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Fabio Soares Da Cruz - One of the best experts on this subject based on the ideXlab platform.
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nota sobre a ocorrencia de foca caranguejeira lobodon carcinophagus hombron jacquinot 1842 mammalia pinnipedia no estado do rio de janeiro brasil
Biotemas, 2005Co-Authors: Luiz Claudio Mayerhofer, Samuel Gomes De Farias, Fabio Soares Da CruzAbstract:Note on the occurrence of the crebeater Seal, Lobodon carcinophagus (Hombron & Jacquinot, 1842) (Mammalia: Pinnipedia), in Rio de Janeiro State, Brazil. On May 12, 2003, a Crabeater Seal (Lobodon carcinophagus) was seen 3km upstream of the mouth of the Cacao River (22o54’S; 43o50’W), southern Rio de Janeiro State. It was a female of 212cm in length, weighing approximately 180kg. A week prior (May 5), the same specimen (identified by a parallel scar pattern) had been observed at Costao Beach (24o19’S; 47o00’W), Peruibe, Sao Paulo State. Two days later, the animal reappeared at Barra do Sahy Beach (23o47’S; 45o33’W), Sao Sebastiao, Sao Paulo. Subsequently, the Seal’s further northerly displacement to Cacao River made a total distance covered of 229km. The occurrence of two cold fronts and the prevalence of southern currents in the first fortnight of May may have favored the displacement of this animal to areas of low latitude in southeastern Brazil. On June 16, 2003, a male of approximately 200cm in length was seen in Tombo Beach (24o00’S ; 46o18’W), Guaruja (Sao Paulo). It was the second appearance of L. carcinophagus in Sao Paulo in 41 days. This note confirms the occasional occurrence of this species along the Brazilian coast, and provides insights into the dispersion of the species in the southwestern Atlantic.
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Nota sobre a ocorrência de focacaranguejeira, Lobodon carcinophagus (Hombron & Jacquinot, 1842) (Mammalia: Pinnipedia), no estado do Rio de Janeiro, Brasil
Universidade Federal de Santa Catarina, 2005Co-Authors: Lodi Liliane, Mayerhofer, Luiz Cláudio, Samuel Gomes De ,farias Júnior, Fabio Soares Da CruzAbstract:Note on the occurrence of the crebeater Seal, Lobodon carcinophagus (Hombron & Jacquinot, 1842) (Mammalia: Pinnipedia), in Rio de Janeiro State, Brazil. On May 12, 2003, a Crabeater Seal (Lobodon carcinophagus) was seen 3km upstream of the mouth of the Cação River (22º54’S; 43º50’W), southern Rio de Janeiro State. It was a female of 212cm in length, weighing approximately 180kg. A week prior (May 5), the same specimen (identified by a parallel scar pattern) had been observed at Costão Beach (24º19’S; 47º00’W), Peruíbe, São Paulo State. Two days later, the animal reappeared at Barra do Sahy Beach (23º47’S; 45º33’W), São Sebastião, São Paulo. Subsequently, the Seal’s further northerly displacement to Cação River made a total distance covered of 229km. The occurrence of two cold fronts and the prevalence of southern currents in the first fortnight of May may have favored the displacement of this animal to areas of low latitude in southeastern Brazil. On June 16, 2003, a male of approximately 200cm in length was seen in Tombo Beach (24º00’S ; 46º18’W), Guarujá (São Paulo). It was the second appearance of L. carcinophagus in São Paulo in 41 days. This note confirms the occasional occurrence of this species along the Brazilian coast, and provides insights into the dispersion of the species in the southwestern Atlantic.Em 12 de maio de 2003, foi registrada a ocorrência de uma foca-caranguejeira (Lobodon carcinophagus) 3km acima da foz do rio Cação (22º54’S; 43º50’W), sul do Rio de Janeiro. Tratava-se de uma fêmea com 212cm de comprimento total e cerca de 180kg. Uma semana antes da sua ocorrência no Rio de Janeiro (05 de maio), o mesmo exemplar (identificado pelo padrão de cicatrizes paralelas) foi registrado na praia do Costão (24º19’S; 47º00’W), Peruíbe, São Paulo. Dois dias depois, o animal reapareceu na praia da Barra do Sahy (23º47’S; 45º33’W), São Sebastião, São Paulo. Da praia do Costão à praia da Barra do Sahy, o indivíduo deslocouse cerca de 161km e até o seu reaparecimento no rio Cação, houve um deslocamento de aproximadamente 229km. A ocorrência de frentes fria e a predominância de correntes de sul na primeira quinzena de maio podem ter favorecido o deslocamento desse animal para áreas de baixa latitude no sudeste do Brasil. Em 16 de junho de 2003, um macho, medindo cerca de 200cm, foi registrado na praia do Tombo (24º00’S ; 46º18’W), Guarujá (São Paulo). Tratase da segunda ocorrência de L. carcinophagus em São Paulo em 41 dias. Essa nota contribui com informações para o conhecimento da ocorrência ocasional da espécie no Brasil bem como sobre sua dispersão no Atlântico Sul Ocidental
Colin Southwell - One of the best experts on this subject based on the ideXlab platform.
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taking account of dependent species in management of the southern ocean krill fishery estimating Crabeater Seal abundance off east antarctica
Journal of Applied Ecology, 2008Co-Authors: Colin Southwell, Charles G M Paxton, David L Borchers, Peter L Boveng, William K De La MareAbstract:Summary 1. The Crabeater Seal Lobodon carcinophaga is considered to be a key species in the krill-based foodweb of the Southern Ocean. Reliable estimates of the abundance of this species are necessary to allow the development of multispecies, predator‐prey models as a basis for management of the krill fishery in the Southern Ocean. 2. A survey of Crabeater Seal abundance was undertaken in 1500 000 km 2 of pack-ice off east Antarctica between longitudes 64‐150 ° E during the austral summer of 1999/2000. Sighting surveys, using double observer line transect methods, were conducted from an icebreaker and two helicopters to estimate the density of Seals hauled out on the ice in survey strips. Satellite-linked dive recorders were deployed on a sample of Seals to estimate the probability of Seals being hauled out on the ice at the times of day when sighting surveys were conducted. Model-based inference, involving fitting a density surface, was used to infer densities in the entire survey region from estimates in the surveyed areas. 3. Crabeater Seal abundance was estimated to be between 0·7 and 1·4 million animals (with 95% confidence), with the most likely estimate slightly less than 1 million. 4. Synthesis and applications. The estimation of Crabeater Seal abundance in Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) management areas off east Antarctic where krill biomass has also been estimated recently provides the data necessary to begin extending from single-species to multispecies management of the krill fishery. Incorporation of all major sources of uncertainty allows a precautionary interpretation of Crabeater abundance and demand for krill in keeping with CCAMLR’s precautionary approach to management. While this study focuses on the Crabeater Seal and management of living resources in the Southern Ocean, it has also led to technical and theoretical developments in survey methodology that have widespread potential application in ecological and resource management studies, and will contribute to a more fundamental understanding of the structure and function of the Southern Ocean ecosystem.
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Crabeater Seal diving behaviour in eastern antarctica
Marine Ecology Progress Series, 2007Co-Authors: Stephen Wall, Corey J A Bradshaw, Colin Southwell, Nick Gales, Mark A HindellAbstract:Southern Ocean waters are highly productive and contain important food resources for many indigenous predators, including humans. Management of these resources has fallen under the regulation of the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR), which has identified a suite of predators as indicator species for monitoring ecosystem fluctuations, including Crabeater Seals. For Crabeater Seals to fulfil this role, however, they must respond predictably to fluctuations in krill distribution and abundance. Here, we investigated the validity of using the diving behaviour of this species as an indicator of krill distribution and abun- dance. We used behavioural data collected from 23 Crabeater Seals fitted with satellite-linked time- depth recorders off eastern Antarctica to quantify habitat use as a function of the amount of time they spent within geographic regions with varying environmental characteristics. This was then linked with diving behaviour in those regions. By integrating geographic location and diving parameters, we demonstrated that habitat use and foraging behaviour within eastern Antarctic waters fluctuated in response to seasonal and spatial environmental variability. Our attempts to use oceanographic variables to develop models of Crabeater Seal habitat use and behaviour demonstrated real limitations in inferring behaviour from a simple set of environmental factors, but we identified ocean depth and the proximity to the ice edge as factors influencing seasonal habitat use and diving behaviour. Whilst our understanding of the influences driving Crabeater Seal distribution has improved as a result of telemetry studies, it would appear premature to infer cross-species patterns in distribution and abun- dance with krill given the low predictive power of models derived in the present study. Furthermore, the dynamic and regionally variable use of pelagic habitat by this widely abundant Antarctic preda- tor has important implications for the estimation of Crabeater Seal biomass.
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optimising the timing of visual surveys of Crabeater Seal abundance haulout behaviour as a consideration
Wildlife Research, 2005Co-Authors: Colin SouthwellAbstract:The most practical means of estimating pack-ice Seal abundance is by conducting visual surveys from ships and aircraft. However, only those Seals hauled out on the ice are ‘available’ to such surveys, and additional information on haulout behaviour is required to adjust counts of Seals on the ice to estimate the total population size. Consideration of the optimal time to undertake visual surveys with respect to availability is important to ensure that bias and uncertainty in the abundance estimate are minimised for a fixed survey effort. In order to assess the optimal time for conducting visual surveys of Crabeater Seals (Lobodon carcinophaga), satellite-linked dive recorders were attached to 24 adult Seals in the pack-ice off east Antarctica to record haulout behaviour over a 4-month period from mid-September to mid-January. The optimal time for visual surveys within these four months was December to mid-January (after the pupping season) when a high, relatively constant proportion of Seals were hauled out over a period of 6–7 h during daylight, and when variation in haulout behaviour between Seals was low. Despite the necessity for breeding Seals to haul out continuously for extended periods during the pupping season, this was not a preferred time for visual surveys because variability in haulout behaviour between breeding and non-breeding Seals was high. The efficiency of surveys before pupping was limited by the relatively short time during daylight when both the proportion of Seals hauled out was high and variability in haulout behaviour among Seals was small.
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shipboard line transect surveys of Crabeater Seal abundance in the pack ice off east antarctica evaluation of assumptions
Marine Mammal Science, 2004Co-Authors: Colin Southwell, David L Borchers, Bill De La Mare, Louise BurtAbstract:We examine the extent to which the assumptions underlying line transect sampling are satisfied in shipboard surveys of Crabeater Seals (Lobodon carcinophaga) hauled out on the Antarctic pack-ice. Measurement of the perpendicular distance of Seal groups from the ship with an electronic inclinometer fitted to a rifle stock was unbiased. Crabeater Seals showed little movement in response to the approaching ship. Movement away from the ship by Seals close to the ship's track was partially responsible for a relative lack of sightings close to the transect-line, but otherwise had little effect on the sighting histogram. Minor deviations from the transect direction to avoid running over Seals violated the assumption of uniform distribution of groups, and contributed to a relative lack in sightings close to (<40 m) the transect-line. We estimate that 5%-10% of Seal groups close to the transect-line were not sighted by bridge observers prior to passing abeam of the ship, but most of these missed groups were likely to have been sighted some distance behind-abeam. Shipboard transects provided a biased sample of four environmental features known to be related to Crabeater Seal abundance because of logistical difficulties in the ship traversing along straight transects through thick ice. Calculation of transect length L from successive GPS locations was mildly sensitive to the frequency of locations. We provide analytical recommendations to reduce or eliminate the effect of assumption violation when present and hence minimize bias in abundance estimation.
David L Borchers - One of the best experts on this subject based on the ideXlab platform.
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taking account of dependent species in management of the southern ocean krill fishery estimating Crabeater Seal abundance off east antarctica
Journal of Applied Ecology, 2008Co-Authors: Colin Southwell, Charles G M Paxton, David L Borchers, Peter L Boveng, William K De La MareAbstract:Summary 1. The Crabeater Seal Lobodon carcinophaga is considered to be a key species in the krill-based foodweb of the Southern Ocean. Reliable estimates of the abundance of this species are necessary to allow the development of multispecies, predator‐prey models as a basis for management of the krill fishery in the Southern Ocean. 2. A survey of Crabeater Seal abundance was undertaken in 1500 000 km 2 of pack-ice off east Antarctica between longitudes 64‐150 ° E during the austral summer of 1999/2000. Sighting surveys, using double observer line transect methods, were conducted from an icebreaker and two helicopters to estimate the density of Seals hauled out on the ice in survey strips. Satellite-linked dive recorders were deployed on a sample of Seals to estimate the probability of Seals being hauled out on the ice at the times of day when sighting surveys were conducted. Model-based inference, involving fitting a density surface, was used to infer densities in the entire survey region from estimates in the surveyed areas. 3. Crabeater Seal abundance was estimated to be between 0·7 and 1·4 million animals (with 95% confidence), with the most likely estimate slightly less than 1 million. 4. Synthesis and applications. The estimation of Crabeater Seal abundance in Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) management areas off east Antarctic where krill biomass has also been estimated recently provides the data necessary to begin extending from single-species to multispecies management of the krill fishery. Incorporation of all major sources of uncertainty allows a precautionary interpretation of Crabeater abundance and demand for krill in keeping with CCAMLR’s precautionary approach to management. While this study focuses on the Crabeater Seal and management of living resources in the Southern Ocean, it has also led to technical and theoretical developments in survey methodology that have widespread potential application in ecological and resource management studies, and will contribute to a more fundamental understanding of the structure and function of the Southern Ocean ecosystem.
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shipboard line transect surveys of Crabeater Seal abundance in the pack ice off east antarctica evaluation of assumptions
Marine Mammal Science, 2004Co-Authors: Colin Southwell, David L Borchers, Bill De La Mare, Louise BurtAbstract:We examine the extent to which the assumptions underlying line transect sampling are satisfied in shipboard surveys of Crabeater Seals (Lobodon carcinophaga) hauled out on the Antarctic pack-ice. Measurement of the perpendicular distance of Seal groups from the ship with an electronic inclinometer fitted to a rifle stock was unbiased. Crabeater Seals showed little movement in response to the approaching ship. Movement away from the ship by Seals close to the ship's track was partially responsible for a relative lack of sightings close to the transect-line, but otherwise had little effect on the sighting histogram. Minor deviations from the transect direction to avoid running over Seals violated the assumption of uniform distribution of groups, and contributed to a relative lack in sightings close to (<40 m) the transect-line. We estimate that 5%-10% of Seal groups close to the transect-line were not sighted by bridge observers prior to passing abeam of the ship, but most of these missed groups were likely to have been sighted some distance behind-abeam. Shipboard transects provided a biased sample of four environmental features known to be related to Crabeater Seal abundance because of logistical difficulties in the ship traversing along straight transects through thick ice. Calculation of transect length L from successive GPS locations was mildly sensitive to the frequency of locations. We provide analytical recommendations to reduce or eliminate the effect of assumption violation when present and hence minimize bias in abundance estimation.
William K De La Mare - One of the best experts on this subject based on the ideXlab platform.
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taking account of dependent species in management of the southern ocean krill fishery estimating Crabeater Seal abundance off east antarctica
Journal of Applied Ecology, 2008Co-Authors: Colin Southwell, Charles G M Paxton, David L Borchers, Peter L Boveng, William K De La MareAbstract:Summary 1. The Crabeater Seal Lobodon carcinophaga is considered to be a key species in the krill-based foodweb of the Southern Ocean. Reliable estimates of the abundance of this species are necessary to allow the development of multispecies, predator‐prey models as a basis for management of the krill fishery in the Southern Ocean. 2. A survey of Crabeater Seal abundance was undertaken in 1500 000 km 2 of pack-ice off east Antarctica between longitudes 64‐150 ° E during the austral summer of 1999/2000. Sighting surveys, using double observer line transect methods, were conducted from an icebreaker and two helicopters to estimate the density of Seals hauled out on the ice in survey strips. Satellite-linked dive recorders were deployed on a sample of Seals to estimate the probability of Seals being hauled out on the ice at the times of day when sighting surveys were conducted. Model-based inference, involving fitting a density surface, was used to infer densities in the entire survey region from estimates in the surveyed areas. 3. Crabeater Seal abundance was estimated to be between 0·7 and 1·4 million animals (with 95% confidence), with the most likely estimate slightly less than 1 million. 4. Synthesis and applications. The estimation of Crabeater Seal abundance in Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) management areas off east Antarctic where krill biomass has also been estimated recently provides the data necessary to begin extending from single-species to multispecies management of the krill fishery. Incorporation of all major sources of uncertainty allows a precautionary interpretation of Crabeater abundance and demand for krill in keeping with CCAMLR’s precautionary approach to management. While this study focuses on the Crabeater Seal and management of living resources in the Southern Ocean, it has also led to technical and theoretical developments in survey methodology that have widespread potential application in ecological and resource management studies, and will contribute to a more fundamental understanding of the structure and function of the Southern Ocean ecosystem.
Luiz Claudio Mayerhofer - One of the best experts on this subject based on the ideXlab platform.
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nota sobre a ocorrencia de foca caranguejeira lobodon carcinophagus hombron jacquinot 1842 mammalia pinnipedia no estado do rio de janeiro brasil
Biotemas, 2005Co-Authors: Luiz Claudio Mayerhofer, Samuel Gomes De Farias, Fabio Soares Da CruzAbstract:Note on the occurrence of the crebeater Seal, Lobodon carcinophagus (Hombron & Jacquinot, 1842) (Mammalia: Pinnipedia), in Rio de Janeiro State, Brazil. On May 12, 2003, a Crabeater Seal (Lobodon carcinophagus) was seen 3km upstream of the mouth of the Cacao River (22o54’S; 43o50’W), southern Rio de Janeiro State. It was a female of 212cm in length, weighing approximately 180kg. A week prior (May 5), the same specimen (identified by a parallel scar pattern) had been observed at Costao Beach (24o19’S; 47o00’W), Peruibe, Sao Paulo State. Two days later, the animal reappeared at Barra do Sahy Beach (23o47’S; 45o33’W), Sao Sebastiao, Sao Paulo. Subsequently, the Seal’s further northerly displacement to Cacao River made a total distance covered of 229km. The occurrence of two cold fronts and the prevalence of southern currents in the first fortnight of May may have favored the displacement of this animal to areas of low latitude in southeastern Brazil. On June 16, 2003, a male of approximately 200cm in length was seen in Tombo Beach (24o00’S ; 46o18’W), Guaruja (Sao Paulo). It was the second appearance of L. carcinophagus in Sao Paulo in 41 days. This note confirms the occasional occurrence of this species along the Brazilian coast, and provides insights into the dispersion of the species in the southwestern Atlantic.
