Variation of age and total length in Sotalia guianensis (Van Bénéden, 1864) (Cetacea, Delphinidae), on the coast of Espírito Santo state, Brazil

Lima, Juliana Ywasaki; Carvalho, Anna Paula Martins de; Azevedo, Carolina Torres; Barbosa, Lupércio A.; Silveira, Leonardo Serafim da

doi:10.1590/1519-6984.13215

Cited by 7 publications

(4 citation statements)

References 19 publications

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“…Previous studies found that most Guiana dolphins stranded in Brazil are immature males (Lima et al 2017), which is consistent with the sex ratio of 68% males recorded in this study. The species is known to be frequently bycaught in gillnets in Espírito Santo (Barros et al 1997, de Freitas Netto and Barbosa 2003, de Freitas Netto and Di Beneditto 2008, especially before reaching sexual maturity, with 80% of bycaught individuals corresponding to male individuals younger than 6 years (Rosas et al 2003, Di Beneditto andRamos 2004).…”

Section: Guiana Dolphin Sotalia Guianensis (Van Bénéden 1864)supporting

confidence: 93%

Strandings of cetaceans on the Espírito Santo coast, southeast Brazil, 1975–2015

Mayorga¹,

Vanstreels²,

Bhering³

et al. 2020

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Espírito Santo state is located on the eastern margin of Brazil, in a transitional tropical-subtropical area (18°S–21°S) dominated by oligotrophic waters. With the exception of humpback whales (Megaptera novaeangliae), the cetacean community of Espírito Santo has been understudied. In addition to the chronic impacts from fisheries, marine pollution, urban development, and coastal habitat degradation, in November 2015 the cetacean communities of Espírito Santo were challenged by the greatest environmental disaster in Brazil’s history. The Mariana dam disaster caused 60 million cubic meters of mining waste to be washed into the Doce River, which ultimately flowed to the coastal waters of Espírito Santo, with a high concentration of heavy metals. This study reviews and updates information on cetacean strandings in the state of Espírito Santo (excluding humpback whales) prior to this disaster. From 1975 to September 2015, there were 461 recorded cetacean strandings, representing 20 species. An average 1.18 strandings per 100 km per month were recorded since a state-wide daily beach survey program was implemented in October 2010, contrasting with the 0.14 strandings per 100 km per month in previous years. Six species comprised the majority (94.7%) of stranding events: Guiana dolphin (Sotalia guianensis), Franciscana (Pontoporia blainvillei), rough-toothed dolphin (Steno bredanensis), bottlenose dolphin (Tursiops truncatus), sperm whale (Physeter macrocephalus), and melon-headed whale (Peponocephala electra). Oceanic cetaceans stranded most frequently on the southern portion of Espírito Santo, where the continental platform is narrower, whereas the strandings of coastal cetaceans such as Guiana dolphins and Franciscanas were concentrated near estuaries, especially the Doce River. This is particularly concerning in face of the Mariana dam disaster, which drastically altered the estuarine and coastal environment associated with the Doce River.

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Section: Guiana Dolphin Sotalia Guianensis (Van Bénéden 1864)supporting

confidence: 93%

Strandings of cetaceans on the Espírito Santo coast, southeast Brazil, 1975–2015

Mayorga¹,

Vanstreels²,

Bhering³

et al. 2020

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“…The following measurements were considered >1.7 m (adult), > 1 m < 1.7 (juvenile), and < 1 m (calf) (Di Beneditto and Ramos, 2004;Riquelme et al, 2011;Lima et al, 2017) to determine the ontogeny of captured individuals. This question • Nylon multifilament or monofilament nets with 3.5-4 inch openings.…”

Section: Knowledge Of the Speciesmentioning

confidence: 99%

Aquatic Wildmeat Consumption of Guiana Dolphins (Sotalia guianensis) in Lake Maracaibo System, Venezuela

et al. 2021

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In many regions of the world, the use of cetaceans as bait or protein source has been reported. In most cases the individuals are from bycatch but also from intentionally killed animals. Cetaceans with coastal habits are more susceptible to negative interactions with small-scale fisheries, as in the case of the Guiana dolphin (Sotalia guianensis) in the Lake Maracaibo system. For decades, the use of Guiana dolphins by local communities has been reported in this region and is culturally supported by recipes for its preparation. Most of these data was outdated and some were anecdotal, so the objective of this work was to collect systematically data through surveys using the snowball method in seven artisanal fishing communities and to try to quantify the capture rate and to inquire about the potential impact of this practice on the population of Guiana dolphin. From 2017 to 2019, 95 semi-structured interviews were applied. An average bycatch of 180 individuals/year was obtained, the highest catch rate in the entire geographic distribution, an alarming situation considering that the surveys were not carried out in all the fishing ports, generating an underestimation. A total of 78% of interviewed recognized at least one bycatch event during their fishing effort. Surveys revealed a higher incidence of entanglement of offspring and juveniles (78%). 77% of the respondents deny the sale and commercialization of the species, while 5% mention some type of trade. The most frequent part exploited was the dorsal muscle, confirmed by fishermen (97%, n = 72) and the rest of the animal is discarded. During this investigation three episodes of directed capture were recorded, affecting a total of 23 individuals, two of them were pregnant females. The interviews also revealed that the majority of fishermen (93%) recognize the capture of this species as illegal. Considering the vulnerability of the Guiana dolphin in the country, the high incidence of capture and consumption and the lack of surveillance and sanctions by government entities, it is imperative to immediate actions to mitigate the negative impact on the population.

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“…For Guiana dolphins, Ramos et al (2000) first provided age estimates, then used them to estimate growth, for a sample of incidentally captured individuals in southeastern Brazil. Since then, although tooth morphology and size make age estimation more straightforward than in the franciscana, just five more published studies on growth throughout the species distribution have been conducted and all were with specimens recovered only in southeastern Brazil (Di Beneditto & Ramos, 2004; Lima et al, 2017; Ramos et al, 2010; Rosas et al, 2003; Santos et al, 2003). For both species, more robust estimates are needed as several studies were based on small sample sizes.…”

Section: Figurementioning

confidence: 99%

Age and growth of franciscana, Pontoporia blainvillei, and Guiana, Sotalia guianensis, dolphins from southeastern Brazil

Conversani

Silva

Barbosa

et al. 2020

Marine Mammal Science

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Variation of age and total length in Sotalia guianensis (Van Bénéden, 1864) (Cetacea, Delphinidae), on the coast of Espírito Santo state, Brazil

Cited by 7 publications

References 19 publications

Strandings of cetaceans on the Espírito Santo coast, southeast Brazil, 1975–2015

Strandings of cetaceans on the Espírito Santo coast, southeast Brazil, 1975–2015

Aquatic Wildmeat Consumption of Guiana Dolphins (Sotalia guianensis) in Lake Maracaibo System, Venezuela

Age and growth of franciscana, Pontoporia blainvillei, and Guiana, Sotalia guianensis, dolphins from southeastern Brazil

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