Abundance Estimates of Guiana Dolphins (Sotalia guianensis; Van Bénéden, 1864) Inhabiting an Estuarine System in Southeastern Brazil

Mello, Aline Boutros de; Molina, Julia Maria Borges; Kajin, Maja; Santos, M. A. L.

doi:10.1578/am.45.1.2019.56

Cited by 13 publications

(13 citation statements)

References 11 publications

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“…and lactation (at least 8.7 months) periods, Guiana dolphin adult annual apparent survival rates are expected to be high to maintain populations numbers (>0.80). Although there are four studies reporting survival rates for this species (Cantor et al, 2012;Espécie, 2015;Azevedo et al, 2017;Mello et al, 2019), we can only compare our results with those that reported annual rates. These were described for two fairly well protected areas of Brazil: the Caravelas Estuary, where Cantor et al (2012) reported an annual rate of 0.88 (95% CI 0.67-0.96); and Ilha Grande Bay, where Espécie (2015) reported an annual rate of 0.92 ± 0.02.…”

Section: Discussionmentioning

confidence: 99%

Abundance and effect of health status on apparent survival of Guiana dolphins, Sotalia guianensis, in an open embayment in north‐eastern Brazil

Meirelles

Choi‐Lima²,

Nova³

et al. 2022

Aquatic Conservation

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1. Guiana dolphins (Sotalia guianensis) inhabit shallow waters of the tropical western Atlantic, an area that is now mostly occupied by cities and harbours. Demographic studies have been concentrated in sheltered areas of south/south-eastern Brazil.2. This study investigated site fidelity and estimated population abundance and apparent survival of Guiana dolphins in Mucuripe Embayment (ME), on the northeastern Brazilian coast, through photo-identification surveys and closed and open population mark-recapture models, from October 2009 to September 2011.3. Forty-six Guiana dolphin groups were recorded (in groups of between one and eight dolphins, with a mean ± SD of 3.49 ± 2.33) in 27 out of 40 surveys. Twentyfive animals were photo-identified, with eight considered to have a 'poor health' status. The standardized site fidelity index (SSFI) was low (0.25).4. Using the program CAPTURE, the time and heterogeneity model (M th ) resulted in a total abundance estimate of 39, with a Coefficient of Variation (CV) of 21% (95% CI 35-80%). In PROGRAM MARK, model averaging resulted in a total abundance estimate of 33 (CV 32%, 95% CI 30-100%). Using a CV of 21%, the power to detect a decline of 50% during the study period was 0.44 and the power to detect a decline of 5% a year was 0.11. To detect these declines with a 0.90 power, 12 years of monitoring would be necessary.5. The annual adult apparent survival rate was low (0.71; CV 19%; 95% CI 0.40-0.90), and differed for dolphins in 'good' (0.64; CV 28%, 95% CI 0.27-0.89) and 'poor' (0.85; CV 22%; 95% CI: 0.23-0.99) health.6. The low abundance of Guiana dolphins in ME indicates that conservation actions should start immediately, such as creating a marine protected area, continuing awareness campaigns, using by-catch reduction technologies, developing new regulations, and promoting law enforcement. Monitoring studies must continue with increased effort to reduce uncertainty in estimates and to improve the power to detect trends of decline.

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Section: Discussionmentioning

confidence: 99%

Abundance and effect of health status on apparent survival of Guiana dolphins, Sotalia guianensis, in an open embayment in north‐eastern Brazil

Meirelles

Choi‐Lima²,

Nova³

et al. 2022

Aquatic Conservation

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“…In addition to line-transect surveys, mark-recapture methods are regularly used to estimate the abundance of many marine mammal species and have largely demonstrated their effectiveness (Nery et al 2008;Cantor et al, 2012;Coimbra et al, 2016;de Mello et al, 2019). A long-term photo-identification monitoring program in Sepetiba Bay in Brazil provided unbiased and more precise estimates of population size than those derived from line-transect surveys (Nery et al, 2008).…”

Section: Discussionmentioning

confidence: 99%

Study and conservation of the Guiana Dolphin (Sotalia guianensis) (Van Bénéden, 1864) in French Guiana

Bordin¹,

Vanhoucke²,

Pineau³

et al. 2022

Lat. Am. J. Aquat. Mamm.

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The Guiana dolphin (Sotalia guianensis) occurs in warm and shallow waters of the Atlantic Ocean and the Caribbean Sea, from southern Brazil to Honduras, including estuarine and freshwater habitats such as Maracaibo Lake (Venezuela), and the Orinoco River. In 2018, the Guiana dolphin was reclassified from Data Deficient to Near Threatened on the global IUCN Red List. Nevertheless, the conservation status identified by national and regional Red Lists is even more alarming. In French Guiana, for example, the species is classified as Endangered based on strong pressures such as bycatch. In this region, the Guiana dolphin inhabits river mouths and coastal waters where most anthropogenic activities occur. Better knowledge of the biology and ecology is needed in French Guiana to help inform effective conservation actions. Here, we present ongoing studies to map the distribution of Guiana dolphins along the French Guiana coast and estimate abundance in a hotspot area. Aerial survey campaigns were conducted during the dry season in 2013, 2014, 2015, and 2019. Eight flights were conducted and 146 dolphins belonging to 39 groups were observed. Boat-based line-transect surveys were also conducted in the coastal waters of Cayenne in 2017 and 2018. Twenty-one survey trips were conducted covering 999.06 km. Three hundred and eighty-two dolphins belonging to 63 groups were observed. The total abundance in the Cayenne area was estimated at 128 dolphins (% CV = 30.92; CI (95%) = 70-235) with a density of 0.80 ind./km² (% CV = 30.92; CI (95%) = 0.44-1.47). Additionally, a descriptive analysis was performed on stranding data collected in French Guiana between 2014 and 2020 to identify the major cause of death and seasonality in the stranding events. In total, 43 dolphins were found, especially on the beaches of Rémire-Montjoly, Cayenne, and Kourou: bycatch was the major identifiable cause of death. We recommend a local conservation strategy and actions to be undertaken in the short- and medium-term to address different issues: knowledge, threats, conservation, and cooperation.

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“…These studies are very important to evaluate the risk of their extinction and in that regard we refer to the Indo-Pacific humpback dolphins (Sousa chinensis) [31], Guiana dolphin (Sotalia guianensis) [35], Australian humpback dolphin (Sousa sahulensis) [49], Southern right whale (Eubalaena australis) [60], common (Balaenoptera acutorostrata) and Antarctic (Balaenoptera bonaerensis) minke whales [24], Ringed seal (Pusa hispida) [30], as well as the cosmopolitan bottlenose dolphins (Tursiops truncatus) [29], [42], [44], [51], [55], [61]. Finally, social dynamics is mainly focused on behaviours with photo ID tools that can recognize groups of individuals and their social evolution over time [28], [33], [36], [45], [46], [54], [59], and it can be particularly helpful with gender recognition.…”

Section: A Field Of Application Of Automated and Semiautomated Photo ...mentioning

confidence: 99%

“…), and any combination of these attributes can be selected to sort the catalogue. FinBase helps analysts, during photo [26], [31], [33], [46], [48], [49], [53], [63] (*) [30] (**) - [25], [28], [29], [35], [42], [45], [59], [61], [ identification studies, sort the entire catalogue based on the similarity of each existing catalogue individuals' attributes to those of a newly sighted individual [51], [54], [55], [61]. This system, while created for a bottlenose dolphin research application, can be adapted to accommodate photo identification research on a variety of other species.…”

Section: Photo Identification Systems Based On Databasementioning

confidence: 99%

“…• DARWIN [64] is an open-source computer vision system designed to identify individual bottlenose dolphins (Tursiops truncatus), facilitating the comparison of the contour of the dorsal fin of an unknown individual with a catalogue of known dolphins. DARWIN works semiautomatedly and has been used in several studies with some species of cetaceans, not only bottlenose dolphins [25], [28], [29], [35], [42], [45], [59], [61].…”

Section: Semiautomated Photo Identification Systemsmentioning

confidence: 99%

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Machine Learning and Image Processing Methods for Cetacean Photo Identification: A Systematic Review

Maglietta

Carlucci

Fanizza³

et al. 2022

IEEE Access

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Photo identification is an essential method to identify cetaceans, by using natural marks over their body, and allows experts to acquire straightforward information on these animals. The importance of cetaceans lies in te fact that they play a crucial role in maintaining the healthiness of marine ecosystems, however they are exposed to several anthropogenic stressors, under which they could collapse with extreme consequences on the marine ecosystem functioning. Hence, obtaining new knowledge on their status is extremely urgent for the marine biodiversity conservation. The smart use of technology to automate the individual recognition can speed up the photo identification process, opening the door to large-scale studies that are manually unfeasible. We performed a systematic review on systems based on machine learning and statistical methods for cetacean photo identification, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. This review highlights that interest has been increasing in recent years and several intelligent systems have been presented. However, there are still some open questions, and further efforts to develop more effective automated systems for cetacean photo identification are recommended.INDEX TERMS machine learning algorithms, Convolutional Neural Networks, feature extraction, reviews, oceanic engineering and marine technology, image processing

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Abundance Estimates of Guiana Dolphins (Sotalia guianensis; Van Bénéden, 1864) Inhabiting an Estuarine System in Southeastern Brazil

Cited by 13 publications

References 11 publications

Abundance and effect of health status on apparent survival of Guiana dolphins, Sotalia guianensis, in an open embayment in north‐eastern Brazil

Abundance and effect of health status on apparent survival of Guiana dolphins, Sotalia guianensis, in an open embayment in north‐eastern Brazil

Study and conservation of the Guiana Dolphin (Sotalia guianensis) (Van Bénéden, 1864) in French Guiana

Machine Learning and Image Processing Methods for Cetacean Photo Identification: A Systematic Review

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