The Experts below are selected from a list of 1332 Experts worldwide ranked by ideXlab platform
Steven J. Cooke - One of the best experts on this subject based on the ideXlab platform.
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Using Behavioral Observations to Develop Escape Devices for Freshwater Turtles Entrapped in Fishing Nets
Journal of Fish and Wildlife Management, 2016Co-Authors: Nicholas A. Cairns, Gabriel Blouin-demers, Lauren J. Stoot, Steven J. CookeAbstract:Abstract The drowning of freshwater turtles following incidental capture in fishing gear has the potential to cause population declines. Fyke Nets can be equipped with bycatch reduction devices that enable the escape of turtles before they drown. We employed quantitative and qualitative behavioral observations (with action cameras deployed underwater) to develop a new, collapsible, escape bycatch-reduction device that mounts internally in the terminal end of a Fyke net. We also used behavioral observations to identify areas of the net most used by turtles, thus revealing the most logical placement for an escape bycatch-reduction device. When turtles were introduced into modified Nets, escape was rapid (mean of 12.4 min), with 100% escape for map Graptemys geographica and musk turtles Sternotherus odoratus and 94% escape for painted turtles Chrysemys picta. Our preliminary field trials indicated that modified Fyke Nets decreased the capture rate of turtles relative to unmodified Nets. Escape devices can be...
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Accidental Bait: Do Deceased Fish Increase Freshwater Turtle Bycatch in Commercial Fyke Nets?
Environmental Management, 2012Co-Authors: Sarah M. Larocque, Paige Watson, Gabriel Blouin-demers, Steven J. CookeAbstract:Bycatch of turtles in passive inland Fyke net fisheries has been poorly studied, yet bycatch is an important conservation issue given the decline in many freshwater turtle populations. Delayed maturity and low natural adult mortality make turtles particularly susceptible to population declines when faced with additional anthropogenic adult mortality such as bycatch. When turtles are captured in Fyke Nets, the prolonged submergence can lead to stress and subsequent drowning. Fish die within infrequently checked passive fishing Nets and dead fish are a potential food source for many freshwater turtles. Dead fish could thus act as attractants and increase turtle captures in fishing Nets. We investigated the attraction of turtles to decomposing fish within Fyke Nets in eastern Ontario. We set Fyke Nets with either 1 kg of one-day or five-day decomposed fish, or no decomposed fish in the cod-end of the net. Decomposing fish did not alter the capture rate of turtles or fish, nor did it alter the species composition of the catch. Thus, reducing fish mortality in Nets using shorter soak times is unlikely to alter turtle bycatch rates since turtles were not attracted by the dead fish. Interestingly, turtle bycatch rates increased as water temperatures did. Water temperature also influences turtle mortality by affecting the duration turtles can remain submerged. We thus suggest that submerged Nets to either not be set or have reduced soak times in warm water conditions (e.g., >20 °C) as turtles tend to be captured more frequently and cannot withstand prolonged submergence.
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Mitigating bycatch of freshwater turtles in passively fished Fyke Nets through the use of exclusion and escape modifications
Fisheries Research, 2012Co-Authors: Sarah M. Larocque, Steven J. Cooke, Gabriel Blouin-demersAbstract:a b s t r a c t Turtles are vulnerable to population declines in response to even low levels of additional adult mortality, for instance bycatch mortality. Inland commercial fisheries that use passive gears such as Fyke Nets cause the drowning of some freshwater turtles. To reduce fisheries impacts on turtles, bycatch reduction devices (BRDs) successfully implemented in marine systems may be adapted to freshwater systems. We tested the efficacy of two BRDs designed to exclude turtles from Fyke Nets by comparing catch rates and composition to unmodified Nets. We also tested the efficacy of a BRD designed to let turtles escape the net by comparing turtle and fish escape capacities to a large hole in the net. The exclusion device with bars across the net opening significantly reduced turtle catch rates, and both exclusion devices did not affect fish catch rates. With the escape device, all turtles escaped (using painted turtles, Chrysemys picta, as an experimental model) and most (88%) fish were retained while a large hole allowed 60% and 77% of turtles and fish to escape, respectively. The escape device was the most effective for avoiding turtle bycatch mortality while retaining fish. Implementing the escape device or a combination of both exclusion and escape devices would reduce turtle bycatch mortality within Fyke net fisheries. However, evaluations are needed to test the effectiveness of escape designs on additional turtle species and in different environments.
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A breath of fresh air: avoiding anoxia and mortality of freshwater turtles in Fyke Nets by the use of floats
Aquatic Conservation: Marine and Freshwater Ecosystems, 2012Co-Authors: Sarah M. Larocque, Steven J. Cooke, Gabriel Blouin-demersAbstract:Freshwater turtles are susceptible to drowning in commercial fishing Nets and this is a major conservation concern. Methods to mitigate turtle bycatch mortality typically involve reducing the capture of bycatch using gear modifications. Another method to reduce mortality is to keep bycatch alive following capture. Using physiological measures of anoxia, this study determined whether providing air spaces using floats within Fyke Nets could prevent turtles from drowning. In a controlled setting, blood lactate and pH of painted turtles (Chrysemys picta) experimentally introduced into submerged Nets, Nets with floats, and Nets that breached the surface were compared. While emulating commercial fishing practices – where turtles and fish voluntarily entered Nets – catch rates and compositions as well as blood lactate in turtles captured were compared in submerged Nets with and without floats. Painted turtles in submerged Nets exhibited elevated blood lactate and pronounced acidosis compared with turtles from Nets with floats and surfaced Nets. Catch rates and compositions from emulated fishing were statistically similar in Nets with and without floats; however, total fish catches were roughly one-third less in Nets with floats. The same pattern of physiological disturbance was observed with turtles captured in submerged Nets with and without floats as in the controlled experiment. Overall, blood physiology indicated that anoxia occurred in turtles in submerged Nets while Nets with floats reduced physiological disturbance. However, variation in blood lactate levels when fishing Fyke Nets with floats suggests that turtles were experiencing slight anoxia and so the size of air spaces may be important in allowing access to air. Creating air spaces in Fyke Nets using floats is a simple and cost-effective method to avoid the drowning of turtles. Copyright © 2012 John Wiley & Sons, Ltd.
Brian G. Blackwell - One of the best experts on this subject based on the ideXlab platform.
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Comparison of Two Escapement Designs for Western Painted Turtles Captured in Modified Fyke Nets
Journal of Fish and Wildlife Management, 2017Co-Authors: Tyrel S. Moos, Brian G. BlackwellAbstract:Abstract Altering sampling methods to reduce bycatch during fish population sampling can introduce biases that affect the capture of target species. Therefore, understanding bycatch reduction devices and how they affect fish sampling is important. Our goal was to test two potential escapement designs intended to reduce bycatch of western painted turtles Chrysemys picta bellii during freshwater-fish population assessments with modified Fyke Nets. Design A tested an escapement flap on the interior of the modified Fyke net and design B tested an escapement throat on the exterior of the modified Fyke net. We completed 4-h and 24-h trials for turtle escapement to determine the effectiveness of each design for reducing turtle bycatch. We also simulated fish population assessments to determine the escapement of fish and turtles from each design. Turtles escaped from each design with mean escapement rates during the 4-h and 24-h trials of 71.1% and 63.8% from design A and 55.6% and 50.0% from design B, respective...
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Condition and mortality of western painted turtle collected as bycatch in modified Fyke Nets during fish population assessments
Journal of Freshwater Ecology, 2017Co-Authors: Tyrel S. Moos, Brian G. BlackwellAbstract:ABSTRACTInformation concerning turtle bycatch and its possible ramifications during biological sampling in freshwater systems is limited. Having such information will enable fisheries researchers and managers to modify fish sampling procedures to potentially minimize any impacts on turtle populations. Therefore, our objective was to utilize reflex response to characterize stress and mortality of western painted turtles (Chrysemys picta bellii) captured as bycatch in modified Fyke Nets during fish population assessments. Reflex-response-based condition classification (i.e. good, poor, unresponsive) data were collected from May to September during fish population assessments in 38 lakes and seven impoundments in northeast South Dakota from 2012 to 2014. We evaluated the relationship between observed condition and water temperature during two time periods, by turtle gender and size. Turtle bycatch mortality was assessed from June to September during fish population assessments in 14 lakes and three impoundme...
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Condition and mortality of western painted turtle collected as bycatch in modified Fyke Nets during fish population assessments
Taylor & Francis Group, 2017Co-Authors: Tyrel S. Moos, Brian G. BlackwellAbstract:Information concerning turtle bycatch and its possible ramifications during biological sampling in freshwater systems is limited. Having such information will enable fisheries researchers and managers to modify fish sampling procedures to potentially minimize any impacts on turtle populations. Therefore, our objective was to utilize reflex response to characterize stress and mortality of western painted turtles (Chrysemys picta bellii) captured as bycatch in modified Fyke Nets during fish population assessments. Reflex-response-based condition classification (i.e. good, poor, unresponsive) data were collected from May to September during fish population assessments in 38 lakes and seven impoundments in northeast South Dakota from 2012 to 2014. We evaluated the relationship between observed condition and water temperature during two time periods, by turtle gender and size. Turtle bycatch mortality was assessed from June to September during fish population assessments in 14 lakes and three impoundments during 2013 and 2014. Delayed (i.e. overnight) mortality was determined for poor and unresponsive condition classifications and the relationship between observed mortality and water temperature for two time periods, by turtle gender and size was evaluated. Turtle condition decreased as water temperature increased. Condition was poorer during the May and June time period than August and September. Female turtles were in significantly worse condition than males. Condition was not related to turtle size. We observed varying mortality rates across condition classifications and the total estimated delayed mortality rate of known sex turtles was 36.4%. Mortality increased as temperature increased. Delayed mortality rates varied between the two sampling periods with higher mortality rates during the May and June time period. Female turtles had higher mortality rates than males. Delayed mortality did not vary by turtle size. Understanding the negative effects on bycatch during biological sampling is important to provide justification for the development and implementation of measures to protect non-target species
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Escapement of Fishes from Modified Fyke Nets with Differing Throat Configurations
North American Journal of Fisheries Management, 2016Co-Authors: Bradley J. Smith, Brian G. Blackwell, Melissa R. Wuellner, Brian D. S. Graeb, David W. WillisAbstract:AbstractWe performed a field experiment in five eastern South Dakota lakes to investigate fish escapement differences between modified Fyke Nets with two common throat configurations (restricted and unrestricted). Nets with restricted and unrestricted throats were deployed in pairs for 24 h on similar habitat. Captured fish were measured for TL and were given day-specific marks. The paired Nets were redeployed, and marked fish were randomly assigned to be stocked into the restricted or unrestricted net for 24 h; stocking densities (stratified into low, medium, and high) were species specific. Marked fish that were retained after 24 h were used to quantify escapement, whereas newly captured fish were used to estimate differences in mean CPUE and size structure. Mean CPUE of Black Bullheads Ameiurus melas, Black Crappies Pomoxis nigromaculatus, and Bluegills Lepomis macrochirus approximately doubled when restricted Nets were used. Mean TL of Black Crappies was 31 mm greater (95% confidence interval [CI] = 6...
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Characterization of Western Painted Turtle Bycatch in Fyke Nets During Freshwater Fish Population Assessments
Journal of Fish and Wildlife Management, 2015Co-Authors: Tyrel S. Moos, Brian G. BlackwellAbstract:Abstract In fisheries management, fish populations are assessed using various net types that invariably also capture nontarget species. Although the bycatch of turtles tends to be a common occurrence, data describing the bycatch of turtles during freshwater fish sampling are lacking. To improve the available knowledge base concerning the bycatch of turtles during fish sampling, we characterize the dynamics of western painted turtle Chrysemys picta bellii bycatch in unbaited modified Fyke Nets used in fish population sampling in northeastern South Dakota. We collected data from June to September during fish population assessments in 39 lakes and nine impoundments between 2007 and 2012. We characterize western painted turtle bycatch relating to water type (lake and impoundment) including catch rates (number of turtles/net night), size structure, and sex ratio. Catch rates were higher in impoundments than lakes. Total mean annual catch rates ranged from 1.07 to 3.28 for lakes and from 0.70 to 6.63 for impoun...
Gabriel Blouin-demers - One of the best experts on this subject based on the ideXlab platform.
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Using Behavioral Observations to Develop Escape Devices for Freshwater Turtles Entrapped in Fishing Nets
Journal of Fish and Wildlife Management, 2016Co-Authors: Nicholas A. Cairns, Gabriel Blouin-demers, Lauren J. Stoot, Steven J. CookeAbstract:Abstract The drowning of freshwater turtles following incidental capture in fishing gear has the potential to cause population declines. Fyke Nets can be equipped with bycatch reduction devices that enable the escape of turtles before they drown. We employed quantitative and qualitative behavioral observations (with action cameras deployed underwater) to develop a new, collapsible, escape bycatch-reduction device that mounts internally in the terminal end of a Fyke net. We also used behavioral observations to identify areas of the net most used by turtles, thus revealing the most logical placement for an escape bycatch-reduction device. When turtles were introduced into modified Nets, escape was rapid (mean of 12.4 min), with 100% escape for map Graptemys geographica and musk turtles Sternotherus odoratus and 94% escape for painted turtles Chrysemys picta. Our preliminary field trials indicated that modified Fyke Nets decreased the capture rate of turtles relative to unmodified Nets. Escape devices can be...
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Accidental Bait: Do Deceased Fish Increase Freshwater Turtle Bycatch in Commercial Fyke Nets?
Environmental Management, 2012Co-Authors: Sarah M. Larocque, Paige Watson, Gabriel Blouin-demers, Steven J. CookeAbstract:Bycatch of turtles in passive inland Fyke net fisheries has been poorly studied, yet bycatch is an important conservation issue given the decline in many freshwater turtle populations. Delayed maturity and low natural adult mortality make turtles particularly susceptible to population declines when faced with additional anthropogenic adult mortality such as bycatch. When turtles are captured in Fyke Nets, the prolonged submergence can lead to stress and subsequent drowning. Fish die within infrequently checked passive fishing Nets and dead fish are a potential food source for many freshwater turtles. Dead fish could thus act as attractants and increase turtle captures in fishing Nets. We investigated the attraction of turtles to decomposing fish within Fyke Nets in eastern Ontario. We set Fyke Nets with either 1 kg of one-day or five-day decomposed fish, or no decomposed fish in the cod-end of the net. Decomposing fish did not alter the capture rate of turtles or fish, nor did it alter the species composition of the catch. Thus, reducing fish mortality in Nets using shorter soak times is unlikely to alter turtle bycatch rates since turtles were not attracted by the dead fish. Interestingly, turtle bycatch rates increased as water temperatures did. Water temperature also influences turtle mortality by affecting the duration turtles can remain submerged. We thus suggest that submerged Nets to either not be set or have reduced soak times in warm water conditions (e.g., >20 °C) as turtles tend to be captured more frequently and cannot withstand prolonged submergence.
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Mitigating bycatch of freshwater turtles in passively fished Fyke Nets through the use of exclusion and escape modifications
Fisheries Research, 2012Co-Authors: Sarah M. Larocque, Steven J. Cooke, Gabriel Blouin-demersAbstract:a b s t r a c t Turtles are vulnerable to population declines in response to even low levels of additional adult mortality, for instance bycatch mortality. Inland commercial fisheries that use passive gears such as Fyke Nets cause the drowning of some freshwater turtles. To reduce fisheries impacts on turtles, bycatch reduction devices (BRDs) successfully implemented in marine systems may be adapted to freshwater systems. We tested the efficacy of two BRDs designed to exclude turtles from Fyke Nets by comparing catch rates and composition to unmodified Nets. We also tested the efficacy of a BRD designed to let turtles escape the net by comparing turtle and fish escape capacities to a large hole in the net. The exclusion device with bars across the net opening significantly reduced turtle catch rates, and both exclusion devices did not affect fish catch rates. With the escape device, all turtles escaped (using painted turtles, Chrysemys picta, as an experimental model) and most (88%) fish were retained while a large hole allowed 60% and 77% of turtles and fish to escape, respectively. The escape device was the most effective for avoiding turtle bycatch mortality while retaining fish. Implementing the escape device or a combination of both exclusion and escape devices would reduce turtle bycatch mortality within Fyke net fisheries. However, evaluations are needed to test the effectiveness of escape designs on additional turtle species and in different environments.
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A breath of fresh air: avoiding anoxia and mortality of freshwater turtles in Fyke Nets by the use of floats
Aquatic Conservation: Marine and Freshwater Ecosystems, 2012Co-Authors: Sarah M. Larocque, Steven J. Cooke, Gabriel Blouin-demersAbstract:Freshwater turtles are susceptible to drowning in commercial fishing Nets and this is a major conservation concern. Methods to mitigate turtle bycatch mortality typically involve reducing the capture of bycatch using gear modifications. Another method to reduce mortality is to keep bycatch alive following capture. Using physiological measures of anoxia, this study determined whether providing air spaces using floats within Fyke Nets could prevent turtles from drowning. In a controlled setting, blood lactate and pH of painted turtles (Chrysemys picta) experimentally introduced into submerged Nets, Nets with floats, and Nets that breached the surface were compared. While emulating commercial fishing practices – where turtles and fish voluntarily entered Nets – catch rates and compositions as well as blood lactate in turtles captured were compared in submerged Nets with and without floats. Painted turtles in submerged Nets exhibited elevated blood lactate and pronounced acidosis compared with turtles from Nets with floats and surfaced Nets. Catch rates and compositions from emulated fishing were statistically similar in Nets with and without floats; however, total fish catches were roughly one-third less in Nets with floats. The same pattern of physiological disturbance was observed with turtles captured in submerged Nets with and without floats as in the controlled experiment. Overall, blood physiology indicated that anoxia occurred in turtles in submerged Nets while Nets with floats reduced physiological disturbance. However, variation in blood lactate levels when fishing Fyke Nets with floats suggests that turtles were experiencing slight anoxia and so the size of air spaces may be important in allowing access to air. Creating air spaces in Fyke Nets using floats is a simple and cost-effective method to avoid the drowning of turtles. Copyright © 2012 John Wiley & Sons, Ltd.
Sarah M. Larocque - One of the best experts on this subject based on the ideXlab platform.
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Accidental Bait: Do Deceased Fish Increase Freshwater Turtle Bycatch in Commercial Fyke Nets?
Environmental Management, 2012Co-Authors: Sarah M. Larocque, Paige Watson, Gabriel Blouin-demers, Steven J. CookeAbstract:Bycatch of turtles in passive inland Fyke net fisheries has been poorly studied, yet bycatch is an important conservation issue given the decline in many freshwater turtle populations. Delayed maturity and low natural adult mortality make turtles particularly susceptible to population declines when faced with additional anthropogenic adult mortality such as bycatch. When turtles are captured in Fyke Nets, the prolonged submergence can lead to stress and subsequent drowning. Fish die within infrequently checked passive fishing Nets and dead fish are a potential food source for many freshwater turtles. Dead fish could thus act as attractants and increase turtle captures in fishing Nets. We investigated the attraction of turtles to decomposing fish within Fyke Nets in eastern Ontario. We set Fyke Nets with either 1 kg of one-day or five-day decomposed fish, or no decomposed fish in the cod-end of the net. Decomposing fish did not alter the capture rate of turtles or fish, nor did it alter the species composition of the catch. Thus, reducing fish mortality in Nets using shorter soak times is unlikely to alter turtle bycatch rates since turtles were not attracted by the dead fish. Interestingly, turtle bycatch rates increased as water temperatures did. Water temperature also influences turtle mortality by affecting the duration turtles can remain submerged. We thus suggest that submerged Nets to either not be set or have reduced soak times in warm water conditions (e.g., >20 °C) as turtles tend to be captured more frequently and cannot withstand prolonged submergence.
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Mitigating bycatch of freshwater turtles in passively fished Fyke Nets through the use of exclusion and escape modifications
Fisheries Research, 2012Co-Authors: Sarah M. Larocque, Steven J. Cooke, Gabriel Blouin-demersAbstract:a b s t r a c t Turtles are vulnerable to population declines in response to even low levels of additional adult mortality, for instance bycatch mortality. Inland commercial fisheries that use passive gears such as Fyke Nets cause the drowning of some freshwater turtles. To reduce fisheries impacts on turtles, bycatch reduction devices (BRDs) successfully implemented in marine systems may be adapted to freshwater systems. We tested the efficacy of two BRDs designed to exclude turtles from Fyke Nets by comparing catch rates and composition to unmodified Nets. We also tested the efficacy of a BRD designed to let turtles escape the net by comparing turtle and fish escape capacities to a large hole in the net. The exclusion device with bars across the net opening significantly reduced turtle catch rates, and both exclusion devices did not affect fish catch rates. With the escape device, all turtles escaped (using painted turtles, Chrysemys picta, as an experimental model) and most (88%) fish were retained while a large hole allowed 60% and 77% of turtles and fish to escape, respectively. The escape device was the most effective for avoiding turtle bycatch mortality while retaining fish. Implementing the escape device or a combination of both exclusion and escape devices would reduce turtle bycatch mortality within Fyke net fisheries. However, evaluations are needed to test the effectiveness of escape designs on additional turtle species and in different environments.
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A breath of fresh air: avoiding anoxia and mortality of freshwater turtles in Fyke Nets by the use of floats
Aquatic Conservation: Marine and Freshwater Ecosystems, 2012Co-Authors: Sarah M. Larocque, Steven J. Cooke, Gabriel Blouin-demersAbstract:Freshwater turtles are susceptible to drowning in commercial fishing Nets and this is a major conservation concern. Methods to mitigate turtle bycatch mortality typically involve reducing the capture of bycatch using gear modifications. Another method to reduce mortality is to keep bycatch alive following capture. Using physiological measures of anoxia, this study determined whether providing air spaces using floats within Fyke Nets could prevent turtles from drowning. In a controlled setting, blood lactate and pH of painted turtles (Chrysemys picta) experimentally introduced into submerged Nets, Nets with floats, and Nets that breached the surface were compared. While emulating commercial fishing practices – where turtles and fish voluntarily entered Nets – catch rates and compositions as well as blood lactate in turtles captured were compared in submerged Nets with and without floats. Painted turtles in submerged Nets exhibited elevated blood lactate and pronounced acidosis compared with turtles from Nets with floats and surfaced Nets. Catch rates and compositions from emulated fishing were statistically similar in Nets with and without floats; however, total fish catches were roughly one-third less in Nets with floats. The same pattern of physiological disturbance was observed with turtles captured in submerged Nets with and without floats as in the controlled experiment. Overall, blood physiology indicated that anoxia occurred in turtles in submerged Nets while Nets with floats reduced physiological disturbance. However, variation in blood lactate levels when fishing Fyke Nets with floats suggests that turtles were experiencing slight anoxia and so the size of air spaces may be important in allowing access to air. Creating air spaces in Fyke Nets using floats is a simple and cost-effective method to avoid the drowning of turtles. Copyright © 2012 John Wiley & Sons, Ltd.
Tyrel S. Moos - One of the best experts on this subject based on the ideXlab platform.
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Comparison of Two Escapement Designs for Western Painted Turtles Captured in Modified Fyke Nets
Journal of Fish and Wildlife Management, 2017Co-Authors: Tyrel S. Moos, Brian G. BlackwellAbstract:Abstract Altering sampling methods to reduce bycatch during fish population sampling can introduce biases that affect the capture of target species. Therefore, understanding bycatch reduction devices and how they affect fish sampling is important. Our goal was to test two potential escapement designs intended to reduce bycatch of western painted turtles Chrysemys picta bellii during freshwater-fish population assessments with modified Fyke Nets. Design A tested an escapement flap on the interior of the modified Fyke net and design B tested an escapement throat on the exterior of the modified Fyke net. We completed 4-h and 24-h trials for turtle escapement to determine the effectiveness of each design for reducing turtle bycatch. We also simulated fish population assessments to determine the escapement of fish and turtles from each design. Turtles escaped from each design with mean escapement rates during the 4-h and 24-h trials of 71.1% and 63.8% from design A and 55.6% and 50.0% from design B, respective...
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Condition and mortality of western painted turtle collected as bycatch in modified Fyke Nets during fish population assessments
Journal of Freshwater Ecology, 2017Co-Authors: Tyrel S. Moos, Brian G. BlackwellAbstract:ABSTRACTInformation concerning turtle bycatch and its possible ramifications during biological sampling in freshwater systems is limited. Having such information will enable fisheries researchers and managers to modify fish sampling procedures to potentially minimize any impacts on turtle populations. Therefore, our objective was to utilize reflex response to characterize stress and mortality of western painted turtles (Chrysemys picta bellii) captured as bycatch in modified Fyke Nets during fish population assessments. Reflex-response-based condition classification (i.e. good, poor, unresponsive) data were collected from May to September during fish population assessments in 38 lakes and seven impoundments in northeast South Dakota from 2012 to 2014. We evaluated the relationship between observed condition and water temperature during two time periods, by turtle gender and size. Turtle bycatch mortality was assessed from June to September during fish population assessments in 14 lakes and three impoundme...
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Condition and mortality of western painted turtle collected as bycatch in modified Fyke Nets during fish population assessments
Taylor & Francis Group, 2017Co-Authors: Tyrel S. Moos, Brian G. BlackwellAbstract:Information concerning turtle bycatch and its possible ramifications during biological sampling in freshwater systems is limited. Having such information will enable fisheries researchers and managers to modify fish sampling procedures to potentially minimize any impacts on turtle populations. Therefore, our objective was to utilize reflex response to characterize stress and mortality of western painted turtles (Chrysemys picta bellii) captured as bycatch in modified Fyke Nets during fish population assessments. Reflex-response-based condition classification (i.e. good, poor, unresponsive) data were collected from May to September during fish population assessments in 38 lakes and seven impoundments in northeast South Dakota from 2012 to 2014. We evaluated the relationship between observed condition and water temperature during two time periods, by turtle gender and size. Turtle bycatch mortality was assessed from June to September during fish population assessments in 14 lakes and three impoundments during 2013 and 2014. Delayed (i.e. overnight) mortality was determined for poor and unresponsive condition classifications and the relationship between observed mortality and water temperature for two time periods, by turtle gender and size was evaluated. Turtle condition decreased as water temperature increased. Condition was poorer during the May and June time period than August and September. Female turtles were in significantly worse condition than males. Condition was not related to turtle size. We observed varying mortality rates across condition classifications and the total estimated delayed mortality rate of known sex turtles was 36.4%. Mortality increased as temperature increased. Delayed mortality rates varied between the two sampling periods with higher mortality rates during the May and June time period. Female turtles had higher mortality rates than males. Delayed mortality did not vary by turtle size. Understanding the negative effects on bycatch during biological sampling is important to provide justification for the development and implementation of measures to protect non-target species
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Characterization of Western Painted Turtle Bycatch in Fyke Nets During Freshwater Fish Population Assessments
Journal of Fish and Wildlife Management, 2015Co-Authors: Tyrel S. Moos, Brian G. BlackwellAbstract:Abstract In fisheries management, fish populations are assessed using various net types that invariably also capture nontarget species. Although the bycatch of turtles tends to be a common occurrence, data describing the bycatch of turtles during freshwater fish sampling are lacking. To improve the available knowledge base concerning the bycatch of turtles during fish sampling, we characterize the dynamics of western painted turtle Chrysemys picta bellii bycatch in unbaited modified Fyke Nets used in fish population sampling in northeastern South Dakota. We collected data from June to September during fish population assessments in 39 lakes and nine impoundments between 2007 and 2012. We characterize western painted turtle bycatch relating to water type (lake and impoundment) including catch rates (number of turtles/net night), size structure, and sex ratio. Catch rates were higher in impoundments than lakes. Total mean annual catch rates ranged from 1.07 to 3.28 for lakes and from 0.70 to 6.63 for impoun...
