The Experts below are selected from a list of 435 Experts worldwide ranked by ideXlab platform
Samuel H Gruber - One of the best experts on this subject based on the ideXlab platform.
-
Regional-Scale Migrations and Habitat Use of Juvenile Lemon Sharks (Negaprion Brevirostris) in the US South Atlantic
2016Co-Authors: Eric A Reyier, Samuel H GruberAbstract:Resolving the geographic extent and timing of coastal shark migrations, as well as their environmental cues, is essential for refining shark management strategies in anticipation of increasing anthropogenic stressors to coastal ecosystems. We employed a regional-scale passive acoustic telemetry array encompassing 300 km of the east Florida coast to assess what factors influence site fidelity of juvenile lemon sharks (Negaprion Brevirostris) to an exposed coastal nursery at Cape Canaveral, and to document the timing and rate of their seasonal migrations. Movements of 54 juvenile lemon sharks were monitored for three years with individuals tracked for up to 751 days. While most sharks demonstrated site fidelity to the Cape Canaveral region December through February under typical winter water temperatures, historically extreme declines in ocean temperature were accompanied by rapid and often temporary, southward displacements of up to 190 km along the Florida east coast. From late February through April each year, most sharks initiated a northward migration at speeds of up to 64 km day21 with several individuals then detected in compatible estuarine telemetry arrays in Georgia and South Carolina up to 472 km from release locations. Nineteen sharks returned for a second or even third consecutive winter, thus demonstrating strong seasonal philopatry to the Cape Canaveral region. The long distance movements and habitat associations of immature lemon sharks along the US southeast coast contrast sharply with the natal site fidelity observed in this species at other sites in the western Atlantic Ocean. These findings validate the existing multi-state managemen
-
behavioral modification of visually deprived lemon sharks Negaprion Brevirostris towards magnetic fields
Journal of Experimental Marine Biology and Ecology, 2014Co-Authors: Craig P Oconnell, Tristan L Guttridge, Jill L Brooks, Jeansebastien Finger, Samuel H Gruber, Pingguo HeAbstract:The ability of elasmobranchs to orient to weak electromagnetic fields is well documented. Recently, scientists have employed the use of strong electrosensory stimuli, such as permanent magnets, as a means to evaluate the repellent responses of elasmobranchs and assess the utility of these materials for bycatch repellent technologies. However, several studies have produced contrasting results both between and within species. To explain these results, we hypothesized that conditions leading to vision loss (i.e. turbid water) may be a factor affecting electrosensory repellent success. To simulate a visually deprived environment, the nictitating membranes of juvenile lemon sharks (Negaprion Brevirostris) were temporarily sutured closed and the behavioral responses of sharks towards a magnetic apparatus were observed in a pen within the shallows of Bimini, Bahamas. Results demonstrate that the magnet-associated behavior of visually deprived sharks significantly differed from control sharks in regard to: (1) avoidance distance, (2) visit quantity prior to first entrance through the magnet zone, and (3) total entrances/total visits. These findings suggest context-dependent switching, where elasmobranchs may exhibit a heightened reliance on their electrosensory system when the extent of their visual range is reduced. These findings also provide insight into favorable environments (e.g. estuary or other coastal ecosystems) and applications (e.g. inshore fisheries and beach nets) that may yield more consistent and successful future implementations of electrosensory repellents for sharks.
-
two decades of genetic profiling yields first evidence of natal philopatry and long term fidelity to parturition sites in sharks
Molecular Ecology, 2014Co-Authors: Kevin A Feldheim, Joseph D Dibattista, Samuel H Gruber, Andrew P Hendry, Steven T Kessel, Elizabeth A Babcock, Ellen K Pikitch, Mary V Ashley, Demian D ChapmanAbstract:Sharks are a globally threatened group of marine fishes that often breed in their natal region of origin. There has even been speculation that female sharks return to their exact birthplace to breed (‘natal philopatry’), which would have important conservation implications. Genetic profiling of lemon sharks (Negaprion Brevirostris) from 20 consecutive cohorts (1993–2012) at Bimini, Bahamas, showed that certain females faithfully gave birth at this site for nearly two decades. At least six females born in the 1993– 1997 cohorts returned to give birth 14–17 years later, providing the first direct evidence of natal philopatry in the chondrichthyans. Long-term fidelity to specific nursery sites coupled with natal philopatry highlights the merits of emerging spatial and local conservation efforts for these threatened predators.
-
Regional-Scale Migrations and Habitat Use of Juvenile Lemon Sharks (Negaprion Brevirostris) in the US South Atlantic
2014Co-Authors: Eric A Reyier, Bryan R Franks, Demian D Chapman, Douglas M. Scheidt, Eric D. Stolen, Samuel H GruberAbstract:Resolving the geographic extent and timing of coastal shark migrations, as well as their environmental cues, is essential for refining shark management strategies in anticipation of increasing anthropogenic stressors to coastal ecosystems. We employed a regional-scale passive acoustic telemetry array encompassing 300 km of the east Florida coast to assess what factors influence site fidelity of juvenile lemon sharks (Negaprion Brevirostris) to an exposed coastal nursery at Cape Canaveral, and to document the timing and rate of their seasonal migrations. Movements of 54 juvenile lemon sharks were monitored for three years with individuals tracked for up to 751 days. While most sharks demonstrated site fidelity to the Cape Canaveral region December through February under typical winter water temperatures, historically extreme declines in ocean temperature were accompanied by rapid and often temporary, southward displacements of up to 190 km along the Florida east coast. From late February through April each year, most sharks initiated a northward migration at speeds of up to 64 km day−1 with several individuals then detected in compatible estuarine telemetry arrays in Georgia and South Carolina up to 472 km from release locations. Nineteen sharks returned for a second or even third consecutive winter, thus demonstrating strong seasonal philopatry to the Cape Canaveral region. The long distance movements and habitat associations of immature lemon sharks along the US southeast coast contrast sharply with the natal site fidelity observed in this species at other sites in the western Atlantic Ocean. These findings validate the existing multi-state management strategies now in place. Results also affirm the value of collaborative passive arrays for resolving seasonal movements and habitat preferences of migratory coastal shark species not easily studied with other tagging techniques.
-
deep danger intra specific predation risk influences habitat use and aggregation formation of juvenile lemon sharks Negaprion Brevirostris
Marine Ecology Progress Series, 2012Co-Authors: Tristan L Guttridge, Samuel H Gruber, Bryan R Franks, Steven T Kessel, Katie S Gledhill, Jen Uphill, Jens Krause, David W SimsAbstract:Non-consumptive or risk effects imposed by predators can influence prey behaviour over different spatio-temporal scales. Prey vulnerability to predation can also be dependent on abiotic conditions, such as tidal height. We conducted direct field observations of juvenile lemon sharks Negaprion Brevirostris in a tidally influenced mangrove-inlet. We also used acoustic tracking to determine the movement patterns of juvenile lemon sharks and their predators (sub-adult lemon sharks) across the tidal cycle. Results showed that greater numbers of juvenile lemon sharks used the mangrove-inlet for longer time periods at deeper and warmer high tide depths. This coincided with an increased presence of potential predators (sub-adult lemon sharks) in the surrounding areas. Furthermore, in accordance with body-size dependent anti-predatory investment, smaller juvenile lemon sharks visited the mangrove inlet more often, spent longer there and left latest on average. Our acoustic tracking data also revealed a tidally-influenced pattern, with both juvenile and sub-adult lemon sharks detected at locations inshore over the high tide and offshore during the low tide. We concluded that the mangrove lake served as a 'refuge' for juvenile lemon sharks over the high tide, providing safe habitat when inshore areas become accessible to large predators, such as sub-adult lemon sharks. We suggest that these decisions are updated through ontogeny and also with daily fluctuations in abiotic factors, such as water depth. This study provides evidence for how intra-specific predatorprey interactions in a top predator species influence juvenile habitat selection, with potential implications for population structure and regulation.
Salomón-aguilar, Carlos Alberto - One of the best experts on this subject based on the ideXlab platform.
-
Enfoque multiespecífico en el manejo de tiburones del golfo de México: identificación de especies con fragilidad biológica alta
Mesoamericana, 2021Co-Authors: Salomón-aguilar, Carlos AlbertoAbstract:The main problem of the shark fishery in the Gulf of Mexico is the lack of reliable statistical data on catches by species. This situation difficult the obtention of maximum yields, optimal effort units and effective population size with the use traditional models. Due to this, the objective was to detect the shark species most susceptible to overexploitation by means of multi-species analysis in order to identify Priority Areas for Research and Conservation (PARC). The biological fragility index that was used consists of life-history characteristics that define the elasmobranchs as K strategists. The selection of PARC was performed using analysis of complementarity and discrepancies. Vulnerable species to intense fishing regimes were Carcharhinus acronotus, Carcharhinus falciformis, Carcharhinus obscurus, Negaprion Brevirostris and Rhizoprionodon terraenovae. The main areas to be considered for conservation are Bahía Ascensión and Espíritu Santo, Quintana Roo, Mexico. Comparing the PARC with Protected Natural Areas and fishing refuges of the NOM-029-PESC- 2006, both coincided 88.89% and 44.44%, respectively. Carcharhinus longimanus, Carcharhinus perezi, Carcharhinus signatus, Galeocerdo cuvier, Ginglymostoma cirratum, Mustelus canis, Squalus asper and Squalus cubensis were not considered in this work by the lack of regional data.La problemática generalizada de la pesquería de tiburones en el Golfo de México es la falta de información estadística confiable de las capturas por especie. Esta situación dificulta la obtención de rendimientos máximos, unidades de esfuerzo óptimo y tamaños efectivos poblacionales con el uso de modelos tradicionales. Debido a lo anterior, el objetivo fue identificar las especies más susceptibles a sobre explotación mediante un análisis multiespecífico para la identificación de Áreas Prioritarias de Investigación y Conservación (APIyC). El índice de fragilidad biológica que se utilizó está integrado por características del ciclo de vida que define a los elasmobranquios como estrategas K. La selección de APIyC se realizó con análisis de complementariedad y discrepancias. Las especies vulnerables a intensos regímenes de pesca fueron Carcharhinus acronotus, Carcharhinus falciformis, Carcharhinus obscurus, Negaprion Brevirostris y Rhizoprionodon terraenovae. Las zonas principales que deben estar sujetas a conservación son Bahía Ascensión y Espíritu Santo, Quintana Roo. Al comparar las APIyC con las Áreas Naturales Protegidas y los refugios pesqueros de la NOM-029-PESC-2006, coincidieron en un 88.89% y 44.44%, respectivamente. Carcharhinus longimanus, Carcharhinus perezi, Carcharhinus signatus, Galeocerdo cuvier, Ginglymostoma cirratum, Mustelus canis, Squalus asper y Squalus cubensis no se consideraron en el presente trabajo por la carencia de datos regionales
-
Enfoque multiespecífico en el manejo de tiburones del Golfo de México: identificación de especies con fragilidad biológica alta
Jaime Raúl Bonilla-Barbosa, 2012Co-Authors: Salomón-aguilar, Carlos AlbertoAbstract:La problemática generalizada de la pesquería de tiburones en el Golfo de México es la falta de información estadística confiable de las capturas por especie. Esta situación dificulta la obtención de rendimientos máximos, unidades de esfuerzo óptimo y tamaños efectivos poblacionales con el uso de modelos tradicionales. Debido a lo anterior, el objetivo fue identificar las especies más susceptibles a sobre explotación mediante un análisis multiespecífico para la identificación de Áreas Prioritarias de Investigación y Conservación (APIyC). El índice de fragilidad biológica que se utilizó está integrado por características del ciclo de vida que define a los elasmobranquios como estrategas K. La selección de APIyC se realizó con análisis de complementariedad y discrepancias. Las especies vulnerables a intensos regímenes de pesca fueron Carcharhinus acronotus, Carcharhinus falciformis, Carcharhinus obscurus, Negaprion Brevirostris y Rhizoprionodon terraenovae. Las zonas principales que deben estar sujetas a conservación son Bahía Ascensión y Espíritu Santo, Quintana Roo. Al comparar las APIyC con las Áreas Naturales Protegidas y los refugios pesqueros de la NOM-029-PESC-2006, coincidieron en un 88.89% y 44.44%, respectivamente. Carcharhinus longimanus, Carcharhinus perezi, Carcharhinus signatus, Galeocerdo cuvier, Ginglymostoma cirratum, Mustelus canis, Squalus asper y Squalus cubensis no se consideraron en el presente trabajo por la carencia de datos regionales
Rada, Danilo De Paula - One of the best experts on this subject based on the ideXlab platform.
-
Interações sociais, uso do habitat e estrutura populacional do tubarão-limão , Negaprion Brevirostris (Poey, 1868), no arquipélago de Fernando de Noronha (PE).
Universidade Federal da Paraíba, 2010Co-Authors: Rada, Danilo De PaulaAbstract:A estrutura populacional e o uso do habitat de Negaprion Brevirostris foram verificados ao longo de cinco expedições para o arquipélago de Fernando de Noronha, utilizando-se três metodologias diferentes: busca ativa, transecções e observações terrestres a partir de um ponto elevado. A estruturação etária configurou-se pela predominância de jovens, seguidos de subadultos, neonatos e adultos. A razão sexual foi fortemente enviesada a favor das fêmeas, sugerindo segregação sexual. Os neonatos geralmente foram observados agregados, em profundidades atingindo no máximo 1,5 m. A análise de covariância (ANCOVA) indicou que o número de avistagens de tubarões se relacionou com o local, a temperatura e a profundidade. De modo geral, os tubarões jovens e subadultos preferiram águas quentes e rasas, com um temperatura ótima de 27º C e uma profundidade menor que 6 m. O local com maior número de avistamentos foi o Buraco da Raquel. Não foi encontrada uma preferência por substrato rochoso ou arenoso e a região do porto foi evitada, provavelmente pela antropização da área. A presença dos tubarões em águas rasas indica fidelidade ao local e, talvez uma forma de se evitar os predadores. A maior quantidade de tubarões observados nas áreas sem interferências humanas revela a importância e necessidade da criação e implementação de áreas marinhas protegidas.The population structure and habitat use of Negaprion Brevirostris were verified through five expeditions to Fernando de Noronha archipelago. To achieve this we used three different methodologies: active search, strip transects and terrestrial observations from an elevated point. The age structure configuration revealed that young sharks are predominant, followed by subadults, adults and neonates. The sex ratio was strongly female skewed, what suggest sexual segregation. Neonates were frequently observed in groups and always at 1.5 m maximum depth. An analysis of covariance (ANCOVA) was performed and we verified that shark’s sightings were correlated to site, temperature and depth. In general, young and subadults sharks preferred shallow and warmer waters, with an optimum temperature around 27 º C and depths of less than 6 m. The greatest number of shark’s sightings took place at Buraco da Raquel. Lemon sharks did not choose between rocky or sandy substrates but they avoided the harbor region, probably because the anthropogenic development. The presence of sharks in nearshore environments indicates their site attachment and, perhaps, predator avoidance. Sharks were mostly observed at non-human interference areas, what reveals the magnitude need for creation and implementation of marine protected areas
-
Interações sociais, uso do habitat e estrutura populacional do tubarão-limão , Negaprion Brevirostris (Poey, 1868), no arquipélago de Fernando de Noronha (PE).
'Portal de Periodicos UFPB', 2010Co-Authors: Rada, Danilo De PaulaAbstract:The population structure and habitat use of Negaprion Brevirostris were verified through five expeditions to Fernando de Noronha archipelago. To achieve this we used three different methodologies: active search, strip transects and terrestrial observations from an elevated point. The age structure configuration revealed that young sharks are predominant, followed by subadults, adults and neonates. The sex ratio was strongly female skewed, what suggest sexual segregation. Neonates were frequently observed in groups and always at 1.5 m maximum depth. An analysis of covariance (ANCOVA) was performed and we verified that shark’s sightings were correlated to site, temperature and depth. In general, young and subadults sharks preferred shallow and warmer waters, with an optimum temperature around 27 º C and depths of less than 6 m. The greatest number of shark’s sightings took place at Buraco da Raquel. Lemon sharks did not choose between rocky or sandy substrates but they avoided the harbor region, probably because the anthropogenic development. The presence of sharks in nearshore environments indicates their site attachment and, perhaps, predator avoidance. Sharks were mostly observed at non-human interference areas, what reveals the magnitude need for creation and implementation of marine protected areas.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESA estrutura populacional e o uso do habitat de Negaprion Brevirostris foram verificados ao longo de cinco expedições para o arquipélago de Fernando de Noronha, utilizando-se três metodologias diferentes: busca ativa, transecções e observações terrestres a partir de um ponto elevado. A estruturação etária configurou-se pela predominância de jovens, seguidos de subadultos, neonatos e adultos. A razão sexual foi fortemente enviesada a favor das fêmeas, sugerindo segregação sexual. Os neonatos geralmente foram observados agregados, em profundidades atingindo no máximo 1,5 m. A análise de covariância (ANCOVA) indicou que o número de avistagens de tubarões se relacionou com o local, a temperatura e a profundidade. De modo geral, os tubarões jovens e subadultos preferiram águas quentes e rasas, com um temperatura ótima de 27º C e uma profundidade menor que 6 m. O local com maior número de avistamentos foi o Buraco da Raquel. Não foi encontrada uma preferência por substrato rochoso ou arenoso e a região do porto foi evitada, provavelmente pela antropização da área. A presença dos tubarões em águas rasas indica fidelidade ao local e, talvez uma forma de se evitar os predadores. A maior quantidade de tubarões observados nas áreas sem interferências humanas revela a importância e necessidade da criação e implementação de áreas marinhas protegidas
Kevin A Feldheim - One of the best experts on this subject based on the ideXlab platform.
-
two decades of genetic profiling yields first evidence of natal philopatry and long term fidelity to parturition sites in sharks
Molecular Ecology, 2014Co-Authors: Kevin A Feldheim, Joseph D Dibattista, Samuel H Gruber, Andrew P Hendry, Steven T Kessel, Elizabeth A Babcock, Ellen K Pikitch, Mary V Ashley, Demian D ChapmanAbstract:Sharks are a globally threatened group of marine fishes that often breed in their natal region of origin. There has even been speculation that female sharks return to their exact birthplace to breed (‘natal philopatry’), which would have important conservation implications. Genetic profiling of lemon sharks (Negaprion Brevirostris) from 20 consecutive cohorts (1993–2012) at Bimini, Bahamas, showed that certain females faithfully gave birth at this site for nearly two decades. At least six females born in the 1993– 1997 cohorts returned to give birth 14–17 years later, providing the first direct evidence of natal philopatry in the chondrichthyans. Long-term fidelity to specific nursery sites coupled with natal philopatry highlights the merits of emerging spatial and local conservation efforts for these threatened predators.
-
long term natal site fidelity by immature lemon sharks Negaprion Brevirostris at a subtropical island
Molecular Ecology, 2009Co-Authors: Demian D Chapman, Tristan L Guttridge, Joseph D Dibattista, Samuel H Gruber, Bryan R Franks, Elizabeth A Babcock, Ellen K Pikitch, Steven Kessel, Kevin A FeldheimAbstract:Although many sharks begin their life confined in nursery habitats, it is unknown how rapidly they disperse away from their natal area once they leave the nursery. We examine this issue in immature lemon sharks (Negaprion Brevirostris) from the time they leave the nursery (� age 3) at a subtropical island (Bimini, Bahamas), through to the onset of sexual maturity (� age 12). From 1995 to 2007 we tagged and genotyped a large fraction of the nursery-bound sharks at this location (0‐3 years of age, N = 1776 individuals). From 2003 to 2007 we sampled immature sharks aged from 3 to 11 years (N = 150) living around the island and used physical ⁄genetic tag recaptures coupled with kinship analysis to determine whether or not each of these ‘large immature sharks’ was locally born. We show that many island-born lemon sharks remain close to their natal area for long periods (years) after leaving the nursery; more than half of the sampled sharks up to 135 cm total length (� 6 years old) were locally born. The fraction of locally born sharks gradually declined with increasing shark size, indicating that dispersal is relatively slow and does not primarily occur after sharks reach a threshold size. Local conservation measures (e.g. localized fishery closures, marine protected areas) can therefore help protect island-born lemon sharks even after they leave the nursery habitat.
-
evolutionary potential of a large marine vertebrate quantitative genetic parameters in a wild population
Evolution, 2009Co-Authors: Joseph D Dibattista, Kevin A Feldheim, Samuel H Gruber, Dany Garant, Andrew P HendryAbstract:Estimating quantitative genetic parameters ideally takes place in natural populations, but relatively few studies have overcome the inherent logistical difficulties. For this reason, no estimates currently exist for the genetic basis of life-history traits in natural populations of large marine vertebrates. And yet such estimates are likely to be important given the exposure of this taxon to changing selection pressures, and the relevance of life-history traits to population productivity. We report such estimates from a long-term (1995-2007) study of lemon sharks (Negaprion Brevirostris) conducted at Bimini, Bahamas. We obtained these estimates by genetically reconstructing a population pedigree (117 dams, 487 sires, and 1351 offspring) and then using an "animal model" approach to estimate quantitative genetic parameters. We find significant additive genetic (co)variance, and hence moderate heritability, for juvenile length and mass. We also find substantial maternal effects for these traits at age-0, but not age-1, confirming that genotype-phenotype interactions between mother and offspring are strongest at birth; although these effects could not be parsed into their genetic and nongenetic components. Our results suggest that human-imposed selection pressures (e.g., size-selective harvesting) might impose noteworthy evolutionary change even in large marine vertebrates. We therefore use our findings to explain how maternal effects may sometimes promote maladaptive juvenile traits, and how lemon sharks at different nursery sites may show "constrained local adaptation." We also show how single-generation pedigrees, and even simple marker-based regression methods, can provide accurate estimates of quantitative genetic parameters in at least some natural systems.
-
are indirect genetic benefits associated with polyandry testing predictions in a natural population of lemon sharks
Molecular Ecology, 2008Co-Authors: Joseph D Dibattista, Kevin A Feldheim, Samuel H Gruber, Andrew P HendryAbstract:Multiple mating has clear fitness benefits for males, but uncertain benefits and costs for females. We tested for indirect genetic benefits of polyandry in a natural population, by using data from a long-term genetic and demographic study of lemon sharks (Negaprion Brevirostris) at Bimini, Bahamas. To do so, we followed the fates of individuals from six cohorts (450 age-0 and 254 age-1 fish) in relation to their individual level of genetic variation, and whether they were from polyandrous or monoandrous litters. We find that offspring from polyandrous litters did not have a greater genetic diversity or greater survival than did the offspring of monoandrous litters. We also find no evidence of positive associations between individual offspring genetic diversity metrics and our surrogate measure of fitness (i.e. survival). In fact, age-1 individuals with fewer heterozygous microsatellite loci and more genetically similar parents were more likely to survive to age-2. Thus, polyandry in female lemon sharks does not appear to be adaptive from the perspective of indirect genetic benefits to offspring. It may instead be the result of convenience polyandry, whereby females mate multiply to avoid harassment by males. Our inability to find indirect genetic benefits of polyandry despite detailed pedigree and survival information suggests the need for similar assessments in other natural populations.
-
reconstruction of parental microsatellite genotypes reveals female polyandry and philopatry in the lemon shark Negaprion Brevirostris
Evolution, 2004Co-Authors: Kevin A Feldheim, Samuel H Gruber, Mary V AshleyAbstract:Because sharks possess an unusual suite of reproductive characteristics, including internal fertilization, sperm storage, relatively low fecundity, and reproductive modes that range from oviparity to viviparity, they can provide important insight into the evolution of mating systems and sexual selection. Yet, to date, few studies have characterized behavioral and genetic mating systems in natural populations of sharks or other elasmobranchs. In this study, highly polymorphic microsatellite loci were used to examine breeding biology of a large coastal shark, the lemon shark, Negaprion Brevirostris, at a tropical lagoon nursery. Over six years, 910 lemon sharks were sampled and genotyped. Young were assigned into sibling groups that were then used to reconstruct genotypes of unsampled adults. We assigned 707 of 735 young sharks to one of 45 female genotypes (96.2%), and 485 (66.0%) were assigned to a male genotype. Adult female sharks consistently returned to Bimini on a biennial cycle to give birth. Over 86% of litters had multiple sires. Such high levels of polyandry raise the possibility that polyandry evolved in viviparous sharks to reduce genetic incompatibilities between mother and embryos. We did not find a relationship between relatedness of mates and the number of offspring produced, indicating that inbreeding avoidance was probably not driving pre- or postcopulatory mate choice. Adult male sharks rarely sired more than one litter at Bimini and may mate over a broader geographic area.
Garla, Ricardo Clapis - One of the best experts on this subject based on the ideXlab platform.
-
Ecologia e conservação dos tubarões do arquipélago de Fernando de Noronha, com ênfase no tubarão-cabeça-de-cesto Carcharhinus perezi (Poey, 1876) (Carcharhiniformes, Carcharhinidae)
Universidade Estadual Paulista (UNESP), 2004Co-Authors: Garla, Ricardo ClapisAbstract:O presente trabalho visa gerar informações básicas sobre a ecologia e a situação populacional do tubarão-cabeça-de-cesto Carcharhinus perezi, lambarú Ginglymostoma cirratum e tubarão-limão Negaprion Brevirostris no Arquipélago de Fernando de Noronha, com ênfase na primeira, por ser numericamente dominante. Utilizou-se a combinação de técnicas de marcação e recaptura e de telemetria ultra-sônica para fornecer informações sobre: estrutura populacional, distribuição espacial dos tubarões e de suas áreas de berçário, época de parto, padrões de movimentação e de utilização do hábitat. Amostras de sangue foram analisadas para caracterização sorológica das espécies. Foi implantado um programa de conscientização e educação sobre a necessidade de conservação dos tubarões, e realizou-se um curso de capacitação em Educação Ambiental para os professores do ensino médio e fundamental. A plataforma insular do arquipélago é utilizada como área de parto e de crescimento de jovens pelas três espécies de tubarões. Carcharhinus perezi apresenta maior segregação espacial por tamanho. Não ocorre segregação espacial em Ginglymostoma cirratum e Negaprion Brevirostris pois foram observados indivíduos neonatos, jovens e adultos freqüentando a região próxima à linha costeira do arquipélago. Os tubarões utilizam com menor freqüência o trecho da Área de Proteção Ambiental (APA) do arquipélago, o que possivelmente está relacionado à intensificação da utilização humana e a indícios de empobrecimento biológico da região nos últimos anos. O monitoramento por telemetria mostra que: os tubarões jovens são residentes em trechos específicos do arquipélago; eles podem ser ativos a qualquer horário do dia, mas os maiores espaços de atividade e deslocamentos ocorrem à noite; aparentemente não existem variações sazonais...The aim of the present study is to provide basic data on the ecology and population status of the reef-shark Carcharhinus perezi, nurse-shark Ginglymostoma cirratum and lemon-shark Negaprion Brevirostris at Fernando de Noronha archipelago, with special reference to Carcharhinus perezi, due to its numerical dominance. A combination of mark and recapture and ultrasonic telemetry methods were used to gather data on: the population structure, spatial distribution of the sharks, location of the nursery grounds, parturition time, patterns of movement and habitat use. Blood samples were analyzed for a serological characterization of the species. An educational program was established to increase the community awareness about shark conservation, and a capacitating course on Environmental Education was offered to teachers of the local school. The archipelago s insular shelf is used as a parturition and growing ground for young sharks of the three species. Carcharhinus perezi shows size segregation. Size segregation was not observed in Ginglymostoma cirratum and Negaprion Brevirostris, and neonate, young and adult sharks of these species were observed to frequent shallow waters of the archipelago. Sharks rarely frequent the archipelago s Environmental Protection Area (EPA), which is probably related to an intensification of human use and evidences of biological impoverishment of this site in recent years. The telemetry monitoring shows that: the young sharks are resident and present site fidelity to specific portions of the archipelago; they may be active at any time of the day, but the larger activity spaces and excursions occur at night; apparently there is no seasonal variation in activity spaces and habitat use; and larger sharks have more extensive activity spaces. The main problems for the management and conservation of the sharks are:... (Complete abstract click electronic access below)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP