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See detailOccurrence of bottlenose dolphins (Tursiops truncatus) in the Río Negro Estuary, Argentina, and their mid-distance movements along the Northeast Patagonian coast
Failla, Mauricio; Seijas, Veronica; Vermeulen, Els ULg

in Latin American Journal of Aquatic Mammals (in press)

A systematic study on the presence of bottlenose dolphins (Tursiops truncatus) in the Río Negro Estuary (RNE), Patagonia Argentina, was carried out between the months March – July from 2008 to 2011. Data ... [more ▼]

A systematic study on the presence of bottlenose dolphins (Tursiops truncatus) in the Río Negro Estuary (RNE), Patagonia Argentina, was carried out between the months March – July from 2008 to 2011. Data on the dolphin’s activity patterns were gathered via an Ad Libitum focal group sampling mode accompanying dorsal fin images taken for identification and re-identification of individuals. A total effort of 188 h resulted in 58 h of positive observation of 124 dolphin groups (sightings per unit effort (SPUE) = 0.66 groups/h). Data analysis showed two main activity states for the observed groups, travelling (65%) and foraging (26%). The remaining 9% of the groups were involved in other activity states. The photo-identification effort, which started opportunistically in 2006, resulted in a catalogue of 21 individual dolphins, with a total mean re-identification rate of 9 days (max = 24 days). When comparing these pictures to the existing catalogue of Bahía San Antonio (approximately 200 km west from the study area) dorsal fins of 20 individuals could be positively matched and most (n = 17) could be subsequently re-identified in both areas, indicating their long distance movements along the North Patagonian coast during the austral autumn months. This season coincides with the lowest amount of feeding activity observed in Bahía San Antonio. This study suggests that bottlenose dolphins enter RNE, mainly during autumn, to forage. It appears that the search for food resources may be the trigger for their movement patterns along the North Patagonian coast during this season, at least for certain individuals. More research is needed to accurately confirm this hypothesis. [less ▲]

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See detailPopulation ecology of coastal bottlenose dolphins (Tursiops truncatus) in Northern Patagonia Argentina
Vermeulen, Els ULg

Doctoral thesis (2014)

The population ecology of bottlenose dolphins (Tursiops truncatus) was assessed between 2006 and 2011 in Northern Patagonia, Argentina. Over these years, 356 systematic photo-identification surveys were ... [more ▼]

The population ecology of bottlenose dolphins (Tursiops truncatus) was assessed between 2006 and 2011 in Northern Patagonia, Argentina. Over these years, 356 systematic photo-identification surveys were conducted in Bahía San Antonio, of which 227 were land-based and 129 were conducted from a small outboard-powered rigid-hull inflatable boat. In total, 1472 h was spend searching for dolphins, and resulted in 215 h of observation of 415 dolphin groups. Photo-identification data resulted in the identification of 67 individual dolphins. Based on mark-recapture analysis, total abundance had a maximum corrected estimate of 83 (95%CI = 46 - 152) individuals. Adult survival rates varied between 0.97 (SE = 0.04) and 0.99 (SE = 0.01). Average calving interval of the 14 reproducing females equalled 3.5 ± 1.0 years. This results in 3.5 births/year in the entire population and a minimum annual birth rate of 4.2%. However, data suggest that calves may have been born and lost before being documented, underestimating birth rate, calf mortality and possibly the number of reproductive females. Either way, the recruitment rate of calves appears to be insufficient to compensate the overall mortality in the population. Additional data further indicated the genetic isolation and extremely low genetic diversity within this community, thus indicating this community of bottlenose dolphins is highly vulnerable and at risk. Association patterns within the studied community were relatively strong (HWI 0.30 ± 0.08), re-indicating the small size of the population. Nonetheless, the fluctuation in prey density and availability appeared to be the most important factor determining their fission-fusion dynamics. It appears that a combination of aspects inherent to the species and this habitat, such as low cost of locomotion, low predation pressure and food predictability, has helped reduce the costs of fission in response to intraspecific competition. Behavioural data indicated that Bahía San Antonio is mainly used to rest and forage, with a marked diurnal and seasonal pattern in their activity. Furthermore, dolphins appeared to show a preference for the shallower waters inside their core area; they moved in and out with the tide to remain in the intertidal zone as much as possible. The observed variation in foraging activity and spatial distribution is suggested to be driven by a seasonal and locally predictable variation in prey density and availability. Most of the identified dolphins showed a yearlong residency and long term site-fidelity to Bahía San Antonio, suggesting it is the core area within the larger home range of this community. Furthermore, based on the frequent presence of calves and high residency of reproductive females, this protected coastal environment appears to provide shelter for nursing calves. Many individuals of this community ranged along the entire northern coastline of the San Matías Gulf, up to the Río Negro Estuary (approx. 200 km). Further to the north, in the southern part of the Province of Buenos Aires, a neighbouring community of bottlenose dolphins was shown to exist. Both communities are largely isolated from each other, and the environmental discontinuities between two adjacent oceanic regimes in which these communities live are hypothesised to promote their co-existence. Additionally, four individuals from another community, originating from the more southern Province of Chubut, are known to reside in Bahía San Antonio. These individuals are genetically differentiated from all other individuals in the area, clearly shown in their distinct morphology. The apparent fine-scale population structure of bottlenose dolphins over the relative small geographical distances in Argentina has conservation implications and indicates the need for further detailed research. Currently, the populations of bottlenose dolphins in the Provinces of Buenos Aires and Chubut are reported to have nearly vanished. However, this disappearance has been largely ignored in the past 40 years resulting in the studied communities to be one of the last ones remaining in the country. It seems that the coastal lifestyle and site-fidelity of coastal bottlenose dolphins, and the belief of the species to be common, may have obfuscated the need for more extensive research and conservation efforts in Argentina in former years. Local declines of common species are easily overlooked when establishing priorities for conservation, and Argentina is not a unique case. An ever-increasing number of coastal bottlenose dolphin populations are reported to be vulnerable or declining worldwide. This study provides insight into how the failure to recognise local population declines can threaten the regional status of a common species like the bottlenose dolphin. Continued research and urgent conservation measures are therefore strongly recommended to prevent the disappearance of the bottlenose dolphin from the coasts of this South American country. [less ▲]

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See detailDolphins of the Bay
Vermeulen, Els ULg; Balbiano, Alejandro; Suarez, Hilda

Book published by LosBiologos Ediciones - 1 (2014)

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See detailRemarkably low genetic diversity and strong population structure in common bottlenose dolphins (Tursiops truncatus) from coastal waters of the Southwestern Atlantic Ocean
Fruet, Pedro; Secchi, Eduardo; Daura-Jorge, Fabio et al

in Conservation Genetics (2014)

Knowledge about the ecology of bottlenose dolphins in the Southwestern Atlantic Ocean is scarce. Increased by-catch rates over the last decade in coastal waters of southern Brazil have raised concerns ... [more ▼]

Knowledge about the ecology of bottlenose dolphins in the Southwestern Atlantic Ocean is scarce. Increased by-catch rates over the last decade in coastal waters of southern Brazil have raised concerns about the decline in abundance of local dolphin communities. Lack of relevant data, including information on population structure and connectivity, have hampered an assessment of the conservation status of bottlenose dolphin communities in this region. Here we combined analyses of 16 microsatellite loci and mitochondrial DNA (mtDNA) control region sequences to investigate genetic diversity, structure and connectivity in 124 biopsy samples collected over six communities of photographically identified coastal bottlenose dolphins in southern Brazil, Uruguay and central Argentina. Levels of nuclear genetic diversity were remarkably low (mean values of allelic diversity and heterozygosity across all loci were 3.6 and 0.21, respectively), a result that possibly reflects the small size of local dolphin communities. On a broad geographical scale, strong and significant genetic differentiation was found between bottlenose dolphins from southern Brazil-Uruguay (SB-U) and Baia San Antonio (BSA), Argentina (AMOVA mtDNA ΦST = 0.43; nuclear FST = 0.46), with negligible contemporary gene flow detected based on Bayesian estimates. On a finer scale, moderate but significant differentiation (AMOVA mtDNA ΦST = 0.29; nuclear FST = 0.13) and asymmetric gene flow was detected between five neighbouring communities in SB-U. Based on the results we propose that BSA and SB-U represent two distinct Evolutionarily Significant Units (ESUs), and that communities from SB-U comprise five distinct Management Units (MUs). Under this scenario, conservation efforts should prioritize the areas in Southern Brazil where dolphins from three MUs overlap in their home ranges and where by-catch rates are reportedly higher. [less ▲]

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See detailAdult survival and reproduction in an Argentine bottlenose dolphin population: The science needed for its conservation
Vermeulen, Els ULg; Bräger, Stefan

Poster (2013, December 11)

Several small populations of bottlenose dolphins (Tursiops truncatus) are known to inhabit the Atlantic coast of Argentina, however, apparently with little exchange between them. The study population in ... [more ▼]

Several small populations of bottlenose dolphins (Tursiops truncatus) are known to inhabit the Atlantic coast of Argentina, however, apparently with little exchange between them. The study population in Bahia San Antonio (San Matías Gulf, province of Río Negro) appears to be one of the southernmost populations (42°S/65°W). Adult survival and calving rates are critical for the survival of this population. Boat-based photo-identification surveys between 2008 and 2011 were used for a mark-recapture analysis of the survival of 35 distinctly marked adults. Survey trips in September 2008 (n=9), August 2009 (n=10), September 2010 (n=6) and in September 2011 (n=6) were used as secondary periods for a Pollock’s Robust Design analysis within MARK. The population was assumed to be closed within the secondary periods, and model selection indicated random migrations (rather than Markovian or No migration) outside the secondary periods. Adult survival was very high. Calving interval was calculated for 14 reproductive females with 28 calves since 2006 with the average being 3.5 ± 1.03 years. Assuming a population size of approximately 100 individuals, the minimum annual birth rate is 4.7% per year. Of the 28 calves, 3 are presumed to have died within the first 2-3 years of life, whereas 14 are known to have survived that period. Although bottlenose dolphins occur further south along the Argentine coast, the study population appears to be the most southerly stable population after the neighboring Valdez population was recently reported to be vanishing. Interactions with fishing and contamination appear to be the most likely impacts on adult survival and reproduction. So far, our results indicate a relatively small population with apparently healthy birth and survival rates. [less ▲]

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See detailAbundance estimates of southern right whales (Eubalaena australis) in Bahía San Antonio, Patagonia, Argentina
Vermeulen, Els ULg

in Journal of Cetacean Research and Management (2013), 13

The abundance of southern right whales (Eubalaena australis) was estimated by the means of aerial line-transect surveys for the area of Bahía San Antonio, a bay located in the north-western region of the ... [more ▼]

The abundance of southern right whales (Eubalaena australis) was estimated by the means of aerial line-transect surveys for the area of Bahía San Antonio, a bay located in the north-western region of the San Matías Gulf (40°50’S 64°50’W), Rio Negro, Patagonia Argentina. In total, seven aerial surveys were conducted in the first week of August and September 2009, September, October and November 2010, and August, September 2011. Survey effort equalled a total flight time of 12.4h, during which 200 whales were counted in 119 whale groups. Half of the encounters were solitary animals and 17% were mating groups. Corrected abundance estimates showed the highest amount of whales present in the bay during the month of September, with 85±71, 207±108 and 117±55 animals in 2009, 2010 and 2011 respectively. In adjacent months, less than half the amount of whales seemed to be present. The correction factor g(0)availability resulted 0.392±0.456. Perception bias was not accounted for. These aerial surveys resulted in the first estimates of southern right whale abundance in this north Patagonian bay and indicated a rather abrupt peak during the month of September. This being the peak month for right whale presence is consistent with data from other regions in the Southwest Atlantic, but data obtained in the other months remained scarce and thus results should be interpreted carefully. The complete absence of whales in the area during November 2010 and August 2011 raises further questions on the predictability of the whale’s presence in the area. Overall, more consistent aerial surveys should be conducted to accurately determine the annual and interannual evolution of southern right whale abundance in the study area. [less ▲]

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See detailAbundance estimates of southern right whales (Eubalaena australis) in Bahía San Antonio, Patagonia, Argentina
Vermeulen, Els ULg; Cammareri, Alejandro

Poster (2012, March 27)

Aerial surveys were conducted to estimate the abundance of southern right whales in Bahía San Antonio, a bay located in the north-western region of the San Matías Gulf (40°50¿S 64°50¿W), Rio Negro ... [more ▼]

Aerial surveys were conducted to estimate the abundance of southern right whales in Bahía San Antonio, a bay located in the north-western region of the San Matías Gulf (40°50¿S 64°50¿W), Rio Negro, Patagonia Argentina. The transect for the realization of aerial surveys was designed using the program DISTANCE 6.0 and consisted out of 14 North-South (up to S 40.9°) parallel transect lines with a 2.5km separation, covering a total surface of 418km² (mean coverage probability=0.78). Transect length was chosen according to the safety restrictions of the pilot. Surveys were conducted in good weather conditions and calm sea state (Beaufort 3 or less) using a high-wing Cessna 152 with a flat window. Due to the small size of the aircraft, only one person could fly besides the pilot; observations where therefore made from one side only. Average speed and height of the aircraft was kept constant over the surveys at 90kn (166km/h) and 700ft (213m) respectively. When a group of southern right whales was sighted, data were taken on location (using a Garmin GPSmap 60csx), time and group size. The downward angle to the group perpendicular to the aircraft¿s track was then measured using a hand-held clinometer (Suunto PM5/360PC). Perpendicular distances were calculated by the means of trigonometry using the aircraft¿s altitude and the declination angle to the sighting. Due the flat windows of the aircraft a left truncation distance was set at 150m. Perpendicular distances were also right-truncated at 10% of the observations. The uniform cosine model was chosen in the view of the minimum AIC to model the detection function of southern right whales in the study area. The estimates of g(0)=(s+t)/(s+d) resulted in a correction factor of 0.392 ± 0.456 In total, 7 aerial surveys were conducted in the beginning of August and September 2009, September, October and November 2010, and August, September 2011, resulting in a total flight time effort of 12.4h. In total, 200 whales were seen in 119 whale groups, equally distributed over the entire bay. Group sizes ranged between 1-5 animals with a mean group size of 1.7 animals (SD=0.83). Results show a peak of averagely 136 ± 63 whales in the bay during the month of September, with less than half the amount of whales present in adjacent months. September being the peak month for right whale presence accords to data from other regions in the country. The aerial surveys resulted in the first estimates of southern right whale abundance in this north Patagonian bay and indicate a marked peak during September. Nevertheless, data obtained over the other months remain scarce. More aerial surveys should be conducted to accurately determine the evolution of southern right whale abundance in the study area. [less ▲]

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See detailSeasonal Variation in Abundance and Time-Budget of Bottlenose Dolphins (Tursiops truncatus) in Bahía San Antonio, Patagonia, Argentina
Vermeulen, Els ULg; Cammareri, Alejandro; Holsbeek, Ludo et al

Poster (2012, March 26)

The abundance and time-budget of bottlenose dolphins (Tursiops truncatus) was assessed in Bahía San Antonio, Patagonia (Argentina) in the years 2009 and 2010. A total of 366.4 boat-based survey hours ... [more ▼]

The abundance and time-budget of bottlenose dolphins (Tursiops truncatus) was assessed in Bahía San Antonio, Patagonia (Argentina) in the years 2009 and 2010. A total of 366.4 boat-based survey hours resulted in 64 contact hours with a total of 88 dolphin groups. Mark-recapture abundance estimations, based on 63 identified dolphins, resulted in a corrected maximum estimate of 97 and 83 individuals during winter, and a minimum of 34 and 38 individuals during autumn of 2009 and 2010 respectively. Between 25% and 68% of the population consisted of unidentifiable individuals depending on the season, indicating the high presence of juveniles and calves. Behavioural data indicated that the dolphin¿s time-budget consisted mainly out of resting and feeding, variable over the seasons. Dolphins increased their time feeding and socializing during winter and spring, whereas feeding dropped to a minimum in autumn. During summer, the dolphins spent up to 46% of their time diving, a behaviour presumably associated with a tail out/peduncle-dive foraging strategy. Based on these data, we assume more prey availability during winter and spring (main food source being pelagic fish) and a notable decrease in prey availability during summer with benthic prey species being the main food source. In autumn, even less prey items might be available. Furthermore, the increase in social behaviour during winter and spring combined with a peak in the presence of calves during these seasons, suggests the existence of a mating and calving season. These estimates of abundance are in line with the sizes of other coastal populations of bottlenose dolphins elsewhere in the world, and fit the occupancy patterns described for other coastal areas with small resident communities. The study furthers suggests that dolphins specifically use the study area to rest and feed, and to give birth and raise their young, specifically during winter and spring. [less ▲]

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See detailAlteration of Southern Right Whale (Eubalaena australis) Behaviour by Human-Induced Disturbance in Bahía San Antonio, Patagonia, Argentina
Vermeulen, Els ULg; Cammareri, Alejandro; Holsbeek, Ludo

in Aquatic Mammals (2012), 38(1), 56-64

A study was conducted to assess the behavioural response of southern right whales (Eubalaena australis) to human-induced disturbance in Bahía San Antonio, Province of Río Negro, Argentina. Behavioural ... [more ▼]

A study was conducted to assess the behavioural response of southern right whales (Eubalaena australis) to human-induced disturbance in Bahía San Antonio, Province of Río Negro, Argentina. Behavioural observations were made from June to October in 2008, 2009, and 2010. Aerial observa-tions carried out in 2010 show that up to one third of the whale groups were mating groups, indicat-ing that the study area is an important reproduction area for the species. The study compares 65.8 h (on a total effort of 120.3 h and 24 groups of whales) of land-based “undisturbed” whale behaviour obser-vations to 43.6 h of boat-based whale behaviour in a “disturbed” state (total effort of 326.1 h and 34 groups of whales). Analysis of the behavioural data show that whales significantly altered their behaviour by cutting social interactions short (on average 13%) when confronted with human short-range presence. At the same time, travelling whales experienced a significant increasing tendency to continue travelling (+21%) instead of starting to rest (-21%). However, social behavioural patterns returned swiftly to normal levels after the approach had ended, with a relative increase in “resting” (+18%) as opposed to “travelling” (-30%) rates.These data show that whale behaviour is altered by human approaches, pointing out the need for effective conservation measures and mitigation of behavioural impacts in relation to whale-based tourism. [less ▲]

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See detailResidency Patterns, Abundance and Social Composition of Bottlenose Dolphins (Tursiops truncatus) in Bahía San Antonio, Patagonia, Argentina
Vermeulen, Els ULg

Master of advanced studies dissertation (2011)

Residency patterns, abundance and social composition of bottlenose dolphins (Tursiops truncatus) were assessed during 2008-2010 in Bahía San Antonio (BSA), Patagonia, Argentina. A total of 462.3 survey ... [more ▼]

Residency patterns, abundance and social composition of bottlenose dolphins (Tursiops truncatus) were assessed during 2008-2010 in Bahía San Antonio (BSA), Patagonia, Argentina. A total of 462.3 survey hours resulted in 80.7 contact hours with in total 107 dolphin groups. Data indicated that dolphins spend most of their time resting, feeding and travelling in BSA, although their time-budget changed over the different seasons. As such, dolphins increased their time feeding and socializing during winter and spring, whereas during summer they spent up to 46% of their time diving, a behaviour presumably associated with a tail out/peduncle-dive foraging strategy. Dolphin groups had a median size of 4 individuals ranging between 1 and 40. Group size seemed to vary significantly over the different seasons and behaviours, with groups being larger during winter and during socializing and feeding. Group size was further positively correlated with the presence of calves. A total of 63 dolphins were individually identified in the bay and re-identified up to 35 days. Of these, 57% could be regarded as resident in the area (year-long or seasonally), including all mother and calf pairs. Using the closed time heterogeneity model (Mth), and accounting for the proportion of unidentifiable individuals, calculations resulted in a maximum corrected abundance estimate of 97 and 83 individuals during winter, and a minimum abundance of 34 and 38 individuals during autumn of 2009 and 2010 respectively. At all times, between 25% and 68% of the population consisted out of unidentifiable individuals (juveniles and calves) depending on the season. Results further revealed that bottlenose dolphins in BSA associated at random and that the entire community existed out of two levels of casual acquaintances. Data presented herein suggest that the shallow and protected waters of BSA support a resident community of bottlenose dolphins, between 35 to 97 individuals depending on the season, living in a fission-fusion society in which companionships frequently change. It was further suggested that dolphins specifically use BSA to rest and feed, and that the region is preferred by females to give birth and raise their young, with a possible increased calving period during winter and spring based on an increasing prey availability. [less ▲]

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See detailBehavioural response of southern right whales (Eubalaena australis) to anthropogenic approaches in Bahía San Antonio, Río Negro Argentina
Cammareri, Alejandro; Vermeulen, Els ULg

in Report to the International Whaling Commission (2010)

The behavioural response of southern right whales (SRWs) to human approaches was studied in Bahia San Antonio, Río Negro Argentina, to obtain essential information for the evaluation of a recent ... [more ▼]

The behavioural response of southern right whales (SRWs) to human approaches was studied in Bahia San Antonio, Río Negro Argentina, to obtain essential information for the evaluation of a recent authorized whale-based tourism and the implementation of accurate regulations and conservation measurements. A total of 50 SRW groups were approached with a small zodiac during the whale-seasons (June-October) of 2008 and 2009, accounting for a total of 39h of behavioural observations. The approaches occurred in a slow and controlled way up to a minimum distance of 100m. A focal animal observation (instantaneous point sample) was used to record three mutual exclusive behavioural states: rest, travel and socializing and/or aerial activity. Groups (chosen ad random) consisted out of solitary animals (0.52), Surface Active Groups (SAG; 0.32) and non-SAGs (0.13). Nevertheless, because of the low amount of data, up to now all behavioural responses were analysed regardless group composition. Results indicated that whales continued travelling during an approach, but doubled their time resting after an approach had finished (22% → 40%) and decreased drastically their time socializing or aerially active (21% → 2%). Although the probability that a whale remained in a social/aerially active behaviour when affected by anthropogenic approaches decreased notably (-22%), no significant effect could be found up to now (Z-test for 2 proportions, p>0.05), probably due to the relative small dataset. Nevertheless, the apparent change in SRW social behaviour requires urgently more detailed information to implement conservation strategies regulating adequately the commercial whale-based tourism in the area. [less ▲]

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See detailVariation in external morphology of resident bottlenose dolphins (Tursiops truncatus) in Bahia San Antonio, Patagonia, Argentina.
Vermeulen, Els ULg; Cammareri, Alejandro

Poster (2010, March 22)

Two geographic variations of bottlenose dolphins were described in Argentina (Bastida & Rodriguez, 2003); bottlenose dolphins characterized by their triangular dorsal fin shape (coast of the province of ... [more ▼]

Two geographic variations of bottlenose dolphins were described in Argentina (Bastida & Rodriguez, 2003); bottlenose dolphins characterized by their triangular dorsal fin shape (coast of the province of Buenos Aires), and bottlenose dolphins characterized by their falcate dorsal fin shape (coast of the province of Chubut). It was stated that `their clear difference would indicate that both geographic forms are isolated¿ (Bastida & Rodriguez, 2003 p.137). A photo-identification study carried out in Bahía San Antonio (BSA), North Patagonia Argentina, showed a similar variation in external morphology among year-round resident bottlenose dolphins. Out of the 15 bottlenose dolphins considered year-round resident in the bay (Vermeulen & Cammareri, 2009), three are clearly distinguishable by a more falcate dorsal fin, a darker coloration and a notably shorter beak. These individuals, with one associated calf, were first identified in September 2008 and could be re-identified in the study area up to 13 days over all the different seasons. On all occasions, they were re-identified in close association with each other and on 10 occasions in close association with triangular dorsal fin shaped bottlenose dolphins. Behavioural observations made during these associations indicated that these mixed dolphin groups were 18% of their time feeding, 18% socialising, 17% slowly travelling and resting, 16% travelling in medium and fast speed and 7% milling (n=380 min). Although both forms show variations in external morphology, the extent to which this phenotypic variation is genetically correlated remains unknown. A clear insight on the differentiation between these regional forms might have important conservation implications for this species in Argentina. [less ▲]

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See detailVariation in external morphology of resident bottlenose dolphins in Bahía San Antonio, Patagonia, Argentina
Vermeulen, Els ULg; Cammareri, Alejandro

in Journal of Marine Animals and Their Ecology (2009), 2(2), 3-6

A photo-identification study carried out in Bahía San Antonio (Patagonia Argentina) showed a variation in external morphology among year-round resident bottlenose dolphins. Out of 63 individually ... [more ▼]

A photo-identification study carried out in Bahía San Antonio (Patagonia Argentina) showed a variation in external morphology among year-round resident bottlenose dolphins. Out of 63 individually identified bottlenose dolphins, 15 were considered year-round residents of which three show variations in external morphology: they have a more falcate dorsal fin, darker coloration and shorter beak, physical characteristics described for the regional form of bottlenose dolphins present in the more southern province Chubut. The three morphologic distinct individuals, with one associated calf, could be re-identified in the study area up to 10 times over all the different seasons and up to now, no other bottlenose dolphins with similar characteristics could be observed in the area. On all occasions, they were re-identified in close occasions with each other and on 8 occasions in close association with other identified individuals. So far it was believed that the two regional forms of bottlenose dolphins present in Argentina were isolated. This communication is meant to document the residency and interaction of both regional forms in the same area. [less ▲]

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See detailResidency Patterns, Abundance, and Social Composition of Bottlenose Dolphins (Tursiops truncatus) in Bahía San Antonio, Patagonia, Argentina
Vermeulen, Els ULg; Cammareri, Alejandro

in Aquatic Mammals (2009), 35(3), 379-386

Residency patterns, abundance, and social composition of bottlenose dolphins (Tursiops truncatus) were assessed from 2006 to 2008 in Bahía San Antonio (BSA), Patagonia, Argentina. A total of 714 survey ... [more ▼]

Residency patterns, abundance, and social composition of bottlenose dolphins (Tursiops truncatus) were assessed from 2006 to 2008 in Bahía San Antonio (BSA), Patagonia, Argentina. A total of 714 survey hours resulted in 132 contact hours with 224 bottlenose dolphin groups. Results indicated that dolphins can be seen year-round on average every 4 h, with sighting periods lasting an average of 45 min. A total of 57 bottlenose dolphins were positively identified in the bay, of which 56% showed a degree of residency, including almost all mother and calf pairs. Using the closed time heterogeneity model (Mth), and accounting for the proportion of unidentifiable individuals, calculations resulted in a corrected abundance estimate of 83 individuals for the study area. Further analysis revealed that individual dolphins associated at random and that the entire community exhibits rapid disassociations and two levels of casual acquaintances. Data suggest that the shallow waters of BSA support a relatively resident community of bottlenose dolphins, living in a fission-fusion society in which companionships frequently change. The relative constant presence of calves in more than 50% of the dolphin groups and the observed presence of neonates might furthermore indicate that dolphins specifically use this area, among others, to give birth and nurse their young. In addition, a reported decline in bottlenose dolphin sightings in the larger area of the Argentinean coast might indicate that BSA is one of the last remaining refuges of the species in the country. Further research seems vital for their conservation. [less ▲]

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See detailAN IDENTIFICATION STUDY ON BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) IN NORTHEAST PATAGONIA, ARGENTINA
Vermeulen, Els ULg; Cammareri, Alejandro; Failla, Mauricio et al

Poster (2008, October 13)

In Argentina, bottlenose dolphin (Tursiops truncatus) sightings decreased notably since the late 80s in regions where it used to be frequent to observe them. Nowadays, Northeast Patagonia is one of the ... [more ▼]

In Argentina, bottlenose dolphin (Tursiops truncatus) sightings decreased notably since the late 80s in regions where it used to be frequent to observe them. Nowadays, Northeast Patagonia is one of the few regions where they still can be seen frequently, although local increasing human activities result in increasing need for information. In general, photo-identification has been established as a helpful tool in cetacean research. However, only few studies have applied this method to bottlenose dolphins in Argentina. This study is therefore aimed to obtain basic information concerning bottlenose dolphins through their identification, this way contributing to their conservation. Land-based observations were made in the northern Gulf of San Matías, Patagonia, Argentina, from August 2006 up to June 2008. Over 15.000 digital pictures of dorsal fins were analysed using the computer assisted identification systems FinEx and FinMatch. Dolphins re-identified during all four seasons in one year were defined as residents. The degree of residency was further estimated by the re-identification frequency (RF); non-resident (RF=1-3) - occasional (RF=4-7) - frequent (RF=8-11) - common (RF¿12). In total, 221 surveys were conducted with an average observation effort of 3.2h per survey, resulting in a total observation effort of 915h of which 124h were spent with 182 dolphin groups. A total of 50 dolphins were identified of which the vast majority (82%) was photographed only in the Natural Protected Area Bahía San Antonio (NPABSA), due to the higher observation effort in this region. Nevertheless, 12% of the catalogued dolphins could be photographed in both NPABSA and the Río Negro estuary, indicating that their home-range might include at least the whole northern region of the Gulf San Matias. Dolphins could be re-identified up to 13 days with 54% showing a degree of residency for NPABSA. This study shows the first data concerning bottlenose dolphins in Northeast Patagonia, but further investigation is highly necessary to improve their conservation. Therefore, the obtained photo-identification catalogue from the presented study is meant to serve as a primary tool for progressing research concerning this species in Argentina. [less ▲]

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See detailA photo-identification catalogue of bottlenose dolphins (Tursiops truncatus) in Northeast Patagonia, Argentina: A tool for the conservation of the species
Vermeulen, Els ULg; Cammareri, Alejandro; Failla, Mauricio

in Report to the International Whaling Commission (2008)

A photo-identification study of bottlenose dolphins (Tursiops truncatus) was performed in the northern Gulf of San Matías, Patagonia Argentina, during the period 2006-2008. In total, 199 surveys were ... [more ▼]

A photo-identification study of bottlenose dolphins (Tursiops truncatus) was performed in the northern Gulf of San Matías, Patagonia Argentina, during the period 2006-2008. In total, 199 surveys were conducted with an average observation effort of 4.2h (SD=1.5) per survey. These surveys resulted in a total observation effort of 824.7h of which 105.7h was spend with 158 dolphin groups. Over 12,500 pictures were analysed using the automatic identification systems FinEx and FinMatch (EuroPhlukes Initiative, Leiden University, The Netherlands), resulting in the first identification catalogue of 47 dolphins for the North Patagonian region. The catalogued dolphins were re-identified up to 13 days with 57% (n=47) showing a degree of residency for the Natural Protected Area Bahía de San Antonio (NPABSA; resighting frequency (RF)≥4). At least 6 dolphins, including one mother with her calf, were additionally re-identified inside the estuary of the river ‘Rio Negro’, 250km east, indicating that their home-range includes at least the whole northern region of the Gulf of San Matias. Data suggest that it concerns a stable but yet unknown population of bottlenose dolphins with a high touristic potential and an urgent need of conservation measurements. The obtained photo-identification catalogue is meant to serve as a tool for the conservation of the species and the realization environmental education projects in the region. [less ▲]

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See detailHistorical records of southern right whales (Eubalaena australis) of the province Río Negro, North Patagonia, Argentina (1991-2008)
Failla, Mauricio; Vermeulen, Els ULg; Cammareri, Alejandro

in Report to the International Whaling Commission (2008)

The increase of the southern right whale (SRW Eubalaena australis) population might rise questions about the reoccupation of previous sites. This report is a compilation of historical records of SRWs ... [more ▼]

The increase of the southern right whale (SRW Eubalaena australis) population might rise questions about the reoccupation of previous sites. This report is a compilation of historical records of SRWs along the coast of the Río Negro province, Northeast Patagonia, to evaluate the tendency of their occurrence in the area over the past decade. A total of 308 records (425 whales) were collected over distinct coastal regions in Northeast Patagonia. The majority of sightings were concentrated between the months July-October with a peak in August-September as was observed similarly in South Brazil, Uruguay and central Patagonia. Groups consisted out of 2 individuals on average whereas mother and calf pairs could be observed in only 11% of the sightings. There was a general increase in sightings over the subsequent years possibly explained by a cause-response relation of increasing sightings and increasing effort. The information presented in this report could suggest a similar hypothesis of reoccupation in the province of Río Negro, Argentina, as was suggested to be occurring along the southeastern coast of Brazil, Uruguay and the Santa Cruz province of Argentina. Data are too preliminary however, to determine the importance of this area for the reproduction and/or migration of this species. Nevertheless, the presented data completes an evolving database of the presence of SRWs along the whole Patagonian coast as was recommended by the International Whaling Commission in 2001. More data and systematic effort is needed to obtain the information on the ecology of SRWs in the Río Negro province, needed for the implementation of conservation measurements in the waters of the provincial jurisdiction, specially in the touristic area of the Natural Protected Area Bahía San Antonio. [less ▲]

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See detailSouthern right whales (Eubalaena australis): a new touristic attraction in the Natural Protected Area Bahía de San Antonio, Northeast Patagonia?
Cammareri, Alejandro; Vermeulen, Els ULg

in Report to the International Whaling Commission (2008)

In Argentina, the southern right whale (SRW Eubalaena australis) was declared a ‘Natural Monument’ in 1984, protecting the species in waters under national jurisdiction. In the Northeast Patagonian ... [more ▼]

In Argentina, the southern right whale (SRW Eubalaena australis) was declared a ‘Natural Monument’ in 1984, protecting the species in waters under national jurisdiction. In the Northeast Patagonian province Río Negro, the SRW is being protected since 1997 by the provincial law 3130. Recently in 2006, this province declared the SRW as a ‘Natural Monument’ in the waters under their jurisdiction by the provincial law 4066. With this law, a commercial whale-watching activity was approved and regulated strictly by provincial authorities, as was the first legalization on ‘immersion with whales’ in Argentina. Data on the sighting frequency (SF), group size and group composition of SRWs were obtained during a preliminary study from March 2007 to February 2008 in the Natural Protected Area Bahía de San Antonio (NPABSA), the most touristic coastal town of this Northeast Patagonian province. Data indicate a peak SF in September with an explicit increase and decrease in the months before and after respectively. The majority of the whales visiting the area were solitary animals (47.7%) followed by non-surface active groups (non-SAG’s; 25%), mothers and calves (M&C; 20.5%) and SAG’s (4.5%). 2.3% of the whale groups could not be classified. Whales in the study area were mainly resting or in a slow travelling behaviour (64%). 22% of the whales were seen socializing whereas only few groups were believed to be engaged in a courtship behaviour (5%). These data might suggest that the area is not a main reproductive area, possibly favouring the region for a whale-based tourism. On the other hand, the unpredictability of their daily presence and the average distance between the whale and the shore raises questions on the viability of such a whale-based business. [less ▲]

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See detailSIGHTING FREQUENCY AND PHOTO-IDENTIFICATION OF BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) ALONG THE COAST OF BAHÍA SAN ANTONIO, PATAGONIA, ARGENTINA
Holsbeek, Ludo; Cammareri, Alejandro; Failla, Mauricio et al

Poster (2008, March 10)

The sighting frequency (SF), site fidelity, home-range and group composition of bottlenose dolphins (Tursiops truncatus) were assessed during a photo-identification study in 2006-2007. This study aims to ... [more ▼]

The sighting frequency (SF), site fidelity, home-range and group composition of bottlenose dolphins (Tursiops truncatus) were assessed during a photo-identification study in 2006-2007. This study aims to provide first data on this unknown austral bottlenose dolphin population to answer to their increasing conservation needs. Data and pictures were collected during 132 surveys with an average observation effort of 2.8h (SD=1.6) per survey. All clear pictures were analysed using the automatic identification systems FinEx and FinMatch (EuroPhlukes Initiative). The SF was obtained dividing the number of sightings by the amount of effort. Site-fidelity was estimated using the Capture Mark Recapture method and the degree of residency by the re-identification frequency following Culloch (2004). In total, 377.4h were spent searching for bottlenose dolphins of which 57.3h were spent in the presence of 126 dolphin groups divided in 105 sightings. The SF was 0.28/h with and average duration of 43.2min/sighting (SD=0.76). A total of 43 dolphins were classified into an identification catalogue. These recognizable dolphins were re-identified up to 10 days with 44% (n=43) showing a degree of residency (resighting frequency (RF)¿4). The average group size was 6.1 (SD=7.9) ranging from one to fifty animals. Group size increased significantly with the presence of calves and with the distance from the coast. Nevertheless, all dolphins were seen in inshore waters ¿20m deep. The most frequent group formation was loose (34.5%), variable (29.8%), disperse (20.2%) and tight (15.5%). At least 6 identified dolphins, including one mother with her calf, were photographed in the mouth of the Rio Negro 250km from the study area indicating that their home-range is far from limited to Bahia de San Antonio. Data indicate that it concerns a resident but yet unknown population of bottlenose dolphins with a high commercial potential and an urgent need of conservation measurements. [less ▲]

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