Journal articles: 'Bottlenosed dolphins'

1

Williams, Jamelia A., Stephen M. Dawson, and Elisabeth Slooten. "The abundance and distribution of bottlenosed dolphins (Tursiops truncatus) in Doubtful Sound, New Zealand." Canadian Journal of Zoology 71, no. 10 (October 1, 1993): 2080–88. http://dx.doi.org/10.1139/z93-293.

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Photographic identification and standardized zigzag surveys were used to study the distribution and abundance of bottlenose dolphins in Doubtful Sound, New Zealand. Forty individuals were identified from nicks and markings on their dorsal fins. Chapman's and Bailey's modifications to the Lincoln–Petersen estimate and the computer program CAPTURE were used to estimate the number of marked individuals in the population, which ranged from 30 to 40 animals for three survey periods (two summers and a winter). The proportion of identifiable individuals in the population was assessed empirically as 65.5%. These data resulted in a total population estimate of approximately 58 individuals. The majority of the dolphins in the catalogue were found in each survey period, indicating their residency in the fiord. Movements of dolphins around the sound were not predictable, but there were areas in which dolphins were more likely to be found and other areas in which dolphins were never seen. However, there were no obvious seasonal or daily movement patterns.

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Möller, LM, SJ Allen, and RG Harcourt. "Group Characteristics, Site Fidelity And Seasonal Abundance Of Bottlenosed Dolphins (Tursiops Aduncus) In Jervis Bay And Port Stephens, South-Eastern Australia." Australian Mammalogy 24, no. 1 (2002): 11. http://dx.doi.org/10.1071/am02011.

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Social organisation and abundance of bottlenose dolphins (Tursiops aduncus) in Jervis Bay (JB) and Port Stephens (PS), NSW, were investigated through behavioural/photo-identification surveys between May 1997 and April 2000. Mean group size was significantly larger at JB (12.3 � 0.87, n =167) compared to PS (6.8 � 0.37, n = 218). At both sites, groups were significantly larger when calves were present. Group size varied with activity, being smallest when feeding and largest when socialising. While mean group size of feeding dolphins did not vary between sites, travelling and socialising groups were significantly larger in JB. Site fidelity was assigned based on sighting rates and presence across seasons. Sighting rates varied significantly between areas, but the proportion of dolphins categorised as residents, occasional visitors and transients did not. Minimum abundance by season, based on mark-resighting of recognisable individuals, ranged from 61 � 3.2 to 108 � 7.1 in JB and 143 � 8.1 to 160 � 8.1 in PS. Differences in group size at the two sites may relate to social factors and/or human impacts, while differences in abundance may be associated with habitat size and complexity. The lack of dolphin matches between areas suggests that they represent distinct populations.

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Mercado, Eduardo, Deirdre A. Killebrew, Adam A. Pack, Inés V. B. Mácha, and Louis M. Herman. "Generalization of ‘same–different’ classification abilities in bottlenosed dolphins." Behavioural Processes 50, no. 2-3 (August 2000): 79–94. http://dx.doi.org/10.1016/s0376-6357(00)00100-5.

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Wright, Katherine A. "Decreased ability to acquire food of a captive deaf dolphin (Tursiops truncatus): Slower reaction times and lower success rates." SURG Journal 4, no. 2 (March 11, 2011): 63–70. http://dx.doi.org/10.21083/surg.v4i2.1253.

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Oceanic anthropogenic noise, such as naval sonar, can cause temporary hearing loss in cetaceans, but it is not known to what extent hearing loss affects cetacean behaviours such as feeding. This study used a captive deaf Atlantic bottlenose dolphin (Tursiops truncatus) to test the hypothesis that hearing loss would decrease a dolphin’s ability to acquire food by preventing echolocation (using echoes to locate fish). Reaction time (time to acquire dropped fish) and success rate (percentage of successfully acquired fish) were measured for the deaf dolphin and for two dolphins with no known hearing disabilities at Dolphins Plus in Florida in May 2009. The deaf dolphin had a significantly slower mean reaction time and a significantly lower mean success rate than those of the two other dolphins. A hydrophone suggested that the deaf dolphin could not echolocate, and thus relied mainly on vision. The results illustrate that hearing loss can negatively affect a dolphin’s ability to acquire food. Therefore, sources and effects of dolphin hearing loss require further investigation in order to provide targets for anthropogenic noise levels.

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Rawson, A. J., G. W. Patton, S. Hofmann, G. G. Pietra, and L. Johns. "Liver Abnormalities Associated with Chronic Mercury Accumulation in Stranded Atlantic Bottlenosed Dolphins." Ecotoxicology and Environmental Safety 25, no. 1 (February 1993): 41–47. http://dx.doi.org/10.1006/eesa.1993.1005.

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6

Tyack, Peter. "Whistle repertoires of two bottlenosed dolphins, Tursiops truncatus: mimicry of signature whistles?" Behavioral Ecology and Sociobiology 18, no. 4 (February 1986): 251–57. http://dx.doi.org/10.1007/bf00300001.

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7

Rossbach, Kelly A., and Denise L. Herzing. "Inshore and offshore bottlenose dolphin (Tursiops truncatus) communities distinguished by association patterns near Grand Bahama Island, Bahamas." Canadian Journal of Zoology 77, no. 4 (September 15, 1999): 581–92. http://dx.doi.org/10.1139/z99-018.

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Little is known about the behavior of offshore dolphin populations. Our purpose was to distinguish and describe stable social groups of bottlenose dolphins (Tursiops truncatus) between inshore and offshore West End, Grand Bahama Island (26°42'N, 79°00'W). Photoidentification was conducted from May to September, 1994 to 1996. A simple ratio index described association patterns between dolphins. Multidimensional scaling of association indices (n = 1711 dolphin pairs) distinguished two dolphin communities consisting of 28 dolphins (19 of known sex) found inshore and 15 dolphins (12 of known sex) found greater than or equal to 27 km offshore. Eight of the 15 offshore dolphins were opportunistically photographed in the same region between 1986 and 1990. The two communities were found at different water depths (Mann-Whitney U test, p < 0.01), over distinct bottom types (Kruskal-Wallis test, p < 0.01), and used different bottom-foraging strategies. Long-term site fidelity of up to 10 years and repeated dolphin associations of up to 8 years occurred greater than or equal to 27 km from shore. Dolphins sighted greater than or equal to 15 times averaged 48 associates (SD = 11, n = 28). A dolphin's closest associate was of the same gender 74% of the time. This study is the first to report long-term site fidelity and association patterns of bottlenose dolphins found far from shore.

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Taylor, Kristen A., Paul E. Nachtigall, Mats Amundin, Pernilla Mosesson, Sunna Edberg, and Stina Karlsson. "Auditory evoked potential hearing measures of a group of bottlenosed dolphins (Tursiops truncatus)." Journal of the Acoustical Society of America 121, no. 5 (May 2007): 3093. http://dx.doi.org/10.1121/1.2748598.

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Bazúa-Durán, Carmen. "Differences in the whistle characteristics and repertoire of Bottlenose and Spinner Dolphins." Anais da Academia Brasileira de Ciências 76, no. 2 (June 2004): 386–92. http://dx.doi.org/10.1590/s0001-37652004000200030.

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Several methods have been used to compare the whistles produced by dolphins. The two methods used in this study are: (1) a classification of whistle contours in six categories (i.e. constant frequency, upsweep, downsweep, concave, convex, and sine) and (2) the extraction of frequency and time parameters from each whistle contour. Bottlenose Dolphin Tursiops truncatus whistles are described in the same way when comparing whistle contour distributions in each of the six categories and whistle frequency and time parameters using Discriminant Function Analysis. For Spinner Dolphin Stenella longirostris whistles, each method describes whistles differently. Several facts may explain these differences in describing dolphin whistles, such as a greater fluidity of Spinner Dolphin groups when compared to Bottlenose Dolphin groups, greater geographic variation in the whistles of Bottlenose Dolphins than in those of Spinner Dolphins, an average beginning frequency 16% lower than the average ending frequency in Spinner Dolphin whistles compared to a varied relationship for Bottlenose Dolphins, and stricter criteria used to define whistle contour categories in the study of Spinner Dolphin whistles than in the Bottlenose Dolphin whistle study.

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Nollens, Hendrik H., Linda G. Green, Diane Duke, Michael T. Walsh, Beth Chittick, Scott Gearhart, Paul A. Klein, and Elliott R. Jacobson. "Development and Validation of Monoclonal and Polyclonal Antibodies for the Detection of Immunoglobulin G of Bottlenose Dolphins (Tursiops Truncatus)." Journal of Veterinary Diagnostic Investigation 19, no. 5 (September 2007): 465–70. http://dx.doi.org/10.1177/104063870701900502.

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Antibodies directed against species-specific immunoglobulin G (IgG) have a broad range of applications in serologic and immunologic research and in the development of clinical assays. Validated anti-IgG antibodies for marine mammal species are in short supply. The objective of this study was to produce and validate antibodies with specificity for IgG of the common bottlenose dolphin ( Tursiops truncatus). Bottlenose dolphin IgG was purified using protein G. Two mouse monoclonal antibodies and a rabbit polyclonal antibody were developed from mice and rabbits immunized with bottlenose dolphin IgG. The specificity of the monoclonal antibodies and the polyclonal antibody for bottlenose dolphin IgG was first verified by Western blot analysis and enzyme-linked immunosorbent assay (ELISA). For further validation, both monoclonal antibodies and the polyclonal antibody were incorporated in an indirect ELISA for the detection of the immune response of bottlenose dolphins to a vaccine antigen. Three bottlenose dolphins were immunized with a commercial Erysipelothrix rhusiopathiae vaccine, and serial blood samples were collected from all dolphins for measurement of levels of circulating antibodies. Seroconversion was observed in all 3 dolphins by use of both monoclonal antibodies and the polyclonal antibody. Circulating antibodies were detectable as early as 6 days after immunization in 1 dolphin. Peak antibody levels were detected 14 days after the immunization. The ability to detect seroconversion in all 3 immunized bottlenose dolphins firmly establishes the specificity of the monoclonal antibodies and the polyclonal antibody for IgG of the common bottlenose dolphin.

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11

Ross, G. J. B., V. G. Cockcroft, and D. G. Butterworth. "Offshore distribution of bottlenosed dolphins in Natal coastal waters and Algoa Bay, eastern Cape." South African Journal of Zoology 22, no. 1 (January 1987): 50–56. http://dx.doi.org/10.1080/02541858.1987.11448020.

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12

Keiver, K. M., K. Ronald, and H. H. Draper. "Plasma levels of vitamin D and some metabolites in marine mammals." Canadian Journal of Zoology 66, no. 6 (June 1, 1988): 1297–300. http://dx.doi.org/10.1139/z88-190.

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Levels of vitamin D, 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, and calcium were determined in the plasma of various captive and wild pinniped and cetacean species. Vitamin D (< 0.4–5 ng∙mL−1) and 25-hydroxyvitamin D (4–84 ng∙mL−1) levels in the pinniped plasma were similar to those found in nonmarine mammals. 24,25-Dihydroxyvitamin D levels in seals (3–48 ng∙mL−1) were high compared with those of other mammals, and the ratios of 24,25-dihydroxyvitamin D to 25-hydroxyvitamin D in fasting pups were extremely high. The belugas and bottlenosed dolphins had very high levels of both 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D compared with the pinnipeds and other mammals, but plasma calcium levels were normal for these species of cetaceans.

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Fruet, Pedro Friedrich, Camilah A. Zappes, Tatiana L. Bisi, Paulo César Simões-Lopes, Paula Laporta, Julio D. Loureiro, and Paulo André C. Flores. "Report of the Working Group on Interactions between Humans and Tursiops truncatus in the Southwest Atlantic Ocean." Latin American Journal of Aquatic Mammals 11, no. 1-2 (January 8, 2017): 79–98. http://dx.doi.org/10.5597/lajam00218.

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In this work we compiled the available information about humans and bottlenose dolphin interactions in the Southwest Atlantic Ocean (SWAO), including issues as historical direct takes, incidental captures in fisheries, positive interactions with fisheries, interactions of dolphins with tourism and boat traffic, habitat modification or degradation, and environmental pollution. The data compiled in this review demonstrated that coastal bottlenose dolphins are under anthropogenic pressure in the SWAO. Direct take of bottlenose dolphins in the wild does not appear to be an issue of conservation concern in the SWAO. Although the species is exposed to bioaccumulation of micropollutants, it is suggested that contamination level is lower when compared to bottlenose dolphins from other continents. Coastal works can impact bottlenose dolphin behavior and habitat use in a short-term, but those seem to be reversible when works stop. Bycatch occurs throughout the species distribution and seems to be occasional in Uruguayan and Argentinean waters, where there is evidence of a historic decline in dolphin sightings. In Brazil, bycatch is apparently low in the northeast and southeast coasts, but is frequent in certain areas of southern Brazil. Studies on the subject are scarce or preliminary and a great effort is still required to understand the real impact of human activities on bottlenose dolphins in the SWAO.

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Estep, J. S., R. E. Baumgartner, F. Townsend, D. A. Pabst, W. A. Mclellan, A. Friedlaender, D. G. Dunn, and T. P. Lipscomb. "Malignant Seminoma with Metastasis, Sertoli Cell Tumor, and Pheochromocytoma in a Spotted Dolphin (Stenella frontalis) and Malignant Seminoma with Metastasis in a Bottlenose Dolphin (Tursiops truncatus)." Veterinary Pathology 42, no. 3 (May 2005): 357–59. http://dx.doi.org/10.1354/vp.42-3-357.

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Seminoma with metastasis was diagnosed in a spotted dolphin ( Stenella frontalis) and an Atlantic bottlenose dolphin ( Tursiops truncatus). Sertoli cell tumor and pheochromocytoma were also diagnosed in the spotted dolphin. The spotted and bottlenose dolphins were adult males that stranded and died on the coasts of northwest Florida and southeast North carolina, respectively. Neoplasia is infrequently reported in cetaceans. This is the first report of seminoma, Sertoli cell tumor, and pheochromocytoma in a dolphin, the first report of three distinct neoplasms in a dolphin, and one of the few reports of malignant neoplasia in dolphins.

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Díaz López, Bruno, and Julia Andrea Bernal Shirai. "Bottlenose dolphin (Tursiops truncatus) presence and incidental capture in a marine fish farm on the north-eastern coast of Sardinia (Italy)." Journal of the Marine Biological Association of the United Kingdom 87, no. 1 (February 2007): 113–17. http://dx.doi.org/10.1017/s0025315407054215.

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On the north-eastern coast of Sardinia, from November 2004 to January 2006, the first attempt in the Mediterranean basin to obtain information on encounter rate, group size and incidental capture of bottlenose dolphins in a marine fish farm was assessed, combining direct observations from fish farm boats with photo-identification studies. During 15 months of research, 79 d (65.3% of the total monitored days) were spent in direct observation of 146 groups of bottlenose dolphins around the fish farm cages. There was a peak in bottlenose dolphin presence during winter. Photographs were taken in the fish farm area during 79 encounters on 61 different days (totalling 34 marked individuals). The regular occurrence of some dolphins suggests individual preferences for the fish farm area. The incidental bottlenose dolphin capture observed in large, loose predator nets (1 dolphin per month) is cause for concern, as it is questionable whether or not the bottlenose dolphins in the area can sustain incidental capture of this magnitude. The information gained from this study shows the necessity for further regulations to be established, both in the use of predator nets and management of marine fish farms.

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Bayas-Rea, Rosa de los Ángeles, Fernando Félix, and Rommel Montufar. "Genetic divergence and fine scale population structure of the common bottlenose dolphin (Tursiops truncatus, Montagu) found in the Gulf of Guayaquil, Ecuador." PeerJ 6 (April 9, 2018): e4589. http://dx.doi.org/10.7717/peerj.4589.

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

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Jepson, P. D., and J. R. Baker. "Bottlenosed dolphins (Tursiops truncatus) as a possible cause of acute traumatic injuries in porpoises (Phocoena phocoena)." Veterinary Record 143, no. 22 (November 28, 1998): 614–15. http://dx.doi.org/10.1136/vr.143.22.614.

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Shyan, Melissa R., David Merritt, Nicole M. Kohlmeier, Keri Barton, and Jessica Tenge. "Effects of Pool Size on Free-Choice Selections by Atlantic Bottlenosed Dolphins at One Zoo Facility." Journal of Applied Animal Welfare Science 5, no. 3 (July 2002): 215–25. http://dx.doi.org/10.1207/s15327604jaws0503_05.

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Díaz López, Bruno. "The bottlenose dolphin Tursiops truncatus foraging around a fish farm: Effects of prey abundance on dolphins’ behavior." Current Zoology 55, no. 4 (August 1, 2009): 243–48. http://dx.doi.org/10.1093/czoolo/55.4.243.

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Abstract The extent to which prey abundance influences both bottlenose dolphin foraging behavior and group size in the presence of human activities has not previously been studied. The primary aim of this study was to identify and quantify how wild bottlenose dolphins respond, individually and as groups, to the relative abundance of prey around a fish farm. Detailed views of dolphins’ behavior were obtained by focal following individual animals whilst simultaneously collecting surface and underwater behavioral data. A total of 2150 dive intervals were analyzed, corresponding to 342 focal samples, lasting over 34 hours. Bottlenose dolphins remained submerged for a mean duration of 46.4 seconds and a maximum of 249 seconds. This study provides the first quantified data on bottlenose dolphin diving behavior in a marine fin-fish farm area. This study’s results indicate that within a fish farm area used intensively by bottlenose dolphins for feeding, dolphins did not modify dive duration. Additionally, underwater observations confirmed that dolphins find it easier to exploit a concentrated food source and it appears that hunting tactic and not group size plays an important role during feeding activities. Thus, bottlenose dolphins appear capable of modifying their hunting tactics according to the abundance of prey. When top predators display behavioral responses to activities not directed at them, the task of studying all possible effects of human activities can become even more challenging.

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Fury, Christine A., and Peter L. Harrison. "Abundance, site fidelity and range patterns of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in two Australian subtropical estuaries." Marine and Freshwater Research 59, no. 11 (2008): 1015. http://dx.doi.org/10.1071/mf08109.

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Bottlenose dolphins are widely studied in marine habitats, but information on estuarine populations is very limited. The present study provides the first published data on bottlenose dolphins in Australian estuaries. Abundance estimates, site fidelity and individual ranging patterns were examined over a 3-year period for Indo-Pacific bottlenose dolphins (Tursiops aduncus) inhabiting the Clarence River (CR) and Richmond River (RR) estuaries in northern New South Wales, Australia. Mark–recapture analyses estimated 71 (62–81 95% CI) dolphins utilised the CR whereas 34 (19–49 95% CI) used the RR. Differences in site fidelity were observed between the estuaries, with 60% and 37% of identified dolphins determined as residents, 26% and 21% as occasional visitors and 14% and 42% as transients for the CR and RR respectively. Resource partitioning was apparent in both estuaries with the mean distance resident dolphins were found upstream from the river mouth being greater than occasional visitors and transients. The Clarence River sustains a larger, predominantly resident dolphin community compared with the Richmond River, which supports a relatively small dolphin community with lower site fidelity. Management of future increased anthropogenic disturbances is needed to ensure the long-term survival of these dolphin populations.

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Cuvertoret-Sanz, M., C. López-Figueroa, A. O’Byrne, A. Canturri, B. Martí-Garcia, E. Pintado, L. Pérez, et al. "Causes of cetacean stranding and death on the Catalonian coast (western Mediterranean Sea), 2012-2019." Diseases of Aquatic Organisms 142 (December 17, 2020): 239–53. http://dx.doi.org/10.3354/dao03550.

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The causes of cetacean stranding and death along the Catalan coast between 2012 and 2019 were systematically investigated. Necropsies and detailed pathological investigations were performed on 89 well-preserved stranded cetaceans, including 72 striped dolphins Stenella coeruleoalba, 9 Risso’s dolphins Grampus griseus, 5 bottlenose dolphins Tursiops truncatus, 1 common dolphin Delphinus delphis, 1 Cuvier’s beaked whale Ziphius cavirostris and 1 fin whale Balaenoptera physalus. The cause of death was determined for 89.9% of the stranded cetaceans. Fisheries interaction was the most frequent cause of death in striped dolphins (27.8%) and bottlenose dolphins (60%). Cetacean morbillivirus (CeMV) was detected on the Catalan coast from 2016 to 2017, causing systemic disease and death in 8 of the 72 (11.1%) striped dolphins. Chronic CeMV infection of the central nervous system was observed from 2018-2019 in a further 5 striped dolphins. Thus, acute and chronic CeMV disease caused mortality in 18% of striped dolphins and 14.6% of all 89 cetaceans. Brucella ceti was isolated in 6 striped dolphins and 1 bottlenose dolphin with typical brucellosis lesions and in 1 striped dolphin with systemic CeMV. Sinusitis due to severe infestation by the nematode parasite Crassicauda grampicola caused the death of 4 out of 6 adult Risso’s dolphins. Maternal separation, in some cases complicated with septicemia, was a frequent cause of death in 13 of 14 calves. Other less common causes of death were encephalomalacia of unknown origin, septicemia, peritonitis due to gastric perforation by parasites and hepatitis caused by Sarcocystis spp.

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Vermeulen, Els. "Intertidal habitat use of bottlenose dolphins (Tursiops truncatus) in Bahía San Antonio, Argentina." Journal of the Marine Biological Association of the United Kingdom 98, no. 5 (May 30, 2017): 1109–18. http://dx.doi.org/10.1017/s0025315417000856.

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Very little information is available on bottlenose dolphin (Tursiops truncatus) habitat use in the South-western Atlantic. It is, however, essential in understanding their ecology and to improve conservation management. In this study, habitat use of bottlenose dolphins was examined in Bahía San Antonio, an area frequented by the species. Given the large tidal amplitude and extended intertidal zone in this bay, special focus was given to the intertidal vs subtidal habitat use patterns. Bottlenose dolphins were observed in only half of the surveyed area, with on average 1 dolphin group encountered per 100 km surveyed. All dolphin groups were seen in shallow waters <10 m deep. GLM analyses showed that especially during high tide, depth had an important effect on the dolphin encounter rate, with most dolphin groups encountered in the intertidal zone. While in the intertidal zone, most dolphin groups were observed to be engaged in surface feeding activities. The presented data indicate dolphins remained in shallow waters, and moved to the intertidal zone during high tide where they appear to find feeding opportunities. This information is believed to be of high value in understanding this population's ecological needs, and essential when aiming to improve marine conservation efforts at times of increased anthropogenic pressures in the area.

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Vuković, Snježana, H. Lucić, H. Gomerčić, Martina Duras Gomerčić, T. Gomerčić, Darinka Škrtić, and Snježana Vurković. "Morphology of the lymph nodes in bottlenose dolphin (Tursiops truncatus) and striped dolphin (Stenella coeruleoalba) from the Adriatic Sea." Acta Veterinaria Hungarica 53, no. 1 (January 1, 2005): 1–11. http://dx.doi.org/10.1556/avet.53.2005.1.1.

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Morphology of the lymph nodes was examined in six bottlenose dolphins (Tursiops truncatus) and three striped dolphins (Stenella coeruleoalba) from the Adriatic Sea. All animals had been found dead in nature. One group of the nodes was taken from the tracheal branching area and was marked as bifurcational lymph node, and the other group was taken from the mesenteric root and was marked as mesenteric lymph node. Microscopic analysis showed that the lymph nodes in both dolphin specieswere surrounded by a connective tissue capsule comprising smooth muscle cells. The parenchyma of the mesenteric and bifurcational lymph nodes in bottlenose dolphinwas divided into the peripherally situated cortex with the lymphatic nodules and diffuse lymphatic tissue, and the centrally situated medulla structured of the medullary cords separated by the medullary sinuses. These lymph nodes structurally correspond to the lymph nodes in the majority of terrestrial mammals. The mesenteric lymph node of striped dolphin also had a peripherally situated cortex and a centrally positioned medulla as the majority of terrestrial mammals. In the bifurcational lymph nodes of striped dolphin, there was a central dense lymphatic tissue with the lymphatic nodules and a peripheral less dense lymphatic tissue structured of the cell cords and sinuses. The bifurcational lymph node in striped dolphinresembledporcine lymph nodes and belonged to the inverse lymph nodes.

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Domit, Camila, Paula Laporta, Camilah A. Zappes, Liliane Lodi, Lilian S. Hoffmann, Rodrigo Genoves, Pedro Friedrich Fruet, and Alexandre F. Azevedo. "Report of the Working Group on the Behavioral Ecology of bottlenose dolphins in the Southwest Atlantic Ocean." Latin American Journal of Aquatic Mammals 11, no. 1-2 (January 8, 2017): 106–20. http://dx.doi.org/10.5597/lajam00220.

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In this report, we present a compilation of the behavioral patterns of bottlenose dolphins and social structure throughout the Southwest Atlantic Ocean. We have compiled and summarized available data concerning: (i) behavioral activities (states and events), (ii) social structures (group size and composition), (iii) acoustic behavior and (iv) intra and interspecific interactions of bottlenose dolphin populations throughout the SWAO, from northern Brazil to southern Argentina. Lack of systematic and standardized methodologies for data collection precludes robust data analyses in respect of bottlenose dolphin behavior. Available information suggests that the studied populations presented weak intra-population associations and that coastal individuals tend to form smaller groups than their oceanic counterparts. Bottlenose dolphins from SWAO produce stylized whistles in which the acoustic parameters are similar to published ranges around the world and some results indicate significant local inter-population variation in the acoustic parameters of the whistles. Data of intra and interspecific interactions of bottlenose dolphins in the SWAO are scarce and therefore do not fully allow a comprehensive analysis of the situational contexts.

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Díaz López, Bruno, Julia Andrea Bernal Shirai, Alberto Bilbao Prieto, and Paula Méndez Fernández. "Diving activity of a solitary wild free ranging bottlenose dolphin (Tursiops truncatus)." Journal of the Marine Biological Association of the United Kingdom 88, no. 6 (March 25, 2008): 1153–57. http://dx.doi.org/10.1017/s0025315408000921.

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Solitary wild bottlenose dolphins and man frequenting the same small areas makes boat interaction more or less inevitable. Here we provide the first quantified data about solitary bottlenose dolphin diving behaviour in the presence and absence of boats. Over 110 hours were spent observing a solitary bottlenose dolphin within a 6 km2 bay on the north-western coast of Spain from April to August 2005. A generalized linear mixed model explaining 77.3% of the variability of duration of dives indicated that the animal did not vary its diving activity in function of the presence of boats. However, the length of dives was related with the behavioural events prior to dive. Dolphin activity was characterized by mean dive intervals (mean = 62.6 seconds) related to a predominance of foraging behaviour. Because of the frequent presence of boats and the manner in which they moved, the dolphin may have become accustomed to their presence. The data reported here could be used to implement precautionary management proposals that take into account the potential effects of boat presence on bottlenose dolphins.

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Savenko, Oksana. "The first record of a piebald common bottlenose dolphin (Tursiops truncatus) in offshore waters of the north-western Black Sea." Theriologia Ukrainica 2020, no. 19 (August 27, 2020): 103–7. http://dx.doi.org/10.15407/tu1911.

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Piebaldism is one of three types of hypopigmentation of animals, when some areas on the skin have no pigments. Anomalously white cetaceans are rare, although they have been reported in more than 20 different cetacean species, including the common bottlenose dolphin, which in the Black Sea is recognized as an endangered endemic subspecies — the Black Sea bottlenose dolphin (Tursiops truncatus ponticus Barabash-Nikiforov, 1940). Its main habitat in the north-western Black Sea region is the coastal waters, however, these dolphins also occur offshore. Thirty cases of anomalously white bottlenose dolphins have been reported from the Black Sea, which were unevenly distributed, and only a few sightings have been reported from the north-western Black Sea. Cetacean observations were conducted in the Ukrainian part of the north-western Black Sea waters in April 2017, onboard the research vessel "Auguste Piccard". All encountered cetaceans were photographed, and individual distinctiveness of dorsal fin images was used for their photo-identification. On 13 April 2017, four groups of up to four individuals of bottlenose dolphins were encountered in the same area at a distance of 61 km south of Odesa (34 km from the nearest coast). The depth at the observation site was about 20 m. The initially observed type of dolphins’ behavior was feeding. However, two groups changed their behavior and followed the vessel by 5–6 individuals for approximately 18 minutes. The joint group consisted of adults and one juvenile individual. Among the adults, there was one piebald specimen with white patches on its dorsal fin, peduncle, and tail fluke. The piebald dolphin was photographed and photo-identified. Our research has shown that piebald Black sea bottlenose dolphins occur not only in the coastal waters, but also in offshore waters of the north-western Black Sea. However, the frequency of such hypopigmentation in local populations remains unknown. Further intensive photo-identification and genetic sampling of local stocks of the Black Sea bottlenose dolphins are necessary for the assessment of their population genetic structure and its divergence.

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Moura, Jailson, Davi Castro Tavares, Helio K. C. Secco, and Salvatore Siciliano. "Bottlenose dolphins (Tursiops truncatus, Montagu 1821) in central-northern coast of Rio de Janeiro State, Brazil: stranding patterns and insights into feeding habits." Latin American Journal of Aquatic Mammals 11, no. 1-2 (January 8, 2017): 191–98. http://dx.doi.org/10.5597/00228.

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The bottlenose dolphin (Tursiops truncatus) may be one of the best known dolphin species worldwide, principally due to its coastal distribution in many regions. However, few studies about ecology, biology and threats have been conducted on the Brazilian coast. The aim of the present work is to analyze the stranding pattern and stomach contents of bottlenose dolphins in the central-north coast of the Rio de Janeiro State, from Saquarema to São Francisco de Itabapoana (~300km of coast line). Forty nine stranding events were recorded through regular beach surveys from 1999 to 2012 and also through access to previous published studies conducted since 1984. The strandings were distributed throughout the study area, but there was a trend of occurrence in the extreme southern and northern regions. Nine specimens showed evidence of accidental mortality in fishing nets. The strandings were more frequently recorded during autumn and winter (χ2; p < 0.05). Male bottlenose dolphins stranded more often than females, showing significant differences in this relationship (χ2; p < 0.05). Most stranded dolphins were classified as adults (> 230cm of body length) (χ2; p < 0.05). The body length varied from 106 to 335cm. Four prey species were found in the stomach contents from the three specimens of bottlenose dolphin analyzed. The most representative prey species was the cutlassfish (Trichiurus lepturus). This study showed that bottlenose dolphins are frequently found dead along the Rio de Janeiro State where they feed mainly on coastal fish. Future studies need to be conducted to improve the knowledge on this poorly known cetacean in Brazil.

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Borges Costa, Ana Paula, Pedro Fruet, Fábio Gonçalves Daura-Jorge, Paulo César Simões-Lopes, Paulo Henrique Ott, Victor Hugo Valiati, and Larissa Rosa de Oliveira. "Bottlenose dolphin communities from the southern Brazilian coast: do they exchange genes or are they just neighbours?" Marine and Freshwater Research 66, no. 12 (2015): 1201. http://dx.doi.org/10.1071/mf14007.

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The genetic structure of bottlenose dolphin communities found along the southern Brazilian coast is reported in this study. Genetic structure analysis using biopsy samples from free ranging dolphins and tissue samples from stranded dolphins revealed a fine-scale population structure among three distinct groups. The first genetically distinct group was composed of resident dolphins of Laguna with a high degree of site fidelity. The second group was composed of one photo-identified dolphin, previously recognised by its interaction with fishermen, and dolphins that stranded near the mouth of Tramandaí Lagoon. Moderate nuclear and low mitochondrial gene diversity was found in dolphins of those coastal communities, whereas most of the dolphins stranded along the coast showed markedly higher levels of gene diversity at both markers. These stranded dolphins of unknown origin formed the third distinct group, which may be part of a larger offshore community. These results demonstrate the presence of at least three bottlenose dolphin clusters along this portion of the Brazilian coast, with the coastal specimens appearing to be only neighbours of a larger offshore community that eventually strands along the coast, highlighting the importance of the establishment of management and conservation measures for the species at a local scale.

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Moreno Escobar, Jesús Jaime, Oswaldo Morales Matamoros, Erika Yolanda Aguilar del Villar, Ricardo Tejeida Padilla, Ixchel Lina Reyes, Brenda Espinoza Zambrano, Brandon David Luna Gómez, and Víctor Hugo Calderón Morfín. "Non-Parametric Evaluation Methods of the Brain Activity of a Bottlenose Dolphin during an Assisted Therapy." Animals 11, no. 2 (February 6, 2021): 417. http://dx.doi.org/10.3390/ani11020417.

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Dolphin-Assisted Therapies (DAT) are alternative therapies aimed to reduce anxiety levels, stress relief and physical benefits. This paper is focused on measuring and analyzing dolphins brain activity when DAT is taking place in order to identify if there is any differences in female dolphin’s neuronal signal when it is interacting with control or intervention subjects, performing our research in Delfiniti, Ixtapa, Mexico facilities. We designed a wireless and portable electroencephalographic single-channel signal capture sensor to acquire and monitor the brain activity of a female bottle-nose dolphin. This EEG sensor was able to show that dolphin activity at rest is characterized by high spectral power at slow-frequencies bands. When the dolphin participated in DAT, a 23.53% increment in the 12–30 Hz frequency band was observed, but this only occurred for patients with some disease or disorder, given that 0.5–4 Hz band keeps it at 17.91% when there is a control patient. Regarding the fractal or Self-Affine Analysis, we found for all samples studied that at the beginning the dolphin’s brain activity behaved as a self-affine fractal described by a power-law until the fluctuations of voltage reached the crossovers, and after the crossovers these fluctuations left this scaling behavior. Hence, our findings validate the hypothesis that the participation in a DAT of a Patient with a certain disease or disorder modifies the usual behavior of a female bottle-nose dolphin.

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Schultz, Kenneth W., and Peter J. Corkeron. "Interspecific differences in whistles produced by inshore dolphins in Moreton Bay, Queensland, Australia." Canadian Journal of Zoology 72, no. 6 (June 1, 1994): 1061–68. http://dx.doi.org/10.1139/z94-143.

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The sounds produced by bottlenose dolphins, Tursiops truncatus, and Indo-Pacific humpback dolphins, Sousa chinensis, were recorded on 11 days from 3 April to 13 August 1990 in Moreton Bay, eastern Australia. Twelve hours and 34 minutes of sound were recorded. The physical structure of whistles was described using a variable for duration and seven variables for frequency. Data were subjected to principal components analysis (PCA) and canonical discriminant analysis (CDA). PCA demonstrated the range of whistle contours recorded. CDA demonstrated differences in the whistles between species. Humpback dolphin whistles differed in shape (frequency modulation) and were generally of shorter duration and higher overall frequency than those of bottlenose dolphin whistles.

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Walton, M. J., M. A. Silva, S. M. Magalhães, R. Prieto, and R. S. Santos. "Using blubber biopsies to provide ecological information about bottlenose dolphins (Tursiops truncatus) around the Azores." Journal of the Marine Biological Association of the United Kingdom 87, no. 1 (February 2007): 223–30. http://dx.doi.org/10.1017/s0025315407054537.

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Fatty acid profiles were used to investigate aspects of bottlenose dolphin populations around the Azores archipelago. Biopsy samples were obtained from 70 dolphins during the period 2002–2004. No statistically significant differences in profiles were found between different island groups, between sexes or between year of sampling. Thus no evidence was seen for island group fidelity, in contrast to bottlenose dolphins found around similar island groups such as the Hawaiian archipelago or the Bahamas. The findings are consistent with concurrent genetic and photo-identification studies on dolphins in the Azores.

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Kiszka, Jeremy J. "Atypical associations between dugongs (Dugong dugon) and dolphins in a tropical lagoon." Journal of the Marine Biological Association of the United Kingdom 87, no. 1 (February 2007): 101–4. http://dx.doi.org/10.1017/s0025315407055129.

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Several types of relationships link organisms to each other, including competition, predation and various types of associations. This paper presents the first case of association/interaction between dugongs, Dugong dugon, the only strictly marine herbivorous mammal, and three species of tropical dolphins in and around the lagoon of Mayotte (45°10'E 12°50'S), in the western tropical Indian ocean. Data were collected opportunistically from 1999 to 2005 in the surrounding waters of Mayotte from boat (N=2 observations) and ULM (ultra-light motorized vessel, N=2). The dolphin species involved in associations with dugongs were Indo-Pacific bottlenose dolphin, Tursips aduncus, Indo-Pacific humpback dolphin, Sousa chinensis, and spinner dolphin, Stenella longirostris. In one case, dugongs were associated with both bottlenose and humpback dolphins. Associations were observed in the protected waters of the lagoon and outside, along the external slope of the barrier reef. Group size, activity and group structure of each species were recorded. Behavioural observations suggest that dugongs and dolphins were engaged in similar activities, such as travelling, on several occasions and were clearly associated when group formation was tight. If dolphins and dugongs may not associate for feeding purposes, then these interactions may occur: (1) for predation avoidance toward sharks; or (2) without any ecological reasons due to dolphin and dugong habitat overlap around the island.

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Allen, Simon J., Daniele D. Cagnazzi, Amanda J. Hodgson, Neil R. Loneragan, and Lars Bejder. "Tropical inshore dolphins of north-western Australia: Unknown populations in a rapidly changing region." Pacific Conservation Biology 18, no. 1 (2012): 56. http://dx.doi.org/10.1071/pc120056.

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Australian Snubfin Orcaella heinsohni, Indo-Pacific Humpback Sousa chinensis and Indo-Pacific Bottlenose Dolphins Tursiops aduncus inhabit Australia’s tropical north-western coastline, a region undergoing extensive port development associated with the massive expansion of the oil, gas and mining industries. The current lack of data on dolphin population sizes or trends precludes impact assessments of developments on these protected species. Furthermore, the Western Australian and Commonwealth Government conservation listings of tropical inshore dolphins do not reflect their international listings. From April to July, 2010, we conducted ad hoc boat-based surveys (n=55) of inshore delphinids at seven sites across north-western Australia from Coral Bay in the south (23.1°S: 113.8°E) to Cable Beach in the north (17.9°S: 122.2°E). We documented the locations of these three species from which we obtained photoidentification and biopsy data, as well as reports of Australian Snubfin Dolphin sightings from researchers and community groups. The data from this limited field effort confirm that Indo-Pacific Humpback and Indo-Pacific Bottlenose Dolphins occur in the waters adjacent to each north-western Australian urban centre and show that the range of the Australian Snubfin Dolphin extends considerably further south-west than previously reported. Given the scale of coastal developments and the vulnerability of isolated cetacean populations to fragmentation or extirpation, assessments of the viability of dolphin populations are required. Our data suggest that the Australian Snubfin, Indo-Pacific Humpback and Indo-Pacific Bottlenose Dolphins need to be considered as likely to be impacted by coastal developments across north-western Australia.

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Anderwald, Pia, Michael Damien Haberlin, Mary Coleman, Oliver Ó Cadhla, Anneli Englund, Fleur Visser, and Michelle Cronin. "Seasonal trends and spatial differences in marine mammal occurrence in Broadhaven Bay, north-west Ireland." Journal of the Marine Biological Association of the United Kingdom 92, no. 8 (September 25, 2012): 1757–66. http://dx.doi.org/10.1017/s0025315412001397.

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Long-term monitoring programmes of a comparatively small area complement larger scale, but temporally limited surveys and can provide extensive datasets on seasonal occurrence and fine-scale habitat use of multiple species. A marine mammal monitoring programme, involving year-round, land-based observations, has been conducted in Broadhaven Bay candidate Special Area of Conservation, north-west Ireland, during 2002, 2005 and 2008–2011. Nine cetacean and two seal species have been recorded, with grey seal, harbour porpoise, common and bottlenose dolphins, and minke whale present throughout the year. Generalized additive models, taking into account observer effort, sighting conditions (sea state) and interannual variation, did not reveal any significant seasonal patterns in the occurrence of grey seals, bottlenose dolphins and minke whales. On the other hand, common dolphin presence in Broadhaven Bay was highest during autumn and winter. Bottlenose dolphins could be separated spatially from both common dolphins and minke whales in a classification tree by their preferential use of the shallower inshore areas of the bay (<30 m depth). However, common dolphins and minke whales, which occurred mainly in the deeper outer section of Broadhaven Bay, could not be spatially distinguished from each other, and grey seals were distributed over the entire bay. Broadhaven Bay represents an important marine mammal habitat with respect to overall species diversity and the regular occurrence of bottlenose dolphin, harbour porpoise, grey and harbour seals (all listed under Annex II of the EU Habitats Directive).

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Mujiyanto, Mujiyanto, Riswanto Riswanto, Dharmadi Dharmadi, and Wildan Ghiffary. "COMPOSITION AND DISTRIBUTION OF DOLPHIN IN SAVU SEA NATIONAL MARINE PARK, EAST NUSA TENGGARA." Indonesian Fisheries Research Journal 23, no. 2 (February 12, 2018): 55. http://dx.doi.org/10.15578/ifrj.23.2.2017.55-67.

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Dolphins are one of the most interesting cetacean types included in family Delphinidae or known as the oceanic dolphins from genus Stenella sp. and Tursiops sp. Migration and abundance of dolphins are affected by the presence of food and oceanographic conditions. The purpose of this research is to determine the composition and distribution of dolphins in relation to the water quality parameters. Benefits of this research are expected to provide information on the relationship between distributions of the family Delphinidae cetacean (oceanic dolphins) and oceanographic conditions. The method for this research is descriptive exploratory, with models onboard tracking survey. Field observations were done in November 2015 and period of March-April 2016 outside and inside Savu Sea National Marine Park waters. The sighting of dolphin in November and March-April found as much seven species: bottlenose dolphin, fraser’s dolphin, pantropical spotted dolphin, risso’s dolphin, rough-toothed dolphin, spinner dolphin and stripped dolphin. The highest species distribution noted in the Savu Sea is spinner dolphin, pantropical spotted dolphin, rough-toothed dolphin and frazer’s dolphin. The existence of dolphins in Savu Sea is more related with sea surface temperature than others oceanographic parameters. This condition is suspected due to the influence of sea surface temperature to body temperature of dolphin especially for foraging activities. The habit of dolphin is more active around Sumba Island and Daratan Timor waters while in the evening the animal is usually going to Manggarai and Rote Ndao Islands waters to rest.

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Laporta, Paula, Pedro Fruet, and Eduardo Secchi. "First estimate of common bottlenose dolphin (Tursiops truncatus) (Cetacea, Delphinidae) abundance off Uruguayan Atlantic coast." Latin American Journal of Aquatic Mammals 11, no. 1-2 (January 8, 2017): 144–54. http://dx.doi.org/10.5597/00223.

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The common bottlenose dolphin Tursiops truncatus is often observed throughout the oceanic coast of Uruguay. Historically, its distribution was wider, including the estuary of the Río de la Plata, but currently its occurrence seems to be restricted mainly to the Uruguayan Atlantic coast (Rocha Department). Conflicting interests and tradeoffs between conservation and development are being generated in Uruguay. On one hand, the establishment of protected areas, responsible tourism and sustainable fisheries are promoted, while on the other hand, foreign exploitation of natural resources and development of mega-infrastructure in coastal zone are facilitated. In this work, we provide the first estimate of bottlenose dolphin’s abundance along the Uruguayan Atlantic coast. These results can be used as baseline information for monitoring population trends and guiding conservation actions for bottlenose dolphins in Uruguay. Mark-recapture models were applied to data of photoidentified animals with long-lasting natural marks. Total population size estimates of 63 individuals (95% CI = 54–74) and 61 (95% CI = 53–73) were obtained from closed and open population models, respectively. Although the estimates are within the range of values obtained for other coastal bottlenose dolphin populations in the Southwest Atlantic Ocean, as well as other regions of the world, it is lower than the values reported for populations inhabiting open habitats. This small population is probably vulnerable to non-natural removals, environmental and demographic stochasticity. Therefore, precautionary actions are recommended given the planned development for this coastal region.

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Sánchez-Cabanes, Alicia, Maja Nimak-Wood, Nicola Harris, and Renaud De Stephanis. "Habitat preferences among three top predators inhabiting a degraded ecosystem, the Black Sea." Scientia Marina 81, no. 2 (June 14, 2017): 217. http://dx.doi.org/10.3989/scimar.04493.07a.

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This study investigated whether there is evidence of widespread niche partitioning based on environmental factors in the Black Sea and tested the hypothesis that physiographic factors may be employed as predictors. It addresses poorly researched areas with good habitat potential for the only three cetacean subspecies living in this area: the Black Sea short-beaked common dolphin (Delphinus delphis spp. ponticus), the Black Sea bottlenose dolphin (Tursiops truncatus spp. ponticus) and the Black Sea harbour porpoise (Phocoena phocoena spp. relicta). Generalized additive models (GAMs) were used to analyse data collected from multiple sources. In total, 745 sightings of the three species between 1998 and 2010 throughout the Black Sea were included. The analysis found depth and sea surface temperature to be the most important variables for separating the occurrence of the three species. Common dolphins occurred mainly in deep waters and in areas where the sea surface temperature was low, bottlenose dolphins were distributed primarily in shallower and warmer waters than common dolphins, and harbour porpoises were distributed in shallower waters with lower sea surface temperature than bottlenose dolphins. This study suggests strong niche segregation among the three cetacean species. The study is also the first contribution to the basic information of cetacean species distribution and habitat preferences in the Black Sea as a whole. Knowledge of the distribution of the three dolphin species in the study area is essential to establish conservation measures for these populations.

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Rodriguez, Lauren Kelly, Amber D. Fandel, Benjamin R. Colbert, Jamie C. Testa, and Helen Bailey. "Spatial and temporal variation in the occurrence of bottlenose dolphins in the Chesapeake Bay, USA, using citizen science sighting data." PLOS ONE 16, no. 5 (May 18, 2021): e0251637. http://dx.doi.org/10.1371/journal.pone.0251637.

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Bottlenose dolphins (Tursiops truncatus) are migratory marine mammals that live in both open-ocean and coastal habitats. Although widely studied, little is known about their occurrence patterns in the highly urbanized estuary of the Chesapeake Bay, USA. The goal of this study was to establish the spatial and temporal distribution of bottlenose dolphins throughout this large estuarine system and use statistical modeling techniques to determine how their distribution relates to environmental factors. Three years (April-October 2017–2019) of dolphin sighting reports from a citizen-science database, Chesapeake DolphinWatch, were analyzed. The dolphins had a distinct temporal pattern, most commonly sighted during summer months, peaking in July. This pattern of observed occurrence was confirmed with systematic, passive acoustic detections of dolphin echolocation clicks from local hydrophones. Using spatially-exclusive Generalized Additive Models (GAM), dolphin presence was found to be significantly correlated to spring tidal phase, warm water temperature (24–30°C), and salinities ranging from 6–22 PPT. We were also able to use these GAMs to predict dolphin occurrence in the Bay. These predictions were statistically correlated to the actual number of dolphin sighting reported to Chesapeake DolphinWatch during that time. These models for dolphin presence can be implemented as a predictive tool for species occurrence and inform management of this protected species within the Chesapeake Bay.

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Hawkins, E. R., and D. F. Gartside. "Social and Behavioural Characteristics of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) in northern New South Wales, Australia." Australian Mammalogy 30, no. 2 (2008): 71. http://dx.doi.org/10.1071/am08009.

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Bottlenose dolphins (Tursiops spp.) are one of the most common genera of cetacea encountered throughout the world?s tropical and temperate regions. However, there is relatively little knowledge on the populations of bottlenose dolphins in Australia. The present study assessed the pod characteristics, behaviour, movement patterns and social structure of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in coastal inshore waters off northern New South Wales, Australia, using vessel-based and land-based surveys. Dolphins spent most time travelling (38%), followed by milling (31%), feeding (19%), and socialising (12%). The mean pod size of dolphins in Byron Bay was 13 (S.D. = 12). The social foundation of this population was characterised by sexual segregation. Significant variations were found between the mean size of mother-calf pods (21; S.D. = 15) and adult-only pods (5; S.D. = 5). Two ?resident? groups of females were identified that occupied adjacent territories of between 177 km� and 320 km�. ?Resident? females appeared to maintain loose associations with other ?resident? females (HWI = 0.28; S.D. = 0.66). Despite the large differences in environmental conditions, habitats and prey species, it appeared that the social organisation, movement patterns and behaviour of T. aduncus populations in coastal regions is similar. The Byron Bay population of dolphins is not presently heavily impacted by interactions with humans, compared to populations with regular commercial dolphin-watching operations. This means the population may provide important base-line data for assessment of potential human impacts on dolphin populations.

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Affinito, Flavio, Cristobal Olaya Meza, Aylin Akkaya Bas, Deborah Brill, Guy Whittaker, and Lasse Capel. "On the behaviour of an under-studied population of bottlenose dolphins in the Southern Adriatic Sea." Journal of the Marine Biological Association of the United Kingdom 99, no. 4 (October 22, 2018): 1017–23. http://dx.doi.org/10.1017/s0025315418000772.

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AbstractPerhaps the world's best-known cetacean, the bottlenose dolphin shows considerable variation in behaviour between and within populations in relation to differences in natural and anthropogenic conditions. Drivers of behavioural variation need to be identified to understand the dynamics of wild dolphin populations. Little research has been published on the bottlenose dolphin population found in the Southern Adriatic Sea. Using a set of spatial, temporal and social predictors, we aimed to investigate what variables are related to the behaviour of an under-studied population of bottlenose dolphins along the coastline of Montenegro. We present the results of a year-long study monitoring the behaviour of bottlenose dolphins along coastal Montenegro. We considered the effect of topography, seasonality and group size. A large proportion of travelling (55%) small groups (mean 4, range 1–9) in shallow waters (<50 m) was observed. We showed that seasonality alone explained behaviour best, with surface-feeding and socializing-resting increasing in autumn and winter. Group size was found to be a result of behavioural choice. We suggest seasonal changes in environmental conditions and anthropogenic pressure may explain the recorded behavioural pattern. This research points to the necessity of increased collaboration in the region to help understand complex patterns in behaviour and habitat use of local dolphin populations if effective conservation measures are to be developed.

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Jiménez, Pedro Jose, and Juan José Alava. "Strand-feeding by coastal bottlenose dolphins (Tursiops truncatus) in the Gulf of Guayaquil, Ecuador." Latin American Journal of Aquatic Mammals 10, no. 1 (August 24, 2015): 33–37. http://dx.doi.org/10.5597/lajam00191.

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

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Lipscomb, Thomas P., Seamus Kennedy, Deborah Moffett, Amy Krafft, Brenda A. Klaunberg, Jack H. Lichy, Gerald T. Regan, Graham A. J. Worthy, and Jeffery K. Taubenberger. "Morbilliviral Epizootic in Bottlenose Dolphins of the Gulf of Mexico." Journal of Veterinary Diagnostic Investigation 8, no. 3 (July 1996): 283–90. http://dx.doi.org/10.1177/104063879600800302.

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Morbillivirus infection was diagnosed in 35/67 bottlenose dolphins (Tursiops truncatus) from the Gulf of Mexico that stranded from October 1993 through April 1994 in Alabama, Mississippi, and Texas (USA) during periods of increased dolphin standings in each of the 3 states. Diagnosis was based on histologic lesions, immunohistochemical demonstration of morbilliviral antigen, and detection of morbilliviral RNA by a reverse transcriptase polymerase chain reaction (RT-PCR) test performed on formalin-fixed, paraffin-embedded tissue (5 dolphins), on histologic lesions and detection of morbilliviral RNA by RT-PCR performed on formalin-fixed, paraffin-embedded tissue (1 dolphin), and on detection of morbilliviral RNA by RT-PCR performed on unfixed lung samples collected from carcasses with advanced postmortem autolysis (29 dolphins). Histologic lesions included proliferative interstitial pneumonia with syncytial cells and eosinophilic intranuclear and intracytoplasmic inclusion bodies, lymphoid depletion and syncytial cells with eosinophilic intranuclear inclusion bodies in lymph nodes, eosinophilic intracytoplasmic inclusion bodies in transitional epithelium of urinary bladder, and a syncytial cell with eosinophilic intranuclear inclusion bodies in epidermis. Concomitant pulmonary aspergillosis was diagnosed histologically in 4 dolphins. This is the 5th reported morbilliviral epizootic of aquatic mammals and the 2nd involving bottlenose dolphins in the United States.

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Clarkson, J., F. Christiansen, T. Awbery, L. Abbiss, N. Nikpaljevic, and A. Akkaya. "Non-targeted tourism affects the behavioural budgets of bottlenose dolphins Tursiops truncatus in the South Adriatic (Montenegro)." Marine Ecology Progress Series 638 (March 19, 2020): 165–76. http://dx.doi.org/10.3354/meps13257.

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We investigated the short-term effects of non-targeted tourism on the behaviour of bottlenose dolphins Tursiops truncatus in the South Adriatic off the coast of Montenegro, by comparing dolphin group behaviour during impact (the presence of non-targeted tourism vessels) and control (absence of all marine vessels) scenarios. Tourism vessel and dolphin behavioural data were collected through systematic weekly land-based surveys. Using instantaneous focal ‘group’ scan sampling, the predominant behaviour of bottlenose dolphin groups was determined. To quantify the effect of vessel interactions on the behavioural budget of the dolphins, we followed a stepwise modelling approach. A first-order Markov chain was used to calculate the transition probabilities between behavioural states before a Monte Carlo simulation estimated the behavioural budgets of dolphins during impact and control situations. In the presence of non-targeted tourism, dolphins were found to be less likely to remain diving (during which dolphins were assumed to be feeding), whilst milling-socialising and surface feeding were completely absent from their behavioural repertoires. Nevertheless, the behavioural budgets demonstrated an increase in resting behaviour in the presence of non-targeted tourism vessels. No significant changes to travelling behaviour were observed. The decrease in foraging behaviour (both surface feeding and diving) could result in a reduction in energy intake for dolphins, which over time (assuming repeated disturbance) could negatively affect body condition, and ultimately survival and reproduction. Regulations on non-targeted tourism should therefore be considered to minimise potential long-term negative effects on dolphins within Montenegrin territorial waters.

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Gladilina, E. V., and P. E. Gol’din. "New Prey Fishes in Diet of Black Sea Bottlenose Dolphins, Tursiops truncatus (Mammalia, Cetacea)." Vestnik Zoologii 48, no. 1 (February 1, 2014): 83–92. http://dx.doi.org/10.2478/vzoo-2014-0009.

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Abstract We report 7 new prey fishes in diet of the Black Sea bottlenose dolphins Tursiops truncatus (Montagu, 1821) and the first records of 9 prey items from their stomach contents: herring (Alosa sp.), sand smelt (Atherina sp.), horse mackerel (Trachurus mediterraneus), picarel (Spicara flexuosa), Mediterranean sand eel (Gymnammodytes cicerellus), Atlantic stargazer (Uranoscopus scaber), garfish (Belone belone), gobies (Gobiidae indet.) and blennies (Blenniidae indet.). Th e Atlantic stargazer was recorded as a prey species for the common bottlenose dolphin for the first time. Th e horse mackerel and the picarel, formerly recorded in the diet of Mediterranean bottlenose dolphins, now were frequently found in the examined Black Sea dolphins. Th e list of prey fishes for Black Sea bottlenose dolphins now includes 23 items, with many small pelagic and demersal fishes, and it is similar to that of Mediterranean dolphins. Whiting (Merlangius merlangus) is still an important prey species, as 50-70 years ago, whereas turbot (Psetta maeotica), not recorded by us, could lose its importance due to population decline. As before, red mullet (Mullus barbatus) is recorded in winter feeding. Feeding on mullets (Mugilidae) is not a universal trait, and it is possibly restricted to local geographical areas.

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Pierce, Graham J., Mara Caldas, Jose Cedeira, M. Begoña Santos, Ángela Llavona, Pablo Covelo, Gema Martinez, Jesus Torres, Mar Sacau, and Alfredo López. "Trends in cetacean sightings along the Galician coast, north-west Spain, 2003–2007, and inferences about cetacean habitat preferences." Journal of the Marine Biological Association of the United Kingdom 90, no. 8 (July 6, 2010): 1547–60. http://dx.doi.org/10.1017/s0025315410000664.

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Since mid-2003, systematic monthly sightings surveys for cetaceans have been carried out in Galicia (north-west Spain) from observation points around the coastline, with the aim of providing baseline data on cetacean distribution and habitat use to underpin future conservation measures. Here we summarize results for September 2003 to October 2007. The most frequently recorded species were the bottlenose dolphin (Tursiops truncatus, seen during 10.7% of observation periods), common dolphin (Delphinus delphis, 3.7%), harbour porpoise (Phocoena phocoena, 1.6%), Risso's dolphin (Grampus griseus, 0.4%) and short-finned pilot whale (Globicephala melas, 0.2%). The three most common species showed different distribution patterns along the coast. In terms of habitat preferences, bottlenose dolphins were seen to be associated with more productive areas (areas with higher chlorophyll-a concentrations) where the continental shelf was wider while both common dolphins and harbour porpoises were seen most frequently in less productive areas where the continental shelf is narrowest. Possible reasons for differences in habitat use include differing diets. In Galician waters, all three main cetacean species feed primarily on fish that are common in shelf waters, and in the case of blue whiting (the most important species in the stomach contents of common and bottlenose dolphins) abundant also on the slope. All three cetaceans feed on blue whiting while scad is important in diets of common dolphin and porpoise. It is also possible that porpoises do not use areas frequented by bottlenose dolphins in order to avoid aggressive interactions. Retrospective evaluation of the sampling regime, using data from the 2500 observation periods during 2003–2007 suggests that the overall sightings rates for all species (taking into account observation time and between-site travel time) would be higher if average observation duration was increased to at least 40 minutes. On the other hand, confidence limits on sightings rates stabilized after around 1000 observation periods, suggesting that the number of sites visited or the frequency of visits could be substantially reduced.

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Mateu, P., J. A. Raga, and F. J. Aznar. "Host specificity ofOschmarinella rochebruniandBrachycladium atlanticum(Digenea: Brachycladiidae) in five cetacean species from western Mediterranean waters." Journal of Helminthology 85, no. 1 (April 1, 2010): 12–19. http://dx.doi.org/10.1017/s0022149x10000180.

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AbstractWe investigated patterns of specificity of liver flukes (fam. Brachycladiidae) in a community of cetaceans from the western Mediterranean. The liver and pancreas of 103 striped dolphins,Stenella coeruleoalba, 18 Risso's dolphins,Grampus griseus, 14 bottlenose dolphins,Tursiops truncatus, 8 common dolphins,Delphinus delphis, and 5 long-finned pilot whales,Globicephala melas, were analysed for brachycladiid species. Two species were found:Oschmarinella rochebruniin striped dolphins (prevalence (P): 61.2%; mean intensity (MI) (95% CI): 34.2 (25.7–45.6)), andBrachycladium atlanticumin striped dolphins (P: 39.8%; MI: 7.1 (4.8–13.1)) and a single individual of common dolphin (P: 12.5%; intensity: 19), which represents a new host record. A molecular analysis using the internal transcribed spacer 2 (ITS2) region of the rDNA gene confirmed that specimens ofB. atlanticumwere conspecific regardless of host species. Available dietary data suggest that Risso's dolphins, bottlenose dolphins and long-finned pilot whales would contact rarely, if at all, the infective stages ofO. rochebruniandB. atlanticum. Neither the prevalence nor the mean abundance ofB. atlanticumdiffered significantly between striped and common dolphins, but a principal component analysis using seven morphometric variables indicated that specimens collected from the common dolphin were stunted. These worms also had fewer eggs compared with specimens typically found in striped dolphins, although the size of the eggs was similar in both host species. Dwarfism and low fecundity have typically been found in helminths infecting unusual host species, and might reflect the lower compatibility ofB. atlanticumfor common dolphins. In summary, bothO. rochebruniandB. atlanticumappear to exhibit a narrow specificity for striped dolphins in the western Mediterranean.

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McGovern, Barry, Ross M. Culloch, Michael O'Connell, and Simon Berrow. "Temporal and spatial trends in stranding records of cetaceans on the Irish coast, 2002–2014." Journal of the Marine Biological Association of the United Kingdom 98, no. 5 (December 8, 2016): 977–89. http://dx.doi.org/10.1017/s0025315416001594.

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Using Irish strandings data collected between 2002 and 2014, seasonal and annual trends in the number of strandings for all strandings identified to species level (N = 1480), and for the five most frequently reported species: common dolphin (25.7% of records), harbour porpoise (22.2%), long-finned pilot whale (8.8%), striped dolphin (6.9%) and bottlenose dolphin (6.9%) were investigated. With the exception of bottlenose dolphins, there was a significant linear increase in the number of strandings across years for all species and for all strandings collectively, that were identified to species-level. Only common dolphins demonstrated a significant increase in the proportion of records relative to all other strandings, which may be indicative of a real rise in the number of strandings of this species. Common dolphins and harbour porpoises showed a similar significant difference in monthly strandings, with more strandings occurring during the earlier months of the year. Significant differences in the gender of stranded animals were found in common, striped, bottlenose and Atlantic white-sided dolphins and sperm and pygmy sperm whales. Live and mass stranding events were primarily comprised of pelagic species. Most strandings occurred on the south and west coasts, with two hotspots for live and mass strandings identified. The patterns and trends identified are discussed in relation to the caveats in interpreting strandings data. Specifically to Ireland, the findings highlight the urgent need to build on the current volunteer reporting network and augment this comprehensive dataset with post-mortem examinations to better understand the cause of the trends identified. The importance of strandings data in informing conservation and management guidelines of these species’ is discussed.

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Delfour, Fabienne, and Ken Marten. "Inter-modal learning task in bottlenosed dolphins (Tursiops truncatus): a preliminary study showed that social factors might influence learning strategies." acta ethologica 8, no. 1 (May 12, 2005): 57–64. http://dx.doi.org/10.1007/s10211-005-0110-z.

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Gómez de Segura, A., P. S. Hammond, and J. A. Raga. "Influence of environmental factors on small cetacean distribution in the Spanish Mediterranean." Journal of the Marine Biological Association of the United Kingdom 88, no. 6 (March 17, 2008): 1185–92. http://dx.doi.org/10.1017/s0025315408000386.

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Habitat distribution models are one of the most up to date methods to study the habitat usage of wildlife populations. They allow animal distribution to be related to environmental features and also the prediction of the distribution of animals based on this relationship. Seasonal aerial surveys were conducted in central Spanish Mediterranean waters from June 2000 to March 2003 to obtain information on the distribution of cetacean species. Data from the three most common cetacean species (striped dolphin, Stenella coeruleoalba, bottlenose dolphin, Tursiops truncatus, and Risso's dolphin, Grampus griseus) were related, using generalized linear models, to local environmental features: depth, slope, sea surface temperature and chlorophyll concentration. For bottlenose dolphins, no significant relationship was found with any covariate and no dolphins were observed in waters greater than 1000 m. The distribution of both striped and Risso's dolphin was significantly related to depth. The striped dolphin showed a preference for waters between 900 and 1500 m deep and Risso's dolphin for waters more than 1500 m deep. In addition, for the latest two species, maps of distribution were predicted by means of the spatial models. The areas of higher probabilities of occurrence coincide to a large extent with the marine protected areas previously proposed for the conservation of oceanic cetacean species.

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Kassamali-Fox, Ayshah, Fredrik Christiansen, Laura J. May-Collado, Eric A. Ramos, and Beth A. Kaplin. "Tour boats affect the activity patterns of bottlenose dolphins (Tursiops truncatus) in Bocas del Toro, Panama." PeerJ 8 (March 30, 2020): e8804. http://dx.doi.org/10.7717/peerj.8804.

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Bottlenose dolphins (Tursiops truncatus) of the Bocas del Toro archipelago are targeted by the largest boat-based cetacean watching operation in Panama. Tourism is concentrated in Dolphin Bay, home to a population of resident dolphins. Previous studies have shown that tour boats elicit short-term changes in dolphin behavior and communication; however, the relationship of these responses to the local population’s biology and ecology is unclear. Studying the effects of tour boats on dolphin activity patterns and behavior can provide information about the biological significance of these responses. Here, we investigated the effects of tour boat activity on bottlenose dolphin activity patterns in Bocas del Toro, Panama over 10 weeks in 2014. Markov chain models were used to assess the effect of tour boats on dolphin behavioral transition probabilities in both control and impact scenarios. Effect of tour boat interactions was quantified by comparing transition probabilities of control and impact chains. Data were also used to construct dolphin activity budgets. Markov chain analysis revealed that in the presence of tour boats, dolphins were less likely to stay socializing and were more likely to begin traveling, and less likely to begin foraging while traveling. Additionally, activity budgets for foraging decreased and traveling increased as an effect of tour boat presence. These behavioral responses are likely to have energetic costs for individuals which may ultimately result in population-level impacts. Boat operator compliance with Panamanian whale watching regulations is urgently needed to minimize potential long-term impacts on this small, genetically distinct population and to ensure the future viability of the local tourism industry.

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Journal articles on the topic 'Bottlenosed dolphins'

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