References of "Vermeulen, Els"
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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 detailSeasonal Variation in Abundance and Time-Budget of Bottlenose Dolphins (Tursiops truncatus) in Bahía San Antonio, Patagonia, Argentina
Vermeulen, Els ULg; Cammareri, Alejandro

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 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 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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