Recreational fishing is a popular activity in aquatic ecosystems around the globe using a variety of gears including rod and line and to a lesser extent handlines, spears, bow and arrow, traps and ...nets. Similar to the propensity to engage in voluntary catch‐and‐release, the propensity to harvest fishes strongly varies among cultures, locations, species and fisheries. There is a misconception that because recreational fishing happens during non‐work (i.e. leisure) time, the nutritional motivation is negligible; therefore, the role of recreational fishing in supporting nutrition (and thus food security) at regional, national or global scales is underappreciated. We consider the factors that influence whether fish will be harvested or released by examining the motives that underlie recreational fishing. Next, we provide an overview of the magnitude and role of recreational fishing harvest in supporting nutrition using regional case‐studies. Then, we address issues such as contaminants and parasites that constrain the ability of fish harvested by recreational fishers to be consumed. Although recreational fishing is foremost a leisure activity, the harvest of fish for personal consumption by recreational fishers has contributed and will continue to contribute to human nutrition by providing an accessible, affordable and generally highly sustainable food source, notwithstanding concerns about food safety and possibly overfishing. Attempts to better quantify the role of fish harvested by recreational fishers and the relative contribution to overall food security and personal nutrition will provide resource managers and policymakers the information needed to guide management activities and policy development.
War is an ever-present force that has the potential to alter the biosphere. Here we review the potential consequences of modern war and military activities on ecosystem structure and function. We ...focus on the effects of direct conflict, nuclear weapons, military training, and military produced contaminants. Overall, the aforementioned activities were found to have overwhelmingly negative effects on ecosystem structure and function. Dramatic habitat alteration, environmental pollution, and disturbance contributed to population declines and biodiversity losses arising from both acute and chronic effects in both terrestrial and aquatic systems. In some instances, even in the face of massive alterations to ecosystem structure, recovery was possible. Interestingly, military activity was beneficial under specific conditions, such as when an exclusion zone was generated that generally resulted in population increases and (or) population recovery; an observation noted in both terrestrial and aquatic systems. Additionally, military technological advances (e.g., GPS technology, drone technology, biotelemetry) have provided conservation scientists with novel tools for research. Because of the challenges associated with conducting research in areas with military activities (e.g., restricted access, hazardous conditions), information pertaining to military impacts on the environment are relatively scarce and are often studied years after military activities have ceased and with no knowledge of baseline conditions. Additional research would help to elucidate the environmental consequences (positive and negative) and thus reveal opportunities for mitigating negative effects while informing the development of optimal strategies for rehabilitation and recovery.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A prerequisite to studying the physiological status of wild animals is the ability to obtain blood samples that reflect the condition prior to capture or handling. Based on research in avian taxa, it ...is recommended that such samples be obtained within 3 min of capture; however, this guideline has not been validated in wild teleosts. The present study addresses the time course of physiological changes in a number of blood metrics across six species of freshwater fish. Fishes were caught using a standardized angling protocol and held in a water-filled trough prior to the collection of a blood sample, via caudal phlebotomy, between 0.5 and 11 min after capture. Changes in whole-blood glucose and lactate concentrations, hematocrit, and plasma cortisol concentrations were assessed. Change-point analyses indicated that blood lactate concentrations and hematocrit did not deviate from baseline values until ∼2–5 min of handling for all species, whereas blood glucose concentrations generally did not deviate significantly from baseline over the 11 min test period. In all species, plasma cortisol concentrations began to increase above baseline between ∼4 and 8 min after capture. Thus, to ensure that blood samples are representative of baseline conditions across multiple metrics, we recommend that sampling be limited to less than 2 min in teleost fishes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Acute elevation of cortisol via activation of the hypothalamic-pituitary-interrenal (HPI) axis aids the fish in dealing with a stressor. However, chronic elevation of cortisol has detrimental effects ...and has been studied extensively in lab settings. However, data pertaining to wild teleosts are lacking. Here, we characterized the metabolic consequences of prolonged cortisol elevation (96 h) in wild-caught pumpkinseed (
Lepomis gibbosus
). Pumpkinseed were implanted with cocoa butter alone (sham) or containing cortisol (25 mg kg
−1
body weight), and at 24, 48, 72, and 96 h, tissue samples were collected, whole-body ammonia excretion was determined, and whole-organism metabolism was assessed using intermittent flow respirometry. Cortisol-treated pumpkinseed exhibited the highest plasma cortisol concentration at 24 h post-implantation, with levels decreasing over the subsequent time points although remaining higher than in sham-treated fish. Cortisol-treated fish exhibited higher standard and maximal metabolic rates than sham-treated fish, but the effect of cortisol treatment on aerobic scope was negligible. Indices of energy synthesis/mobilization, including blood glucose concentrations, hepatosomatic index, hepatic glycogen concentrations, and ammonia excretion rates, were higher in cortisol-treated fish compared with controls. Our work suggests that although aerobic scope was not diminished by prolonged elevation of cortisol levels, higher metabolic expenditures may be of detriment to the animal’s performance in the longer term.
Paternal care, where the male provides sole care for the developing brood, is a common form of reproductive investment among teleost fish and ubiquitous in the Centrarchidae family. Throughout the ...parental care period, nesting males expend energy in a variety of swimming behaviours, including routine and burst swimming, vigilantly monitoring the nest area and protecting the brood from predators. Parental care is an energetically demanding period, which is presumably made even more difficult if fish are exposed to additional challenges such as those arising from human disturbance, resulting in activation of the hypothalamic-pituitary-interrenal axis (i.e., elevation of cortisol). To study this situation, we examined the effects of experimental manipulation of the stress hormone cortisol on locomotor activity and behaviour of nest guarding male smallmouth bass (Micropterus dolomieu). We exogenously elevated circulating cortisol levels (via intracoelomic implants) and attached tri-axial accelerometers to wild smallmouth bass for three days. During the recovery period (i.e., ≤4h post-release), cortisol-treated fish exhibited significantly reduced locomotor activity and performed significantly less burst and routine swimming relative to control fish, indicating cortisol uptake was rapid, as were the associated behavioural responses. Post-recovery (i.e., >4h post-release), fish with high cortisol exhibited lower locomotor activity and reduced routine swimming relative to controls. Fish were less active and reduced routine and burst swimming at night compared to daylight hours, an effect independent of cortisol treatment. Collectively, our results suggest that cortisol treatment (as a proxy for anthropogenic disturbance and stress) contributed to altered behaviour, and consequently cortisol-treated males decreased parental investment in their brood, which could have potential fitness implications.
•Cortisol-treated fish exhibited reduced locomotor activity level relative to controls•Cortisol-treated fish spent less time routine and burst swimming relative to controls•Locomotor activity and swimming behaviours varied according to diel period
Research in a variety of vertebrate taxa has found that cardiac function is a major limiting factor in the ability of animals to cope with physiological challenges, and thus is suggested to play an ...important role in mediating fitness-related behaviors in the wild. Yet, there remains a paucity of empirical assessments of the relationships between physiological performance and biological fitness in wild animals, partially due to challenges in measuring these metrics remotely. Using male smallmouth bass (Micropterus dolomieu) as a model, we tested for relationships between cardiac performance (measured using heart rate biologgers) and fitness-related behaviors (assessed using videography and snorkeler observations) in the wild during the parental care period. Our results showed that heart rates were not significantly related to any measured parental care behaviors (e.g., nest tending) except for individual aggression level. After accounting for the effect of water temperature on heart rate, we found within-individual heart rate differed between days and also differed between nights. There was, however, evidence of diel variation in heart rate, where heart rate was higher during the day than at night. Although fitness is thought to be dependent on physiological capacity for exercise in wild animals, inter-individual variation in heart rate alone does not appear to relate to parental care behavior in smallmouth bass at the temporal scales examined here (i.e., hours to days). Further studies are required to confirm relationships between physiological performance and parental care behavior to elucidate the apparently complex relationships between physiology, behavior, and fitness in wild animals.
•Wild, male smallmouth bass (Micropterus dolomieu) were implanted with temperature and heart rate biologgers and released.•Fish parental care behavior was monitored for two days to relate routine heart rate to parental care behavior.•Smallmouth bass show individual physiological and behavioral variation during parental care.•There was a positive relationship between heart rate and individual aggression level.•The relationship between physiology, behavior, and fitness in wild animals is complex.
Ecological light pollution occurs when artificial lights disrupt the natural regimes of individual organisms or their ecosystems. Increasing development of shoreline habitats leads to increased light ...pollution (e.g., from cottages, docks, automobile traffic), which could impact the ecology of littoral zones of lakes and rivers. Smallmouth bass (
Micropterus dolomieu
) engage in sole paternal care, guarding their nest continually, day and night, to protect their developing offspring. Any alterations to their behaviour—either directly because of the response to light or indirectly due to changes in nest predator activity and associated response of the bass—could lead to increased energetic demands for fish that have a fixed energy budget and ultimately reduce reproductive success. To examine this issue, tri-axial accelerometer biologgers were externally attached to nesting smallmouth bass during the egg stage to determine whether light pollution (i.e., dock lights with low levels of continuous light and spotlights with high intensity irregular light simulating automobile traffic) altered behaviour of nesting males relative to control fish. Our study revealed that both types of light pollution increased overall bass activity level compared with the control group. The intermittent light treatment group had the highest activity and exhibited large fluctuations between night and day activity levels. Fish in the continual light treatment group displayed statistically higher activity than the control fish but showed limited fluctuations between day and night activity levels. Our results suggest that continuous or intermittent light sources, common in shoreline habitats that have been developed, have the potential to alter the behaviour and thus energy use of nest-guarding fish. This study contributes to the growing body of literature on the ecological consequences of light pollution in aquatic ecosystems.
•Lure choice is an important aspect of managing catch-and-release fisheries.•Physical characteristics of lures can impact fish injury and stress.•Angler experience was not as important as lure choice ...during this study.•There may be tradeoffs between minimizing injury and reducing stress.
Catch-and-release (C&R) angling is common with anglers releasing a portion of their catch to comply with harvest regulations or because of their conservation ethic. The basis of C&R lies in the assumption that a large proportion of the fish survive and experience limited fitness consequences – that is, the welfare status of individual fish is maintained. However, the level of experience of an angler, as well as use of different gear and lure types, can greatly influence the rate of hooking injury and mortality. These relationships have been documented for a variety of fish species, but few studies have considered the influence of both angler experience and gear or lure type simultaneously. The aim of this study was to evaluate the relationships between angler experience, lure characteristics, landing time, hooking injury, and handling time in the Largemouth Bass (Micropterus salmoides). Largemouth Bass were captured by hook and line between July and September 2018 by anglers with a wide range of experience (novice to professional). During and after these events, measurements were taken on fish characteristics, angler experience, lure characteristics, and welfare outcomes. Generalized linear models indicated that lure characteristics (lure type, size, and number of hooks) had a significant influence on fish injury and handling time, whereas angler experience did not. Specifically, lures with more hook points resulted in shallower hooking depths but longer dehooking times. These results indicate that lure choice is an important aspect of managing C&R fisheries. When choosing a lure, there may be a tradeoff between minimizing the physiological stress associated with handling and air exposure, and reducing the chances of injury and deep hooking. Additional research is needed to better understand such trade-offs across a range of environmental conditions and species.
The capacity to extract oxygen from the water, and the ability of the heart to drive tissue oxygen transport, are fundamental determinants of important life-history performance traits in fish. ...Cardiac performance is in turn dependent on the heart's own oxygen supply, which in some teleost species is partly delivered via a coronary circulation originating directly from the gills that perfuses the heart, and is crucial for cardiac, metabolic and locomotory capacities. It is currently unknown, however, how a compromised branchial blood flow (e.g., by angling-induced hook damage to the gills), constraining oxygen uptake and coronary blood flow, affects the energetically demanding parental care behaviours and reproductive fitness in fish. Here, we tested the hypothesis that blocking ¼ of the branchial blood flow and abolishing coronary blood flow would negatively affect parental care behaviours, cardiac performance (heart rate metrics, via implanted Star-Oddi heart rate loggers) and reproductive fitness of paternal smallmouth bass (Micropterus dolomieu). Our findings reveal that branchial/coronary ligation compromised reproductive fitness, as reflected by a lower proportion of broods reaching free-swimming fry and a tendency for a higher nest abandonment rate relative to sham operated control fish. While this was associated with a tendency for a reduced aggression in ligated fish, parental care behaviours were largely unaffected by the ligation. Moreover, the ligation did not impair any of the heart rate performance metrics. Our findings highlight that gill damage may compromise reproductive output of smallmouth bass populations during the spawning season. Yet, the mechanism(s) behind this finding remains elusive.
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•The effects of induced gill damage on parental care was assessed in smallmouth bass.•Fish were instrumented with heart rate bio-loggers to assess heart rate performances.•Induced gill damage during spawning reduced reproductive fitness in bass.•Heart rate performances was unaffected by induced gill damage in smallmouth bass.
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