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Bottom topography and division of the Adriatic Sea (Oceanlab, 2017; Meteorological and Hydrological Service, 2017).
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The Montenegro Dolphin Project ran the first dedicated annual survey effort within the coastal and offshore waters of Montenegro between 2016 and 2017, with plans to keep the survey effort going until 2020. The results presented here contribute to fill the gaps in knowledge and provide baseline information on the cetaceans of Montenegro. We urge ma...
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Context 1
... study carried out from 1990 to 1999 focused the first time on the heavy metal concentration of beached bottlenose and striped dolphins along the Croatian coast. The research aims to indicate the extent of contamination in the Adriatic. A total of 49 samples (17 muscle, 16 liver and 16 kidney) was collected from stranded specimens. The total mercury levels were high in each tissue whereas the highest concentrations were found in liver tissues of adult dolphins. The cause, however, is ascribed to natural and anthropogenic sources (Pompe -Gotal et al., 2009). Later, a genetic study was conducted from 1994 to 2003 in Croatia to identify the genetic diversity and the existence of a bottlenose dolphins in the past, and the extend of the genetic diversity to the amount that sub populations of bottlenose dolphins could be identified through microsatellites. It appeared that the genetic diversity was rather high ( Galov et al., ...
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... 2002 and 2008, the first attempt to provide data on the ecology of bottlenose dolphins in Slovenian and adjacent waters was carried out and its result served as a baseline for conservation effort. Through boat and land based survey, 101 individuals were identified, with 75% re-sighted later. The group size ranged from 1-43 and calves were present in 53.3% of the groups. A yearly mark-recapture density of 0.069 dolphins/km 2 was measured ( Genov et al., 2008). Between 2003 and, the environmental factors that influence the habitat use of bottlenose dolphins were investigated in the North-western portion of the Adriatic off the coast of Italy. The research combined hydrological and physiological variables with dolphin related data. It turned out that habitat use is influenced by oxygen saturation, water temperature, gradient of density anomaly, turbidity, distance to nearest coast and bottom depth. The major changes in hydrological variables are primarily caused by seasonal changes (Bearzi et al., 2008). Between 2005 and, the well-studied population of the Cres-Losinj archipelago was assessed by long-term noise monitoring. The acoustic analysis identified the area around three marine petrol station and tourist beach camps as the noisiest spots in the area ( Rako et al., ...
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... three major regions differ in characteristics (UNEP/MAP RAC/SPA, 2015). The Adriatic has an average depth of 252 m and shows a gradient of increasing depth towards the south. Hence, the northern part is very shallow and does not exceed a depth of 100 m, whereas it reaches a maximum depth of 1,233 m in the south (Blake & Topalović, 1996). In the Central Adriatic, a maximum depth of 280 m can be found in the Jabuka Pit (Blake & Topalović, 1996;Grbec et al., 1998). This intricate subsidence, located between the Italian and Croatian coasts, is characteristic for the Central Adriatic region and embodies an important and highly productive region for fish life ( Silva et al., 2014). Further southwards, the Palagruža (Pelagosa) Sill separates the central Adriatic from the southern (Cushman-Rosin et al., 2001). The sea reaches its maximum depth of 1,233 m in the South Adriatic Pit ( Grbec et al., 1998) (Figure 2). (Oceanlab, 2017;Meteorological and Hydrological Service, ...
Context 4
... cetacean field studies began from the late 1980's and have been continued until today in the Mediterranean Sea (Bearzi et al., 2008). However, most studies have been carried out in the northern parts of the western basin than the eastern Mediterranean Basin ( . Research topics varied over time. While distribution, population structure, ecology and behaviour were the primary subject, nowadays the emphasis lies on threats and human induced impacts from the past and the present (such as fisheries, culling pollution and marine traffic). The primary aim of the researches is presently, conservation management and the establishment of population trends ( ...
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Citations
... During surveys with low boat density, the Middle region of Montenegro shows a plateau suggesting focal groups are unresponsive, when vessel count reached three boats, a positive relationship is observed. This region has the greatest trawl fishery activity ( Figure 12: [8]), trawlerscavenging is a global phenomenon [28], thought to be provoked by the energetic cost of vessel evasion [6] Despite the small abundance and geographic range (<12nm) of the Montenegrin trawler fleet [17] this behavior occurs in its waters [13]. This may account for the persistence of delphinid groups during high vessel densities in this region. ...
... software was used to convert these angles into geographical positions. As well as recording data on the number of marine vessels, their type (FB (fishing boat), FV (fishing vessel), HSB (high-speed boat), RB (research boat), SB (sailing boat), FE (ferry) HSFE (high-speed ferry), CS (cargo ship), CR (cruise ship), and JET (jet-ski), their activity, and their distance from cetaceans was recorded following the methodology used by Bas et al. (2017Bas et al. ( , 2018. This study focused particularly on fisheries data and fishing activity was divided into two separate categories: commercial fishing vessels (FV), consisting of trawlers and purse seiners (>12 m in length) and artisanal fishing boats ((FB), consisting of smaller purpose-built fishing boats and other recreational boats where fishing F I G U R E 1 Study area including total coverage of land and boat survey efforts. ...
... The predominant behavior of the focal group was determined at the start of each 5 min sampling interval using an instantaneous focal group scan sampling method following the methodology of Bas et al. (2017Bas et al. ( , 2018. For each sampling interval, the behavioral states of individuals within the focal group were scanned and the number of individuals partaking in each behavioral state definition was recorded (Table 2). ...
The spatial–temporal distribution of cetacean species often overlaps with fishing practices in the Mediterranean, having direct and indirect consequences. This is the first long‐term study focusing on the effects of fisheries on the behavior of T. truncatus in Montenegro. Focal group scan sampling was used during surveys between September 2016 and August 2020 to create transition probability matrices using first‐order Markov chains for behavioral states in both control (absence of fishery practices) and impact chains (presence of fishery practices). Despite the low number of dolphin‐fishery interactions in Montenegro, results revealed that the behavioral budgets of T. truncatus were significantly altered both for commercial and artisanal fisheries. However, the magnitude of the threat differed between practices, with commercial fisheries altering three out of the four behaviors in the behavioral budget while artisanal fisheries altered just one. Significant behavioral changes due to disturbance can have negative consequences on the energy budget of individuals and while the Montenegrin fishing fleet is currently limited to 224 vessels, the significant effects already witnessed are concerning for Montenegrin bottlenose dolphins. To develop in‐situ mitigation strategies, there is a clear need to better understand the impact that fisheries interactions have on these individuals.
... It is worth noting that the protection status often does not so much reflect real threats, but often rather the sympathy that the species attracts. For example, all dolphin species are protected today, including Tursiops truncatus and Stenella coeruleoalba, for which there is no evidence that their abundance is below the baseline, and which might even have benefited from human action, which has eliminated some of their competitors [62][63][64]. (iv) Iconic (or charismatic, flagship) species are species that arouse the sympathy of the public, either because of their beauty [65], their intelligence, or an image acquired through films. In the PCNP, the dusky grouper Epinephelus marginatus and the meagre Sciaena umbra are iconic species. ...
The Port-Cros National Park (PCNP), established in 1963, was one of the earliest terrestrial and marine parks in the Mediterranean Sea. From 2012, it engaged in a major redefinition and extension of its territory (N-PCNP—New Port-Cros National Park). This case is particularly interesting insofar as the protected area has been competently and efficiently managed since its creation, and protection and management measures have been strictly implemented: in the Mediterranean, the PCNP has often been considered as a benchmark. Here, we critically analyse almost 60 years of the management of the biodiversity and the human uses, with their share of successes and failures, certain operations which are today regarded as errors, and a doctrine today of a priori non-interventionism, in contrast to the doctrine in vogue in the early years. Of particular interest is the change in outlook with regard to actions favouring flagship species, such as building a tower for bats, setting up artificial nests for seabirds, and constructing an artificial reef at sea. The question of the natural arrival of the wild boar, a native species, and the hostility of the public and some species-centred scientists, is particularly instructive. We analyse these changes in the light of the ongoing trends in concepts in ecology and nature conservation, and the shift from a species-centred to an ecosystem-centred approach. It is worth emphasizing that a critical review of almost 60 years of management is a very rare exercise in a national park anywhere in the world.
... Cetacean surveys started in the late 1980s within the Adriatic Sea, mainly targeting the northern and central waters (Notarbartolo di Sciara, et al., 1993). Occasional survey efforts began in Montenegro with the first aerial survey and first boat surveys in 2010 and 2013 respectively (Ðurovic et al., 2016;Fortuna et al., 2011) but it wasn't until 2016, that the first long term surveys on cetaceans were conducted, covering the entire coastline of Montenegro (Affinito et al., 2019;Awbery et al., 2019a;Bas et al., 2018). ...
... Montenegro Dolphin Research was established in 2016 and since then has run dedicated research effort within the coastal waters of Montenegro (Affinito et al., 2019;Awbery et al., 2019a;Bas et al., 2018). The research scope ranged from spatial-temporal distribution of bottlenose dolphins to residency and site fidelity patterns, key habitat identification and threat assessment (Affinito et al., 2019;Awbery et al., 2019a;Bas et al., 2018;Clarkson et al., 2020). ...
... Montenegro Dolphin Research was established in 2016 and since then has run dedicated research effort within the coastal waters of Montenegro (Affinito et al., 2019;Awbery et al., 2019a;Bas et al., 2018). The research scope ranged from spatial-temporal distribution of bottlenose dolphins to residency and site fidelity patterns, key habitat identification and threat assessment (Affinito et al., 2019;Awbery et al., 2019a;Bas et al., 2018;Clarkson et al., 2020). ...
Five cetacean species are known to inhabit the Adriatic Sea. While bottlenose dolphins (Tursiops truncatus) are the most commonly reported species of the Adriatic, they show mainly coastal distribution from its southern to the northern boundaries. On the other hand, striped dolphins (Stenella coeruleoalba), Risso’s dolphins (Grampus griseus) and Cuvier’s beaked whales (Ziphius cavirostris) show deep sea preferences to the neighbouring waters of the Adriatic Pit. Lastly, fin whales (Balaenoptera physalus) are occasionally reported in the coastal waters of Croatia, with a recent report in Montenegro in 2021. All the cetacean species present in the Adriatic Sea are classified as under threat by the IUCN Red List with extremely limited information on the deep-sea cetacean species.
The dedicated research effort of Slovenia and Croatia highlighted the presence of resident bottlenose dolphins and their effort for over 20 years further advanced knowledge on species baseline information with a threat assessment which eventually resulted with the implementation of MPAs and management plans within their territorial waters. Therefore, while the northern and central Adriatic Sea is relatively well-studied, the southern Adriatic Sea still holds knowledge gaps and thus mitigation strategies are far from being implemented. Despite the scarce research efforts until the late 2010s, cetaceans have been identified as a community interest with strict protection measures enforced by the Montenegrin Government.
Montenegro Dolphin Research started its dedicated cetacean research of Montenegrin waters in September 2016 and since then has been in the field for over 700 days to gather the missing knowledge on cetacean species and to understand the level of human impact on these magnificent creatures. Our results identified critical habitats of bottlenose dolphins in neighbouring waters of Ulcinj, Bar and Boka Kotorska Bay. While the estimated population size of bottlenose dolphins was 116±17 individuals in 2017, it showed a sharp decline to 79±21 individuals in 2019. However, the sighting rates of bottlenose dolphins increased from 24% in 2019 to 27% in 2020 and 47% in 2021. Since March 2020, Montenegro has had reduced human presence within the marine environment due to the COVID19 pandemic. It is interesting and also promising to see that the number of dolphin sightings immediately increased once the human pressure in the area decreased. Additionally, the inclusion of acoustic techniques in addition to the visual surveys revealed the dominant presence of foraging behaviour within the Bay of Kotor, with rare and specific vocalisation types being recorded in the area. Our previous studies in Montenegro highlighted the dominant presence of ‘travelling state’, proposing that Montenegro was mainly a migration corridor for the bottlenose dolphins. However, our recent acoustic results revealed that it also holds both foraging and socialising grounds. Last but not least, both the effect of tourism and fishery related boats revealed significant alterations to the behavioural budget of bottlenose dolphins in Montenegro, even when their exposure level to those specific boats are below 20% of the time.
Montenegro is a country with a growing economy and tourism related activities are one of the main income sources. Even though eco-tourism is the one and only sustainable tourism source, the tourism industry is generally directed towards coastal development of hotels with little to no investment in their environmental impact assessment. As a result, uncontrolled coastal destruction, noise and chemical pollution, and plastic debris are already showing an impact on the marine ecosystem of Montenegro. Further, oil and gas explorations have started to take place within the coastal waters of Bar as well as in the unique deep-sea ecosystem of the Adriatic Pit with no publicly available report on the activities. Even though we are fully aware of the importance of economic growth in a country, any human activities that may be carried out in an uncontrolled and unregulated nature are likely to form severe threats to marine species and their associated habitats. Therefore, our project and its research and conservation outcomes form one of the most important steps towards effective conservation strategies that promote not only the protection of nature, but also sustainable blue economic growth.
Montenegro Dolphin Research continues to be the only annual project on the field of marine mammals in Montenegro. With dedicated research efforts and engagement of the local community, knowledge about the marine mammal population in Montenegro will increase, which will give us the ability to turn our knowledge into a management plan for the conservation of cetacean populations in Montenegrin waters and its habitat. For this reason, we have created the ‘Montenegro Sighting Network’, through which we have involved the citizens of Montenegro and in 11 months we have received 23 reports, which shows that public awareness about cetaceans and marine ecosystems in general is increasing in Montenegro. By establishing networks and producing influential documentation within the community, the conservation implications of our actions will be more effective and longer lasting.
... Marine vessel presence was not recorded in a standardized way and therefore not included in the model. It is recommended that data on marine vessel presence as described in Bas et al. (2017) is included in future surveys. ...
Little is known about the humpback whales (Megaptera novaeangliae) of the East-African Coast genetic sub-unit (C1). With an estimated population size of 7000 whales, they demonstrate the resilience of the species after commercial whaling caused population numbers to decline drastically. Zavora Bay, Mozambique offers an ideal observation point of the passage of the whales during their annual migration towards the breeding ground of southern Africa and serves as an operating base to monitor this population. This study aimed at identifying the importance of Zavora Bay as part of this breeding ground and the core regions for humpback whale use within the study area. Results showed the waters off the coast of Zavora are actively used for breeding and do not merely serve as passage towards the wintering habitats. A mother-calf pair separation with a preference for shallower waters closer to shore was observed. Besides depth and distance to shore, slope also proved to have a significant influence on the distribution of adult humpback whales. Increased survey effort and more detailed investigation of the threats to humpback whales within the waters of Zavora are recommended.
... second part of the program, a matrix of 6 × 6 receivers distributed at intervals of equal width was set up as reported inFigure 4b. Characterization maps of the Adriatic Sea: (a) depth map,[43][44][45]; (b) water temperature distribution (c) water salinity distribution. ...
... Characterization maps of the Adriatic Sea: (a) depth map,[43][44][45]; (b) water temperature distribution (c) water salinity distribution. ...
An increasing attention has recently been paid to the effect of the underwater noise field generated by ship activities on the marine environment. Although this problem is widely discussed in international treaties and conventions, it has not yet found a consolidated technical-scientific treatment capable of quantifying the level of underwater noise emissions produced by naval systems. As part of a national research collaboration, a novel code has been developed to predict noise propagation according to the Ray Tracing approach. Such optical geometry-based technique allows for calculating the Transmission Loss (TL) trend in its respective contributions: geometrical loss (due to the distance between the source and receiver), dissipation loss (due to the characteristics of the propagation environment), and reflection loss (due to the surfaces that delimit the field). The simulation requires as input parameters the source info as spatial position, frequency, and sound pressure level (SPL) as well as the sea properties like seabed depth, the speed of sound profile, the layers thickness the water column is divided into, the sea salinity, temperature, and pH. The simulation code provides the SPL spatial distribution useful as a fast industrial tool in the future studies addressed to identify the emission limits for the protection of marine wildlife.
... Studies have shown the common bottlenose dolphin to be one of the most common marine mammal species found regularly in the Adriatic (Bearzi et al., 1997). Long term studies in Slovenia (Genov et al., 2008;2009;Halpin et al., 2009;Genov, 2013), throughout Croatia (Impetuoso et al., 2003;Fortuna et al., 2011;UNEP-MAP-RAC/SPA, 2014;Gaspari et al., 2015;Pleslic et al., 2015;Ribarič, 2018), Italy (Bearzi & Fortuna, 2006;Bearzi et al., 2008;Genov, 2016) and most recently Montenegro (Fortuna et al., 2011;Ðurovic et al., 2016;Bas et al., 2018;Affinitio et al., 2018), demonstrate the species to be widely distributed throughout the entire Adriatic. Unfortunately, due to extermination and directed kill campaigns in the 1960's alongside long-term bycatch mortality (Bearzi et al., 2008), the species Mediterranean subpopulation is listed as 'vulnerable' under the International Union for Conservation of Nature (IUCN) Red List criteria (Bearzi et al., 2012). ...
... Increased boat and acoustic disturbances in recent years have increased the potential for behavioural disruptions and habitat loss. Widely documented interactions between bottlenose dolphins and anthropogenic vessels have resulted in negative impacts on their behaviour and critical habitats (Lusseau, 2003;Lusseau & Higham, 2004;Arcangeli et al., 2008;Christiansen et al., 2010;Gonzalvo et al., 2013;Pennino et al., 2016;Bas et al., 2017), whilst seismic air gun use and marine construction practises are also concerning (Nowacek et al., 2007;Finneran et al., 2015). Striped dolphins are thought to be the most widely distributed cetacean species in the Mediterranean, found in deep waters both towards the coastline and beyond the continental shelf (Aguilar, 2000;IUCN, 2012;UNEP-MAP-RAC/SPA, 2014;Bas et al., 2018). ...
... Widely documented interactions between bottlenose dolphins and anthropogenic vessels have resulted in negative impacts on their behaviour and critical habitats (Lusseau, 2003;Lusseau & Higham, 2004;Arcangeli et al., 2008;Christiansen et al., 2010;Gonzalvo et al., 2013;Pennino et al., 2016;Bas et al., 2017), whilst seismic air gun use and marine construction practises are also concerning (Nowacek et al., 2007;Finneran et al., 2015). Striped dolphins are thought to be the most widely distributed cetacean species in the Mediterranean, found in deep waters both towards the coastline and beyond the continental shelf (Aguilar, 2000;IUCN, 2012;UNEP-MAP-RAC/SPA, 2014;Bas et al., 2018). In the Adriatic, their distribution can predominantly be found across the entire Southern Adriatic sub-basin (Fortuna et al., 2011;UNEP-MAP-RAC/SPA, 2014;Notarbartolo di Scaria, 2016). ...
The Adriatic Sea is home to five cetacean species, classified as at risk by the IUCN. Bottlenose dolphins (Tursiops truncates), striped dolphins (Stenella coeruleoalba), Risso’s dolphins (Grampus griseus), Cuvier’s beaked whales (Ziphius cavirostris) and fin whales (Balaenoptera physalus), are all identified as species in which the community has a vested interest and are under strict protection by the Montenegrin Government and by law. Since 2016, our studies, alongside existing data, have demonstrated the presence of resident bottlenose and striped dolphins in Montenegro, in addition to sightings of Cuvier's beaked whales and Risso's dolphins in its offshore waters. The regional status of species, assessments of threats and future conservation efforts can only be determined with dedicated and systematic surveys. Further, the Adriatic Pit, the deepest region of the entire Adriatic, holds the highest levels of biodiversity, whilst also being one of the most vulnerable regions to anthropogenic threats.
The purpose of our survey effort is to expand upon the data we have already acquired within the coastal and offshore waters of Montenegro to cover data deficient species such as Cuvier's beaked whales and Risso's dolphins and to explore the possible presence of common dolphins that were thought to be regionally extinct until recent sightings in the summer of 2018 by the Blue World Institute.
As a result of the necessity for economic growth, Montenegro is rapidly developing its tourism industry and more recently, the country has participated in oil and gas explorations. Yet any human activities that remain unregulated, are likely to form severe threats to marine species and their associated habitats. Therefore, our research and conservation outcomes form one of the most important steps towards effective conservation strategies, which promote not only the protection of nature, but also sustainable economic growth. For this reason, our project continues its dedicated survey effort in 2019, covering both the coastal and the offshore waters of Montenegro. Coupled with the recent addition of our sighting and stranding networks, we hope to aid the relevant authorities in the creation of regulation measures for the benefit of both nature and the economy.
The dedicated survey effort of Montenegro Dolphin Research revealed the annual presence of bottlenose dolphins within coastal waters of Montenegro, with the Boka Kotorsko Bay hosting a high density of dolphin presence independent of season. Even though the sighting proportion for each season is around 36%, there is little significant variation between seasons. The northern region of Montenegro, (mainly the waters of Herceg Novi) is shown to be significantly more likely to have sightings compared to the central and southern waters of Montenegro. Furthermore, our photo identification study identified 72 individuals, with variations in their residency patterns. Additionally, the re-sighting rate of individuals and their site fidelities were very high, underlining the importance of Montenegrin waters for its bottlenose dolphin population. Striped dolphins were also documented sporadically in the offshore waters of Montenegro, which is likely to be the result of isolated survey efforts in offshore waters. The distribution and residency patterns of striped dolphins can only be fully understood with further dedicated survey effort towards offshore waters. The majority of the encountered groups, both for bottlenose dolphins and striped dolphins, were engaged in diving and travelling behaviours, which once again indicates that the area is likely to hold an important migration corridor between the neighbouring waters, as well as its importance as a foraging ground. Further, it is important to highlight that the majority of the sighted bottlenose dolphin groups hold several sub-adults, underlining the importance of Montenegrin and its adjacent waters containing possible nursing grounds. Socialising and resting behaviours were the least recorded within Montenegro for bottlenose dolphins. Nevertheless, socialising behaviours of striped dolphins were recorded in deep waters.
Lastly, when marine traffic distribution and the presence of dolphins were mapped, the core bottlenose dolphin habitats overlapped with areas of dense marine traffic, resulting in the likelihood that several negative impacts ranging from ship strikes to noise pollution could occur. However, further studies are necessary in order to examine the effect of each threat on the populations. Striped dolphins appeared to have a lower occurrence of interaction with marine traffic. Despite this, their habitat is currently under the pressure of seismic activities related to oil and gas exploration, signifying the necessity for understanding both the short and long term effects of seismic practices in Montenegro.
Montenegro Dolphin Research remains the first, and continues to be, the only annual cetacean monitoring project in Montenegro. By combining dedicated research effort with stakeholder engagement, not only will our understanding of cetacean populations in Montenegrin waters be considerably enhanced, but also our ability to turn this knowledge into a subsequent management plan. By establishing networks and producing influential documentation within the community, the conservation implications will be more effective and longer lasting.
... Studies have shown the common bottlenose dolphin to be one of the most common marine mammal species found regularly in the Adriatic (Bearzi et al., 1997). Long term studies in Slovenia (Genov et al., 2008;2009;Halpin et al., 2009;Genov, 2013), throughout Croatia (Impetuoso et al., 2003;Fortuna et al., 2011;UNEP-MAP-RAC/SPA, 2014;Gaspari et al., 2015;Pleslic et al., 2015;Ribarič, 2018), Italy (Bearzi & Fortuna, 2006;Bearzi et al., 2008;Genov, 2016) and most recently Montenegro (Fortuna et al., 2011;Ðurovic et al., 2016;Bas et al., 2018;Affinitio et al., 2018), demonstrate the species to be widely distributed throughout the entire Adriatic. Unfortunately, due to extermination and directed kill campaigns in the 1960's alongside long-term bycatch mortality (Bearzi et al., 2008), the species Mediterranean subpopulation is listed as 'vulnerable' under the International Union for Conservation of Nature (IUCN) Red List criteria (Bearzi et al., 2012). ...
... Increased boat and acoustic disturbances in recent years have increased the potential for behavioural disruptions and habitat loss. Widely documented interactions between bottlenose dolphins and anthropogenic vessels have resulted in negative impacts on their behaviour and critical habitats (Lusseau, 2003;Lusseau & Higham, 2004;Arcangeli et al., 2008;Christiansen et al., 2010;Gonzalvo et al., 2013;Pennino et al., 2016;Bas et al., 2017), whilst seismic air gun use and marine construction practises are also concerning (Nowacek et al., 2007;Finneran et al., 2015). Striped dolphins are thought to be the most widely distributed cetacean species in the Mediterranean, found in deep waters both towards the coastline and beyond the continental shelf (Aguilar, 2000;IUCN, 2012;UNEP-MAP-RAC/SPA, 2014;Bas et al., 2018). ...
... Widely documented interactions between bottlenose dolphins and anthropogenic vessels have resulted in negative impacts on their behaviour and critical habitats (Lusseau, 2003;Lusseau & Higham, 2004;Arcangeli et al., 2008;Christiansen et al., 2010;Gonzalvo et al., 2013;Pennino et al., 2016;Bas et al., 2017), whilst seismic air gun use and marine construction practises are also concerning (Nowacek et al., 2007;Finneran et al., 2015). Striped dolphins are thought to be the most widely distributed cetacean species in the Mediterranean, found in deep waters both towards the coastline and beyond the continental shelf (Aguilar, 2000;IUCN, 2012;UNEP-MAP-RAC/SPA, 2014;Bas et al., 2018). In the Adriatic, their distribution can predominantly be found across the entire Southern Adriatic sub-basin (Fortuna et al., 2011;UNEP-MAP-RAC/SPA, 2014;Notarbartolo di Scaria, 2016). ...
The Adriatic Sea is home to five cetacean species, classified as at risk by the IUCN. Bottlenose dolphins (Tursiops truncates), striped dolphins (Stenella coeruleoalba), Risso’s dolphins (Grampus griseus), Cuvier’s beaked whales (Ziphius cavirostris) and fin whales (Balaenoptera physalus), are all identified as species in which the community has a vested interest and are under strict protection by the Montenegrin Government and by law. Since 2016, our studies, alongside existing data, have demonstrated the presence of resident bottlenose and striped dolphins in Montenegro, in addition to sightings of Cuvier's beaked whales and Risso's dolphins in its offshore waters. The regional status of species, assessments of threats and future conservation efforts can only be determined with dedicated and systematic surveys. Further, the Adriatic Pit, the deepest region of the entire Adriatic, holds the highest levels of biodiversity, whilst also being one of the most vulnerable regions to anthropogenic threats.
The purpose of our survey effort is to expand upon the data we have already acquired within the coastal and offshore waters of Montenegro to cover data deficient species such as Cuvier's beaked whales and Risso's dolphins and to explore the possible presence of common dolphins that were thought to be regionally extinct until recent sightings in the summer of 2018 by the Blue World Institute.
As a result of the necessity for economic growth, Montenegro is rapidly developing its tourism industry and more recently, the country has participated in oil and gas explorations. Yet any human activities that remain unregulated, are likely to form severe threats to marine species and their associated habitats. Therefore, our research and conservation outcomes form one of the most important steps towards effective conservation strategies, which promote not only the protection of nature, but also sustainable economic growth. For this reason, our project continues its dedicated survey effort in 2019, covering both the coastal and the offshore waters of Montenegro. Coupled with the recent addition of our sighting and stranding networks, we hope to aid the relevant authorities in the creation of regulation measures for the benefit of both nature and the economy.
The dedicated survey effort of Montenegro Dolphin Research revealed the annual presence of bottlenose dolphins within coastal waters of Montenegro, with the Boka Kotorsko Bay hosting a high density of dolphin presence independent of season. Even though the sighting proportion for each season is around 36%, there is little significant variation between seasons. The northern region of Montenegro, (mainly the waters of Herceg Novi) is shown to be significantly more likely to have sightings compared to the central and southern waters of Montenegro. Furthermore, our photo identification study identified 72 individuals, with variations in their residency patterns. Additionally, the re-sighting rate of individuals and their site fidelities were very high, underlining the importance of Montenegrin waters for its bottlenose dolphin population. Striped dolphins were also documented sporadically in the offshore waters of Montenegro, which is likely to be the result of isolated survey efforts in offshore waters. The distribution and residency patterns of striped dolphins can only be fully understood with further dedicated survey effort towards offshore waters. The majority of the encountered groups, both for bottlenose dolphins and striped dolphins, were engaged in diving and travelling behaviours, which once again indicates that the area is likely to hold an important migration corridor between the neighbouring waters, as well as its importance as a foraging ground. Further, it is important to highlight that the majority of the sighted bottlenose dolphin groups hold several sub-adults, underlining the importance of Montenegrin and its adjacent waters containing possible nursing grounds. Socialising and resting behaviours were the least recorded within Montenegro for bottlenose dolphins. Nevertheless, socialising behaviours of striped dolphins were recorded in deep waters.
Lastly, when marine traffic distribution and the presence of dolphins were mapped, the core bottlenose dolphin habitats overlapped with areas of dense marine traffic, resulting in the likelihood that several negative impacts ranging from ship strikes to noise pollution could occur. However, further studies are necessary in order to examine the effect of each threat on the populations. Striped dolphins appeared to have a lower occurrence of interaction with marine traffic. Despite this, their habitat is currently under the pressure of seismic activities related to oil and gas exploration, signifying the necessity for understanding both the short and long term effects of seismic practices in Montenegro.
Montenegro Dolphin Research remains the first, and continues to be, the only annual cetacean monitoring project in Montenegro. By combining dedicated research effort with stakeholder engagement, not only will our understanding of cetacean populations in Montenegrin waters be considerably enhanced, but also our ability to turn this knowledge into a subsequent management plan. By establishing networks and producing influential documentation within the community, the conservation implications will be more effective and longer lasting.
Astonishing species richness and high number of endemics
make the Mediterranean Sea a biodiversity hotspot.
Unfortunately, the Mediterranean Sea is also a hotspot of
human pressure, because of the high population density
along its coasts, the intensity of tourism, the huge volume
of maritime traffic, and a rate of marine invasion with few
equals in the world. Being a semi-closed basin, the
Mediterranean Sea is also particularly exposed to the
consequence of sea water warming. Conserving the
Mediterranean marine biodiversity has therefore become a
priority. A major step towards this goal has been the
Barcelona Convention, adopted in 1976 and signed by all
Mediterranean countries and the European Union, with the
aim of protecting the marine environment and the coastal
region of the Mediterranean. The aim of this Special Issue is
to collate papers reporting on the results of these
conservation initiatives: present status of protected
habitats and species, trajectory of change in marine
ecosystems, activities of marine protected areas,
biodiversity monitoring and management plans.
Bottlenose dolphins have a complex vocal repertoire that varies depending on behavioral context, social structure, group composition, and anthropogenic pressures. This current study describes the whistle characteristics of bottlenose dolphins for the first time in the South Adriatic Sea while assessing the potential differences between whistle characteristics of geographically separated dolphins within neighbouring waters of the North Ionian Sea. The results show that whistle characteristics were similar between Taranto Gulf (Italy) and Boka Bay (Montenegro), despite their spatial differences. The mean peak frequency was 10kHz for each study location while the mean minimum and maximum frequency ranged from 7 to 14kHz. The average duration of whistles was 500 milliseconds. These results share similarities with previous literature, although several studies reported slightly different mean peak frequencies, ranging up to 15kHz in the neighbouring waters of Croatia and Italy. Further, harmonics were produced and formed in 40% of the whistles in Taranto Gulf and 30% of the whistles in Boka Bay. A high incidence of harmonics has previously been associated with behavioral states (i.e., travelling) and with certain types of marine traffic (i.e., fishing vessels). Therefore, it is important to collect simultaneous data on the visual behavior of the focal group as well as document the type and density of marine traffic within the proximity of the dolphins to have an in-depth understanding of vocal behavior. Despite the similarities of whistle characteristics of Taranto and Boka Bay, the whistle contours showed notable variations. Upsweep whistles were the most regularly produced whistle type in each location, which coincides with previous studies in the Mediterranean Sea. However, the least produced whistle had a concave contour in Taranto and was flat in Boka Bay. Previous studies have confirmed that flat whistles account for the least produced whistle contour in the Mediterranean Basin. Examining the whistle characteristics and the variation in whistle contours provides an in-depth understanding of the behavioral complexity as well as its plasticity in the presence of pressure. Therefore, future studies need to include behavior, group composition, noise levels, and human presence to enable an effective understanding of variation in whistle characteristics of bottlenose dolphins.
