The Experts below are selected from a list of 171 Experts worldwide ranked by ideXlab platform
Chugey A Sepulveda - One of the best experts on this subject based on the ideXlab platform.
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gill morphometrics of the Thresher sharks genus alopias correlation of gill dimensions with aerobic demand and environmental oxygen
Journal of Morphology, 2015Co-Authors: Thomas P Wootton, Chugey A Sepulveda, Nicholas C WegnerAbstract:Gill morphometrics of the three Thresher shark species (genus Alopias) were determined to examine how metabolism and habitat correlate with respiratory specialization for increased gas exchange. Thresher sharks have large gill surface areas, short water-blood barrier distances, and thin lamellae. Their large gill areas are derived from long total filament lengths and large lamellae, a morphometric configuration documented for other active elasmobranchs (i.e., lamnid sharks, Lamnidae) that augments respiratory surface area while limiting increases in branchial resistance to ventilatory flow. The bigeye Thresher, Alopias superciliosus, which can experience prolonged exposure to hypoxia during diel vertical migrations, has the largest gill surface area documented for any elasmobranch species studied to date. The pelagic Thresher shark, A. pelagicus, a warm-water epi-pelagic species, has a gill surface area comparable to that of the Common Thresher shark, A. vulpinus, despite the latter's expected higher aerobic requirements associated with regional endothermy. In addition, A. vulpinus has a significantly longer water-blood barrier distance than A. pelagicus and A. superciliosus, which likely reflects its cold, well-oxygenated habitat relative to the two other Alopias species. In fast-swimming fishes (such as A. vulpinus and A. pelagicus) cranial streamlining may impose morphological constraints on gill size. However, such constraints may be relaxed in hypoxia-dwelling species (such as A. superciliosus) that are likely less dependent on streamlining and can therefore accommodate larger branchial chambers and gills.
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Post-release survivorship studies on Common Thresher sharks (Alopias vulpinus) captured in the southern California recreational fishery
Fisheries Research, 2015Co-Authors: Chugey A Sepulveda, Diego Bernal, Scott A. Aalbers, C. Heberer, N. Spear, Michael J. Kinney, Suzanne KohinAbstract:Abstract The Common Thresher shark ( Alopias vulpinus ) is the focus of a popular southern California recreational fishery that targets individuals using multiple fishing gears and techniques. Despite increasing trends in the use of catch and release techniques in the recreational fishery for Thresher sharks, a comprehensive estimate of post-release survival is not available for all modes of capture. This study focused on assessing post-release survival in two modes of capture routinely observed in the southern California recreational fishery: (1) sharks that are caught using caudal-based angling techniques and unintentionally released with trailing gear left embedded and (2) sharks that are caught and released using mouth-based angling techniques. Post-release survivorship was assessed using pop-up satellite archival tags programed for 10- and 90-day deployments, with the former used for mouth-caught sharks and the latter for individuals with trailing gear. Post-release survivorship estimates for the trailing gear studies were based on data from nine Common Thresher sharks (111-175 cm FL) while the mouth-based experiments utilized data from an additional seven sharks (125-187 cm fork length, FL). For the trailing gear studies, six sharks died within 5 days after release, one died after 81 days, and two sharks survived the deployment period for an overall survivorship rate of 22%. All seven mouth-hooked Common Thresher sharks survived the acute (∼10 days) effects of capture (100% survivorship). These results suggest that in the southern California recreational Thresher shark fishery, caudal-based angling techniques, which often result in trailing gear left embedded in the shark, can negatively affect post-release survivorship. This work also reveals that mouth-based angling techniques can, when performed properly, result in high survivorship of released sharks.
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Effects of temperature on power output and contraction kinetics in the locomotor muscle of the regionally endothermic Common Thresher shark (Alopias vulpinus).
Fish physiology and biochemistry, 2012Co-Authors: Jeanine M. Donley, Chugey A Sepulveda, Scott A. Aalbers, David G. Mcgillivray, Douglas A. Syme, Diego BernalAbstract:The Common Thresher shark (Alopias vulpinus) is a pelagic species with medially positioned red aerobic swimming musculature (RM) and regional RM endothermy. This study tested whether the contractile characteristics of the RM are functionally similar along the length of the body and assessed how the contractile properties of the Common Thresher shark compare with those of other sharks. Contractile properties of the RM were examined at 8, 16 and 24 °C from anterior and posterior axial positions (0.4 and 0.6 fork length, respectively) using the work loop technique. Experiments were performed to determine whether the contractile properties of the RM are similar along the body of the Common Thresher shark and to document the effects of temperature on muscle power. Axial differences in contractile properties of RM were found to be small or absent. Isometric twitch kinetics of RM were ~fivefold slower than those of white muscle, with RM twitch durations of about 1 s at 24 °C and exceeding 5 s at 8 °C, a Q10 of nearly 2.5. Power increased approximately tenfold with the 16 °C increase in temperature, while the cycle frequency for maximal power only increased from about 0.5–1.0 Hz over this temperature range. These data support the hypothesis that the RM is functionally similar along the body of the Common Thresher shark and corroborate previous findings from shark species both with and without medial RM. While twitch kinetics suggest the endothermic RM is not unusually temperature sensitive, measures of power suggest that the RM is not well suited to function at cool temperatures. The cycle frequency at which power is maximized appeared relatively insensitive to temperature in RM, which may reflect the relatively cooler temperature of the Thresher RM compared to that observed in lamnid sharks as well as the relatively slow RM phenotype in these large fish.
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archival tagging of subadult and adult Common Thresher sharks alopias vulpinus off the coast of southern california
Marine Biology, 2011Co-Authors: Daniel P. Cartamil, Andres Baquero, Chugey A Sepulveda, Nicholas C Wegner, Scott A. Aalbers, Jeffrey B. GrahamAbstract:The Common Thresher shark (Alopias vulpinus) is a secondary target species of the California drift gillnet fishery (CA-DGN) and supports a growing recreational fishery in California waters. This study used archival tags to examine the movement patterns and habitat preferences of Common Threshers of the size range captured in the CA-DGN (>120 cm fork length). Depth and temperature-logging archival tags were deployed on 57 subadult and adult Common Threshers in the Southern California Bight. Tags from five individuals (8.8%) were recovered, and 154 days of data were successfully obtained from four of these. By night, shark movements were primarily limited to waters above the thermocline, which ranged in depth from 15 to 20 m. Sharks were significantly deeper by day, and daytime vertical distribution consisted of two distinct modes: a ‘shallow mode’ (wherein sharks occupied only the upper 20 m of the water column) and a ‘deep mode’ (characterized by frequent vertical excursions below the thermocline). This modal switch is interpreted as relating to regional differences in abundance of surface-oriented prey and prey in deeper water. Maximum dive depth was 320 m, greatest dive duration was 712 min, minimum temperature experienced during a dive was 9.1°C, and dive descent rate was significantly greater than ascent rate. Sharks inhabited waters corresponding to a sea surface temperature range of 16 to 21°C. The nocturnal depth distribution of Common Threshers has implications for management of drift gillnet deployment depths in the CA-DGN.
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function of the medial red muscle during sustained swimming in Common Thresher sharks contrast and convergence with thunniform swimmers
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2010Co-Authors: Diego Bernal, Scott A. Aalbers, Jeanine M. Donley, David G. Mcgillivray, Douglas A. Syme, Chugey A SepulvedaAbstract:Through convergent evolution tunas and lamnid sharks share thunniform swimming and a medial position of the red, aerobic swimming musculature. During continuous cruise swimming these muscles move uniformly out of phase with local body curvature and the surrounding white muscle tissue. This design results in thrust production primarily from the caudal fin rather than causing whole-body undulations. The Common Thresher shark (Family Alopiidae) is the only other fish known to share the same medial red muscle anatomy as the thunniform swimmers. However, the overall body shape and extremely heterocercal caudal fin of the Common Thresher is not shared with the thunniform swimmers, which have both fusiform bodies and high aspect-ratio, lunate caudal fins. Our study used sonomicrometry to measure the dynamics of red and white muscle movement in Common Thresher sharks swimming in the ocean to test whether the medial position of red muscle is associated with uncoupling of muscle shortening and local body bending as characteristic of thunniform swimmers. Common Threshers ( approximately 60-100kg) instrumented with sonomicrometric and electromyographic (EMG) leads swam alongside of the vessel with a tail-beat frequency of approximately 0.5Hz. EMG signals confirmed that only the red muscle was active during sustained swimming. Despite the more medial position of the red muscle relative to the white muscle, its strain was approximately 1.5-times greater than that of the overlying white muscle, and there was a notable phase shift between strain trajectories in the red muscle and adjacent white muscle. These results suggest an uncoupling (shearing) of the red muscle from the adjacent white muscle. Although the magnitude of the phase shift between red and white muscle strain was relatively constant within individuals, it varied among sharks, ranging from near zero (red and white in phase) to almost 180 degrees out of phase. This extent in variability has not been documented previously for thunniform swimmers with a medial red muscle position and may be a characteristic of the Thresher's unique body and caudal fin morphology. Nonetheless, the uncoupling of red and white muscle strain remains a consistent character associated with fishes having a medially positioned red muscle.
Diego Bernal - One of the best experts on this subject based on the ideXlab platform.
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the denticle surface of Thresher shark tails three dimensional structure and comparison to other pelagic species
Journal of Morphology, 2020Co-Authors: Meagan Popp, Diego Bernal, Connor F White, Dylan K Wainwright, George V LauderAbstract:Shark skin denticles (scales) are diverse in morphology both among species and across the body of single individuals, although the function of this diversity is poorly understood. The extremely elongate and highly flexible tail of Thresher sharks provides an opportunity to characterize gradients in denticle surface characteristics along the length of the tail and assess correlations between denticle morphology and tail kinematics. We measured denticle morphology on the caudal fin of three mature and two embryo Common Thresher sharks (Alopias vulpinus), and we compared Thresher tail denticles to those of eleven other shark species. Using surface profilometry, we quantified 3D-denticle patterning and texture along the tail of Threshers (27 regions in adults, and 16 regions in embryos). We report that tails of Thresher embryos have a membrane that covers the denticles and reduces surface roughness. In mature Thresher tails, surfaces have an average roughness of 5.6 μm which is smoother than some other pelagic shark species, but similar in roughness to blacktip, porbeagle, and bonnethead shark tails. There is no gradient down the tail in roughness for the middle or trailing edge regions and hence no correlation with kinematic amplitude or inferred magnitude of flow separation along the tail during locomotion. Along the length of the tail there is a leading-to-trailing-edge gradient with larger leading edge denticles that lack ridges (average roughness = 9.6 μm), and smaller trailing edge denticles with 5 ridges (average roughness = 5.7 μm). Thresher shark tails have many missing denticles visible as gaps in the surface, and we present evidence that these denticles are being replaced by new denticles that emerge from the skin below.
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Post-release survivorship studies on Common Thresher sharks (Alopias vulpinus) captured in the southern California recreational fishery
Fisheries Research, 2015Co-Authors: Chugey A Sepulveda, Diego Bernal, Scott A. Aalbers, C. Heberer, N. Spear, Michael J. Kinney, Suzanne KohinAbstract:Abstract The Common Thresher shark ( Alopias vulpinus ) is the focus of a popular southern California recreational fishery that targets individuals using multiple fishing gears and techniques. Despite increasing trends in the use of catch and release techniques in the recreational fishery for Thresher sharks, a comprehensive estimate of post-release survival is not available for all modes of capture. This study focused on assessing post-release survival in two modes of capture routinely observed in the southern California recreational fishery: (1) sharks that are caught using caudal-based angling techniques and unintentionally released with trailing gear left embedded and (2) sharks that are caught and released using mouth-based angling techniques. Post-release survivorship was assessed using pop-up satellite archival tags programed for 10- and 90-day deployments, with the former used for mouth-caught sharks and the latter for individuals with trailing gear. Post-release survivorship estimates for the trailing gear studies were based on data from nine Common Thresher sharks (111-175 cm FL) while the mouth-based experiments utilized data from an additional seven sharks (125-187 cm fork length, FL). For the trailing gear studies, six sharks died within 5 days after release, one died after 81 days, and two sharks survived the deployment period for an overall survivorship rate of 22%. All seven mouth-hooked Common Thresher sharks survived the acute (∼10 days) effects of capture (100% survivorship). These results suggest that in the southern California recreational Thresher shark fishery, caudal-based angling techniques, which often result in trailing gear left embedded in the shark, can negatively affect post-release survivorship. This work also reveals that mouth-based angling techniques can, when performed properly, result in high survivorship of released sharks.
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Effects of temperature on power output and contraction kinetics in the locomotor muscle of the regionally endothermic Common Thresher shark (Alopias vulpinus).
Fish physiology and biochemistry, 2012Co-Authors: Jeanine M. Donley, Chugey A Sepulveda, Scott A. Aalbers, David G. Mcgillivray, Douglas A. Syme, Diego BernalAbstract:The Common Thresher shark (Alopias vulpinus) is a pelagic species with medially positioned red aerobic swimming musculature (RM) and regional RM endothermy. This study tested whether the contractile characteristics of the RM are functionally similar along the length of the body and assessed how the contractile properties of the Common Thresher shark compare with those of other sharks. Contractile properties of the RM were examined at 8, 16 and 24 °C from anterior and posterior axial positions (0.4 and 0.6 fork length, respectively) using the work loop technique. Experiments were performed to determine whether the contractile properties of the RM are similar along the body of the Common Thresher shark and to document the effects of temperature on muscle power. Axial differences in contractile properties of RM were found to be small or absent. Isometric twitch kinetics of RM were ~fivefold slower than those of white muscle, with RM twitch durations of about 1 s at 24 °C and exceeding 5 s at 8 °C, a Q10 of nearly 2.5. Power increased approximately tenfold with the 16 °C increase in temperature, while the cycle frequency for maximal power only increased from about 0.5–1.0 Hz over this temperature range. These data support the hypothesis that the RM is functionally similar along the body of the Common Thresher shark and corroborate previous findings from shark species both with and without medial RM. While twitch kinetics suggest the endothermic RM is not unusually temperature sensitive, measures of power suggest that the RM is not well suited to function at cool temperatures. The cycle frequency at which power is maximized appeared relatively insensitive to temperature in RM, which may reflect the relatively cooler temperature of the Thresher RM compared to that observed in lamnid sharks as well as the relatively slow RM phenotype in these large fish.
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function of the medial red muscle during sustained swimming in Common Thresher sharks contrast and convergence with thunniform swimmers
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2010Co-Authors: Diego Bernal, Scott A. Aalbers, Jeanine M. Donley, David G. Mcgillivray, Douglas A. Syme, Chugey A SepulvedaAbstract:Through convergent evolution tunas and lamnid sharks share thunniform swimming and a medial position of the red, aerobic swimming musculature. During continuous cruise swimming these muscles move uniformly out of phase with local body curvature and the surrounding white muscle tissue. This design results in thrust production primarily from the caudal fin rather than causing whole-body undulations. The Common Thresher shark (Family Alopiidae) is the only other fish known to share the same medial red muscle anatomy as the thunniform swimmers. However, the overall body shape and extremely heterocercal caudal fin of the Common Thresher is not shared with the thunniform swimmers, which have both fusiform bodies and high aspect-ratio, lunate caudal fins. Our study used sonomicrometry to measure the dynamics of red and white muscle movement in Common Thresher sharks swimming in the ocean to test whether the medial position of red muscle is associated with uncoupling of muscle shortening and local body bending as characteristic of thunniform swimmers. Common Threshers ( approximately 60-100kg) instrumented with sonomicrometric and electromyographic (EMG) leads swam alongside of the vessel with a tail-beat frequency of approximately 0.5Hz. EMG signals confirmed that only the red muscle was active during sustained swimming. Despite the more medial position of the red muscle relative to the white muscle, its strain was approximately 1.5-times greater than that of the overlying white muscle, and there was a notable phase shift between strain trajectories in the red muscle and adjacent white muscle. These results suggest an uncoupling (shearing) of the red muscle from the adjacent white muscle. Although the magnitude of the phase shift between red and white muscle strain was relatively constant within individuals, it varied among sharks, ranging from near zero (red and white in phase) to almost 180 degrees out of phase. This extent in variability has not been documented previously for thunniform swimmers with a medial red muscle position and may be a characteristic of the Thresher's unique body and caudal fin morphology. Nonetheless, the uncoupling of red and white muscle strain remains a consistent character associated with fishes having a medially positioned red muscle.
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The functional role of the caudal fin in the feeding ecology of the Common Thresher shark Alopias vulpinus.
Journal of fish biology, 2010Co-Authors: Scott A. Aalbers, Diego Bernal, Chugey A SepulvedaAbstract:This study tests the hypothesis that the Common Thresher shark Alopias vulpinus uses its elongate caudal fin to both produce thrust and immobilize prey during feeding. Underwater video recorded in southern California from 2007 to 2009 revealed 34 feeding events, all of which were initiated with the upper lobe of the caudal fin.
Suzanne Kohin - One of the best experts on this subject based on the ideXlab platform.
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Data from Elements of time and place: manganese and barium in shark vertebrae reflect age and upwelling histories
2018Co-Authors: John A. Mohan, Heidi Dewar, Suzanne Kohin, Nathan R. Miller, Sharon Z. Herzka, Oscar Sosa-nishizaki, Michael Kinney, Owyn Snodgrass, R. David J. WellsAbstract:As upper-level predators, sharks are important for maintaining marine food web structure, but populations are threatened by fishery exploitation. Sustainable management of shark populations requires improved understanding of migration patterns and population demographics, which has traditionally been sought through physical and/or electronic tagging studies. The application of natural tags such as elemental variations in mineralized band pairs of elasmobranch vertebrae cartilage could also reveal endogenous and exogenous processes experienced by sharks throughout their life histories. Here, elemental profiles were characterized in vertebrae encompassing complete life histories (birth-to-death) of shortfin mako (Isurus oxyrinchus), Common Thresher (Alopias vulpinus) and blue shark (Prionace glauca) of known tag and recapture locations in the eastern North Pacific Ocean. All sharks were injected with oxytetracycline at initial capture, released and subsequently recaptured, with individual liberty times ranging from 215 days to 6 years. Vertebral band pairs forming over the liberty intervals were verified by counting the number of band pairs deposited since the oxytetracycline band. Regular oscillations in vertebrae manganese (Mn) content corresponded well with the number of validated band pairs, suggesting that Mn variation could be used to age sharks. Increases in vertebrae barium concentration were correlated with times when individuals occupied areas with high coastal upwelling indices, the timing and spatial intensity of which varied from year to year. Interspecific relationships were probably influenced by behavioural differences in horizontal and vertical habitat use, feeding habits and thermoregulatory physiology. These results indicate that vertebral sclerochronology has the potential to advance our knowledge of elasmobranch life history including age and growth estimation and environmental reconstruction
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Data from Elements of time and place: manganese and barium in shark vertebrae reflect age and upwelling histories
2018Co-Authors: John A. Mohan, Heidi Dewar, Suzanne Kohin, Nathan R. Miller, Sharon Z. Herzka, Oscar Sosa-nishizaki, Michael Kinney, Owyn Snodgrass, R. David J. WellsAbstract:As upper-level predators, sharks are important for maintaining marine food web structure, but populations are threatened by fishery exploitation. Sustainable management of shark populations requires improved understanding of migration patterns and population demographics, which has traditionally been sought through physical and/or electronic tagging studies. The application of natural tags such as elemental variations in mineralized band pairs of elasmobranch vertebrae cartilage could also reveal endogenous and exogenous processes experienced by sharks throughout their life histories. Here, elemental profiles were characterized in vertebrae encompassing complete life histories (birth-to-death) of shortfin mako (Isurus oxyrinchus), Common Thresher (Alopias vulpinus) and blue shark (Prionace glauca) of known tag and recapture locations in the eastern North Pacific Ocean. All sharks were injected with oxytetracycline at initial capture, released and subsequently recaptured, with individual liberty times ranging from 215 days to 6 years. Vertebral band pairs forming over the liberty intervals were verified by counting the number of band pairs deposited since the oxytetracycline band. Regular oscillations in vertebrae manganese (Mn) content corresponded well with the number of validated band pairs, suggesting that Mn variation could be used to age sharks. Increases in vertebrae barium concentration were correlated with times when individuals occupied areas with high coastal upwelling indices, the timing and spatial intensity of which varied from year to year. Interspecific relationships were likely influenced by behavioural differences in horizontal and vertical habitat use, feeding habits and thermoregulatory physiology. These results indicate that vertebral sclerochronology has the potential to advance our knowledge of elasmobranch life history including age and growth estimation and environmental reconstruction
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Figures S1 and S2 from Elements of time and place: manganese and barium in shark vertebrae reflect age and upwelling histories
2018Co-Authors: John A. Mohan, Heidi Dewar, Suzanne Kohin, Nathan R. Miller, Sharon Z. Herzka, Oscar Sosa-nishizaki, Michael Kinney, Owyn Snodgrass, R. David J. WellsAbstract:As upper-level predators, sharks are important for maintaining marine food web structure, but populations are threatened by fishery exploitation. Sustainable management of shark populations requires improved understanding of migration patterns and population demographics, which has traditionally been sought through physical and/or electronic tagging studies. The application of natural tags such as elemental variations in mineralized band pairs of elasmobranch vertebrae cartilage could also reveal endogenous and exogenous processes experienced by sharks throughout their life histories. Here, elemental profiles were characterized in vertebrae encompassing complete life histories (birth-to-death) of shortfin mako (Isurus oxyrinchus), Common Thresher (Alopias vulpinus) and blue shark (Prionace glauca) of known tag and recapture locations in the eastern North Pacific Ocean. All sharks were injected with oxytetracycline at initial capture, released and subsequently recaptured, with individual liberty times ranging from 215 days to 6 years. Vertebral band pairs forming over the liberty intervals were verified by counting the number of band pairs deposited since the oxytetracycline band. Regular oscillations in vertebrae manganese (Mn) content corresponded well with the number of validated band pairs, suggesting that Mn variation could be used to age sharks. Increases in vertebrae barium concentration were correlated with times when individuals occupied areas with high coastal upwelling indices, the timing and spatial intensity of which varied from year to year. Interspecific relationships were likely influenced by behavioural differences in horizontal and vertical habitat use, feeding habits and thermoregulatory physiology. These results indicate that vertebral sclerochronology has the potential to advance our knowledge of elasmobranch life history including age and growth estimation and environmental reconstruction
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Figures S1 and S2 from Elements of time and place: manganese and barium in shark vertebrae reflect age and upwelling histories
2018Co-Authors: John A. Mohan, Heidi Dewar, Suzanne Kohin, Nathan R. Miller, Sharon Z. Herzka, Oscar Sosa-nishizaki, Michael Kinney, Owyn Snodgrass, R. David J. WellsAbstract:As upper-level predators, sharks are important for maintaining marine food web structure, but populations are threatened by fishery exploitation. Sustainable management of shark populations requires improved understanding of migration patterns and population demographics, which has traditionally been sought through physical and/or electronic tagging studies. The application of natural tags such as elemental variations in mineralized band pairs of elasmobranch vertebrae cartilage could also reveal endogenous and exogenous processes experienced by sharks throughout their life histories. Here, elemental profiles were characterized in vertebrae encompassing complete life histories (birth-to-death) of shortfin mako (Isurus oxyrinchus), Common Thresher (Alopias vulpinus) and blue shark (Prionace glauca) of known tag and recapture locations in the eastern North Pacific Ocean. All sharks were injected with oxytetracycline at initial capture, released and subsequently recaptured, with individual liberty times ranging from 215 days to 6 years. Vertebral band pairs forming over the liberty intervals were verified by counting the number of band pairs deposited since the oxytetracycline band. Regular oscillations in vertebrae manganese (Mn) content corresponded well with the number of validated band pairs, suggesting that Mn variation could be used to age sharks. Increases in vertebrae barium concentration were correlated with times when individuals occupied areas with high coastal upwelling indices, the timing and spatial intensity of which varied from year to year. Interspecific relationships were probably influenced by behavioural differences in horizontal and vertical habitat use, feeding habits and thermoregulatory physiology. These results indicate that vertebral sclerochronology has the potential to advance our knowledge of elasmobranch life history including age and growth estimation and environmental reconstruction
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the pelagic habitat analysis module for ecosystem based fisheries science and management
Fisheries Oceanography, 2017Co-Authors: Daniel P Harrison, Suzanne Kohin, Michael G Hinton, Edward M Armstrong, Stephanie Snyder, Frank Obrien, Dale KieferAbstract:We have developed a set of tools that operate within an aquatic geographic information system to improve the accessibility, and usability of remote-sensed satellite and computer-modeled oceanographic data for marine science and ecosystem-based management. The tools form the Pelagic Habitat Analysis Module (PHAM), which can be applied as a modeling platform, an investigative aid in scientific research, or utilized as a decision support system for marine ecological management. Applications include fisheries, marine biology, physical and biological oceanography, and marine spatial management. The GIS provides a home for diverse data types and automated tools for downloading remote sensed and global circulation model data. Within the GIS environment, PHAM provides a framework for seamless interactive four-dimensional visualization, for matching between disparate data types, for flexible statistic or mechanistic model development, and for dynamic application of user developed models for habitat, density, and probability predictions. Here we describe PHAM in the context of ecosystem-based fisheries management, and present results from case study projects which guided development. In the first, an analysis of the purse seine fishery for tropical tuna in the eastern Pacific Ocean revealed oceanographic drivers of the catch distribution and the influence of climate-driven circulation patterns on the location of fishing grounds. To support management of the Common Thresher Shark (Alopias vulpinus) in the California Current Ecosystem, a simple empirical habitat utilization model was developed and used to dynamically predict the seasonal range expansion of Common Thresher shark based on oceanographic conditions.
Scott A. Aalbers - One of the best experts on this subject based on the ideXlab platform.
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Post-release survivorship studies on Common Thresher sharks (Alopias vulpinus) captured in the southern California recreational fishery
Fisheries Research, 2015Co-Authors: Chugey A Sepulveda, Diego Bernal, Scott A. Aalbers, C. Heberer, N. Spear, Michael J. Kinney, Suzanne KohinAbstract:Abstract The Common Thresher shark ( Alopias vulpinus ) is the focus of a popular southern California recreational fishery that targets individuals using multiple fishing gears and techniques. Despite increasing trends in the use of catch and release techniques in the recreational fishery for Thresher sharks, a comprehensive estimate of post-release survival is not available for all modes of capture. This study focused on assessing post-release survival in two modes of capture routinely observed in the southern California recreational fishery: (1) sharks that are caught using caudal-based angling techniques and unintentionally released with trailing gear left embedded and (2) sharks that are caught and released using mouth-based angling techniques. Post-release survivorship was assessed using pop-up satellite archival tags programed for 10- and 90-day deployments, with the former used for mouth-caught sharks and the latter for individuals with trailing gear. Post-release survivorship estimates for the trailing gear studies were based on data from nine Common Thresher sharks (111-175 cm FL) while the mouth-based experiments utilized data from an additional seven sharks (125-187 cm fork length, FL). For the trailing gear studies, six sharks died within 5 days after release, one died after 81 days, and two sharks survived the deployment period for an overall survivorship rate of 22%. All seven mouth-hooked Common Thresher sharks survived the acute (∼10 days) effects of capture (100% survivorship). These results suggest that in the southern California recreational Thresher shark fishery, caudal-based angling techniques, which often result in trailing gear left embedded in the shark, can negatively affect post-release survivorship. This work also reveals that mouth-based angling techniques can, when performed properly, result in high survivorship of released sharks.
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Effects of temperature on power output and contraction kinetics in the locomotor muscle of the regionally endothermic Common Thresher shark (Alopias vulpinus).
Fish physiology and biochemistry, 2012Co-Authors: Jeanine M. Donley, Chugey A Sepulveda, Scott A. Aalbers, David G. Mcgillivray, Douglas A. Syme, Diego BernalAbstract:The Common Thresher shark (Alopias vulpinus) is a pelagic species with medially positioned red aerobic swimming musculature (RM) and regional RM endothermy. This study tested whether the contractile characteristics of the RM are functionally similar along the length of the body and assessed how the contractile properties of the Common Thresher shark compare with those of other sharks. Contractile properties of the RM were examined at 8, 16 and 24 °C from anterior and posterior axial positions (0.4 and 0.6 fork length, respectively) using the work loop technique. Experiments were performed to determine whether the contractile properties of the RM are similar along the body of the Common Thresher shark and to document the effects of temperature on muscle power. Axial differences in contractile properties of RM were found to be small or absent. Isometric twitch kinetics of RM were ~fivefold slower than those of white muscle, with RM twitch durations of about 1 s at 24 °C and exceeding 5 s at 8 °C, a Q10 of nearly 2.5. Power increased approximately tenfold with the 16 °C increase in temperature, while the cycle frequency for maximal power only increased from about 0.5–1.0 Hz over this temperature range. These data support the hypothesis that the RM is functionally similar along the body of the Common Thresher shark and corroborate previous findings from shark species both with and without medial RM. While twitch kinetics suggest the endothermic RM is not unusually temperature sensitive, measures of power suggest that the RM is not well suited to function at cool temperatures. The cycle frequency at which power is maximized appeared relatively insensitive to temperature in RM, which may reflect the relatively cooler temperature of the Thresher RM compared to that observed in lamnid sharks as well as the relatively slow RM phenotype in these large fish.
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archival tagging of subadult and adult Common Thresher sharks alopias vulpinus off the coast of southern california
Marine Biology, 2011Co-Authors: Daniel P. Cartamil, Andres Baquero, Chugey A Sepulveda, Nicholas C Wegner, Scott A. Aalbers, Jeffrey B. GrahamAbstract:The Common Thresher shark (Alopias vulpinus) is a secondary target species of the California drift gillnet fishery (CA-DGN) and supports a growing recreational fishery in California waters. This study used archival tags to examine the movement patterns and habitat preferences of Common Threshers of the size range captured in the CA-DGN (>120 cm fork length). Depth and temperature-logging archival tags were deployed on 57 subadult and adult Common Threshers in the Southern California Bight. Tags from five individuals (8.8%) were recovered, and 154 days of data were successfully obtained from four of these. By night, shark movements were primarily limited to waters above the thermocline, which ranged in depth from 15 to 20 m. Sharks were significantly deeper by day, and daytime vertical distribution consisted of two distinct modes: a ‘shallow mode’ (wherein sharks occupied only the upper 20 m of the water column) and a ‘deep mode’ (characterized by frequent vertical excursions below the thermocline). This modal switch is interpreted as relating to regional differences in abundance of surface-oriented prey and prey in deeper water. Maximum dive depth was 320 m, greatest dive duration was 712 min, minimum temperature experienced during a dive was 9.1°C, and dive descent rate was significantly greater than ascent rate. Sharks inhabited waters corresponding to a sea surface temperature range of 16 to 21°C. The nocturnal depth distribution of Common Threshers has implications for management of drift gillnet deployment depths in the CA-DGN.
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function of the medial red muscle during sustained swimming in Common Thresher sharks contrast and convergence with thunniform swimmers
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2010Co-Authors: Diego Bernal, Scott A. Aalbers, Jeanine M. Donley, David G. Mcgillivray, Douglas A. Syme, Chugey A SepulvedaAbstract:Through convergent evolution tunas and lamnid sharks share thunniform swimming and a medial position of the red, aerobic swimming musculature. During continuous cruise swimming these muscles move uniformly out of phase with local body curvature and the surrounding white muscle tissue. This design results in thrust production primarily from the caudal fin rather than causing whole-body undulations. The Common Thresher shark (Family Alopiidae) is the only other fish known to share the same medial red muscle anatomy as the thunniform swimmers. However, the overall body shape and extremely heterocercal caudal fin of the Common Thresher is not shared with the thunniform swimmers, which have both fusiform bodies and high aspect-ratio, lunate caudal fins. Our study used sonomicrometry to measure the dynamics of red and white muscle movement in Common Thresher sharks swimming in the ocean to test whether the medial position of red muscle is associated with uncoupling of muscle shortening and local body bending as characteristic of thunniform swimmers. Common Threshers ( approximately 60-100kg) instrumented with sonomicrometric and electromyographic (EMG) leads swam alongside of the vessel with a tail-beat frequency of approximately 0.5Hz. EMG signals confirmed that only the red muscle was active during sustained swimming. Despite the more medial position of the red muscle relative to the white muscle, its strain was approximately 1.5-times greater than that of the overlying white muscle, and there was a notable phase shift between strain trajectories in the red muscle and adjacent white muscle. These results suggest an uncoupling (shearing) of the red muscle from the adjacent white muscle. Although the magnitude of the phase shift between red and white muscle strain was relatively constant within individuals, it varied among sharks, ranging from near zero (red and white in phase) to almost 180 degrees out of phase. This extent in variability has not been documented previously for thunniform swimmers with a medial red muscle position and may be a characteristic of the Thresher's unique body and caudal fin morphology. Nonetheless, the uncoupling of red and white muscle strain remains a consistent character associated with fishes having a medially positioned red muscle.
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The functional role of the caudal fin in the feeding ecology of the Common Thresher shark Alopias vulpinus.
Journal of fish biology, 2010Co-Authors: Scott A. Aalbers, Diego Bernal, Chugey A SepulvedaAbstract:This study tests the hypothesis that the Common Thresher shark Alopias vulpinus uses its elongate caudal fin to both produce thrust and immobilize prey during feeding. Underwater video recorded in southern California from 2007 to 2009 revealed 34 feeding events, all of which were initiated with the upper lobe of the caudal fin.
Jeffrey B. Graham - One of the best experts on this subject based on the ideXlab platform.
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ORIGINAL PAPER Archival
2016Co-Authors: Andres Baquero, Jeffrey B. GrahamAbstract:tagging of subadult and adult Common Thresher sharks (Alopias vulpinus) off the coast of southern Californi
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archival tagging of subadult and adult Common Thresher sharks alopias vulpinus off the coast of southern california
Marine Biology, 2011Co-Authors: Daniel P. Cartamil, Andres Baquero, Chugey A Sepulveda, Nicholas C Wegner, Scott A. Aalbers, Jeffrey B. GrahamAbstract:The Common Thresher shark (Alopias vulpinus) is a secondary target species of the California drift gillnet fishery (CA-DGN) and supports a growing recreational fishery in California waters. This study used archival tags to examine the movement patterns and habitat preferences of Common Threshers of the size range captured in the CA-DGN (>120 cm fork length). Depth and temperature-logging archival tags were deployed on 57 subadult and adult Common Threshers in the Southern California Bight. Tags from five individuals (8.8%) were recovered, and 154 days of data were successfully obtained from four of these. By night, shark movements were primarily limited to waters above the thermocline, which ranged in depth from 15 to 20 m. Sharks were significantly deeper by day, and daytime vertical distribution consisted of two distinct modes: a ‘shallow mode’ (wherein sharks occupied only the upper 20 m of the water column) and a ‘deep mode’ (characterized by frequent vertical excursions below the thermocline). This modal switch is interpreted as relating to regional differences in abundance of surface-oriented prey and prey in deeper water. Maximum dive depth was 320 m, greatest dive duration was 712 min, minimum temperature experienced during a dive was 9.1°C, and dive descent rate was significantly greater than ascent rate. Sharks inhabited waters corresponding to a sea surface temperature range of 16 to 21°C. The nocturnal depth distribution of Common Threshers has implications for management of drift gillnet deployment depths in the CA-DGN.
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Binational Studies Leading to an Ecosystems-based Management Strategy for Common Thresher Shark in the Southern California Bight (SCB).
California Sea Grant College Program, 2010Co-Authors: Jeffrey B. Graham, Daniel P. CartamilAbstract:Survey of the Mexican SCB Sector Artisanal and Commercial Shark Fisheries Hypotheses: a) Common Thresher sharks represent a substantial portion of the catch of artisanal and commercial shark fisheries in the Mexican SCB sector. b) Exploitation of Common Threshers and other elasmobranchs is important to the economy of northern Baja California and, by extension, is directly linked to U.S. fishery management. Mexican SCB Longlining Survey Hypotheses: a) Thresher shark nursery grounds extend south throughout the Mexican sector of the SCB. b) Juvenile Threshers in Mexican SCB waters will exhibit seasonal patterns of abundance similar to those observed in the California SCB (i.e. higher abundance in early Spring and Summer when pupping is thought to occur). Tracking and Archival Tagging Hypotheses: a) Juvenile Thresher sharks utilize distinct inshore areas as nursery grounds and have a strong preference for continental shelf waters. b) Within these nursery grounds, juveniles have specific habitat preferences (e.g., substrate composition, algal coverage, topography, etc.). c) Juvenile Threshers display the same diel movement patterns noted for adults, remaining in the warmer mixed layer by night, and making vertical forays by day. However, we expect that juveniles will inhabit shallower depths and higher temperatures than adults, and also swim at slower speeds. d) Juveniles undergo relatively large-scale movements that take them throughout the SCB and further south.
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Diel movement patterns and habitat preferences of the Common Thresher shark (Alopias vulpinus) in the Southern California Bight
Marine and Freshwater Research, 2010Co-Authors: Daniel P. Cartamil, Chugey A Sepulveda, Nicholas C Wegner, S. Aalbers, A. Baquero, Jeffrey B. GrahamAbstract:The Common Thresher shark, Alopias vulpinus, is the basis of the largest commercial shark fishery in California waters. We used acoustic telemetry to determine the diel movement patterns and habitat preferences of this species inthe Southern California Bight (SCB),where commercial fishing for the Common Thresher sharkis concentrated. EightCommonThreshers (forklength: 122-203cm) weretaggedwith temperature anddepth-sensingacoustic transmitters and tracked for periods ranging from 22 to 49h. Tracked sharks preferentially utilized deep offshore waters, and avoided shallower waters over the continental shelf. Mean rate of movement (ROMs.d.) was 2.15 � 0.46kmh � 1 . ROM and angularconcentration(r,ameasureofrelativelinearity)bothshowedastrongdaytimepattern,withhighestvaluesatdawn that decreased throughout the day, whereas nocturnal ROM and r were less variable. Daytime vertical movements consisted of either vertical excursions below the thermocline or relatively level swimming within the upper portion of the thermocline. Nocturnally, all sharks remained within the mixed layer. These findings suggest that the Common Thresher shark is primarily a daytime predator, and have relevance for estimating how the alteration of the set depth of fishing-gear could affect catch rates of this species in the SCB.
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plasma catecholamine levels as indicators of the post release survivorship of juvenile pelagic sharks caught on experimental drift longlines in the southern california bight
Marine and Freshwater Research, 2007Co-Authors: Barbara V Hight, Jeffrey B. Graham, Chugey A Sepulveda, Diego Bernal, Darlene A Ramon, David B Holts, Brian P Kennedy, Valerie Taylor, Randall Rasmussen, Chin N LaiAbstract:Between 1983 and 2004, nearly 12 000 shortfin mako (Isurus oxyrinchus), Common Thresher (Alopias vulpinus) and blue (Prionace glauca) sharks were tagged in the Southern California Bight; however, only 1.97% of these have been returned. One possible reason for this low return rate could be post-release mortality caused by capture stress from the experimental longline. Plasma catecholamine levels were analysed to evaluate stress levels in longline-captured, rod-and- reel-captured and unstressed docile sharks. The mean catecholamine values determined for the three tag-release species ranged from 6539 to 22 079 pg mL −1 . The level of adrenaline found in moribund I. oxyrinchus (94 807 pg mL −1 ) was much higher than in either P. glauca (46 845 pg mL −1 )o rA. vulpinus (36 890 pg mL −1 ). In contrast, blood obtained from sharks that were landed within minutes had lower catecholamine values (P. glauca, 889 and 1347 pg mL −1 ; I. oxyrinchus, 2960 and 3946 pg mL −1 , adrenaline and noradrenaline respectively). Among the nine I. oxyrinchus specimens that were recaptured long after their longline capture and release, the highest adrenaline level measured just before release was 33 352 pg mL −1 . Because these mako sharks survived sufficiently long to be recaptured, their time-of-release catecholamine levels provide a conservative estimate of ∼80% viability on the longline-captured and released population.
