scholarly journals Strand-feeding by coastal bottlenose dolphins (Tursiops truncatus) in the Gulf of Guayaquil, Ecuador

2015 ◽  
Vol 10 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Pedro Jose Jiménez ◽  
Juan José Alava
Keyword(s):  
South Carolina ◽  
South America ◽  
Tursiops Truncatus ◽  
Bottlenose Dolphins ◽  
Photo Identification ◽  
The Pacific ◽  
Predatory Strategy ◽  
Gulf Of Guayaquil ◽  
Term Field

Strand-feeding as a predatory strategy was first observed in bottlenose dolphins, Tursiops truncatus, inhabiting waters of Spartina marshes of South Carolina and Georgia, United States. While a substantial body of documented observations exists for many regions of the world, current evidences and photo-documentation of these types of foraging behaviors by bottlenose dolphins in the Pacific coast of South America are scarce. To the best of our knowledge, behaviors resembling strand-feeding by bottlenose dolphins have been described very briefly without supporting photos in the inner estuary of the Gulf of Guayaquil. As a part of a long-term field study (2001-2011) on photo-identification, population ecology and monitoring of the bottlenose dolphin in the El Morro Mangrove and Wildlife Refuge, we provide some insights on its conservation, and photo-documented the occurrence of strand-feeding as a recurrent behavioral foraging tactic in this region of South America.

scholarly journals Occurrence of Brucella ceti in stranded bottlenose dolphins Tursiops truncatus coincides with calving season

2020 ◽  
Vol 141 ◽  
pp. 185-193
Author(s):  
WE McFee ◽  
D Wu ◽  
K Colegrove ◽  
K Terio ◽  
L Balthis ◽  
...  
Keyword(s):  
South Carolina ◽  
Tursiops Truncatus ◽  
Marine Mammals ◽  
Marine Bacterium ◽  
Bottlenose Dolphins ◽  
Global Public Health ◽  
Terrestrial Species ◽  
Long Term Study ◽  
Calving Season

Brucellosis is a disease caused by the Gram-negative facultative intracellular bacterium Brucella spp. In terrestrial species, this zoonotic bacterium is a global public health risk, but there is also concern over the zoonotic potential of marine forms, such as B. ceti, which affects cetaceans. Due to the detection of B. ceti in samples from bottlenose dolphins Tursiops truncatus during the 2010-2014 Gulf of Mexico Unusual Mortality Event, a long-term study of the prevalence of Brucella in stranded bottlenose dolphins from South Carolina, USA, was conducted. From 2012 through 2017, 282 stranded bottlenose dolphins were tested for B. ceti via real-time PCR. Nearly 32% of the dolphins tested positive in at least one sample (brain, lung, blowhole swab). Very little information exists in the literature on the occurrence of Brucella spp. in marine mammals, though in terrestrial species, such as cattle and elk, higher prevalence is often reported in spring. Similar results were found in this study with the peak occurrence being between March and June, a known period of calving in South Carolina. Results from this study provide important insights into the occurrence of the marine bacterium B. ceti.

scholarly journals Long-term site fidelity and residency patterns of bottlenose dolphins (Tursiops truncatus) in the Tramandaí Estuary, southern Brazil

10.5597/00224 ◽  
2017 ◽  
Vol 11 (1-2) ◽  
pp. 155-161 ◽  
Author(s):  
Amanda Baron Di Giacomo ◽  
Paulo Henrique Ott
Keyword(s):  
Tursiops Truncatus ◽  
Site Fidelity ◽  
Bottlenose Dolphins ◽  
Southern Brazil ◽  
Local Conservation ◽  
Entire Study ◽  
Photo Identification ◽  
Average Observation ◽  
Number Of Individuals

The occurrence of common bottlenose dolphins (Tursiops truncatus) in Tramandaí Estuary, southern Brazil, is described based on a photo-identification study conducted between January 2009 and February 2010. A total of 128 survey days were conducted with an average observation effort of 2.6 hours per day (SD = 0.6). Approximately 2050 photographs were taken from a shore land location at the mouth of the estuary. A total of nine dolphins were identified, including three calves. The dolphins were observed during all seasons, with a greater frequency during fall (79.3% of the days) and winter (60.7% of the days). The summer presented the lowest occurrence (2.4% of the days) of dolphins. During the entire study period, the maximum number of individuals sighted in any given day ranged from one to seven (average = 2.8 dolphins; SD = 1.35; n = 51). The residence indices, based on the resighting frequency of dolphins during the study period, ranged from 0.02 to 0.24 (average = 0.13; SD = 0.08; n = 9). However, most of the animals (67%) were resighted in over five months during a year and could be classified as residents. Longterm site fidelity was detected by resightings of four dolphins for over 18 years. These data combined reinforce the importance of the Tramandaí Estuary for the common bottlenose dolphins in the region and highlight the need for local conservation efforts to guarantee the long-term persistence of these coastal populations.

scholarly journals Abundance and seasonal distribution of the Southern North Carolina estuarine system stock (USA) of common bottlenose dolphins (Tursiops truncatus)

2020 ◽  
Vol 21 (1) ◽  
pp. 33-43
Author(s):  
Daniela Silva
Keyword(s):  
North Carolina ◽  
South Carolina ◽  
Tursiops Truncatus ◽  
Bottlenose Dolphins ◽  
Atlantic Coast ◽  
Population Decline ◽  
The United States ◽  
Estuarine System ◽  
Southern Boundary ◽  
Photo Identification

ABSTRACT   Under the U.S. Marine Mammal Protection Act, bottlenose dolphins [Tursiops truncatus] along the United States Atlantic coast are managed as a series of 17 distinct stocks.  To determine the status of each stock, the Potential Biological Removal (PBR) is compared with anthropogenic removals, primarily as a result of fisheries bycatch.  Estimates of abundance, with associated measures of variance, are required to generate the PBR for each stock.  The objectives of the current study were to estimate abundance for the Southern North Carolina Estuarine System Stock (SNCESS) of bottlenose dolphins and to refine the southern boundary of this stock.  To meet these objectives, photo-identification surveys were conducted during the summer and winter of 2014 in estuarine and nearshore coastal waters in southern North Carolina.  The surveys extended 25km south of the defined southern stock boundary, along the northern South Carolina coast.  One mark and one recapture survey were conducted for each season.  Each survey was completed in four or five days and covered over 300km of survey tracklines.  Dorsal fin images were processed and managed using FinBase, and only images of suitable quality and distinctiveness were used for estimates of abundance.  A three-step decision tree was used to assign each dolphin group to either the SNCESS or an adjacent coastal stock, based on sighting location, ranging patterns derived from matches to photo-identification catalogs, and statistical modeling.  Only sightings classified as SNCESS were used to estimate stock abundance.  Abundance estimates were calculated using three methods:  the Chapman modification to the Lincoln-Petersen method, package Rcapture in Program R, and program MARK 6.2.  The most parsimonious estimate was generated using the package Rcapture for program R, with the bias corrected M0 model yielding an estimate of 283 dolphins (CV = 0.33, 95% CI 170-396) in the summer of 2014.  The distribution of SNCESS dolphins shifted south in the winter and several individuals were observed up to 70km southwest of the currently recognized southern boundary.  The results of this study support the current definition of the SNCESS but suggest revisions to the southern boundary.  The SNCESS is the smallest bottlenose dolphin stock off the east coast of the USA and is at risk of population decline as a result of fisheries-related mortality.

scholarly journals Capitoline Dolphins: Residency Patterns and Abundance Estimate of Tursiops truncatus at the Tiber River Estuary (Mediterranean Sea)

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 275
Author(s):  
Daniela Silvia Pace ◽  
Chiara Di Marco ◽  
Giancarlo Giacomini ◽  
Sara Ferri ◽  
Margherita Silvestri ◽  
...  
Keyword(s):  
Population Size ◽  
Tursiops Truncatus ◽  
Site Fidelity ◽  
Bottlenose Dolphins ◽  
River Estuary ◽  
Suitable Habitat ◽  
Tyrrhenian Sea ◽  
Abundance Estimate ◽  
Photo Identification ◽  
Tiber River

Periodic assessments of population status and trends to detect natural influences and human effects on coastal dolphin are often limited by lack of baseline information. Here, we investigated for the first time the site-fidelity patterns and estimated the population size of bottlenose dolphins (Tursiops truncatus) at the Tiber River estuary (central Mediterranean, Tyrrhenian Sea, Rome, Italy) between 2017 and 2020. We used photo-identification data and site-fidelity metrics to study the tendency of dolphins to remain in, or return to, the study area, and capture–recapture models to estimate the population abundance. In all, 347 unique individuals were identified. The hierarchical cluster analysis highlighted 3 clusters, labeled resident (individuals encountered at least five times, in three different months, over three distinct years; n = 42), part-time (individuals encountered at least on two occasions in a month, in at least two different years; n = 73), and transient (individuals encountered on more than one occasion, in more than 1 month, none of them in more than 1 year; n = 232), each characterized by site-fidelity metrics. Open POPAN modeling estimated a population size of 529 individuals (95% CI: 456–614), showing that the Capitoline (Roman) coastal area and nearby regions surrounding the Tiber River estuary represent an important, suitable habitat for bottlenose dolphins, despite their proximity to one of the major urban centers in the world (the city of Rome). Given the high number of individuals in the area and the presence of resident individuals with strong site fidelity, we suggest that conservation plans should not be focused only close to the Tiber River mouths but extended to cover a broader scale of area.

scholarly journals Occurrence of bottlenose dolphins (Tursiops truncatus) in the Río Negro Estuary, Argentina, and their mid-distance movements along the northeastern Patagonian coast

10.5597/00226 ◽  
2017 ◽  
Vol 11 (1-2) ◽  
pp. 170-177
Author(s):  
Mauricio Failla ◽  
Verónica A. Seijas ◽  
Els Vermeulen
Keyword(s):  
Tursiops Truncatus ◽  
Feeding Activity ◽  
Bottlenose Dolphins ◽  
Activity Patterns ◽  
Long Distance ◽  
Identification Rate ◽  
Photo Identification ◽  
Rio Negro ◽  
Patagonian Coast ◽  
Main Activity

A systematic study was carried out on bottlenose dolphins (Tursiops truncatus) in the Río Negro Estuary (RNE), Patagonia, Argentina, to analyze their occurrence and activity patterns in this region. The photo-identification data of this study was further compared to data from an adjacent region to gain information on the animals' movements along the northeastern Patagonian coast. Information was gathered through land-based observations between the months of March and July of 2008 up to 2011. Data on dolphin activity patterns were collected via an ad libitum focal-group sampling mode. At the same time, dorsal fin images were obtained from as many dolphins as possible for identification and subsequent re-identification of individuals. Total effort equaled 188h, resulting in 58h of observation of 124 dolphin groups [sightings per unit effort (SPUE) = 0.66 group/h]. Most of the groups observed contained between one and five individuals, and two main activity states could be determined, namely traveling (65%) and foraging (26%). The photo-identification effort, which started opportunistically in 2006, resulted in a catalogue of 17 individual dolphins, with a total mean re-identification rate of nine days (max. = 24 days). When comparing these pictures to the existing catalogue of Bahía San Antonio (BSA; approximately 200km west from the study area) dorsal fins of 15 individuals could be matched and most (n = 12) could be subsequently re-identified in both areas, indicating their long distance movements along the northeastern Patagonian coast during the austral autumn months. This season coincides with the lowest dolphin abundance and feeding activity in BSA. This study indicates that bottlenose dolphins enter the RNE to forage at least during autumn. It further suggests that the search for food resources is the main trigger for their movement patterns along the northeastern Patagonian coast during this season, at least for certain individuals. More research is needed to accurately confirm these hypotheses.

Ecology and comparison of coastal and offshore bottlenose dolphins (Tursiops truncatus) in California

2009 ◽  
Vol 60 (6) ◽  
pp. 584 ◽  
Author(s):  
Maddalena Bearzi ◽  
Charles A. Saylan ◽  
Alice Hwang
Keyword(s):  
Tursiops Truncatus ◽  
Site Fidelity ◽  
Bottlenose Dolphins ◽  
Photo Identification ◽  
Santa Monica Bay ◽  
Santa Monica ◽  
Inshore Waters

Populations of coastal and offshore bottlenose dolphins (Tursiops truncatus) are considered to differ ecologically, with implications for their protection and management. We assessed occurrence, distribution and behaviour of coastal and offshore populations of dolphins during a photo-identification study in Santa Monica Bay and nearby areas (1997–2007). Bottlenose dolphins occurred year-round and were encountered on 44.2% of all surveys (n = 425). We photo-identified 647 individuals; of these, 375 (58.0%) were coastal (<1 km from shore), 241 (37.2%) offshore (1–65 km from shore) and 31 were both (4.8%). Dolphins mostly travel (69.0%) and travel-dive (61.5%), with offshore dolphins socialising more (22.6%) than coastal. There were low re-sighting rates for both coastal and offshore dolphins. Low re-sighting rates of coastal individuals provide little evidence of year-round site fidelity, suggesting their range is greater than the study area. Several individuals were re-sighted between and over 1-year periods, often foraging. This suggests that coastal dolphins: (1) are highly mobile within inshore waters, but spend time foraging in the study area, and (2) range >1 km from shore, contrary to what has been previously reported.

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