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Monitoring marine fauna is essential for mitigating the effects of disturbances in the marine environment, as well as reducing the risk of negative interactions between humans and marine life. Drone-based aerial surveys have become popular for detecting and estimating the abundance of large marine fauna. However, sightability errors, which affect detection reliability, are still apparent. This study tested the utility of spectral filtering for improving the reliability of marine fauna detections from drone-based monitoring. A series of drone-based survey flights were conducted using three identical RGB (red-green-blue channel) cameras with treatments: (i) control (RGB), (ii) spectrally filtered with a narrow 'green' bandpass filter (transmission between 525 and 550 nm), and, (iii) spectrally filtered with a polarising filter. Video data from nine flights comprising dolphin groups were analysed using a machine learning approach, whereby ground-truth detections were manually created and compared to AI-generated detections. The results showed that spectral filtering decreased the reliability of detecting submerged fauna compared to standard unfiltered RGB cameras. Although the majority of visible contrast between a submerged marine animal and surrounding seawater (in our study, sites along coastal beaches in eastern Australia) is known to occur between 515–554 nm, isolating the colour input to an RGB sensor does not improve detection reliability due to a decrease in the signal to noise ratio, which affects the reliability of detections. [ABSTRACT FROM AUTHOR]

The social intelligence hypothesis holds that complex social relationships are the major selective force underlying the evolution of large brain size and intelligence. Complex social relationships are exemplified by coalitions and alliances that are mediated by affiliative behavior, resulting in differentiated but shifting relationships. Male Indo-Pacific bottlenose dolphins in Shark Bay, Australia, form three alliance levels or 'orders', primarily among non-relatives. Strategic alliance formation has been documented within both first- and second-order alliances and between second-order alliances ('third-order alliances'), revealing that the formation of strategic inter-group alliances is not limited to humans. Here we conducted a fine-scale study on 22 adult males over a 6-year period to determine if third-order alliance relationships are differentiated, and mediated by affiliative interactions. We found third-order alliance relationships were strongly differentiated, with key individuals playing a disproportionate role in maintaining alliances. Nonetheless, affiliative interactions occurred broadly between third-order allies, indicating males maintain bonds with third-order allies of varying strength. We also documented a shift in relationships and formation of a new third-order alliance. These findings further our understanding of dolphin alliance dynamics and provide evidence that strategic alliance formation is found in all three alliance levels, a phenomenon with no peer among non-human animals. [ABSTRACT FROM AUTHOR]

It is challenging to collect robust, long-term datasets to properly monitor the viability and social structure of large, long-lived animals, especially marine mammals. The present study used a unique long-term dataset to investigate the population parameters and social structure of a poorly studied population of bottlenose dolphins (Tursiops sp.) in southern Port Phillip Bay, south-eastern Australia. Photo-identification images have been collected between 2012–2022 both opportunistically and following a protocol by patrons, staff, and volunteers of ecotourism companies using their vessels as platforms. The resulting large dataset was available to be processed through the online platform Flukebook and used in capture recapture models to estimate abundance and demographic parameters. In addition, the social structure of the population and the reproductive parameters were investigated. The marked adult population abundance (45.2 ± 2.7 individuals) was found to be stable over the last decade and the calving rate ranged between 0.06–0.19 new calves per identified individuals per year, while the inter-birth interval was 3.7 ± 0.8 years. Social analysis suggested the population has a fission-fusion structure with no apparent clusters. The stability of the population over the study period suggests no deleterious effect of anthropogenic or environmental factors during the last decade. This study is the outcome of the effort of the ecotourism organisations and the results obtained, along with their similarity to those of other dolphin populations worldwide, highlight the importance of such data sources for long-term information that would otherwise be too expensive or logistically difficult to obtain. [ABSTRACT FROM AUTHOR]

Aerial surveys are frequently used to estimate the abundance of marine mammals, but their accuracy is dependent upon obtaining a measure of the availability of animals to visual detection. Existing methods for characterizing availability have limitations and do not necessarily reflect true availability. Here, we present a method of using small, vessel‐launched, multi‐rotor Unoccupied Aerial Vehicles (UAVs, or drones) to collect video of dolphins to characterize availability and investigate error surrounding group size estimates. We collected over 20 h of aerial video of dive‐surfacing behaviour across 32 encounters with Australian humpback dolphins Sousa sahulensis off north‐western Australia. Mean surfacing and dive periods were 7.85 sec (se = 0.26) and 39.27 sec (se = 1.31) respectively. Dolphin encounters were split into 56 focal follows of consistent group composition to which example approaches to estimating availability were applied. Non‐instantaneous availability estimates, assuming a 7 sec observation window, ranged between 0.22 and 0.88, with a mean availability of 0.46 (CV = 0.34). Availability tended to increase with increasing group size. We found a downward bias in group size estimation, with true group size typically one individual more than would have been estimated by a human observer during a standard aerial survey. The variability of availability estimates between focal follows highlights the importance of sampling across a variety of group sizes, compositions and environmental conditions. Through data re‐sampling exercises, we explored the influence of sample size on availability estimates and their precision, with results providing an indication of target sample sizes to minimize bias in future research. We show that UAVs can provide an effective and relatively inexpensive method of characterizing dolphin availability with several advantages over existing approaches. The example estimates obtained for humpback dolphins are within the range of values obtained for other shallow‐water, small cetaceans, and will directly inform a government‐run program of aerial surveys in the region. [ABSTRACT FROM AUTHOR]

Indo-Pacific bottlenose dolphins (Tursiops aduncus) around Mikura Island are important both commercially (swim-with-dolphin programs) and scientifically (long-term underwater behavioral studies). However, this population experienced a substantial population decline (31% of identified dolphins) between 2008 and 2011, which prompted us to monitor population health using body length. A decrease in the growth rate of neonates and calves is a warning sign of unhealthy conditions in the population. This study examined the total length of free-ranging Indo-Pacific bottlenose dolphins off Mikura Island, using a low-cost commercially available 3D underwater camera system. Length-at-age data from 129 measurements of 108 identified dolphins were successfully obtained and were best described by the Richards growth model compared to the Gompertz and von Bertalanffy models. Body length did not differ significantly between females and males, with an estimated population asymptotic length of 246.9 cm (95% confidence interval: 241.7–252.7 cm). Calves were approximately 100 cm in length at birth and reached 178.2 cm at 1 year of age and 208.6 cm at 3 years when many calves became independent from their mothers. Length-at-age estimates of the Mikura Island population are similar to and greater than those reported in southwestern Australia and Shark Bay, respectively. Our simple non-invasive underwater technique demonstrated to be effective in quantifying the growth pattern in a free-ranging dolphin population without using dead or stranded specimens, which provides essential information for monitoring of dolphin populations and sustainable swim-with-dolphin programs. [ABSTRACT FROM AUTHOR]

The photo-identification of uniquely marked individuals has revealed much about mammalian behaviour and social structure in recent decades. In bottlenose dolphins (Tursiops spp.), for example, the long-term tracking of individuals has unveiled considerable variation in social structure among populations and various spatio-temporal aspects of group formation. In this study, we investigated associations among individual males in a small community of Indo-Pacific bottlenose dolphins (T. aduncus) residing in an urbanized estuary in southwestern Australia. Given the relative proximity of our study area to other populations in which complex male alliances form for the purpose of mate acquisition, we used long-term photo-identification records and social analyses to assess whether such alliances also occur in smaller and more isolated settings. Our work revealed strong social bonds and long-term, non-random associations among individual males, suggesting the occurrence of male alliances. Behavioural observations of alliances interacting with potentially receptive adult females from the estuary community and from adjacent communities, and exhibiting sexual display behaviours near females, suggest that these alliances occur in a reproductive context. As the first formal analysis indicating the occurrence of male alliances outside Shark Bay along the vast western coastline of Australia, this study complements previous research and extends our understanding of the evolutionary and ecological processes that drive alliance formation. [ABSTRACT FROM AUTHOR]

Vessels cause considerable disturbance to cetaceans world-wide, with potential long-term impacts to population viability. Here we present a comprehensive review of vessel impacts to cetacean behavior in Australian waters (2003–2015), finding inadequate protections to be in place. The majority of these studies found trends of decreased animal travel and resting behavioral states as well as low compliance to regulations, and they recommended further regulatory action such as greater enforcement or monitoring, or passive management strategies. As a case study, we conducted the first field assessment of vessel compliance with the Wildlife (Marine Mammal) Regulations 2009 in Gippsland Lakes, Australia, and provide the first assessment of the endangered Gippsland Lakes Burrunan dolphin (Tursiops australis) population's behavioral ecology. Dolphin behavior and vessel regulation compliance data were collected during boat-based surveys of Gippsland Lakes from July 2017 to January 2018, with a total of 22 dolphin group sightings resulting in 477 five-minute point samples. 77% of dolphin sightings involved vessel interactions (within 400 m), and 56 regulation breaches were observed. These breaches were most severe in summer (mean = 4.54 breaches/hour). Vessels were found to alter dolphin behavior before, during, and after interactions and regulation breaches, including increased mating (mate guarding) and milling behavioral states, and increased 'fish catch', 'high leap' and 'tail slap' behavioral events. These behavioral changes may indicate masking of the dolphins' acoustic communication, disturbance of prey, increased dolphin transition behaviors, and/or induced stress and changes to group structure (including increased mate guarding). While our results provide evidence of short-term altered behavior, the potential for long-term effects on population dynamics for this threatened species is high. In the context of reported inadequate cetacean protection Australia-wide, our management recommendations include greater monitoring and enforcement, and the utilisation of adaptive management. [ABSTRACT FROM AUTHOR]

Globally, fisheries bycatch threatens the survival of many whale and dolphin species. Strategies for reducing bycatch can be expensive. Management is inclined to prioritize investment in actions that are inexpensive, but these may not be the most effective. We used an economic tool, return‐on‐investment, to identify cost‐effective measures to reduce cetacean bycatch in the trawl, net, and line fisheries of Australia. We examined 3 management actions: spatial closures, acoustic deterrents, and gear modifications. We compared an approach for which the primary goal was to reduce the cost of bycatch reduction to fisheries with an approach that aims solely to protect whale and dolphin species. Based on cost‐effectiveness and at a fine spatial resolution, we identified the management strategies across Australia that most effectively abated dolphin and whale bycatch. Although trawl‐net modifications were the cheapest strategy overall, there were many locations where spatial closures were the most cost‐effective solution, despite their high costs to fisheries, due to their effectiveness in reducing all fisheries interactions. Our method can be used to delineate strategies to reduce bycatch threats to mobile marine species across diverse fisheries at relevant spatial scales to improve conservation outcomes. Article impact statement: A cost‐effectiveness approach to mitigate dolphin and whale bycatch is cheaper and provides greater benefits over traditional conservation methods. [ABSTRACT FROM AUTHOR]

Mortality of dolphins in fishing operations is often under-estimated, as shown by studies of beach-washed carcasses. Linking evidence obtained during necropsies with fishing method is fundamental to understanding the extent of mortality and the manner in which animals die. The South Australian Sardine Fishery (SASF) has operated a purse-seine industry since 1991. This study characterised injuries, pathological changes and life history of 49 dead dolphins collected from SASF during 2006-2019. Histology examination was conducted on 25 animals. Neonates, calves and juveniles accounted for 63% of the sample. Of mature females (n = 14), 11 were pregnant or lactating, with cryptic mortality estimated to be 20% of dolphins studied. Body condition was robust in 48 dolphins. Net marks were seen on 82%, mostly on the head, trunk and peduncle. Broken/missing teeth were noted in 63%. All dolphins had subdermal haemorrhage (moderate to severe in 96%), particularly around the head. Deep haemorrhage was common, including around occipital and flipper condyles, and organs. Copious fluid was present in the thoracic (pleural) and abdominal (ascites) cavities of half of the dolphins. Within the lungs, watery fluid and froth were observed in 100 and 39%, respectively. Recent bone fractures were documented in 43% of dolphins, mostly associated with haemorrhage. Severe blunt trauma appeared to be the primary cause of death, and 10 dolphins also had other significant pathologies. Visceral organ congestion and mild cardiomyopathy were observed. Stomachs contained prey remains in 75% of cases. The results of this study may help identify unreported purse-seine mortalities washed up in South Australia and elsewhere.

Infectious diseases are significant demographic and evolutionary drivers of populations, but studies about the genetic basis of disease resistance and susceptibility are scarce in wildlife populations. Cetacean morbillivirus (CeMV) is a highly contagious disease that is increasing in both geographic distribution and incidence, causing unusual mortality events (UME) and killing tens of thousands of individuals across multiple cetacean species worldwide since the late 1980s. The largest CeMV outbreak in the Southern Hemisphere reported to date occurred in Australia in 2013, where it was a major factor in a UME, killing mainly young Indo‐Pacific bottlenose dolphins (Tursiops aduncus). Using cases (nonsurvivors) and controls (putative survivors) from the most affected population, we carried out a genome‐wide association study to identify candidate genes for resistance and susceptibility to CeMV. The genomic data set consisted of 278,147,988 sequence reads and 35,493 high‐quality SNPs genotyped across 38 individuals. Association analyses found highly significant differences in allele and genotype frequencies among cases and controls at 65 SNPs, and Random Forests conservatively identified eight as candidates. Annotation of these SNPs identified five candidate genes (MAPK8, FBXW11, INADL, ANK3 and ACOX3) with functions associated with stress, pain and immune responses. Our findings provide the first insights into the genetic basis of host defence to this highly contagious disease, enabling the development of an applied evolutionary framework to monitor CeMV resistance across cetacean species. Biomarkers could now be established to assess potential risk factors associated with these genes in other CeMV‐affected cetacean populations and species. These results could also possibly aid in the advancement of vaccines against morbilliviruses. [ABSTRACT FROM AUTHOR]

Abstract This study provides the first assessment of the occurrence, distribution and abundance of cetaceans in shelf and coastal waters off the western Eyre Peninsula, eastern Great Australian Bight, South Australia. We undertook aerial line transect surveys to estimate the abundance of common dolphins, and to assess the occurrence and distribution of other small and large cetaceans. Two along shore surveys were also flown to assess occurrence of endangered southern right whales in coastal waters. Five cetacean species were detected: seven southern right whales, three humpback whales, one minke whale (unknown species), 71 schools of common dolphins, and 14 schools of bottlenose dolphins. Abundance of common dolphins was estimated to be 20,000–22,000 using distance sampling methods with densities of 0.67–0.73 dolphin/km2. Comparisons of common dolphin densities off the Eyre Peninsula in the eastern GAB with other regions around the world show that shelf waters off the Eyre Peninsula represent an important habitat for common dolphins. [ABSTRACT FROM AUTHOR]

Predation risk has a profound influence on the behavior of marine mammals, affecting grouping patterns and habitat use. Dolphins frequently bear evidence of shark bites, which can provide an indirect measure of predation pressure. Using photo-identification data, we investigated the prevalence of shark bites on three sympatric species of inshore dolphin, the Australian snubfin ( Orcaella heinsohni), Australian humpback ( Sousa sahulensis), and Indo-Pacific bottlenose dolphin ( Tursiops aduncus), among four study sites in northwestern Australia. Bite prevalence varied markedly between species, with 72% of snubfin, 46% of humpback, and 18% of bottlenose dolphins exhibiting evidence of shark bites. Binomial logistic regression confirmed a high likelihood of bite presence on snubfin dolphins, and at one particular site for snubfin and bottlenose dolphins. The prevalence of tiger shark ( Galeocerdo cuvier) bites on snubfin dolphins was high, and bites attributed to other carcharhinid sharks were observed on all species. While acknowledging methodological differences with other studies, the prevalence of shark bites on snubfin dolphins is among the highest reported for any dolphins, suggesting predation risk represents an important but varying influence thereon. This study provides a baseline for future investigations into the affect of predation risk on the behavioral ecology of these sympatric species. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Taxonomic revision of the humpback dolphins and description of a new species from Australia" by Thomas A. Jefferson and Howard C. Rosenbaum.

Little is known about the Australian snubfin (Orcaella heinsohni) and Indo-Pacific humpback (Sousa chinensis) dolphins (‘snubfin’ and ‘humpback dolphins’, hereafter) of north-western Australia. While both species are listed as ‘near threatened’ by the IUCN, data deficiencies are impeding rigorous assessment of their conservation status across Australia. Understanding the genetic structure of populations, including levels of gene flow among populations, is important for the assessment of conservation status and the effective management of a species. Using nuclear and mitochondrial DNA markers, we assessed population genetic diversity and differentiation between snubfin dolphins from Cygnet (n = 32) and Roebuck Bays (n = 25), and humpback dolphins from the Dampier Archipelago (n = 19) and the North West Cape (n = 18). All sampling locations were separated by geographic distances >200 km. For each species, we found significant genetic differentiation between sampling locations based on 12 (for snubfin dolphins) and 13 (for humpback dolphins) microsatellite loci (FST = 0.05–0.09; P<0.001) and a 422 bp sequence of the mitochondrial control region (FST = 0.50–0.70; P<0.001). The estimated proportion of migrants in a population ranged from 0.01 (95% CI 0.00–0.06) to 0.13 (0.03–0.24). These are the first estimates of genetic diversity and differentiation for snubfin and humpback dolphins in Western Australia, providing valuable information towards the assessment of their conservation status in this rapidly developing region. Our results suggest that north-western Australian snubfin and humpback dolphins may exist as metapopulations of small, largely isolated population fragments, and should be managed accordingly. Management plans should seek to maintain effective population size and gene flow. Additionally, while interactions of a socio-sexual nature between these two species have been observed previously, here we provide strong evidence for the first documented case of hybridisation between a female snubfin dolphin and a male humpback dolphin. [ABSTRACT FROM AUTHOR]

The article analyzes the feeding ecology of Australian snubfin (Orcaella heinsohni) and Indo-Pacific humpback dolphins (Sousa chinensis). These two subspecies of dolphins are found in coastal waters of Queensland, Northern Territory and north Western Australia. The feeding ecology of them is important to understand their potential effects on ecosystem function.

The bycatch of small cetaceans in commercial fisheries is a global wildlife management problem. We used data from skippers' logbooks and independent observers to assess common bottlenose dolphin (Tursiops truncatus) bycatch patterns between 2003 and 2009 in the Pilbara Trawl Fishery, Western Australia. Both datasets indicated that dolphins were caught in all fishery areas, across all depths and throughout the year. Over the entire datasets, observer reported bycatch rates (n = 52 dolphins in 4,124 trawls, or 12.6 dolphins/1,000 trawls) were ca. double those reported by skippers (n = 180 dolphins in 27,904 trawls, or 6.5 dolphins/1,000 trawls). Generalised Linear Models based on observer data, which better explained the variation in dolphin bycatch, indicated that the most significant predictors of dolphin catch were: (1) vessel - one trawl vessel caught significantly more dolphins than three others assessed; (2) time of day – the lowest dolphin bycatch rates were between 00:00 and 05:59; and (3) whether nets included bycatch reduction devices (BRDs) - the rate was reduced by ca. 45%, from 18.8 to 10.3 dolphins/1,000 trawls, after their introduction. These results indicated that differences among vessels (or skippers' trawling techniques) and dolphin behavior (a diurnal pattern) influenced the rates of dolphin capture; and that spatial or seasonal adjustments to trawling effort would be unlikely to significantly reduce dolphin bycatch. Recent skipper's logbook data show that dolphin bycatch rates have not declined since those reported in 2006, when BRDs were introduced across the fishery. Modified BRDs, with top-opening escape hatches from which dolphins might escape to the surface, may be a more effective means of further reducing dolphin bycatch. The vulnerability of this dolphin population to trawling-related mortality cannot be assessed in the absence of an ongoing observer program and without information on trawler-associated dolphin community size, broader dolphin population size and connectivity with adjacent populations. [ABSTRACT FROM AUTHOR]

The recent industrial boom along the Australian coastline has increased concerns about the long term conservation of snubfin dolphins along the Queensland coast. National assessment of the conservation status and management of the Australian snubfin dolphin is currently hindered by the lack of adequate biological and ecological information throughout most of its range. In response to the issue of determining the conservation status of species with broad ranges, the IUCN has provided a framework for assessing the threatened status of regional populations. In this study we assessed the conservation status of a small geographically isolated population of snubfin dolphins living in the Fitzroy River region, Queensland, Australia, against the IUCN criteria for regional populations. A review of all available sightings data and stranding information indicates that this is the southernmost resident population of snubfin dolphins in Australian waters. The Fitzroy River snubfin dolphin population is composed of less than 100 individuals, with a representative range and core area of less than 400 and 300 km2 respectively. The area most often used by snubfin dolphins within the representative range and core area was estimated to be about 292 and 191 km2, respectively. A decrease in representative range, core area and preferred habitat between 14 and 25% is projected to occur if a planned industrial port development were to occur. These results are robust to uncertainty and considering the low level of formal protection and future threats, a classification of this subpopulation under the IUCN Red List as “Endangered” is appropriate. [ABSTRACT FROM AUTHOR]

Human-caused mortality of wildlife is a pervasive threat to biodiversity. Assessing the population-level impact of fisheries bycatch and other human-caused mortality of wildlife has typically relied upon deterministic methods. However, population declines are often accelerated by stochastic factors that are not accounted for in such conventional methods. Building on the widely applied potential biological removal (PBR) equation, we devised a new population modeling approach for estimating sustainable limits to human-caused mortality and applied it in a case study of bottlenose dolphins affected by capture in an Australian demersal otter trawl fishery. Our approach, termed sustainable anthropogenic mortality in stochastic environments (SAMSE), incorporates environmental and demographic stochasticity, including the dependency of offspring on their mothers. The SAMSE limit is the maximum number of individuals that can be removed without causing negative stochastic population growth. We calculated a PBR of 16.2 dolphins per year based on the best abundance estimate available. In contrast, the SAMSE model indicated that only 2.3-8.0 dolphins could be removed annually without causing a population decline in a stochastic environment. These results suggest that reported bycatch rates are unsustainable in the long term, unless reproductive rates are consistently higher than average. The difference between the deterministic PBR calculation and the SAMSE limits showed that deterministic approaches may underestimate the true impact of human-caused mortality of wildlife. This highlights the importance of integrating stochasticity when evaluating the impact of bycatch or other human-caused mortality on wildlife, such as hunting, lethal control measures, and wind turbine collisions. Although population viability analysis (PVA) has been used to evaluate the impact of human-caused mortality, SAMSE represents a novel PVA framework that incorporates stochasticity for estimating acceptable levels of human-caused mortality. It offers a broadly applicable, stochastic addition to the demographic toolbox to evaluate the impact of human-caused mortality on wildlife., (© 2022 The Authors. Conservation Biology published by Wiley Periodicals LLC on behalf of Society for Conservation Biology.)

Since 1992, wild dolphin provisioning has occurred on a nightly basis at Tangalooma, a resort located on Moretón Island, Australia. Each evening at dusk up to 12 bottlenose dolphins (Tursiops sp.) are provided with fish in a regulated provisioning program. Since July 1998, biologists managing the program have documented 23 occurrences of "gift giving," when several of the provisioned dolphins have offered wild-caught cephalopod or fin fish species to staff members. The characteristics of each of these events are presented, and we explore the relationships between these events and their temporal patterns, and the age and sex of the dolphins involved. We also consider the behavioral explanations for the "gift giving," including prey sharing, play, and teaching behaviors, which have previously been described for cetaceans and other higher mammals. Gift giving may occur either as a discreet behavior (that may be a sequel to one or more other behaviors such as play or food preparation), or as a part of other behaviors, such as play and/or food sharing. It is most likely a manifestation of the particular relationship between the provisioned dolphins and the human participants in the provisioning. Gift giving has become an established but infrequent part of the culture of the provisioned dolphins at Tangalooma. [ABSTRACT FROM AUTHOR]

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 photo-identification 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. [ABSTRACT FROM AUTHOR]

The essay describes developments in the coastal area in northwest Australia and their impact on the Snubfin and Humpback dolphins. Conservation laws provide guidelines for the protection of these dolphins that are considered threatened by expansion of the mining and petroleum industries in Western Australia (WA). With the limitation of the current environmental impact assessment (EIA), it is urged that more data on the dolphin species should be included.

Small coastal dolphins endemic to south-eastern Australia have variously been assigned to described species Tursiops truncatus, T. aduncus or T. maugeanus; however the specific affinities of these animals is controversial and have recently been questioned. Historically 'the southern Australian Tursiops' was identified as unique and was formally named Tursiops maugeanus but was later synonymised with T. truncatus. Morphologically, these coastal dolphins share some characters with both aforementioned recognised Tursiops species, but they also possess unique characters not found in either. Recent mtDNA and microsatellite genetic evidence indicates deep evolutionary divergence between this dolphin and the two currently recognised Tursiops species. However, in accordance with the recommendations of the Workshop on Cetacean Systematics, and the Unified Species Concept the use of molecular evidence alone is inadequate for describing new species. Here we describe the macro-morphological, colouration and cranial characters of these animals, assess the available and new genetic data, and conclude that multiple lines of evidence clearly indicate a new species of dolphin. We demonstrate that the syntype material of T. maugeanus comprises two different species, one of which is the historical 'southern form of Tursiops' most similar to T. truncatus, and the other is representative of the new species and requires formal classification. These dolphins are here described as Tursiops australis sp. nov., with the common name of 'Burrunan Dolphin' following Australian aboriginal narrative. The recognition of T. australis sp. nov. is particularly significant given the endemism of this new species to a small geographic region of southern and south-eastern Australia, where only two small resident populations in close proximity to a major urban and agricultural centre are known, giving them a high conservation value and making them susceptible to numerous anthropogenic threats. [ABSTRACT FROM AUTHOR]

The Broome Shire Council's decision in 2009 to suspend the sister-town relationship because of controversy over Taiji's practice of culling dolphins galvanized Broome's Asian and Asian-Aboriginal community (hereafter referred to as poly-ethnic community) to oppose this move. This, and other examples explored in this paper, attests to the strong connection between these two groups that has shaped a distinctive 'Broome culture'. This paper explores ways in which Japanese working in the pearling industry contributed to the emergence of a Broome culture through their historic ties with Aborigines. Some of these ties are through family lineage; others are through vast interlocking familial and friendship networks in Broome's Asian-Aboriginal community. Recent interviews attest to the enduring nature of these networks. [ABSTRACT FROM AUTHOR]

Understanding the foraging ecology and diet of animals can play a crucial role in conservation of a species. This is particularly true where species are cryptic and coexist in environments where observing feeding behaviour directly is difficult. Here we present the first information on the foraging ecology of a recently identified species of dolphin (Southern Australian bottlenose dolphin (SABD)) and comparisons to the common bottlenose dolphin (CBD) in Victoria, Australia, using stable isotope analysis of teeth. Stable isotope signatures differed significantly between SABD and CBD for both δ13C (-14.4% vs. -15.5% respectively) and δ15N (15.9% vs. 15.0% respectively), suggesting that the two species forage in different areas and consume different prey. This finding supports genetic and morphological data indicating that SABD are distinct from CBD. In Victoria, the SABD is divided into two distinct populations, one in the large drowned river system of Port Phillip Bay and the other in a series of coastal lakes and lagoons called the Gippsland Lakes. Within the SABD species, population differences were apparent. The Port Phillip Bay population displayed a significantly higher δ15N than the Gippsland Lakes population (17.0% vs. 15.5%), suggesting that the Port Phillip Bay population may feed at a higher trophic level - a result which is supported by analysis of local food chains. Important future work is required to further understand the foraging ecology and diet of this newly described, endemic, and potentially endangered species of dolphin. [ABSTRACT FROM AUTHOR]

Oceanographic processes play a significant role in shaping the genetic structure of marine populations, but it is less clear whether they affect genetic differentiation of highly mobile vertebrates. We used microsatellite markers and mtDNA control region sequences to investigate the spatial genetic structure of short-beaked common dolphins ( Delphinus delphis) in southeastern Australia, a region characterised by complex oceanographic conditions associated with the East Australian Current (EAC). A total of 115 biopsy samples of dolphins were collected from six localities spanning approximately 1,000 km of the New South Wales (NSW) coastline. We found evidence for contrasting genetic diversity and fine-scale genetic structure, characterised by three genetically differentiated populations with varying levels of admixture. Spatial genetic structure was not explained by a model of isolation by distance, instead it coincides with main patterns of oceanographic variation along the EAC. We propose that common dolphins along the EAC may be adapted to three water masses recently characterised in this region. [ABSTRACT FROM AUTHOR]

Interactions between short-beaked common dolphins Delphinus delphis and the fishing industry of South Australia (SA) have lead to serious concerns over the long-term viability of the local dolphin population. Common dolphins are gregarious animals with high vagility and are expected to display limited genetic differentiation over large spatial scales. Here, we investigate population genetic structure of southern Australian common dolphins using mitochondrial DNA control region sequences and seven microsatellite markers. We found unexpected levels of genetic differentiation for short-beaked common dolphins over a distance of ∼1500 km. Although no genetic structure was observed in common dolphins along the coast of SA, we detected marked differentiation between dolphins from SA and south-eastern Tasmania, suggesting a minimum of two genetic populations in southern Australia. We hypothesize that the ephemeral distribution of small pelagic fish enhances movement and dispersal between dolphin groups at a local level. However, clear differences in water temperature, habitat features and fish abundance between SA and Tasmania may contribute to the contemporary isolation observed between dolphin populations. Our findings have important consequences for developing conservation management strategies, because SA has the largest purse-seine fishery by weight in Australia, and substantial numbers of fatal common dolphin interactions have occurred. In 2004/2005 alone, an estimated 1728 common dolphins were encircled and 377 died over a 7-month period. If these impacts lead to a reduction in population size, it is unlikely that dolphins from the adjacent south-eastern Tasmanian population will replace the lost individuals. Recommendations for assessing the impacts of the fishery are presented. The information herein may also have implications for fisheries–marine mammal interactions in coastal and neritic habitats in other areas of the world. Moreover, we demonstrate that a species commonly thought to be wide ranging can show an unexpected degree of genetic differentiation. [ABSTRACT FROM AUTHOR]

Mortality of calves born to provisioned mothers is identified in the literature as an issue of concern in dolphin provisioning programs. Wild dolphin provisioning at Tangalooma, Moreton Island, Australia has been occurring since 1992. Each evening, up to eight dolphins are provided with fish in a regulated provisioning program. In this paper, calf survival at the Tangalooma provisioning program is reported and contrasted with that from wild populations and from a similar provisioning program at Monkey Mia, Western Australia. At Tangalooma, the calf survival rate is 100%, including both orphaned and first-born calves, both of which are expected to have relatively low survival rates. Possible explanations for the high calf survival rate are explored. These include site attributes such as isolated location and high water quality, aspects of foraging ecology likely to benefit calves of provisioned mothers, and the management regime used in the provisioning program (e.g., duration and timing of provisioning; quality of provisioned fish). [ABSTRACT FROM AUTHOR]

Metal and selenium concentrations (wet weight) were determined in the liver (Cd, Hg, Pb, Zn, Cu and Se) and bone (Pb and Cd) of common dolphins (Delphinus delphis, N =71) and bottlenose dolphins (Tursiops truncatus, N =12, and Tursiops aduncus, N =71) stranded or by-caught in South Australia from 1988 to 2004. Differences in metal burdens existed between species, stranding location, and relative age. T. aduncus had the greatest mean tissue burdens of liver Pb (0.45 mg/kg), Cd (6.45 mg/kg), Hg (475.78 mg/kg), Se (178.85 mg/kg) and Zn (93.88 mg/kg) and bone Pb (2.78 mg/kg), probably reflecting their coastal habitat and benthic prey. Mean Cu was highest in T. truncatus (21.18 mg/kg). Bone Cd was measured only in T. aduncus and averaged 0.05 mg/kg. Stranding location impacted metal burdens. Dolphins from Spencer Gulf had higher mean levels of liver Pb (0.39 mg/kg) while Gulf St Vincent dolphins had greater liver Hg (444.64 mg/kg), liver Se (163.12 mg/kg), and bone Pb (2.85 mg/kg). This may be due to high anthropogenic inputs of Pb and Hg into Spencer Gulf and Gulf St Vincent respectively. Liver Cd, Hg, Se and Pb increased with age in all species while Cu decreased with age, in keeping with previous studies. Se and Hg were positively correlated. The possibility that metallothioneins are driving observed correlations between Zn, Cd, Hg and Cu are discussed. Future research must investigate the toxicological consequences of the metal concentrations reported. [Copyright &y& Elsevier]

We documented immediate, behavioural responses of Indo-Pacific bottlenose dolphins (Tursiops sp.) to experimental vessel approaches in regions of high and low vessel traffic in Shark Bay, Western Australia. Experimental vessel approaches elicited significant changes in the behaviour of targeted dolphins when compared with their behaviour before and after approaches. During approaches, focal dolphin groups became more compact, had higher rates of change in membership and had more erratic speeds and directions of travel. Dolphins in the region of low vessel traffic (control site) had stronger and longer-lasting responses than did dolphins in the region of high vessel traffic (impact site). In the absence of additional information, the moderated behavioural responses of impact-site dolphins probably would be interpreted to mean that long-term vessel activity within a region of tourism had no detrimental effect on resident dolphins. However, another study showed that dolphin-watching tourism in Shark Bay has contributed to a long-term decline in dolphin abundance within the impact site (Bejder et al., in press, Conservation Biology). Those findings suggest that we documented moderated responses not because impact-site dolphins had become habituated to vessels but because those individuals that were sensitive to vessel disturbance left the region before our study began. This reinterpretation of our findings led us to question the traditional premise that short-term behavioural responses are sufficient indicators of impacts of anthropogenic disturbance on wildlife. [Copyright &y& Elsevier]

1. Many species of delphinids co-occur in space and time. However, little is known of their ecological interactions and the underlying mechanisms that mediate their coexistence. 2. Snubfin Orcaella heinsohni, and Indo-Pacific humpback dolphins Sousa chinensis, live in sympatry throughout most of their range in Australian waters. I conducted boat-based surveys in Cleveland Bay, north-east Queensland, to collect data on the space and habitat use of both species. Using Geographic Information Systems, kernel methods and Euclidean distances I investigated interspecific differences in their space use patterns, behaviour and habitat preferences. 3. Core areas of use (50% kernel range) for both species were located close to river mouths and modified habitat such as dredged channels and breakwaters close to the Port of Townsville. Foraging and travelling activities were the dominant behavioural activities of snubfin and humpback dolphins within and outside their core areas. 4. Their representative ranges (95% kernel range) overlapped considerably, with shared areas showing strong concordance in the space use by both species. Nevertheless, snubfin dolphins preferred slightly shallower (1–2 m) waters than humpback dolphins (2–5 m). Additionally, shallow areas with seagrass ranked high in the habitat preferences of snubfin dolphins, whereas humpback dolphins favoured dredged channels. 5. Slight differences in habitat preferences appear to be one of the principal factors maintaining the coexistence of snubfin and humpback dolphins. I suggest diet partitioning and interspecific aggression as the major forces determining habitat selection in these sympatric species. [ABSTRACT FROM AUTHOR]

Abstract: Powerboats are potentially a significant source of disturbance to coastal cetaceans. Information is scarce, however, on the nature of interactions between powerboats and dolphins, particularly when both surface and acoustic behaviour are combined. The surface behaviour and acoustic response of travelling dolphins to approaches by a powerboat were assessed by a series of experimental trials between November 2001 and November 2003 in Jervis Bay, New South Wales, Australia. Dolphin behaviour was monitored continuously from an independent research boat before, during and after a powerboat approached (n =12). Treatments were interspersed with control observations (n =12). Changes in surface behaviour indicated differences between the treatment and control periods (z =2.24, p =0.025), with dolphins tending to alter their surface behaviour when exposed to the powerboat approach. Analysis also revealed a change in the direction of travel by dolphin groups when approached (z =3.22, p =0.001). Changes in surface behaviour occurred at vessel approach distances outside the minimum approach distance of 30m for recreational and commercial vessels, as proposed by the New South Wales National Parks and Wildlife Service. In contrast, there were no changes in dolphin whistle rates (F 3,12 =0.74, p =0.54) or the duration of echolocation click bouts (F 3,12 =0.76, p =0.59) when approached. These findings indicate that powerboats do affect the surface behaviour and direction of travelling inshore bottlenose dolphins in Jervis Bay; however it appears that this impact is not reflected in their acoustic behaviour. [Copyright &y& Elsevier]

Comparisons of the Irrawaddy dolphin, Orcaella brevirostris, between Australian and Asian sites documented geographic differences in height of dorsal fin, presence or absence of a median dorsal groove in front of the dorsal fin, and coloration (presence or absence of a dorsal cape). Analysis of genetic data provided support for two clades within the Asian samples, the Mekong River samples from Cambodia and southern Laos, and all other marine and freshwater sites from Thailand, Indonesia, and the Philippines. The major separation, however, was between sites in Asia and those from Australia (5.9% of base pair differences, compared with 1.2% for within Australia and 1.5% for within Asia). Within a 403 base segment of the mrDNA control region, Australian specimens had 17 diagnostic sites with 16 fixed base pair differences and one insertion/deletion. Consistent, statistically significant differences in skull characters of Australian specimens have previously been demonstrated and are reviewed in this paper. There was a high concordance in character differences demonstrated between O. brevirostris from all Asian sites and Australian specimens, especially in the genetic and osteological characters. Based on the range and concordance of character differences, we propose that the Australian dolphins be recognized as a new species, Orcaella heinsohni (suggested common name: Australian snubfin dolphin). [ABSTRACT FROM AUTHOR]

Managing the activities of commercial wildlife viewing tends to involve either restricting the number of industry participants and/or regulating the activities or industry participants. We report on operator compliance with regulations regarding humans swimming with free-ranging bottlenose dolphins (Tursiops sp.) in Port Phillip Bay, Victoria, Australia. A total of 128 commercial dolphin-swim trips was studied between September 1998 and April 2000. Four permit conditions were investigated: approach type, swim time, time in proximity of dolphins, and presence of “fetal fold” calves. Results demonstrate noncompliance by operators to all of the four permit conditions studied. Compliance with temporal conditions was poorer than with other conditions. When conducting studies on the extent to which tourism affects cetaceans, investigators should consider whether tourist operations comply with existing regulations or guidelines. [ABSTRACT FROM AUTHOR]

Published eyewitness accounts and stories from Aboriginal Australians are used to provide an overview of the geographical extent and characteristics of cooperative fishing between Aboriginal Australians and dolphins in eastern Australia. These sources indicate that cooperative fishing was geographically widespread in eastern Australia, involved both bottlenose dolphins and orcas, and had a significance (emotional and spiritual) to Aboriginal people beyond the acquisition of food. These fishing interactions represent both context and precedent for the economic and emotional objectives of contemporary human-dolphin interactions such as dolphin provisioning. [ABSTRACT FROM AUTHOR]

This study examines factors influencing female reproductive success in wild Indian Ocean bottlenose dolphins (Tursiops sp.) in Shark Bay, Australia. Eighty-three females and their 142 calves were surveyed between 1988 and 1998 (3457 surveys); 42 calves were also observed during focal follows for 1330 h. Calf mortality is 44% by age 3 (n = 110). Reproduction is moderately seasonal (September-January), peaking from October to December. Calf loss between August and December is followed by rapid conception (1-2 months), whereas conception is delayed (2-9 months) if calf loss occurs between January and July. Weaning ages ranged from 2.7 to 8.0 years, but 66.7% (42 calves) were weaned by their fourth birthday. Females tended to wean mid-pregnancy. Accordingly, median interbirth interval was 4.1 years. Female reproductive success was classified as 0, 1, 2, or 3 according to the number of calves who survived to age 3 over a 10-year period (n = 38 females with complete histories). We examined whether factors affecting predation or food availability, water depth, and group size, were related to female reproductive success. Group size was unrelated to water depth or female reproductive success, but reproductive success was predicted by water depth (p <.002). Shallow water may allow mothers and calves to detect and avoid predatory sharks. Alternatively, or additionally, prey density may be higher in shallow water compared to deep water. [ABSTRACT FROM AUTHOR]