- Gainesville, Florida, United States
George Burgess
University of Florida, Florida Museum of Natural History, Department Member
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The aim of this study is to report a scavenging event, involving the consumption of a nurse shark, Ginglymostoma cirratum, by tiger sharks, Galeocerdo cuvier, at Fernando de Noronha archipelago, Brazil. Recreational divers found and... more
The aim of this study is to report a scavenging event, involving the consumption of a nurse shark, Ginglymostoma cirratum, by tiger sharks, Galeocerdo cuvier, at Fernando de Noronha archipelago, Brazil. Recreational divers found and photographed a bitten nurse shark carcass, just after sighting two tiger sharks near of the site. We estimated the sharks total lengths and discussed aspects of this feeding interaction using of images of forensic analysis. A straight cut on the nurse shark caudal fin, whose total lenght was estimated as 200 cm, suggest that it was caught by illegal fishing. A skin peeling process on the nurse shark fins indicates that the tiger sharks consumed it after its death, in a scavenging event. This is the first published report of a scavenging event involving the consumption ofan elasmobranch by tiger sharks, allowing a better comprehension of tiger sharks’ alimentary biology.
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A small, poorly known deepwater catshark of the continental and insular slopes in the Caribbean at depths of 329–676 m. Reaches a maximum size of at least 54 cm total length, but little is known of the species’ biology. Despite its... more
A small, poorly known deepwater catshark of the continental and insular slopes in the Caribbean at depths of 329–676 m. Reaches a maximum size of at least 54 cm total length, but little is known of the species’ biology. Despite its restricted geographic range, no trawl fisheries are currently known to operate at the depths at which this species occurs. As such, the species is assessed as Least Concern. If demersal trawl fisheries expand into this species’ range in the future, this assessment should be revisited
The Wageningen UR Library Catalogue contains bibliographic data on books and periodicals held by the libraries of Wageningen University and Research Centre and some 15 associated libraries. Holding data are added to each record.
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Animals across taxa have shown behaviors linked to moon phase (or the proxy of lunar illumination), and marine organisms are well-documented to calibrate certain activities with the moon. Few studies have looked at a possible connection... more
Animals across taxa have shown behaviors linked to moon phase (or the proxy of lunar illumination), and marine organisms are well-documented to calibrate certain activities with the moon. Few studies have looked at a possible connection between moon phase and shark attacks on humans, and the results have been preliminary or lacking relationships. We used nearly 50 years of shark attack data from across the globe to test for a relationship between shark attacks and moon phase. We examined factors of geography, shark species, and outcome of attack. From 12 relationships that we tested (totaling 120 comparisons), we found 12 significant outcomes, of which five were positive (i.e., more attacks than expected) and seven were negative (i.e., fewer attacks than expected). Specifically, all the instances of more shark attacks than expected occurred at lunar illumination >50%, while all the instances of fewer shark attacks than expected occurred at lunar illumination of <50%. The findi...
The rapid expansion of human activities threatens ocean-wide biodiversity. Numerous marine animal populations have declined, yet it remains unclear whether these trends are symptomatic of a chronic accumulation of global marine extinction... more
The rapid expansion of human activities threatens ocean-wide biodiversity. Numerous marine animal populations have declined, yet it remains unclear whether these trends are symptomatic of a chronic accumulation of global marine extinction risk. We present the first systematic analysis of threat for a globally distributed lineage of 1,041 chondrichthyan fishes—sharks, rays, and chimaeras. We estimate that one-quarter are threatened according to IUCN Red List criteria due to overfishing (targeted and incidental). Large-bodied, shallow-water species are at greatest risk and five out of the seven most threatened families are rays. Overall chondrichthyan extinction risk is substantially higher than for most other vertebrates, and only one-third of species are considered safe. Population depletion has occurred throughout the world’s ice-free waters, but is particularly prevalent in the Indo-Pacific Biodiversity Triangle and Mediterranean Sea. Improved management of fisheries a...
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Habitat use, movement and residency of bull sharks Carcharhinus leucas were determined using satellite pop-up archival transmitting (PAT) tags throughout coastal areas in the U.S., Gulf of Mexico and waters off the south-east U.S. From... more
Habitat use, movement and residency of bull sharks Carcharhinus leucas were determined using satellite pop-up archival transmitting (PAT) tags throughout coastal areas in the U.S., Gulf of Mexico and waters off the south-east U.S. From 2005 to 2007, 18 fish (mean size = 164 cm fork length, L(F)) were tagged over all seasons. Fish retained tags for up to 85 days (median = 30 days). Based on geolocation data from initial tagging location to pop-off location, C. leucas generally travelled c. 5-6 km day(-1) and travelled an average of 143.6 km. Overall, mean proportions of time at depth revealed C. leucas spent the majority of their time in waters &lt;20 m. They exhibited significant differences among depths but were not found at a particular depth regardless of diurnal period. Most fish occupied temperatures c. 32 degrees C with individuals found mostly between 26 and 33 degrees C. Geolocation data for C. leucas were generally poor and varied considerably but tracks for two individuals revealed long distance movements. One fish travelled from the south-east coast of the U.S. to coastal Texas near Galveston while another moved up the east coast of the U.S. to South Carolina. Data on C. leucas movements indicated that they are found primarily in shallower waters and tend to remain in the same location over long periods. While some individuals made large-scale movements over open ocean areas, the results emphasize the importance of the coastal zone for this species as potential essential habitat, particularly in areas of high freshwater inflow.
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White sharks are highly migratory and segregate by sex, age and size. Unlike marine mammals, they neither surface to breathe nor frequent haul-out sites, hindering generation of abundance data required to estimate population size. A... more
White sharks are highly migratory and segregate by sex, age and size. Unlike marine mammals, they neither surface to breathe nor frequent haul-out sites, hindering generation of abundance data required to estimate population size. A recent tag-recapture study used photographic identifications of white sharks at two aggregation sites to estimate abundance in "central California" at 219 mature and sub-adult individuals. They concluded this represented approximately one-half of the total abundance of mature and sub-adult sharks in the entire eastern North Pacific Ocean (ENP). This low estimate generated great concern within the conservation community, prompting petitions for governmental endangered species designations. We critically examine that study and find violations of model assumptions that, when considered in total, lead to population underestimates. We also use a Bayesian mixture model to demonstrate that the inclusion of transient sharks, characteristic of white sha...
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White sharks are highly migratory and segregate by sex, age and size. Unlike marine mammals, they neither surface to breathe nor frequent haul-out sites, hindering generation of abundance data required to estimate population size. A... more
White sharks are highly migratory and segregate by sex, age and size. Unlike marine mammals, they neither surface to breathe nor frequent haul-out sites, hindering generation of abundance data required to estimate population size. A recent tag-recapture study used photographic identifications of white sharks at two aggregation sites to estimate abundance in "central California" at 219 mature and sub-adult individuals. They concluded this represented approximately one-half of the total abundance of mature and sub-adult sharks in the entire eastern North Pacific Ocean (ENP). This low estimate generated great concern within the conservation community, prompting petitions for governmental endangered species designations. We critically examine that study and find violations of model assumptions that, when considered in total, lead to population underestimates. We also use a Bayesian mixture model to demonstrate that the inclusion of transient sharks, characteristic of white sha...
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White sharks are highly migratory and segregate by sex, age and size. Unlike marine mammals, they neither surface to breathe nor frequent haul-out sites, hindering generation of abundance data required to estimate population size. A... more
White sharks are highly migratory and segregate by sex, age and size. Unlike marine mammals, they neither surface to breathe nor frequent haul-out sites, hindering generation of abundance data required to estimate population size. A recent tag-recapture study used photographic identifications of white sharks at two aggregation sites to estimate abundance in "central California" at 219 mature and sub-adult individuals. They concluded this represented approximately one-half of the total abundance of mature and sub-adult sharks in the entire eastern North Pacific Ocean (ENP). This low estimate generated great concern within the conservation community, prompting petitions for governmental endangered species designations. We critically examine that study and find violations of model assumptions that, when considered in total, lead to population underestimates. We also use a Bayesian mixture model to demonstrate that the inclusion of transient sharks, characteristic of white sha...
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Despite recent advances in field research on white sharks (Carcharodon carcharias) in several regions around the world, opportunistic capture and sighting records remain the primary source of information on this species in the northwest... more
Despite recent advances in field research on white sharks (Carcharodon carcharias) in several regions around the world, opportunistic capture and sighting records remain the primary source of information on this species in the northwest Atlantic Ocean (NWA). Previous studies using limited datasets have suggested a precipitous decline in the abundance of white sharks from this region, but considerable uncertainty in these studies warrants additional investigation. This study builds upon previously published data combined with recent unpublished records and presents a synthesis of 649 confirmed white shark records from the NWA compiled over a 210-year period (1800-2010), resulting in the largest white shark dataset yet compiled from this region. These comprehensive records were used to update our understanding of their seasonal distribution, relative abundance trends, habitat use, and fisheries interactions. All life stages were present in continental shelf waters year-round, but medi...
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The status of the Atlantic sharpnose shark (Rhizoprionodon terraenovae) was assessed using a Bayesian agestructured population model. The results of the model indicated that the best estimate of the mature female biomass in 2000 was 69.6%... more
The status of the Atlantic sharpnose shark (Rhizoprionodon terraenovae) was assessed using a Bayesian agestructured population model. The results of the model indicated that the best estimate of the mature female biomass in 2000 was 69.6% of the 1972 biomass. Sensitivity tests indicated that changes in data on catches, catch rates and biology did not significantly change the estimates of biomass. The results of risk assessment indicated that the probability of depletion of the population to below 5% or 30% of the 1972 level by 2020 is low, even with substantial increases in future catches. The results show a high level of uncertainty, indicating a need to improve the quality of data collected if assessments are to be improved. The implications of the assessment results for fisheries management are discussed.
The U.S. Atlantic coast and Gulf of Mexico commercial shark fisheries have greatly expanded over the last 30 years, yet fishery managers still lack much of the key information required to accurately assess many shark stocks. Fishery... more
The U.S. Atlantic coast and Gulf of Mexico commercial shark fisheries have greatly expanded over the last 30 years, yet fishery managers still lack much of the key information required to accurately assess many shark stocks. Fishery observer programs are one tool that can be utilized to acquire this information. The Commercial Shark Fishery Observer Program monitors the U.S. Atlantic coast and Gulf of Mexico commercial bottom longline (BLL) large coastal shark fishery. Data gathered by observers were summarized for the 10-year period, 1994 to 2003. A total of 1,165 BLL sets were observed aboard 96 vessels, with observers spending a total of 1,509 days at sea. Observers recorded data regarding the fishing gear and methods used, species composition, disposition of the catch, mortality rates, catch per unit of effort (sharks per 10,000 hook hours), and bycatch of this fishery. Fishing practices, species composition, and bycatch varied between regions, while catch rates, mortality rates...
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The sandbar shark (Carcharhinus plumbeus) was the cornerstone species of western North Atlantic and Gulf of Mexico large coastal shark fisheries until 2008 when they were allocated to a research-only fishery. Despite decades of fishing on... more
The sandbar shark (Carcharhinus plumbeus) was the cornerstone species of western North Atlantic and Gulf of Mexico large coastal shark fisheries until 2008 when they were allocated to a research-only fishery. Despite decades of fishing on this species, important life history parameters, such as age and growth, have not been well known. Some validated age and growth information exists for sandbar shark, but more comprehensive life history information is needed. The complementary application of bomb radiocarbon and tag-recapture dating was used in this study to determine valid age-estimation criteria and longevity estimates for this species. These two methods indicated that current age interpretations based on counts of growth bands in vertebrae are accurate to 10 or 12 years. Beyond these years, we could not determine with certainty when such an underestimation of age begins; however, bomb radiocarbon and tag-recapture data indicated that large adult sharks were considerably older th...
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Six new species of squaloid sharks of the genus Etmopterus are described from the Arafura and Banda Seas (south-east Indian Ocean), and the Coral Sea (south-west Pacific): E. fusus sp. nov. from the slope of northwestern Australia; E.... more
Six new species of squaloid sharks of the genus Etmopterus are described from the Arafura and Banda Seas (south-east Indian Ocean), and the Coral Sea (south-west Pacific): E. fusus sp. nov. from the slope of northwestern Australia; E. evansi sp. nov. from northwestern Australia and eastern Indonesia; E. dianthus sp. nov. from the Coral Sea; E. dislineatus sp. nov. off tropical eastern Australia; and E. caudistigmus sp. nov. and E. pseudosqualiolus sp. nov. from the slopes of the Chesterfield Islands, New Caledonia, and the northern part of the Norfolk Ridge. They can be distin- guished by their coloration, body shape, teeth morphology, vertebral counts, dermal denticles, the position of their fins, and the size and shape of luminescent markings on the flank, caudal peduncle and caudal fin. A key for the Etmopterus species of tropical Australasia is provided. Over the last two decades, French and A u s t r a l i a n research agencies have undertaken several deepwater exploratory traw...
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... Post a Comment. CONTRIBUTORS: Author: Schwartz, Frank J. (b. 1929, d. ----. PUBLISHER: Division of Marine Fisheries (Raleigh). SERIES TITLE: YEAR: 1979. PUB TYPE: Book. VOLUME/EDITION: Rev. edition. PAGES (INTRO/BODY): 59 p. ...
The National Shark Research Consortium (NSRC) includes the Center for Shark Research at Mote Marine Laboratory, the Pacific Shark Research Center at Moss Landing Marine Laboratories, the Shark Research Program at the Virginia Institute of... more
The National Shark Research Consortium (NSRC) includes the Center for Shark Research at Mote Marine Laboratory, the Pacific Shark Research Center at Moss Landing Marine Laboratories, the Shark Research Program at the Virginia Institute of Marine Science, and the Florida Program for Shark Research at the University of Florida. The consortium objectives include shark-related research in the Gulf of Mexico and along the Atlantic and Pacific coasts of the U.S., education and scientific cooperation.
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We investigated spatial use patterns of 77 Caribbean reef sharks ( Carcharhinus perezi ) at Lighthouse Reef Atoll, Belize over 7 years using residency patterns, kernel density (KD) estimation and network analysis. We found a high degree... more
We investigated spatial use patterns of 77 Caribbean reef sharks ( Carcharhinus perezi ) at Lighthouse Reef Atoll, Belize over 7 years using residency patterns, kernel density (KD) estimation and network analysis. We found a high degree individual variation in spatial use of the atoll, but there were significant differences in residency and activity space between sexes, with females being overall more resident. Ontogenetic shifts in movement and residency were largely limited to females, as the residency index increased and activity space estimates decreased as females matured, while for males there was no relationship between space use or residency and size. KD analysis revealed many mature females were highly resident to discrete locations, and average activity space of the intermediate-sized sharks was significantly larger than that of the adults, but not the smallest sharks. Markov chain analyses indicated that the southwestern portion of the atoll was the most important movemen...
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Research treatment protocols are rare regarding an unusual anxiety disorder, namely the fear of sharks (squalophobia). As a possible solution, the effectiveness of virtual reality (VR) exposure therapy for this phobia was tested. The... more
Research treatment protocols are rare regarding an unusual anxiety disorder, namely the fear of sharks (squalophobia). As a possible solution, the effectiveness of virtual reality (VR) exposure therapy for this phobia was tested. The advantage of using VR becomes clearer when a real life set up is impractical, such as exposing a phobic patient to a feared large marine organism, the shark. The effects were evaluated in a single case study involving multiple context-graded aquatic virtual environments with a virtual shark and using affordable VR apparatus and software. Assessment was based on self-report questionnaires. Scores the psychometric instruments exhibited a discernable reduction in fear toward sharks. Such gains were maintained at a 12-month follow-up. Presence rates indicated immersion when confronted to a three-dimensional (3D) virtual shark. This initial study revealed the potential of VR for the treatment of marine biota phobia and its potential to recreate diverse situa...
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This research examines a series of six Florida forensic anthropology cases that exhibit taphonomic evidence of marine deposition and shark-feeding activities. In each case, we analyzed patterns of trauma/damage on the skeletal remains... more
This research examines a series of six Florida forensic anthropology cases that exhibit taphonomic evidence of marine deposition and shark-feeding activities. In each case, we analyzed patterns of trauma/damage on the skeletal remains (e.g., sharp-force bone gouges and punctures) and possible mechanisms by which they were inflicted during shark predation/scavenging. In some cases, shark teeth were embedded in the remains; in the absence of this evidence, we measured interdental distance from defects in the bone to estimate shark body length, as well as to draw inferences about the potential species responsible. We discuss similarities and differences among the cases and make comparisons to literature documenting diagnostic shark-inflicted damage to human remains from nearby regions. We find that the majority of cases potentially involve bull or tiger sharks scavenging the remains of previously deceased, adult male individuals. This scavenging results in a distinctive taphonomic signature including incised gouges in cortical bone.
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The tiger shark (Galeocerdo cuvier) has a global distribution in tropical and warm temperate seas, and it is caught in numerous fisheries worldwide, mainly as bycatch. It is currently assessed as near threatened by the International Union... more
The tiger shark (Galeocerdo cuvier) has a global distribution in tropical and warm temperate seas, and it is caught in numerous fisheries worldwide, mainly as bycatch. It is currently assessed as near threatened by the International Union for Conservation of Nature (IUCN) Red List. In this study, we identified nine microsatellite loci through next generation sequencing (454 pyrosequencing) using 29 samples from the western Atlantic. The genetic diversity of these loci were assessed and revealed a total of 48 alleles ranging from 3 to 7 alleles per locus (average of 5.3 alleles). Cross-species amplification was successful at most loci for other species such asCarcharhinus longimanus, C. acronotusandAlopias superciliosus. Given the potential applicability of genetic markers for biological conservation, these data may contribute to the population assessment of this and other species of sharks worldwide.
Research Interests: Genetics, Reproduction, Molecular Ecology, Biological Sciences, Molecular, and 15 moreNorth Atlantic, Atlantic Ocean, Female, Animals, Reproductive skew, Male, Regression Analysis, Microsatellite, Reproductive Success, Body Size, Biological evolution, Gulf of Mexico, Multiple Mating, Genotype, and Genetic Markers
... J. Elisha Mitchell SeL Soc. ... L. ovalis has been reported on Pomatomas saltatrix (L.), Lagadon rhom-boides (L.), Pristis peetinate Latham, Stenotomus chrysops (L.), Selar crumenophthalmus (Bloch), Cynoscion regalis (Bloch and... more
... J. Elisha Mitchell SeL Soc. ... L. ovalis has been reported on Pomatomas saltatrix (L.), Lagadon rhom-boides (L.), Pristis peetinate Latham, Stenotomus chrysops (L.), Selar crumenophthalmus (Bloch), Cynoscion regalis (Bloch and Schneider) and Micro-pogon undulatus (L ...
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ABSTRACT Long-term standardized elasmobranch monitoring can provide a robust gauge of a population’s status and reveal where management interventions may be necessary for the target species’ persistence. A standardized annual longline... more
ABSTRACT Long-term standardized elasmobranch monitoring can provide a robust gauge of a population’s status and reveal where management interventions may be necessary for the target species’ persistence. A standardized annual longline survey for elasmobranchs has been conducted at Lighthouse Reef Atoll, the most remote of Belize’s barrier reef atolls, during the dry season (April-early June) since 2007. Ten species of sharks and one species of stingray were captured, with over 500 individuals caught, measured and sexed, tagged, and released. The most commonly captured shark species was the Caribbean reef shark, Carcharhinus perezi, followed by nurse sharks, Ginglymostoma cirratum, and silky sharks, C. falciformis. Length-frequency analyses showed a distinct bimodal distribution in size structure of Caribbean reef sharks, and the distribution was prevalent between sexes and among different habitats and regions within the atoll. Catch per unit effort was calculated (#sharks/hook hour) overall by year, habitat, and region: the annual index was also standardized using the delta lognormal approach. Abundance was highest in the Blue Hole Natural Monument and the windward southeastern region of the atoll that encompasses the fully protected Halfmoon Caye Natural Monument. Annual catch per unit effort estimates revealed declining abundance of Caribbean reef sharks since 2011, though the standardized index gave a slightly more optimistic indication, with a slight uptick in the terminal year. The factors Year, Region, Habitat, and Protected Area were included in the final model. Recapture rates were very low with only three Caribbean reef sharks recaptured after at least one year at large. This study represents the most comprehensive and longest time series analysis of shark abundance in the Caribbean and will provide much needed information about the population dynamics and management needs of coral reef-associated sharks.
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Page 1. BULLETIN OF MARINE SCIENCE, 82(2): 199212, 2008 199 Bulletin of Marine Science © 2008 Rosenstiel School of Marine and Atmospheric Science of the University of Miami A ShARk ATTACk OUTBREAk OFF RECIFE, PERNAMBUCO, BRAzIL:... more
Page 1. BULLETIN OF MARINE SCIENCE, 82(2): 199212, 2008 199 Bulletin of Marine Science © 2008 Rosenstiel School of Marine and Atmospheric Science of the University of Miami A ShARk ATTACk OUTBREAk OFF RECIFE, PERNAMBUCO, BRAzIL: 19922006 ...
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For many species, particularly pelagic sharks, the status of their abundance is subject to further scientific analysis.
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Humans share a fascination and fear of sharks. We predict that most shark attacks are nonfatal but require skilled, timely medical intervention. The development of a shark bite severity scoring scale will assist communication and... more
Humans share a fascination and fear of sharks. We predict that most shark attacks are nonfatal but require skilled, timely medical intervention. The development of a shark bite severity scoring scale will assist communication and understanding of such an injury. We retrospectively reviewed records of the prospectively maintained International Shark Attack File (ISAF) at the University of Florida. The ISAF contains 4409 investigations, including 2979 documented attacks, 96 of which have complete medical records. We developed a Shark-Induced Trauma (SIT) Scale and calculated the level of injury for each attack. Medical records were reviewed for the 96 documented shark attack victims since 1921. Calculated levels of injury in the SIT Scale reveal 40 Level 1 injuries (41.7%), 16 Level 2 injuries (16.7%), 18 Level 3 injuries (18.8%), 14 Level 4 injuries (14.6%), and eight Level 5 injuries (8.3%). The overall mortality of shark attacks was 8.3 per cent. However, SIT Scale Level 1 injuries...