Little is known about the thermal tolerances of fish that occupy tropical intertidal habitats or how their distribution, physiological condition, and survival are influenced by water temperature. We ...used a combination of laboratory and field approaches to study the thermal biology of bonefish,
Albula vulpes, a fish species that relies on nearshore intertidal habitats throughout the Caribbean. The critical thermal maximum (CTMax) for bonefish was determined to be 36.4±0.5 and 37.9±0.5
°C for fish acclimated to 27.3±1.3 and 30.2±1.4
°C, respectively, and these tolerances are below maximal temperatures recorded in the tropical tidal habitats where bonefish frequently reside (i.e., up to 40.6
°C). In addition, daily temperatures can fluctuate up to 11.4
°C over a 24-h period emphasizing the dramatic range of temperatures that could be experienced by bonefish on a diel basis. Use of an acoustic telemetry array to monitor bonefish movements coupled with hourly temperature data collected within tidal creeks revealed a significant positive relationship between the amount of time bonefish spent in the upper portions of the creeks with the increasing maximal water temperature. This behavior is likely in response to feeding requirements necessary to fuel elevated metabolic demands when water temperatures generally warm, and also to avoid predators. For fish held in the laboratory, reaching CTMax temperatures elicited a secondary stress response that included an increase in blood lactate, glucose, and potassium levels. A field study that involved exposing fish to a standardized handling stressor at temperatures approaching their CTMax generated severe physiological disturbances relative to fish exposed to the same stressor at cooler temperatures. In addition, evaluation of the short-term survival of bonefish after surgical implantation of telemetry tags revealed that there was a positive relationship between water temperature at time of tagging and mortality. Collectively, the data from these laboratory and field studies suggest that bonefish occupy habitats that approach their laboratory-determined CTMax and can apparently do so without significant sub-lethal physiological consequences or mortality, except when exposed to additional stressors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
To date, most studies of commercial fisheries bycatch have focused on mortality at time of capture as an endpoint. However, sub-lethal indicators of organismal condition have the potential to reveal ...mechanisms associated with mortality (both at time of capture and post-release) and opportunities for improving fish welfare. In this study, we simulated commercial fishing efforts in inland lakes with fyke nets during a typical fishing season (early April to late June) in southeastern Ontario, Canada, where bycatch of non-target fish species had previously been documented. Using non-target gamefish (i.e., largemouth bass Micropterus salmoides, Lacépède, northern pike Esox Lucius, L.), as well as a target species (i.e., bluegill Lepomis macrochirus, Rafinesque), we examined the sub-lethal consequences of capture (e.g., blood physiology, reflex impairment, and injury) and compared the effects of being retained in the net for two different durations (i.e., two or six days) over a range of water temperatures (i.e., 3–28°C). Sub-lethal physiological disturbances (i.e., blood glucose and lactate) in largemouth bass and bluegill tended to be greater at higher water temperatures. However, fish retained for six days generally did not exhibit greater stress than those retained for two days, with the exception of plasma glucose in largemouth bass. Reflex impairment was similar among temperature and retention periods. Fish retained in nets experienced a range of injuries (including fin frays, scale loss, and mouth damage) that had the potential to facilitate the development of opportunistic pathogenic infections. Greater incidences of injury on fish bycatch tended to be associated with higher temperatures and longer retention. To reduce physiological disturbances and injury that could lead to delayed mortality, we suggest that regulations for inland commercial fishers require them to check their nets more frequently as water temperatures increase. We suggest that future studies of bycatch incorporate sub-lethal endpoints given that they serve as an objective measure of fish welfare and can provide quantitative mechanistic information to support management actions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) is a common tool used to examine aspects of elasmobranch biology and ecology; however, accurate ecological interpretation of stable ...isotope values requires knowledge of lipid and urea dynamics, and the variable turnover rates of different tissue types. Here we examined lipid and urea dynamics and inter-tissue comparisons of stable isotope values in 3 nearshore elasmobranch species, the nurse shark Ginglymostoma cirratum, southern stingray Hypanus americanus, and the Atlantic chupare stingray Styracura schmardae. Chemical extraction had no significant effect on δ13C and δ15N values of nurse shark muscle, and southern and chupare stingray fin, suggesting negligible lipid and urea components associated with these tissues. For nurse sharks, δ13C values were higher in muscle compared to dermis and δ15N was lower. The causes of this variability are underpinned by the metabolic variability between tissue types, the physiological function of which remains undetermined. Finally, we observed a significant relationship between muscle and dermis δ13C and δ15N, providing the first inter-tissue isotopic correction for nurse sharks. The results provide insight into lipid and urea dynamics, and aid sample preparation and ecological interpretation of stable isotope data in these taxa.
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Freshwater habitats and biota worldwide are in a conservation crisis, yet scientists and nongovernmental organizations have struggled to effectively engage the public to broaden awareness of needs ...for protecting aquatic ecosystems. As a result, the spectacular diversity and increasing imperilment of freshwater taxa remain poorly known outside our profession. Declining public trust of scientists creates further challenges as we try to limit losses of freshwater biodiversity. Reversing these trends requires a targeted collaborative effort from a variety of stakeholders that builds public and political support for freshwater science and conservation. Public aquaria can be key partners in this effort by providing a large audience (>150 million visitors annually) for conservation messaging in a trusted arena. Exhibits provide a visual connection to freshwater biota and their habitats, granting access to the underwater world for people who may have no prior exposure to river or lake ecosystems, particularly in urban centers. We identify a host of opportunities for fisheries scientists and aquarium staff to publicize conservation concerns, craft messages that connect with the public, and engage citizen scientists. Successfully fostering appreciation of freshwater biodiversity is requisite to protecting it in the future.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Coded electromyogram telemetry transmitters were used to examine the effects of varying flows on the relative activity of brook trout Salvelinus fontinalis and walleye Sander vitreus in a regulated ...river. The relative activity levels of two brook trout and two walleyes were continuously monitored for a minimum of 24 h, and measurements were compared with river flow values logged at nearby gauging stations. Generally, fish relative activity levels mimicked patterns of flow change, peaks in activity level corresponding to peaks in flow. Mean relative activity was generally greatest at extreme high (≥25‐m3/s) and low (<15‐m3/s) flows. High flows may have elicited hyperactivity (increased activity) as fish sought suitable refugia, increased activity to hold position in the water column, or increased feeding activity on increased levels of drifting invertebrates. Hyperactivity at low flows may have been caused by relocation due to habitat loss or ease of movement at lower flow regimes. Physiological telemetry provides researchers with a method of quantifying the immediate effects of flow changes on fish. Increasing our knowledge of the effects of river regulation on fish is essential to the development of more effective management strategies that balance ecology and economics.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Throughout their circumtropical distribution, bonefish (Albula spp.) play a vital role in local economies as a highly prized sport fish. Recent interest in stock enhancement to sustain bonefish ...fisheries has led to the recognition that there currently are no data on how to live capture large numbers of adults (potential broodstock), transport them to captive facilities and how to handle them to ensure high survival. The objective of this study was to develop strategies for the capture and relocation of wild bonefish to a marine research holding facility to enable basic research and explore the potential for culturing bonefish for stock enhancement. Bonefish Albula vulpes (Linnaeus, 1758) were captured as they entered or left tidal creeks on Eleuthera, The Bahamas using seine nets and then transported by boat or truck to the laboratory. The relocation process evoked secondary stress responses at the metabolic, osmoregulatory and haematological levels as indicated by changes in blood glucose, lactate, haematocrit and ion values, relative to control fish. Physical and behavioural disturbances were also observed in bonefish that were unable to acclimate to laboratory conditions. Successful laboratory acclimation and long-term holding of wild bonefish was achieved through an adaptive learning process, whereby we identified a series of strategies and handling techniques to facilitate the acclimation of wild adult bonefish to captivity. This knowledge will enable future laboratory research on bonefish and is a prerequisite to the culture of this highly prized sport fish, and other sub-tropical and tropical marine species.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Journal of International Wildlife Law & Policy To Tag or not to Tag: Animal Welfare, Conservation, and Stakeholder Considerations in Fish Tracking Studies That Use Electronic Tags
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38.
Corrigendum Shipley, Oliver N.; Murchie, Karen J.; Frisk, Michael G. ...
Marine ecology. Progress series (Halstenbek),
01/2018, Volume:
587
Journal Article
Peer reviewed
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Body composition and fish health indices of bonefish Albula vulpes were investigated to elucidate the energy dynamics in poorly studied tropical tidal flat environments. In general, bonefish were ...composed of 72% water, 21% protein, 4% ash, and 3% lipids, which is consistent with the wet weight values of the majority of freshwater and marine fish studied to date. Significant inverse relationships between the water and lipid contents of whole-body, gonad, and liver tissues revealed that the percentage of water is a good indicator of the relative amount of stored energy in bonefish and may be used as a surrogate for lipid content in future studies. The liver was the main storage site for lipids, containing more than twice the fat in the whole body. While both abiotic (e.g., season and location) and biotic (e.g., sex and size) factors contributed to the predictive power of the general linear models generated for all constituent analyses, there were no significant differences in whole-body or liver lipid content between seasons, which may be explained by there being a consistent food supply year-round. There was, however, a significant relationship between lipid content and body size with respect to season. Lipid content decreased in the winter and increased in the summer with increasing body size, a trend that can be explained by the timing of the reproductive season in bonefish. Seasonal changes in the condition factor and gonadosomatic indices were also linked to the winter spawning season, with decreasing body condition and increasing gonad development in the winter. Observed site-specific differences in the lipid content and liver somatic indices of bonefish may be accounted for by local trophodynamics as well as subtle differences in life history strategies. The energy reserve and fish health index data collected in this study may provide a useful baseline for future comparative work and help elucidate fish energetics in dynamic tropical tidal flat systems.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The sustainable seafood movement has adopted a variety of certification and ecolabeling systems, as well as seafood-awareness campaigns, to influence industry and help consumers make informed ...decisions regarding their seafood consumption. However, a review of these programs revealed that the majority are focused on marine and coastal fisheries. Globally, freshwaters and their fish assemblages represent some of the most threatened systems and taxa because of multiple anthropogenic stressors. There is an urgent need to harness the momentum of the sustainable seafood movement for marine systems to benefit all aquatic systems, including freshwater. Moreover, given that freshwater systems are at particular risk in developing countries in which small-scale fisheries dominate, it is essential to expand awareness campaigns, through grassroots initiatives that differ significantly from current awareness campaigns that are global in focus, involve industrialized large-scale fisheries, and assume significant exports of seafood. Addressing the limitations of marine campaigns is a logical first step before launching new programs aimed at inland fisheries. In the long term, failure of the sustainable seafood movement to incorporate freshwater fisheries will lead to public perception that these fisheries are not in peril and may allow unsustainable practices to continue.
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BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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