Impacts of Fishing Entanglement on the Bottlenose Dolphin Society in the Gulf of Guayaquil, Ecuador

We report the case of a young coastal bottlenose dolphin (Tursiops truncatus) hooked and entangled in artisanal fishing gear on two occasions in a period of six months. In both occasions the animal managed to get rid of the gear by itself. The case occurred in the inner estuary of Gulf of Guayaquil, Ecuador. The animal survived both events, but scars remained in various parts of the body and missed fluke tips. Photographs of the individual after the events allowed to evaluate the healing process. This case demonstrated that longlines represents a threat for this population.

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Genetic divergence and fine scale population structure of the common bottlenose dolphin (Tursiops truncatus, Montagu) found in the Gulf of Guayaquil, Ecuador

PeerJ ◽

10.7717/peerj.4589 ◽

2018 ◽

Vol 6 ◽

pp. e4589 ◽

Cited By ~ 6

Author(s):

Rosa de los Ángeles Bayas-Rea ◽

Fernando Félix ◽

Rommel Montufar

Keyword(s):

Population Structure ◽

Bottlenose Dolphin ◽

Tursiops Truncatus ◽

Bottlenose Dolphins ◽

Western Coast ◽

Common Bottlenose Dolphin ◽

Dolphin Population ◽

The Common ◽

Gulf Of Guayaquil ◽

Outer Estuary

The common bottlenose dolphin, Tursiops truncatus, is widely distributed along the western coast of South America. In Ecuador, a resident population of bottlenose dolphins inhabits the inner estuarine area of the Gulf of Guayaquil located in the southwestern part of the country and is under threat from different human activities in the area. Only one genetic study on South American common bottlenose dolphins has been carried out to date, and understanding genetic variation of wildlife populations, especially species that are identified as threatened, is crucial for defining conservation units and developing appropriate conservation strategies. In order to evaluate the evolutionary link of this population, we assessed the phylogenetic relationships, phylogeographic patterns, and population structure using mitochondrial DNA (mtDNA). The sampling comprised: (i) 31 skin samples collected from free-ranging dolphins at three locations in the Gulf of Guayaquil inner estuary, (ii) 38 samples from stranded dolphins available at the collection of the “Museo de Ballenas de Salinas,” (iii) 549 mtDNA control region (mtDNA CR) sequences from GenBank, and (iv) 66 concatenated sequences from 7-mtDNA regions (12S rRNA, 16S rRNA, NADH dehydrogenase subunit I–II, cytochrome oxidase I and II, cytochrome b, and CR) obtained from mitogenomes available in GenBank. Our analyses indicated population structure between both inner and outer estuary dolphin populations as well as with distinct populations of T. truncatus using mtDNA CR. Moreover, the inner estuary bottlenose dolphin (estuarine bottlenose dolphin) population exhibited lower levels of genetic diversity than the outer estuary dolphin population according to the mtDNA CR. Finally, the estuarine bottlenose dolphin population was genetically distinct from other T. truncatus populations based on mtDNA CR and 7-mtDNA regions. From these results, we suggest that the estuarine bottlenose dolphin population should be considered a distinct lineage. This dolphin population faces a variety of anthropogenic threats in this area; thus, we highlight its fragility and urge authorities to issue prompt management and conservation measures.

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Prevalence of scars of anthropogenic origin in coastal bottlenose dolphin in Ecuador

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315417000686 ◽

2017 ◽

Vol 98 (5) ◽

pp. 1177-1186 ◽

Cited By ~ 4

Author(s):

Fernando Félix ◽

Ruby Centeno ◽

Juan Romero ◽

Melanie Zavala ◽

Óscar Vásconez

Keyword(s):

Bottlenose Dolphin ◽

Marine Protected Area ◽

Population Decline ◽

Fishing Effort ◽

Fishing Gear ◽

Western Coast ◽

Anthropogenic Origin ◽

Management Measures ◽

Gulf Of Guayaquil ◽

Free Ranging

The prevalence of scars and wounds of anthropogenic origin was assessed in seven different coastal bottlenose dolphin communities (Tursiops truncatus) on the south-western coast of Ecuador. Between 2011 and 2017 a total of 117 trips were conducted representing a total sampled distance of 6281 km. Twenty-five of the 189 (13.2%) free-ranging photo-identified dolphins were recorded with dorsal fin damage, V-shaped wounds, sawed edges and deformities in the caudal region. The scarring prevalence ranged from 0 to 44.4% and was associated with either fishing interactions or vessel strikes. Dolphin scarring increased five times in the last 25 years from 2.2 to 11.1% and was correlated with a decrease in population in the inner estuary of the Gulf of Guayaquil. Damaged dorsal fins are associated mainly with fishing gear. V-shaped wounds were recorded in three different communities, Posorja, Estero Salado and Salinas, and given their severity associated with either fishing gear or vessel strikes. During the study period three dolphins were found entangled in fishing gears, two in gillnets and one in a long-line, emphasizing the threats posed by current fishing practice to the species. More effective management measures are urgently needed to reverse the observed population decline. This may include reduction of fishing effort, implementation of area-based approaches to coastal planning (including Marine Protected Area designations) and support for further research to understand the problem. Given the difficulty in taking direct observations, scarring prevalence is proposed as a proxy for estimating boat traffic and fishing gear impacts upon cetaceans.

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