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At least 91 records · Page 5Linked to original sources

Effects of high flow experiments on warm-water native and nonnative fishes

The harsh environmental conditions and extreme flooding that created Grand Canyon also shaped the unique native fish that evolved in the Colorado River. Native fish have evolved their physiology, morphology and behavior to withstand high flood events. Flooding has been shown to benefit spawning, survival and recruitment of juvenile native fishes in many southwestern rivers. Annual pre-dam flooding on the Colorado River was sometimes more than double the flows released during a typical High-Flow Experiment (HFE). It is therefore unlikely that the 3-4 days of high flow created by HFEs will have negative impacts on native fish directly. However, HFEs can cause dispersal of flood adapted non-native species like green sunfish that utilize floods to invade and colonize new environments. Continued efforts to reduce known populations of green sunfish that inhabit backwater ponds before conducting HFEs may be necessary to reduce risks of spreading invasive green sunfish downstream.

Arizona↗

Rapid embryonic development supports the early onset of gill functions in two coral reef damselfishes

The gill is one of the most important organs for growth and survival of fishes. Early life stages in coral reef fishes often exhibit extreme physiological and demographic characteristics that are linked to well-established respiratory and ionoregulatory processes. However, gill development and function in coral reef fishes is not well-understood. Therefore, we investigated gill morphology, oxygen uptake, and ionoregulatory systems throughout embryogenesis in two coral reef damselfishes, Acanthochromis polyacanthus and Amphiprion melanopus (Pomacentridae). In both species, we found key gill structures to develop rapidly early in the embryonic phase. Ionoregulatory cells appear on gill filaments 3-4 days post fertilization and increase in density, whilst disappearing or shrinking in cutaneous locations. Primary respiratory tissue (lamellae) appears 5-7 days post fertilization, coinciding with a peak in oxygen uptake rates of the developing embryos. Oxygen uptake was unaffected by phenylhydrazine across all ages (pre-hatch), indicating that haemoglobin is not yet required for oxygen uptake. This suggests that gills have limited contribution to respiratory functions during embryonic development, at least until hatching. Rapid gill development in damselfishes, when compared to most of the previously investigated fishes, may reflect preparations for a high-performance, challenging lifestyle on tropical reefs, but may also make reef fishes more vulnerable to anthropogenic stressors.

Journal of Experimental Biology↗

Fish diseases and parasites in relation to the environment

Although some diseases are not affected by subtle environmental changes, others are. Factors which may influence infection or the course of disease are: temperature, gaseous supersaturation, oxygen deficiency, mechanical and physiological trauma of the fish, malappropriate water chemistry, pollution, eutrophication, media for spore retention, and presence of intermediate hosts. Aviatminoses and neoplasias are often related to environmental changes.

Fish Pathology↗

Differences in energy expenditures and growth dilution explain higher PCB concentrations in male summer flounder

Comparison of polychlorinated biphenyl (PCB) concentrations between the sexes of mature fish may reveal important behavioral and physiological differences between the sexes. We determined whole-fish PCB concentrations in 23 female summer flounder Paralichthys dentatus and 27 male summer flounder from New Jersey coastal waters. To investigate the potential for differences in diet or habitat utilization between the sexes, carbon and nitrogen stable isotope ratios were also determined. In 5 of the 23 female summer flounder, PCB concentrations in the somatic tissue and ovaries were determined. In addition, we used bioenergetics modeling to assess the contribution of the growth dilution effect to the observed difference in PCB concentrations between the sexes. Whole-fish PCB concentrations for females and males averaged 87 and 124 ng/g, respectively; thus males were 43% higher in PCB concentration compared with females. Carbon and nitrogen stable isotope ratios did not significantly differ between the sexes, suggesting that diet composition and habitat utilization did not vary between the sexes. Based on PCB determinations in the somatic tissue and ovaries, we predicted that PCB concentration of females would increase by 0.6%, on average, immediately after spawning due to release of eggs. Thus, the change in PCB concentration due to release of eggs did not explain the higher PCB concentrations observed in males. Bioenergetics modeling results indicated that the growth dilution effect could account for males being 19% higher in PCB concentration compared with females. Thus, the bulk of the observed difference in PCB concentrations between the sexes was not explained by growth dilution. We concluded that a higher rate of energy expenditure in males, stemming from greater activity and a greater resting metabolic rate, was most likely the primary driver for the observed difference in PCB concentrations between the sexes.

New Jersey↗

Mercury accumulation and the mercury-PCB-sex interaction in summer flounder

Patterns in the relative differences in contaminant concentrations between the sexes of mature fish may reveal important behavioral and physiological differences between the sexes. We determined whole-fish total mercury (Hg) concentrations in 23 female summer flounder (Paralichthys dentatus) and 27 male summer flounder from New Jersey coastal waters. To estimate the change in Hg concentration due to release of eggs at spawning, Hg concentration in the somatic tissue and ovaries of 5 of the 23 female summer flounder were also determined. To ascertain whether most of the Hg in the summer flounder was methylmercury (MeHg), whole-fish MeHg concentrations were determined in all 50 summer flounder. Whole-fish Hg concentrations averaged 113 ng/g for females and 111 ng/g for males. Thus, females were 2% higher in Hg concentration than males, on average, but the difference was not statistically significant. Based on Hg determinations in the somatic tissue and ovaries, we predicted that Hg concentration of females would increase by 3.6%, on average, immediately after spawning due to release of eggs. On average, 92% of the Hg in the summer flounder was MeHg. To determine whether the effect of sex on Hg concentration was significantly different from the effect of sex on polychlorinated biphenyl (PCB) concentration, we paired our Hg determinations with PCB determinations from a previous study, and applied regression analysis. Sex significantly interacted with contaminant type (Hg or PCBs), as males were 43% higher in PCB concentration than females, whereas females were 2% higher in Hg concentration than males. Males eliminating Hg from their bodies at a faster rate than females was a likely explanation for this discrepancy between the two contaminant types. Overall, the Hg and PCB concentrations in the summer flounder were relatively low, and therefore our findings also had implications for continued operation of the summer flounder fishery.

Journal of Marine Science: Research & Development↗

Environmental factors influencing entry of fishes into a Great Lakes tributary during spring and summer

Stream entry of many fishes is influenced by environmental factors including water temperature, stream discharge, and photoperiod (Leggett 1977; Jonsson 1991). Environmental factors influence stream entry differently depending on the species and life stage of fish, likely because of varying physiologies and life histories (Lucas and Baras 2008). Many spring-run migratory fishes occupy Laurentian Great Lakes Basin (e.g., lake sturgeon, Acipenser fulvescens; steelhead, Oncorhynchus mykiss; white sucker, Catostomus commersonii; coho salmon, Oncorhynchus kisutch; and sea lamprey, Petromyzon marinus), and the timing of when they enter a river system each year is likely influenced by different environmental variables. For example, water temperature and stream discharge seem to be two of the triggers to upstream movement for many migratory fishes in the Great Lakes region (Hamel et al. 1997; Workman et al. 2002; Binder et al. 2010). Although much is known about the environmental cues for upstream migration of many species in the Great Lakes, understanding fish migration at higher spatial and temporal resolutions is needed (Landsman et al. 2011), especially in and around fishways. Therefore, our goal was to determine what factors influence the timing of fish entry into a Lake Michigan tributary at a relatively high temporal resolution using a noninvasive and continuous monitoring technique. Enhanced understanding of the environmental cues that trigger fish movement in Great Lakes tributaries is important because it can improve recreation, native fish restoration, and invasive species control. For example, fisheries managers need to know when and at which life stage fish are moving into the rivers to establish closed seasons and catch limits. Additionally, knowing when native or invasive species move upstream can inform the operation of selective fishways and hydropower facilities that protect native or economically valuable fishes (e.g., lake sturgeon, white sucker, steelhead, coho salmon) while blocking invasive species (e.g., sea lamprey). Here, we evaluate the environmental triggers of stream entry for three size classes of migratory fishes in the Lower Boardman River. Located in northern Michigan, the Boardman River is an important system for improving knowledge of fish migration because of its high productivity and value to the local community. Many fishes would benefit from increased habitat connectivity in the Boardman River, which connects a productive and relatively pristine tributary with a large and productive bay. The Boardman River is valued by both recreational and tribal stakeholders and is the focus of a restoration project aimed at improving habitat connectivity by removing and modifying all existing dams. For these reasons, the Great Lakes Fishery Commission is leading a project to replace the Union Street Dam on the Boardman River with a facility that integrates various technologies to pass desirable fish up- and down-stream while blocking and removing undesirable fish (the FishPass project). Using Dual-frequency Identification Sonar (DIDSON) cameras, we characterized the sizes of fishes migrating into the Boardman River below the Union Street Dam as well as the timing of their movements. Our results provide fine-scale details on the timing of fish movements in the Boardman River and directly inform the FishPass project. We were specifically interested in the movement timing of sea lamprey, an undesirable invasive fish that must not be passed upstream at FishPass, and lake sturgeon, a highly desired native fish that should pass upstream.

Report↗

Physiological responses of juvenile rainbow trout to fasting and swimming activity: Effects on body composition and condition indices

The physiological traits that allow fish to survive periods of limited food resources are poorly understood. We assessed changes in proximate body composition, relative organ mass, blood metabolites, and relative weight (Wr) of sedentary and actively swimming (15 cm/s) juvenile rainbow trout (154-182 mm total length) over 147 d of fasting. Fasting caused measurable responses that were augmented when fish were swimming. Lipids and plasma triacylglycerides declined over time. Proteins were catabolized simultaneously with lipid reserves, but ammonia concentrations in plasma did not increase. The liver somatic index (LSI) did not change substantially over 105 d, suggesting that gluconeogenesis maintained blood glucose concentrations and hepatic glycogen reserves for a substantial period of fasting. The gut somatic index (GSI) and Wr declined linearly during fasting, but the LSI did not decline until after 105 d of fasting. Consequently, the use of different body condition indices could lead to different conclusions about the condition of juvenile rainbow trout. Swimming activity caused fish to have lower lipid and protein reserves than those of sedentary fish. No mortalities were observed among sedentary fish, but mortalities occurred among actively swimming fish after 97 d of fasting when 3.2% or less lipid remained in their bodies. Body condition indices did not account for differences in proximate body composition between sedentary and actively swimming fish and were relatively poor predictors of lipid content and risk of mortality. The probability of mortality was most accurately predicted by percent lipid content. Therefore, we suggest that fisheries scientists consider using percent lipid content when evaluating the physiological status and risk of mortality due to starvation among juvenile rainbow trout.

Transactions of the American Fisheries Society↗

Physiological measures of neurotoxicity of diazinon and malathion to larval rainbow trout ( Oncorhynchus mykiss ) and their correlation with behavioral measures

Relations between neurotoxicants and changes in physiological parameters and behavior were investigated in larval rainbow trout (RBT; Oncorhynchus mykiss ) exposed to sublethal concentrations of two organophosphate pesticides (OPs). Fish were exposed to diazinon and malathion in static-renewal experiments. After exposures for 24, 96, or 96 h, followed by 48 h of recovery, individual RBT were videotaped to assess locomotory behaviors. Brain tissue from the same fish was assayed for the physiological endpoints, cholinesterase (ChE) activity, muscarinic cholinergic receptor (MChR) number (B max ), and MChR affinity (K D ). Cholinesterase activity decreased significantly with increasing concentrations of both diazinon and malathion and differed significantly among exposure durations, with 24- and 96-h means less than 48-h recovery means. Decreases in B max with OP concentration were not significant for either chemical, and K D was unaffected. Changes in swimming speed and distance were significantly correlated with changes in ChE activity for both chemicals; rate of turning was significantly correlated with ChE activity in malathion exposures. These results suggest that correlations between physiological and behavioral changes previously seen in mammals also occur in fish.

Environmental Toxicology and Chemistry↗

Exploiting the physiology of lampreys to refine methods of control and conservation

Lampreys (order: Petromyzontiformes) represent one of two extant groups of jawless fishes, also called cyclostomes. Lampreys have a variety of unique features that distinguish them from other fishes. Here we review the physiological features of lampreys that have contributed to their evolutionary and ecological success. The term physiology is used broadly to also include traits involving multiple levels of biological organization, like swimming performance, that have a strong but not exclusively physiological basis. We also provide examples of how sea lamprey traits are currently being used or investigated to control invasive populations in the Great Lakes, such as reduced capacity to detoxify lampricides, inability to surmount low barriers or dams, and sensitivity to several lamprey-specific chemosensory pheromones and alarm cues. Specific suggestions are also provided for how an improved knowledge of lamprey physiological traits could be exploited for more effective conservation of native lampreys and lead to the development of next generation sea lamprey control and conservation tools.

Journal of Great Lakes Research↗

Effects of biologically-active chemical mixtures on fish in a wastewater-impacted urban stream

Stream flow in urban aquatic ecosystems often is maintained by water-reclamation plant (WRP) effluents that contain mixtures of natural and anthropogenic chemicals that persist through the treatment processes. In effluent-impactedstreams, aquatic organisms such as fish are continuously exposed to biologically-activechemicals throughout their life cycles. The North Shore Channel of the Chicago River (Chicago, Illinois) is part of an urban ecosystem in which > 80% of the annual flow consists of effluent from the North Side WRP. In this study, multiple samplings of the effluent and stream water were conducted and fish (largemouth bass and carp) were collected on 2 occasions from the North Shore Channel. Fish also were collected once from the Outer Chicago Harbor in Lake Michigan, a reference site not impacted by WRP discharges. Over 100 organic chemicals with differing behaviors and biological effects were measured, and 23 compounds were detected in all of the water samples analyzed. The most frequently detected and highest concentration (> 100 &mu;g/L) compounds were ethylenediaminetetraacetic acid and 4-nonylphenolmono-to-tetraethoxycarboxylic acids. Other biologically-activechemicals including bisphenol A, 4-nonylphenol, 4-nonylphenolmono-to-tetraethoxylates, 4- tert -octylphenol, and 4- tert -octylphenolmono-to-tetraethoxylates were detected at lower concentrations (< 5 &mu;g/L). The biogenic steroidal hormones 17&beta;-estradiol, estrone, testosterone, 4-androstene-3,17-dione, and cis -androsterone were detected at even lower concentrations (< 0.005 &mu;g/L). There were slight differences in concentrations between the North Side WRP effluent and the North Shore Channel, indicating minimal in-stream attenuation. Fish populations are continuously exposed to mixtures of biologically-activechemicals because of the relative persistency of the chemicals with respect to stream hydraulic residence time, and the lack of a fresh water source for dilution. The majority of male fish exhibited vitellogenin induction, a physiological response consistent with exposure to estrogenic compounds. Tissue-level signs of reproductive disruption, such as ovatestis, were not observed.

Illinois↗

The effect of thiamine injection on upstream migration, survival, and thiamine status of putative thiamine-deficient coho salmon

A diet containing a high proportion of alewives Alosa pseudoharengus results in a thiamine deficiency that has been associated with high larval salmonid mortality, known as early mortality syndrome (EMS), but relatively little is known about the effects of the deficiency on adults. Using thiamine injection (50 mg thiamine/kg body weight) of ascending adult female coho salmon Oncorhynchus kisutch on the Platte River, Michigan, we investigated the effects of thiamine supplementation on migration, adult survival, and thiamine status. The thiamine concentrations of eggs, muscle (red and white), spleen, kidney (head and trunk), and liver and the transketolase activity of the liver, head kidney, and trunk kidney of fish injected with thiamine dissolved in physiological saline (PST) or physiological saline only (PS) were compared with those of uninjected fish. The injection did not affect the number of fish making the 15-km upstream migration to a collection weir but did affect survival once fish reached the upstream weir, where survival of PST-injected fish was almost twice that of controls. The egg and liver thiamine concentrations in PS fish sampled after their upstream migration were significantly lower than those of uninjected fish collected at the downstream weir, but the white muscle thiamine concentration did not differ between the two groups. At the upper weir, thiamine levels in the liver, spleen, head kidney, and trunk kidney of PS fish were indistinguishable from those of uninjected fish (called "wigglers") suffering from a severe deficiency and exhibiting reduced equilibrium, a stage that precedes total loss of equilibrium and death. For PST fish collected at the upstream weir, total thiamine levels in all tissues were significantly elevated over those of PS fish. Based on the limited number of tissues examined, thiamine status was indicated better by tissue thiamine concentration than by transketolase activity. The adult injection method we used appears to be a more effective means of increasing egg thiamine levels than immersion of eggs in a thiamine solution. ?? Copyright by the American Fisheries Society 2005.

Journal of Aquatic Animal Health↗

Warmwater and coldwater fish in two-story stranding waters

Two-story fisheries occur in lakes or reservoirs characterized by two distinct spatial strata, warmwater and coldwater. These strata develop as the system begins to warm in the spring or summer in response to solar radiation and then separate into an upper warmwater stratum (epilimnion, hereafter referred to as the upper stratum) and a lower coldwater stratum (hypolimnion, hereafter referred to as the lower stratum) separated by the thermocline, a zone of rapidly declining temperatures with depth (i.e., stratification; Figure 10.1). Each stratum or story is dominated by fish species with different physiological constraints, dietary preferences, and behavior. The original use of the term “two-story” described lentic systems in which the lower stratum was less than 21°C during summer and dominated by stocked salmonids, the upper stratum was dominated by sunfishes or perches, and attempts were made to simultaneously manage both strata as sport fisheries (e.g., Jones 1982). However, the terminology is now used more generally to describe any two-stratum system where a coldwater species dominates the lower stratum, often piscivores; a warmwater species dominates the upper stratum, often a planktivore or omnivore; and both contribute to the sport fishery. In general, the upper stratum is characterized by a large, relatively shallow, littoral zone where a diverse assemblage of fishes interact with the bottom, whereas the lower stratum is characterized as deep and pelagic with fewer fish species.

Book chapter↗

Energy depletion and stress levels of Sockeye Salmon migrating at the northern edge of their distribution

The physiological challenge for anadromous fish to migrate upriver is influenced by river temperature, but the impacts of river temperature can be difficult to predict due to an incomplete understanding of how temperature influences migration costs, especially in high‐latitude (>60°N) ecosystems. To assess temperature influences on migrating Pacific salmon Oncorhynchus spp., we measured heat shock protein 70 (HSP70), as an indicator of cellular stress, and energy content of Sockeye Salmon Oncorhynchus nerka throughout their upriver migration in the Pilgrim River, Alaska. Although HSP70 was elevated as fish moved to the spawning grounds and was higher in fish with low energy content, HSP70 did not increase with warmer river temperatures. We verified in an experiment that HSP70 abundance in Sockeye Salmon does respond to temperatures above 20.5°C. Over the 4 years of sampling, energy content decreased at similar rates as Sockeye Salmon moved upstream. We expected Sockeye Salmon energy levels would be lower when migrating in warmer river temperatures; however, we found higher energy levels occurred with higher temperatures in the Pilgrim River. We hypothesize that the relationship between temperature and energy content is due to river temperatures often occurring below optimal temperatures for migration. Lower temperatures could be energetically costly or reduce migration rates, both of which would result in lower energy content with cooler temperature. Understanding interactions between environmental drivers and physiological responses will help managers anticipate future changes for Sockeye Salmon at the northern edge of their distribution.

Alaska↗

Behavioral thermoregulation by juvenile spring and fall chinook salmon, Oncorhynchus tshawytscha, during smoltification

Fall chinook salmon evolved to emigrate during the summer months. The shift in the temperature preference we observed in smolting fall chinook but not spring chinook salmon may reflect a phylogenetic adaptation to summer emigration by (1) providing directional orientation as fall chinook salmon move into the marine environment, (2) maintaining optimal gill function during emigration and seawater entry, and/or (3) resetting thermoregulatory set-points to support physiological homeostasis once smolted fish enter the marine environment. Phylogenetically determined temperature adaptations and responses to thermal stress may not protect fall chinook salmon from the recent higher summer water temperatures, altered annual thermal regimes, and degraded cold water refugia that result from hydropower regulation of the Columbia and Snake rivers. The long-term survival of fall chinook salmon will likely require restoration of normal annual thermographs and rigorous changes in land use practices to protect critical thermal refugia and control maximum summer water temperatures in reservoirs.

Environmental Biology of Fishes↗

Salmonids, stream temperatures, and solar loading--modeling the shade provided to the Klamath River by vegetation and geomorphology

The U.S. Geological Survey is studying approaches to characterize the thermal regulation of water and the dynamics of cold water refugia. High temperatures have physiological impacts on anadromous fish species. Factors affecting the presence, variability, and quality of thermal refugia are known, such as riverine and watershed processes, hyporheic flows, deep pools and bathymetric factors, thermal stratification of reservoirs, and other broader climatic considerations. This research develops a conceptual model and methodological techniques to quantify the change in solar insolation load to the Klamath River caused by riparian and floodplain vegetation, the morphology of the river, and the orientation and topographic characteristics of its watersheds. Using multiple scales of input data from digital elevation models and airborne light detection and ranging (LiDAR) derivatives, different analysis methods yielded three different model results. These models are correlated with thermal infrared imagery for ground-truth information at the focal confluence with the Scott River. Results from nonparametric correlation tests, geostatistical cross-covariograms, and cross-correlograms indicate that statistical relationships between the insolation models and the thermal infrared imagery exist and are significant. Furthermore, the use of geostatistics provides insights to the spatial structure of the relationships that would not be apparent otherwise. To incorporate a more complete representation of the temperature dynamics in the river system, other variables including the factors mentioned above, and their influence on solar loading, are discussed. With similar datasets, these methods could be applied to any river in the United States—especially those listed as temperature impaired under Section 303(d) of the Clean Water Act—or international riverine systems. Considering the importance of thermal refugia for aquatic species, these methods can help investigate opportunities for riparian restoration, identify problematic reaches unlikely to provide good habitat, and simulate changes to solar loading estimates from alternative landscape configurations.

California↗

Sex difference in PCB concentrations of a catostomid fish

Unraveling the complexities associated with the relative differences in contaminant concentrations between the sexes of mature fish may provide insights into important behavioral and physiological differences between the sexes of not just fish but higher vertebrates as well. Whole-fish polychlorinated biphenyl (PCB) concentrations were determined in 25 mature female white suckers (Catostomus commersoni) and 26 mature male white suckers caught during their spawning run in the Kewaunee River, a tributary to Lake Michigan. Total length and weight were measured for each fish, and age of each fish was estimated from thin-sectioned otoliths. PCB concentration significantly increased with increasing total length, weight, and age. Consequently, three analysis of covariance (ANCOVA) models were fitted to the data to assess the effect of sex on white sucker PCB concentration. Based on model averaging, estimates of mean PCB concentrations in female and male white suckers were 185 and 219 ng/g, respectively. Thus, males were 18% greater in PCB concentration than females. We conclude that this difference between the sexes was most likely mainly driven by a higher rate of energy expenditure in males compared with females. Greater energy expenditure, owing to greater swimming activity and a higher resting metabolic rate , resulted in a higher rate of food consumption, which in turn led to a greater rate of PCB accumulation. Higher whole-fish PCB concentration in males compared with females has now been shown in nine different fish species. Our study represented the first documentation of this type of sex difference in a catostomid fish.

Kewaunee River, Lake Michigan↗

Guidelines for use of fishes in research

The 2004 and 2014 Guidelines were developed to provide a structure that advances appropriate attention toward valid experimental designs and procedures with aquatic animals while ensuring humane treatment of the experimental subjects. At a practical level, the Guidelines are intended to provide general recommendations on field and laboratory endeavors, such as sampling, holding, and handling fishes; to offer information on administrative matters, including regulations and permits; and to address typical ethical concerns, such as perceptions of pain or discomfort experienced by experimental subjects. These Guidelines must be recognized as guidelines . They are not intended to provide detailed instructions but rather to alert investigators to a broad array of topics and concerns to consider prior to initiating study. At a comprehensive level, the principles upon which these Guidelines are based are broadly applicable, and many of the described practices and approaches can be adapted to situations involving other aquatic animal species and conditions. Understanding the differences between fishes and other vertebrates, especially mammals, is critically important to conducting scientifically sound research with fishes. Disparities in life histories and mortality rates in fishes versus other vertebrates are critical in designing sustainable sampling levels in fish populations. The UFR Committee points out that (1) compared to mammalian populations, adult populations of many fish species persist despite very high natural mortality rates in juvenile stages by virtue of the fact that most species lay thousands or tens of thousands of eggs; (2) because of these mortality patterns, research on fishes, especially field research or research on early life stages, can involve, and often requires, much larger numbers of research subjects than does research on mammals; and (3) the animal handling and husbandry requirements for fishes are fundamentally different from those for mammals and other vertebrates, in general. Policies, regulations, and recommendations developed for research on mammals, birds, reptiles, or even amphibians are frequently inappropriate for research with fishes. The Guidelines also address some of the ethical concerns that motivate guidelines used for research with other vertebrates, while being mindful of the unique physiology and general nature of fishes. The Guidelines were developed for general use by investigators within the United States; therefore, the roles, responsibilities, and informational needs of Institutional Animal Care and Use Committees (IACUCs) were given specific attention. All United States institutions that use vertebrate animals for research, teaching, research training, and biological testing are required to create an IACUC to oversee and evaluate all aspects of the institution’s animal care and use program. Investigators from other nations who read this document may disregard specific references to U.S. state and federal laws and regulations, as their institutional infrastructure and processes may differ from those of an internal committee such as IACUCs. The principles described herein, however, are applicable to research on fishes regardless of geographic location. Investigators in other nations may benefit by modifying any of the specific provisions pertaining to the United States, thereby adopting guidelines consistent with the laws and regulations of their own government. The UFR Committee urges that the Guidelines be endorsed and adopted (adapted, where necessary) by those state and federal authorities with regulatory responsibilities for fishes, offices with federal oversight (e.g., National Institutes of Health, Office of Laboratory Animal Welfare; http://grants.nih.gov/grants/olaw/olaw.htm ) as well as by universities and other institutions and authorities using fishes and aquatic animals within their research and teaching programs.

Report↗

The value of electronic tagging and tracking studies for understanding fish–hypoxia interactions

Objective Hypoxia (i.e., low dissolved oxygen availability) is a natural phenomenon but can also be induced by human activities (e.g., nutrient enrichment from runoff). Given that dissolved oxygen is essential for aquatic life, periods of hypoxia tend to have negative consequences (e.g., sublethal disturbances, mortality) for most fishes. Extensive laboratory research has documented hypoxia thresholds and physiological and behavioral outcomes for a variety of freshwater and marine fishes and there is also an extensive body of fieldwork assessing population-level responses (e.g., survival, distribution). Yet, studying how individual fish respond to hypoxia in the wild has proved challenging; electronic tagging and tracking tools (e.g., biotelemetry, biologging) have made it easier to study individual responses to hypoxia and complement other tools like hydroacoustics that tend to focus on population-level responses. Methods We review what has been learned from contemporary studies that employ electronic tagging and tracking tools to understand how fish respond to hypoxia in the wild. Topics explored include identifying and validating hypoxia thresholds, habitat compression, connectivity, mortality, physiological and bioenergetic consequences, and extreme weather conditions. We also consider what we have learned about evaluating various management plans for hypoxia and reflect on how electronic tags have also been used in aquaculture systems and in hybrid studies that combine laboratory and field research. We highlight fishes in Lake Erie as a research narrative to demonstrate how electronic tagging and tracking have markedly improved our understanding of a longstanding hypoxia issue. Results Our synthesis revealed that electronic tagging and tracking have provided critical information on how fish respond to hypoxia in the field, revealing complex trade-offs and compensatory mechanisms as well as cryptic hypoxia-induced mortality. Beyond just illuminating space use and mortality, tags equipped with various sensors are revealing how fish deal with hypoxia in real time in terms of physiology, bioenergetics, and behavior. Conclusions As electronic tagging and tracking methods experience further innovation and are increasingly applied to understand the effects of hypoxia on fish, we expect more unanticipated findings about the effects of hypoxia on fish in all aquatic ecosystems, which will strengthen our ability to manage and mitigate hypoxia. Combining tools and approaches (e.g., lab and field) is perhaps the best way to generate comprehensive understanding.

Transactions of the American Fisheries Society↗