An Aggressive Interaction Between Bottlenose Dolphins (&lt;I&gt;Tursiops truncatus&lt;/I&gt;) and Estuarine Dolphins (&lt;I&gt;Sotalia guianensis&lt;/I&gt;) in Southern Brazil

Wedekin, Leonardo L.; Daura‐Jorge, Fábio G.; Simões‐Lopes, Paulo C.

doi:10.1578/am.30.3.2004.391

Cited by 48 publications

(30 citation statements)

References 18 publications

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“…Competitive interactions between species are either ‘directly’ observed through aggressive behaviours or ‘indirectly’ observed when a species applies a negative pressure on the available resources, when they share common prey species. The degree to which one species dominates another may vary depending on their ecological similarity, where in general the larger species dominates the smaller species (which is the case between bottlenose and humpback dolphins; Wedekin, Daura‐Jorge, & Simoes‐Lopes, ). Aggressive behaviours were not observed during this study, but have been reported between bottlenose and humpback dolphins ( Sousa spp.)…”

Section: Discussionmentioning

confidence: 99%

Another dolphin in peril? Photo‐identification, occurrence, and distribution of the endangered Indian Ocean humpback dolphin (Sousa plumbea) in Algoa Bay

Bouveroux

Melly

McGregor

et al. 2018

Aquatic Conservation

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1. In South Africa, the humpback dolphin (Sousa plumbea) has been recognized as the most endangered marine mammal, with a low abundance, a discontinuous distribution, and numerous threats. This research was initiated in 2008 to estimate the number of individual humpback dolphins in Algoa Bay, as well as studying their residency patterns and distribution.2. The last boat-based study on humpback dolphins, conducted 24 years ago, formed an important reference against which to compare current findings. This study reveals that since the 1990s the number of identified animals decreased from 70 to 50 individuals, and the mean group size of humpback dolphins has also decreased, from seven to three animals.3. Humpback dolphin behaviour was predominantly that of foraging and travelling, although the overall frequency of foraging still seems to have decreased since early 1990s. 4. Although the species was seen almost all year round, the number of sightings per survey was lowest in January, March, and April. The number of sightings per kilometre surveyed substantially decreased from 0.018 sightings per kilometre in 2008 to 0.004 in 2011, and the number of animals per kilometre also decreased from 0.042 to 0.009. The re-sighting rates were low, ranging from one to eight times, with 52% of identified dolphins seen only once throughout the study period. Only 6% of the individuals were seen more than three times. 5. Reduced humpback dolphin numbers and sighting rates could be indicative of the rise in anthropogenic activities, such as shipping and recreational boating, as well as a rise in pollution from vessels and urban development.6. Conservation strategies, such as a Biodiversity Management Plan for the species, are urgently needed in Algoa Bay, especially in the south-west part of the bay, between Cape Recife and the Port Elizabeth Harbour, where the species occurs most frequently.

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Section: Discussionmentioning

confidence: 99%

Another dolphin in peril? Photo‐identification, occurrence, and distribution of the endangered Indian Ocean humpback dolphin (Sousa plumbea) in Algoa Bay

Bouveroux

Melly

McGregor

et al. 2018

Aquatic Conservation

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“…Another factor that may influence the size of the groups is the presence of predators or other species of small cetaceans, which may result in aggressive interactions. There is evidence of antagonistic interaction between Sotalia guianensis and Tursiops truncatus, which may contribute towards the formation of large groups (WEDEKIN et al 2004). It also seems that the formation of larger groups may be related to greater availability and abundance of prey (FLORES & FONTOURA 2006).…”

Section: Discussionmentioning

confidence: 99%

The behavior of Sotalia guianensis (Van Bénéden) in Pernambuco coastal waters, Brazil, and a further analysis of its reaction to boat traffic

et al. 2008

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There is still little knowledge about the behavior of the estuarine dolphins and also the way they react to the presence of different types of vessels. The aim of the present study was twofold: to investigate the behavior of estuarine dolphins in four locations in Pernambuco, Brazil, and also their reaction to the presence of common types of nautical crafts. The data of this study resulted from 48 fieldtrips to each of the four localities studied (ports of Recife and Suape, and beaches of Bairro Novo and Piedade), thus totaling 192 days of observations, with approximately 380 hours of actual sampling. Ten types of behavioral activities were counted for Bairro Novo beach and the port areas, but only four for Piedade beach. The greatest flows of boats were recorded in the port of Recife. Fishing boats were the commonest type in the port area of Recife and Bairro Novo beach, while tourist vessels predominated in the port of Suape and Piedade beach. During the observations of encounters between these boats and the estuarine dolphins, neutral reactions predominated for all the vessel types studied. The same type of reaction predominated when the distances at which the interactions between the animals and vessels occurred were correlated.

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“…Bottlenose dolphins are residents in the Canary Islands (31), and are well-known for interacting aggressively worldwide within these species with different motivations (37). Either way, bottlenose dolphins are well-known for their aggressive interaction with other species (37,54,55). Additionally, two females of stripped dolphin presented intraspecific tooth-rake marks.…”

Section: Speciesmentioning

confidence: 99%

Retrospective Study of Traumatic Intra-Interspecific Interactions in Stranded Cetaceans, Canary Islands

et al. 2020

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Aggressive encounters involving cetacean species are widely described in the literature. However, detailed pathological studies regarding lesions produced by these encounters are scarce. From January 2000 to December 2017, 540 cetaceans stranded and were necropsied in the Canary Islands, Spain. Of them, 24 cases of eight species presented social traumatic lesions produced by cetaceans of the same or different species. All the cases presented severe multifocal vascular changes, 50% (12/24) presented fractures affecting mainly the thoracic region, 41.7% (10/24) acute tooth-rake marks, 37.5% (9/24) undigested food in the stomach, 33.3% (8/24) tracheal edema, and 12.5% (3/24) pulmonary perforation. In 10 cases with tooth-rake marks, the distance between the teeth, allowed us to further identify the aggressor species: four cases were compatible with killer whales (Orcinus orca) affecting three species [pigmy sperm whale (Kogia breviceps), Cuvier's beaked whale (Ziphius cavirostris), and short-finned pilot whale (Globicephala macrorhynchus)] and four cases compatible with common bottlenose dolphins (Tursiops truncatus) affecting two species [short-beaked common dolphin (Delphinus delphis) and Atlantic spotted dolphin (Stenella frontalis)]. We also described two cases of intraspecific interaction in stripped dolphin (Stenella coeruleoalba). Microscopically, 70.8% (17/24) of the cases presented acute degenerative myonecrosis, 66.7% (14/21) presented vacuoles in the myocardiocytes, 36.8% (7/19) pigmentary tubulonephrosis, 31.6% (6/19) cytoplasmic eosinophilic globules within hepatocytes, 21.4% (3/14) hemorrhages in the adrenal gland, and 17.3% (4/23) bronchiolar sphincter contraction. The statistical analysis revealed that deep divers, in good body condition and nearby La Gomera and Tenerife were more prone to these fatal interactions. Additionally, in this period, three animals died due to an accident during predation: a false killer whale (Pseudorca crassidens) died because of a fatal attempt of predation on a stingray, and two Risso's dolphins (Grampus griseus) died as a consequence of struggling while predating on large squids.

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An Aggressive Interaction Between Bottlenose Dolphins (<I>Tursiops truncatus</I>) and Estuarine Dolphins (<I>Sotalia guianensis</I>) in Southern Brazil

Cited by 48 publications

References 18 publications

Another dolphin in peril? Photo‐identification, occurrence, and distribution of the endangered Indian Ocean humpback dolphin (Sousa plumbea) in Algoa Bay

Another dolphin in peril? Photo‐identification, occurrence, and distribution of the endangered Indian Ocean humpback dolphin (Sousa plumbea) in Algoa Bay

The behavior of Sotalia guianensis (Van Bénéden) in Pernambuco coastal waters, Brazil, and a further analysis of its reaction to boat traffic

Retrospective Study of Traumatic Intra-Interspecific Interactions in Stranded Cetaceans, Canary Islands

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