P. Fruet, L. D. Rosa, Rodrigo C Genoves, V. Valiati, T. Freitas, L. Möller
Cetacean biopsy sampling is a widely used technique with undisputable scientific value. Although it is generally considered as a harmless technique with no apparent long-lasting effects, studies have recommended examining behavioral responses to evaluate potential impacts on individuals, groups and sampled populations. In this study, we evaluated individual behavioral reactions and wound-healing in common bottlenose dolphins (Tursiops truncatus) during a biopsy sampling program carried out in southern Brazil from 2003 to 2012, and compared sampling effectiveness between dedicated and opportunistic sampling surveys. Two hundred and fiftytwo biopsy attempts were made, resulting in 118 hits (48% of attempts) and 134 samples (52% of attempts) collected successfully. Responses to biopsy sampling were low-level, of short-term duration, and elicited similar reactions on the dolphins, irrespective of shot distance, sex of individuals, dolphins’ group size and pre-behavioral state. Dolphins subjected to multiple biopsy attempts reacted in a similar manner as in previous attempt(s), with no evidence of increasing the intensity of the reaction. Wounds could be monitored in 18 animals and healed over 18 to 35 days. Generally, wounds appeared to be covered by epidermis in about three weeks with no observed signs of skin infection. Our results agree with previous studies suggesting that biopsy sampling does not cause significant disturbance to the behavior of dolphins. At a local level, this study demonstrates that biopsy sampling of bottlenose dolphins in the Patos Lagoon Estuary is more effective, less costly and less intrusive when conducted opportunistically, but that long-term sampling is required to achieve a relatively good sample size from photoidentified individuals in the population.
{"title":"Biopsy darting of common bottlenose dolphins (Tursiops truncatus) in southern Brazil: evaluating effectiveness, short-term responses and wound healing","authors":"P. Fruet, L. D. Rosa, Rodrigo C Genoves, V. Valiati, T. Freitas, L. Möller","doi":"10.5597/LAJAM00221","DOIUrl":"https://doi.org/10.5597/LAJAM00221","url":null,"abstract":"Cetacean biopsy sampling is a widely used technique with undisputable scientific value. Although it is generally considered as a harmless technique with no apparent long-lasting effects, studies have recommended examining behavioral responses to evaluate potential impacts on individuals, groups and sampled populations. In this study, we evaluated individual behavioral reactions and wound-healing in common bottlenose dolphins (Tursiops truncatus) during a biopsy sampling program carried out in southern Brazil from 2003 to 2012, and compared sampling effectiveness between dedicated and opportunistic sampling surveys. Two hundred and fiftytwo biopsy attempts were made, resulting in 118 hits (48% of attempts) and 134 samples (52% of attempts) collected successfully. Responses to biopsy sampling were low-level, of short-term duration, and elicited similar reactions on the dolphins, irrespective of shot distance, sex of individuals, dolphins’ group size and pre-behavioral state. Dolphins subjected to multiple biopsy attempts reacted in a similar manner as in previous attempt(s), with no evidence of increasing the intensity of the reaction. Wounds could be monitored in 18 animals and healed over 18 to 35 days. Generally, wounds appeared to be covered by epidermis in about three weeks with no observed signs of skin infection. Our results agree with previous studies suggesting that biopsy sampling does not cause significant disturbance to the behavior of dolphins. At a local level, this study demonstrates that biopsy sampling of bottlenose dolphins in the Patos Lagoon Estuary is more effective, less costly and less intrusive when conducted opportunistically, but that long-term sampling is required to achieve a relatively good sample size from photoidentified individuals in the population.","PeriodicalId":17967,"journal":{"name":"Latin American Journal of Aquatic Mammals","volume":"19 1","pages":"121-132"},"PeriodicalIF":0.0,"publicationDate":"2017-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72910208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Oliveira, P. H. Ott, I. Moreno, M. Tavares, S. Siciliano, S. Bonatto
The Sao Pedro and Sao Paulo Archipelago (SPSPA) (00°56’N, 29°22’W) lies approximately 1010km northeast off the coast of Rio Grande do Norte State in Brazilian waters. Recently, through photo-identification and group size analysis, around 20-30 individual bottlenose dolphins, Tursiops truncatus, from SPSPA were recognized as a resident, and potentially genetically isolated, population. The effective population size (Ne), not the census number (Nc), as well the sex ratio, are of primary concern from an evolutionary and conservation management perspectives. The estimate of Ne reflects the number of individuals responsible for the maintenance of genetic diversity of a species or population as well its evolutionary potential. For this reason, we present here the first Ne and sex ratio estimates for the bottlenose dolphin population from SPSPA. Sex was molecularly determined for 19 biopsy samples collected from bottlenose dolphins from SPSPA between January and February 2005. The Ne was estimated by direct counting of reproductive adults sexed by DNA analysis. The resulting Ne was 12 individuals and the sex ratio was 1.11 male to 1 female, however, it was not significantly different from the expected 1:1 ratio (χ2 test, α= 0.05; df = 1). The effective population size based on the genetic diversity of 19 sequences of the mtDNA control region resulted in a female effective population size of 223 individuals, and the total long-term effective size of ~470 individuals. We believe that the estimated Ne for the SPSPA population is a critical value, because it is significantly lower than the mean minimum viable population (MVP) suggested for vertebrates (around 5000 breeding age adults). This small Ne is of great concern and should be taken into account in future management plans to ensure the conservation and protection of this small population at SPSPA.
圣佩德罗和圣保罗群岛(SPSPA)(北纬00°56′，西经29°22′)位于巴西海域里约热内卢Grande do Norte州海岸东北约1010公里处。最近，通过照片识别和群体大小分析，来自SPSPA的大约20-30只宽吻海豚(Tursiops truncatus)被认为是一个潜在的遗传隔离种群。从进化和保护管理的角度来看，有效种群规模(Ne)，而不是人口普查数量(Nc)，以及性别比例是主要关注的问题。Ne的估计值反映了负责维持一个物种或种群遗传多样性的个体数量及其进化潜力。出于这个原因，我们在这里提出了SPSPA对宽吻海豚种群的第一个Ne和性别比例估计。在2005年1月至2月期间从SPSPA收集的19个宽吻海豚活检样本进行了分子性测定。Ne是通过DNA分析直接计数生殖成虫来估算的。结果Ne为12只，雌雄比为1.11比1，但与预期的1:1比无显著差异(χ2检验，α= 0.05;df = 1)。基于mtDNA控制区19个序列遗传多样性的有效种群大小计算得到雌性有效种群大小为223个个体，总长期有效种群大小为~470个个体。我们认为SPSPA种群的Ne值是一个临界值，因为它明显低于脊椎动物(约5000个繁殖年龄的成年动物)的平均最小生存种群(MVP)。这个小的Ne非常令人担忧，在未来的管理计划中应该考虑到这一点，以确保SPSPA的这个小种群得到养护和保护。
{"title":"Effective population size of an offshore population of bottlenose dolphins, Tursiops truncatus, from the São Pedro and São Paulo Archipelago, Brazil","authors":"L. Oliveira, P. H. Ott, I. Moreno, M. Tavares, S. Siciliano, S. Bonatto","doi":"10.5597/00225","DOIUrl":"https://doi.org/10.5597/00225","url":null,"abstract":"The Sao Pedro and Sao Paulo Archipelago (SPSPA) (00°56’N, 29°22’W) lies approximately 1010km northeast off the coast of Rio Grande do Norte State in Brazilian waters. Recently, through photo-identification and group size analysis, around 20-30 individual bottlenose dolphins, Tursiops truncatus, from SPSPA were recognized as a resident, and potentially genetically isolated, population. The effective population size (Ne), not the census number (Nc), as well the sex ratio, are of primary concern from an evolutionary and conservation management perspectives. The estimate of Ne reflects the number of individuals responsible for the maintenance of genetic diversity of a species or population as well its evolutionary potential. For this reason, we present here the first Ne and sex ratio estimates for the bottlenose dolphin population from SPSPA. Sex was molecularly determined for 19 biopsy samples collected from bottlenose dolphins from SPSPA between January and February 2005. The Ne was estimated by direct counting of reproductive adults sexed by DNA analysis. The resulting Ne was 12 individuals and the sex ratio was 1.11 male to 1 female, however, it was not significantly different from the expected 1:1 ratio (χ2 test, α= 0.05; df = 1). The effective population size based on the genetic diversity of 19 sequences of the mtDNA control region resulted in a female effective population size of 223 individuals, and the total long-term effective size of ~470 individuals. We believe that the estimated Ne for the SPSPA population is a critical value, because it is significantly lower than the mean minimum viable population (MVP) suggested for vertebrates (around 5000 breeding age adults). This small Ne is of great concern and should be taken into account in future management plans to ensure the conservation and protection of this small population at SPSPA.","PeriodicalId":17967,"journal":{"name":"Latin American Journal of Aquatic Mammals","volume":"46 1","pages":"162-169"},"PeriodicalIF":0.0,"publicationDate":"2017-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86126527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Laporta, Cristiane C. A. Martins, L. Lodi, C. Domit, E. Vermeulen, J. C. Tullio
The review compiles available information about the habitat use patterns of bottlenose dolphins within the SWAO, including temporal analysis of survey effort allocation, and spatial analysis indicating areas of resident or seasonally resident populations.
{"title":"Report of the Working Group on Habitat Use of Tursiops truncatus in the Southwest Atlantic Ocean","authors":"P. Laporta, Cristiane C. A. Martins, L. Lodi, C. Domit, E. Vermeulen, J. C. Tullio","doi":"10.5597/00215","DOIUrl":"https://doi.org/10.5597/00215","url":null,"abstract":"The review compiles available information about the habitat use patterns of bottlenose dolphins within the SWAO, including temporal analysis of survey effort allocation, and spatial analysis indicating areas of resident or seasonally resident populations.","PeriodicalId":17967,"journal":{"name":"Latin American Journal of Aquatic Mammals","volume":"53 1","pages":"47-61"},"PeriodicalIF":0.0,"publicationDate":"2017-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87414062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This note reviews and updates records of bottlenose dolphin in Rio de Janeiro State, combining unpublished data with previously published information to evaluate the current state of knowledge of the occurrence of this species in the state.
{"title":"Update on the current occurrence of Tursiops truncatus (Montagu, 1821) in Rio de Janeiro State","authors":"L. Lodi","doi":"10.5597/LAJAM00231","DOIUrl":"https://doi.org/10.5597/LAJAM00231","url":null,"abstract":"This note reviews and updates records of bottlenose dolphin in Rio de Janeiro State, combining unpublished data with previously published information to evaluate the current state of knowledge of the occurrence of this species in the state.","PeriodicalId":17967,"journal":{"name":"Latin American Journal of Aquatic Mammals","volume":"72 1","pages":"220-226"},"PeriodicalIF":0.0,"publicationDate":"2017-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90483623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cetacean populations in coastal habitats are increasingly threatened by multiple anthropogenic impacts. Monitoring these populations to obtain robust estimates of abundance and detect trends over time is critical to achieve conservation goals. Here, we conducted a pilot study to evaluate the effectiveness of two commonly used abundance estimation methods: mark-recapture and distance sampling line-transect. Surveys were conducted to estimate the abundance of bottlenose dolphins in Laguna, southern Brazil. We implemented power-analysis models and compared both techniques in terms of cost, time and effectiveness to detect trends over a five-year period. Mark-recapture models were analyzed in MARK and resulted in an abundance of 50 individuals (CI = 39-64) with a coefficient of variation (CV) of 0.13. The line-transect models were implemented using the program DISTANCE and resulted in an estimate of 62 individuals (CI = 38-103), with a CV of 0.24. Comparing both approaches, mark-recapture resulted 1.30 time more expensive than line-transect for a single season of effort, but was twice as effective in terms of precision. As a consequence, the probability of detecting a 5% trend during a five-year period is 2.08 times higher with mark recapture. Conversely, the final cost to detect a trend with distance sampling is 1.19 time higher but considering six more years of effort. These results highlight the importance of selecting a-priori sampling design techniques that include developing pilot studies that evaluate the bias, precision and accuracy of estimates while considering costs involved. Considering the small population size estimated herein, the sensitivity of both approaches for detecting trends is not sufficient because the original population would be markedly reduced by the time a declining trend was detected. Thus, a precautionary approach is still imperative, even when robust estimates are obtained.
{"title":"Mark-recapture vs. line-transect abundance estimates of a coastal dolphin population: a case study of Tursiops truncatus from Laguna, southern Brazil","authors":"F. Daura-Jorge, P. C. Simões‐Lopes","doi":"10.5597/LAJAM00222","DOIUrl":"https://doi.org/10.5597/LAJAM00222","url":null,"abstract":"Cetacean populations in coastal habitats are increasingly threatened by multiple anthropogenic impacts. Monitoring these populations to obtain robust estimates of abundance and detect trends over time is critical to achieve conservation goals. Here, we conducted a pilot study to evaluate the effectiveness of two commonly used abundance estimation methods: mark-recapture and distance sampling line-transect. Surveys were conducted to estimate the abundance of bottlenose dolphins in Laguna, southern Brazil. We implemented power-analysis models and compared both techniques in terms of cost, time and effectiveness to detect trends over a five-year period. Mark-recapture models were analyzed in MARK and resulted in an abundance of 50 individuals (CI = 39-64) with a coefficient of variation (CV) of 0.13. The line-transect models were implemented using the program DISTANCE and resulted in an estimate of 62 individuals (CI = 38-103), with a CV of 0.24. Comparing both approaches, mark-recapture resulted 1.30 time more expensive than line-transect for a single season of effort, but was twice as effective in terms of precision. As a consequence, the probability of detecting a 5% trend during a five-year period is 2.08 times higher with mark recapture. Conversely, the final cost to detect a trend with distance sampling is 1.19 time higher but considering six more years of effort. These results highlight the importance of selecting a-priori sampling design techniques that include developing pilot studies that evaluate the bias, precision and accuracy of estimates while considering costs involved. Considering the small population size estimated herein, the sensitivity of both approaches for detecting trends is not sufficient because the original population would be markedly reduced by the time a declining trend was detected. Thus, a precautionary approach is still imperative, even when robust estimates are obtained.","PeriodicalId":17967,"journal":{"name":"Latin American Journal of Aquatic Mammals","volume":"1 1","pages":"133-143"},"PeriodicalIF":0.0,"publicationDate":"2017-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89282526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Domit, P. Laporta, C. Zappes, L. Lodi, L. S. Hoffmann, Rodrigo C Genoves, P. Fruet, A. Azevedo
In this report, we present a compilation of the behavioral patterns of bottlenose dolphins and social structure throughout the Southwest Atlantic Ocean. We have compiled and summarized available data concerning: (i) behavioral activities (states and events), (ii) social structures (group size and composition), (iii) acoustic behavior and (iv) intra and interspecific interactions of bottlenose dolphin populations throughout the SWAO, from northern Brazil to southern Argentina. Lack of systematic and standardized methodologies for data collection precludes robust data analyses in respect of bottlenose dolphin behavior. Available information suggests that the studied populations presented weak intra-population associations and that coastal individuals tend to form smaller groups than their oceanic counterparts. Bottlenose dolphins from SWAO produce stylized whistles in which the acoustic parameters are similar to published ranges around the world and some results indicate significant local inter-population variation in the acoustic parameters of the whistles. Data of intra and interspecific interactions of bottlenose dolphins in the SWAO are scarce and therefore do not fully allow a comprehensive analysis of the situational contexts.
{"title":"Report of the Working Group on the Behavioral Ecology of bottlenose dolphins in the Southwest Atlantic Ocean","authors":"C. Domit, P. Laporta, C. Zappes, L. Lodi, L. S. Hoffmann, Rodrigo C Genoves, P. Fruet, A. Azevedo","doi":"10.5597/LAJAM00220","DOIUrl":"https://doi.org/10.5597/LAJAM00220","url":null,"abstract":"In this report, we present a compilation of the behavioral patterns of bottlenose dolphins and social structure throughout the Southwest Atlantic Ocean. We have compiled and summarized available data concerning: (i) behavioral activities (states and events), (ii) social structures (group size and composition), (iii) acoustic behavior and (iv) intra and interspecific interactions of bottlenose dolphin populations throughout the SWAO, from northern Brazil to southern Argentina. Lack of systematic and standardized methodologies for data collection precludes robust data analyses in respect of bottlenose dolphin behavior. Available information suggests that the studied populations presented weak intra-population associations and that coastal individuals tend to form smaller groups than their oceanic counterparts. Bottlenose dolphins from SWAO produce stylized whistles in which the acoustic parameters are similar to published ranges around the world and some results indicate significant local inter-population variation in the acoustic parameters of the whistles. Data of intra and interspecific interactions of bottlenose dolphins in the SWAO are scarce and therefore do not fully allow a comprehensive analysis of the situational contexts.","PeriodicalId":17967,"journal":{"name":"Latin American Journal of Aquatic Mammals","volume":"17 1","pages":"106-120"},"PeriodicalIF":0.0,"publicationDate":"2017-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83364592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Fruet, P. Laporta, J. C. Tullio, E. Secchi, E. Morteo, G. Tezanos‐Pinto, L. Möller, M. Marmontel, D. Palacios
{"title":"Introduction to the Special Volume on Tursiops in the Southwest Atlantic Ocean","authors":"P. Fruet, P. Laporta, J. C. Tullio, E. Secchi, E. Morteo, G. Tezanos‐Pinto, L. Möller, M. Marmontel, D. Palacios","doi":"10.5597/00212","DOIUrl":"https://doi.org/10.5597/00212","url":null,"abstract":"","PeriodicalId":17967,"journal":{"name":"Latin American Journal of Aquatic Mammals","volume":"12 1","pages":"1-15"},"PeriodicalIF":0.0,"publicationDate":"2017-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83456004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The information herein presented were compiled from six scientific articles, one undergraduate monographs, four master and three doctoral thesis and six working papers presented during the “I South American Meeting of Research and Conservation of Tursiops truncatus”, which was held in Rio Grande, Rio Grande do Sul, Brazil between May 21-23, 2010. Some personal communications complement the information. Each topic discussed in the present report followed the geographical sub-divisions established in the Report of the Working Group on Distribution (this volume): a) Northern Brazil; b) North-eastern Brazil; c) South-eastern Brazil; d) Southern Brazil and Uruguay and e) Argentina.
{"title":"Report of the Working Group on Population Parameters and Demography of Tursiops truncatus in the Southwest Atlantic Ocean","authors":"P. Fruet, P. Laporta, P. Flores","doi":"10.5597/00217","DOIUrl":"https://doi.org/10.5597/00217","url":null,"abstract":"The information herein presented were compiled from six scientific articles, one undergraduate monographs, four master and three doctoral thesis and six working papers presented during the “I South American Meeting of Research and Conservation of Tursiops truncatus”, which was held in Rio Grande, Rio Grande do Sul, Brazil between May 21-23, 2010. Some personal communications complement the information. Each topic discussed in the present report followed the geographical sub-divisions established in the Report of the Working Group on Distribution (this volume): a) Northern Brazil; b) North-eastern Brazil; c) South-eastern Brazil; d) Southern Brazil and Uruguay and e) Argentina.","PeriodicalId":17967,"journal":{"name":"Latin American Journal of Aquatic Mammals","volume":"144 1","pages":"71-78"},"PeriodicalIF":0.0,"publicationDate":"2017-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75085367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Defining the age of attainment of physical maturity is important for many studies, including identification of stocks, populations or species. In order to identify the age when the skull of the bottlenose dolphin, Tursiops truncatus, reaches maturity, skulls of fifty-three specimens found stranded along the coasts of southern Brazil, Uruguay and northern Argentina (27o35’S, 48o34’W-36o49’S, 55o19’W) were analyzed. Sixty skull measurements were taken to compare the growth rate of the different functional apparatuses. Age was estimated by counts of growth layer groups in the dentine of decalcified, stained longitudinal sections of teeth. Von Bertalanffy’s equation was applied to assess the growth and determine the age at maturity of each apparatus. Generally the maturation of skull starts at age two and stabilizes at age five, and the age of reaching the mature size varies amongst different characters. The braincase is the most precocious apparatus, while the feeding is the one that last stabilizes. The development patterns observed for the hearing, vision and breathing apparatuses were similar. Statistic analysis revealed significant differences among the ages at maturity, but not for von Bertalanffy’s growth equation parameters for each functional apparatus. For the studied population it is suggested that skulls can be considered mature in animals with more than five years.
{"title":"Growth of the skull of the bottlenose dolphin, Tursiops truncatus, in the Southwest Atlantic Ocean","authors":"A. Barreto","doi":"10.5597/00229","DOIUrl":"https://doi.org/10.5597/00229","url":null,"abstract":"Defining the age of attainment of physical maturity is important for many studies, including identification of stocks, populations or species. In order to identify the age when the skull of the bottlenose dolphin, Tursiops truncatus, reaches maturity, skulls of fifty-three specimens found stranded along the coasts of southern Brazil, Uruguay and northern Argentina (27o35’S, 48o34’W-36o49’S, 55o19’W) were analyzed. Sixty skull measurements were taken to compare the growth rate of the different functional apparatuses. Age was estimated by counts of growth layer groups in the dentine of decalcified, stained longitudinal sections of teeth. Von Bertalanffy’s equation was applied to assess the growth and determine the age at maturity of each apparatus. Generally the maturation of skull starts at age two and stabilizes at age five, and the age of reaching the mature size varies amongst different characters. The braincase is the most precocious apparatus, while the feeding is the one that last stabilizes. The development patterns observed for the hearing, vision and breathing apparatuses were similar. Statistic analysis revealed significant differences among the ages at maturity, but not for von Bertalanffy’s growth equation parameters for each functional apparatus. For the studied population it is suggested that skulls can be considered mature in animals with more than five years.","PeriodicalId":17967,"journal":{"name":"Latin American Journal of Aquatic Mammals","volume":"28 1","pages":"199-211"},"PeriodicalIF":0.0,"publicationDate":"2017-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90471545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. F. Moura, D. Tavares, Helio Secco, S. Siciliano
The bottlenose dolphin (Tursiops truncatus) may be one of the best known dolphin species worldwide, principally due to its coastal distribution in many regions. However, few studies about ecology, biology and threats have been conducted on the Brazilian coast. The aim of the present work is to analyze the stranding pattern and stomach contents of bottlenose dolphins in the central-north coast of the Rio de Janeiro State, from Saquarema to Sao Francisco de Itabapoana (~300km of coast line). Forty nine stranding events were recorded through regular beach surveys from 1999 to 2012 and also through access to previous published studies conducted since 1984. The strandings were distributed throughout the study area, but there was a trend of occurrence in the extreme southern and northern regions. Nine specimens showed evidence of accidental mortality in fishing nets. The strandings were more frequently recorded during autumn and winter (χ2; p 230cm of body length) (χ2; p < 0.05). The body length varied from 106 to 335cm. Four prey species were found in the stomach contents from the three specimens of bottlenose dolphin analyzed. The most representative prey species was the cutlassfish (Trichiurus lepturus). This study showed that bottlenose dolphins are frequently found dead along the Rio de Janeiro State where they feed mainly on coastal fish. Future studies need to be conducted to improve the knowledge on this poorly known cetacean in Brazil.
{"title":"Bottlenose dolphins (Tursiops truncatus, Montagu 1821) in central-northern coast of Rio de Janeiro State, Brazil: stranding patterns and insights into feeding habits","authors":"J. F. Moura, D. Tavares, Helio Secco, S. Siciliano","doi":"10.5597/00228","DOIUrl":"https://doi.org/10.5597/00228","url":null,"abstract":"The bottlenose dolphin (Tursiops truncatus) may be one of the best known dolphin species worldwide, principally due to its coastal distribution in many regions. However, few studies about ecology, biology and threats have been conducted on the Brazilian coast. The aim of the present work is to analyze the stranding pattern and stomach contents of bottlenose dolphins in the central-north coast of the Rio de Janeiro State, from Saquarema to Sao Francisco de Itabapoana (~300km of coast line). Forty nine stranding events were recorded through regular beach surveys from 1999 to 2012 and also through access to previous published studies conducted since 1984. The strandings were distributed throughout the study area, but there was a trend of occurrence in the extreme southern and northern regions. Nine specimens showed evidence of accidental mortality in fishing nets. The strandings were more frequently recorded during autumn and winter (χ2; p 230cm of body length) (χ2; p < 0.05). The body length varied from 106 to 335cm. Four prey species were found in the stomach contents from the three specimens of bottlenose dolphin analyzed. The most representative prey species was the cutlassfish (Trichiurus lepturus). This study showed that bottlenose dolphins are frequently found dead along the Rio de Janeiro State where they feed mainly on coastal fish. Future studies need to be conducted to improve the knowledge on this poorly known cetacean in Brazil.","PeriodicalId":17967,"journal":{"name":"Latin American Journal of Aquatic Mammals","volume":"80 1","pages":"191-198"},"PeriodicalIF":0.0,"publicationDate":"2017-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86895240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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