial migration is common in a variety of taxa and has important ecological and evolutionary implications, yet the underlying factors that lead to different migratory strategies are not clearly understood. Given the importance of temperature in serving as a cue for migration, along with its role in regulating metabolism, growth, reproduction, and survival, we examined how intraspecific variation in critical thermal maximum (CTmax) values influenced migratory strategy (residency vs. migration), timing of migration, growth, and predation vulnerability in a wild population of partially anadromous juvenile brown trout (Salmo trutta). Using passive integrated transponder telemetry and mark-recapture techniques, we identified individuals that out-migrated to sea, assumed residency, and were predated by cormorants several months later. Acute thermal stress induced by conducting CTmax trials did not affect the final fate of assayed fish compared with controls. We found that mass and body condition predicted CTmax and migration timing, but CTmax failed to predict migratory strategy or timing, growth (of resident fish), or predation vulnerability. Although there may be links between mass, thermal tolerance, and migration strategy, the relationship between CTmax and migration remains unclear. The role of upper thermal tolerance in influencing life-history strategies should not be neglected, however, as alternative indicators of thermal tolerance could be further explored. The high degree of variation in CTmax estimates warrants additional investigation of how increasingly prevalent high-temperature events might drive selection toward thermally tolerant extremes, which is particularly relevant in a rapidly warming world.
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Adaptación Fisiológica/fisiología , Migración Animal/fisiología , Trucha/fisiología , Sistemas de Identificación Animal , Animales , Peso Corporal , Conducta Predatoria/fisiología , Ríos , Temperatura , Factores de Tiempo , Trucha/crecimiento & desarrolloRESUMEN
Pro-environmental behaviours (PEBs) are important for mitigation and restoration efforts in the Anthropocene. As recreationists are motivated to engage in leisure activities to increase their own personal wellbeing, we submit that threats to wellbeing (an egocentric motivator) predict engagement in PEBs amongst recreationists. We also predict that differences in experiences across groups of recreationists leads to differences in PEB engagement. Using an online survey, we test our two hypotheses (if recreationists perceive there is a threat to their wellbeing and that their behaviours can yield environmental successes, then they will be more likely to engage in PEBs, and if recreationists differ in recreational experiences then they will demonstrate differences in PEB engagement) amongst outdoor recreationists, specifically Canadian rainbow trout and steelhead anglers in British Columbia (n = 894 respondents). We define 'threat to wellbeing' as the interaction of environmental threat-perceptions of used environments for fishing, and level of centrality fishing has to one's lifestyle. To test our first hypothesis, we conducted three linear regressions corresponding to three different PEBs related to catch-and-release (C&R) fishing. Our egocentric predictor 'threat to wellbeing' was only significant for one out of the three PEBs tested, showing mixed support for our first hypothesis. It is of note that 'environmental threat perceptions' and one's belief in successes resulting from PEB engagement were found to be significant predictors for all three PEBs tested. These results suggest that predictors of PEB may not always be transferable across PEBs relating to recreational activities, and environmental threat perception and one's belief in successes resulting from PEB engagement are strong predictors of PEBs amongst recreationists. To test our second hypothesis, we conducted a Kruskal Wallis test to determine if there were significant differences across angler groups in PEB predictor scores and PEB engagement and conducted pairwise population Z-tests to determine proportional participation rates across angler groups for the three PEBs and PEB predictors investigated. Experiences were found to shape predictors of PEBs, as well as likelihood to engage in PEBs, as different angler groups targeting different fish (i.e., rainbow trout vs steelhead) and using different aquatic habitats (i.e., rivers vs. lakes) demonstrated significantly different scores for PEB predictors, as well as significantly different likelihood to engage in two of the three PEBs tested. These findings support the notion that recreationists are not a homogenous group, and that their beliefs and resulting behaviours during recreational activities are determined by their experiences in nature and can be influenced by the species with which they interact, and the habitats they use for recreation.
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Explotaciones Pesqueras , Recreación , Animales , Colombia Británica , Conservación de los Recursos Naturales , Ecosistema , LagosRESUMEN
The COVID-19 pandemic and corresponding public health mitigation strategies have altered many facets of human life. And yet, little is known about how public health measures have impacted complex socio-ecological systems such as recreational fisheries. Using an online snowball survey, we targeted resident anglers in Ontario, Canada, to obtain preliminary insights on how the pandemic has impacted recreational fishing and related activity. We also explored angler perspectives on pandemic-related restrictions and other aspects of fisheries management. Our results point to the value of recreational fisheries for the mental and physical well-being of participants, as well as the value and popularity of outdoor recreation during a pandemic. Although angling effort and fish consumption appeared to decline during the early phases of the pandemic, approximately 21 % of the anglers who responded to our survey self-identified as new entrants who had begun or resumed fishing in that time. Self-reported motivations to fish during the pandemic suggest that free time, importance to mental and physical health, and desires for self-sufficiency caused some anglers to fish more, whereas a lack of free time, poor or uncertain accessibility, and perceived risks caused some anglers to fish less. Respondents also expressed their desires for more clear and consistent communication about COVID-19 fishing restrictions from governments, and viewed angling as a safe pandemic activity. Information on recreational angler behaviours, motivations, and perspectives during the pandemic may prove valuable to fisheries managers and policy makers looking to optimize their strategies for confronting this and other similar crises.
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Female-biased mortality has been repeatedly reported in Pacific salmon during their upriver migration in both field studies and laboratory holding experiments, especially in the presence of multiple environmental stressors, including thermal stress. Here, we used coho salmon (Oncorhynchus kisutch) to test whether females exposed to elevated water temperatures (18°C) (i) suppress circulating sex hormones (testosterone, 11-ketotestosterone and estradiol), owing to elevated cortisol levels, (ii) have higher activities of enzymes supporting anaerobic metabolism (e.g. lactate dehydrogenase, LDH), (iii) have lower activities of enzymes driving oxidative metabolism (e.g. citrate synthase, CS) in skeletal and cardiac muscle, and (iv) have more oxidative stress damage and reduced capacity for antioxidant defense [lower catalase (CAT) activity]. We found no evidence that a higher susceptibility to oxidative stress contributes to female-biased mortality at warm temperatures. We did, however, find that females had significantly lower cardiac LDH and that 18°C significantly reduced plasma levels of testosterone and estradiol, especially in females. We also found that relative gonad size was significantly lower in the 18°C treatment regardless of sex, whereas relative liver size was significantly lower in females held at 18°C. Further, relative spleen size was significantly elevated in the 18°C treatments across both sexes, with larger warm-induced increases in females. Our results suggest that males may better tolerate bouts of cardiac hypoxia at high temperature, and that thermal stress may also disrupt testosterone- and estradiol-mediated protein catabolism, and the immune response (larger spleens), in migratory female salmon.
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Lactato Deshidrogenasas , Oncorhynchus kisutch , Salmón , Animales , Estradiol , Femenino , Hormonas Esteroides Gonadales , Masculino , Salmón/fisiologíaRESUMEN
For Pacific salmon captured and released by fisheries, post-release behaviour and survival may be influenced by their health and condition at time of capture. We sought to characterize the interactions between infectious agent burden, fish immune and stress physiology and fisheries stressors to investigate the potential for capture-mediated pathogen-induced mortality in adult coho salmon Oncorhynchus kisutch. We used radio-telemetry paired with high-throughput qPCR of non-lethal gill biopsies for infectious agents and host biomarkers from 200 tagged fish experimentally displaced and exposed to various experimental fisheries treatments (gill net entanglement, recreational angling and recreational angling with air exposure vs. non-sampled control). We characterized relationships among post-release behaviour and survival, infectious agent presence and loads, physiological parameters and transcription profiles of stress and immune genes. All infectious agents detected were endemic and in loads consistent with previous adult Pacific salmon monitoring. Individuals exposed to fisheries treatments were less likely to reach spawning habitat compared to controls, and handling duration independent of fisheries gear had a negative effect on survival. High infectious agent burden was associated with accelerated migration initiation post-release, revealing behavioural plasticity in response to deteriorating condition in this semelparous species. Prevalence and load of infectious agents increased post-migration as well as transcription signatures reflected changes in immune and stress profiles consistent with senescence. Results from this study further our understanding of factors associated with fisheries that increase risk of post-release mortality and characterize some physiological mechanisms that underpin migratory behaviour.
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Researchers have surmised that the ability to obtain dominance during reproduction is related to an individual's ability to better sequester the energy required for reproductive behaviors and develop secondary sexual characteristics, presumably through enhanced physiological performance. However, studies testing this idea are limited. Using sockeye salmon (Oncorhynchus nerka), we explored the relationship between heart rate and dominance behavior during spawning. We predicted that an individual's reproductive status and energy requirements associated with dominance can be assessed by relating routine heart rate to changes in spawning status over time (i.e., shifts among aggregation, subordinance, and dominance). Thus, we used routine heart rate as a proxy of relative energy expenditure. Heart rate increased with temperature, as expected, and was higher during the day than at night, a known diel pattern that became less pronounced as the spawning period progressed. Routine heart rate did not differ between sexes and average heart rate of the population did not differ among reproductive behaviors. At the individual level, heart rate did not change as behavior shifted from one state to another (e.g., dominance versus aggregation). No other trends existed between routine heart rate and sex, secondary sexual characteristics, survival duration or spawning success (for females only). Therefore, while our study revealed the complexity of the relationships between cardiac performance and reproductive behaviors in wild fish and demonstrated the importance of considering environmental factors when exploring individual heart rate, we found no support for heart rate being related to specific spawning behavioral status or secondary sexual characteristics.
Rendimiento Cardíaco del Salmón Rojo Salvaje que Natación Libre durante el Período ReproductivoLos investigadores han conjeturado que la capacidad de obtener dominio durante la reproducción está relacionada con la capacidad de un individuo de obtener mejor la energía requerida para los comportamientos reproductivos y desarrollar características sexuales secundarias, presumiblemente a través de un mejor rendimiento fisiológico. Sin embargo, los estudios que prueban esta idea son limitados. Usando Salmón rojo (Oncorhynchus nerka), exploramos la relación entre la frecuencia cardíaca y el comportamiento de dominación durante el desove. Predijimos que el estado reproductivo de un individuo y los requisitos de energía asociados con el dominio pueden evaluarse relacionando la frecuencia cardíaca de rutina con los cambios en el estado de desove a lo largo del tiempo (es decir, cambios entre la agregación, la subordinación y el dominio). Por lo tanto, utilizamos la frecuencia cardíaca de rutina como un proxy del gasto energético relativo. La frecuencia cardíaca aumentó con la temperatura, como se esperaba, y fue más alta durante el día que por la noche, un patrón conocido que se hizo menos pronunciado a medida que avanzaba el período de desove. La frecuencia cardíaca de rutina no difirió entre sexos y la frecuencia cardíaca promedio de la población no difirió entre los comportamientos reproductivos. A nivel individual, la frecuencia cardíaca no cambió a medida que el comportamiento cambió de un estado a otro (i.e., dominación vs. agregación). No se observaron otras tendencias entre la frecuencia cardíaca y el sexo de rutina, las características sexuales secundarias, la duración de la supervivencia o el éxito del desove (solo para hembras). Por lo tanto, si bien nuestro estudio reveló la complejidad de las relaciones entre el rendimiento cardíaco y los comportamientos reproductivos en el Salmón rojo y demostró la importancia de considerar los factores ambientales al explorar la frecuencia cardíaca individual, no encontramos respaldo para la frecuencia cardíaca relacionada con el estado conductual de desove específico o características sexuales secundarias.Translated to Spanish by J. Heras (herasj01@gmail.com).
Desempenho Cardíaco de Natação Livre em Salmão Sockeye Selvagem durante o Período ReprodutivoOs pesquisadores supuseram que a capacidade de obter dominância durante a reprodução está relacionada à capacidade de um indivíduo em melhor obter e aplicar a energia necessária para comportamentos reprodutivos e desenvolver características sexuais secundárias, presumivelmente por meio de um desempenho fisiológico aprimorado. No entanto, os estudos que testam essa ideia são limitados. Usando salmão sockeye (Oncorhynchus nerka), exploramos a relação entre a frequência cardíaca e o comportamento de dominância durante a desova.Previmos que o estado reprodutivo de um indivíduo e os requisitos de energia associados à dominância podem ser avaliados relacionando a freqüência cardíaca de rotina às mudanças no status de desova ao longo do tempo (ou seja, mudanças entre agregação, subordinação e dominância). Assim, usamos a frequência cardíaca de rotina como um indicador do relativo gasto energético. A frequência cardíaca aumentou com a temperatura, conforme o esperado, e foi maior durante o dia do que à noite, um conhecido padrão de diel que se tornou menos pronunciado à medida que o período de desova progredia. A frequência cardíaca de rotina não diferiu entre os sexos e a frequência cardíaca média da população não diferiu entre os comportamentos reprodutivos. No nível individual, a frequência cardíaca não mudou à medida que o comportamento mudou de um estado para outro (por exemplo, dominância versus agregação). Não foram observadas outras tendências entre freqüência cardíaca de rotina e sexo, características sexuais secundárias, duração da sobrevivência ou sucesso da desova (somente para mulheres). Portanto, embora nosso estudo tenha revelado a complexidade das relações entre desempenho cardíaco e comportamentos reprodutivos em peixes selvagens e demonstrado a importância de considerar fatores ambientais ao explorar a frequência cardíaca individual, não encontramos suporte que frequência cardíaca esteja relacionada ao status comportamental de desova específico ou à características sexuais secundárias.Translated to Portuguese by Diego Vaz (dbistonvaz@vims.edu).
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Anadromous fishes such as steelhead trout, Oncorhynchus mykiss, are exposed to a suite of infectious agents and migratory challenges during their freshwater migrations. We assessed infectious agent load and richness and immune system gene expression in gill tissue of Bulkley River (British Columbia, CA) steelhead captured at and upstream of a migratory barrier to evaluate whether infectious burdens impacted migration success. We further considered the potential influences of water temperature, sex and fish size on host infectious agents and transcription profiles. There were eight infectious agents detected in steelhead gill tissue, with high prevalence of the bacteria Candidatus Branchiomonas cysticola (80%) and Flavobacterium psychrophilum (95%) and the microparasite Sphaerothecum destruens (53%). Fish sampled at the falls had significantly greater relative loads of Ca. B. cysticola and F. psychrophilum, higher infectious agent richness and differential gene expression compared to fish captured upstream. Flavobacterium psychrophilum was only associated with immune gene expression (particularly humoral immunity) of fish sampled at the falls, while water temperature was positively correlated with genes involved in the complement system, metabolic stress and oxidative stress for fish captured upstream. This work highlights interesting differences in agent-host interactions across fisheries and suggests that hydraulic barriers may reduce the passage of fish with the heaviest infectious agent burdens, emphasizing the selective role of areas of difficult passage. Further, this work expands our knowledge of infectious agent prevalence in wild salmonids and provides insight into the relationships between infectious agents and host physiology.
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This study demonstrates that vegetable shortening and cocoa butter are two effective vehicles for intraperitoneal cortisol implants in juvenile teleosts, specifically brown trout Salmo trutta, residing in north temperate freshwater environments. Each vehicle showed a different pattern of cortisol elevation. Vegetable shortening was found to be a more suitable vehicle for long-term cortisol elevation [elevated at 3, 6 and 9 days post treatment (dpt)], while cocoa butter may be better suited for short-term cortisol elevation (only elevated at 3 dpt). Additionally, plasma cortisol levels were higher with cortisol-vegetable shortening than with cortisol-cocoa butter implants. Plasma glucose levels were elevated 6 and 9 dpt for fishes injected with cortisol-vegetable shortening, but did not change relative to controls and shams in cortisol-cocoa butter fishes. In conclusion, vegetable shortening and cocoa butter are both viable techniques for cortisol manipulation in fishes in temperate climates, providing researchers with different options depending on study objectives.
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Grasas de la Dieta , Hidrocortisona/farmacología , Bombas de Infusión Implantables , Animales , Glucemia , Trucha/sangre , Trucha/metabolismoRESUMEN
Freshwater ecosystems provide many ecosystem services; however, they are often degraded as a result of human activity. To address ecosystem degradation in the Laurentian Great Lakes, Canada and the United States of America established the Great Lakes Water Quality Agreement (GLWQA). In 1987, 43 highly polluted and impacted areas were identified under the GLWQA as having one or more of 14 Beneficial Use Impairments (BUIs) to the physical and chemical habitat for fish, wildlife and humans, and were designated as Areas of Concern (AOC). Subnational jurisdictions combined with local stakeholders, with support from federal governments, developed plans to remediate and restore these sites. Biotelemetry (the tracking of animals using electronic tags) provides information on the spatial ecology of fish in the wild relevant to habitat management and stock assessment. Here, seven case studies are presented where biotelemetry data were directly incorporated within the AOC Remedial Action Plan (RAP) process. Specific applications include determining seasonal fish-habitat associations to inform habitat restoration plans, identifying the distribution of pollutant-indicator species to identify exposure risk to contamination sources, informing the development of fish passage facilities to enable fish to access fragmented upstream habitats, and assessing fish use of created or restored habitats. With growing capacity for fish biotelemetry research in the Great Lakes, we discuss the strengths and weaknesses of incorporating biotelemetry into AOC RAP processes to improve the science and practice of restoration and to facilitate the delisting of AOCs.