Context The taxonomic status of Orcaella spp. in Papua New Guinea waters is unknown. The Australian snubfin dolphin (Orcaella heinsohni) has been identified from northern Australian waters south of Papua New Guinea, and the Irrawaddy dolphin (Orcaella brevirostris) from Borneo north-west of Papua New Guinea. Aims This study analysed samples of Orcaella spp. from Papua New Guinea and northern Australia to confirm the species of Orcaella that occurs in Papua New Guinea waters. Methods Genetic analyses were conducted on 11 Orcaella spp. samples from Papua New Guinea and eight new Australian snubfin dolphin samples from northern Australia, including the type specimen. A 489-base sequence of the mitochondrial control region (HVR-1) was analysed using Maximum Likelihood and Bayesian Inference to infer phylogenetic relationships. Key results Phylogenetic reconstruction showed that the Papua New Guinea samples are nested within Australian snubfin dolphin samples and did not form a monophyletic group. Conclusions These results confirm that the Australian snubfin dolphin occurs in southern Papua New Guinea. Implications There are no confirmed records of Orcaella spp. from other regions of Papua New Guinea, or the Pacific Islands. The geographic demarcation between Australian snubfin and Irrawaddy dolphin populations remains unknown, although it is located within the Wallacea region. The viability of this apparently small, isolated population of Australian snubfin dolphins is uncertain. The main threat to this population is accidental by-catch in gillnet fisheries. Conservation and management strategies that focus on mitigating by-catch are urgently required.

The Irrawaddy dolphin (Orcaella brevirostris) is an endangered cetacean that ranges throughout much of Southeast Asia and lives in coastal, estuarine, and riverine habitats including three river systems: Ayeyarwady, Mekong, and Mahakam. Many populations face risks from human interference, but overall rangewide diversity and connectivity is not well-understood. Here we sequenced 77 complete mitogenomes from across the range of the Irrawaddy dolphin including all obligate riverine populations; eighteen of these were sequenced from historical museum specimens. Phylogenetic analysis showed haplotypes from each riverine population formed separate clades nested within the wider species implying each river system was separately invaded only once. All Irrawaddy dolphin mitogenomes were dated to a last common ancestor similar to 764 kya. Most lineages appeared after inundation cycles of the Sunda Shelf were initiated similar to 400 kya. Despite the lack of monophyly among many haplotypes from the same population, no population shared any haplotypes. Rangewide nucleotide diversity was average compared to other odontocetes, but riverine populations were especially low. Differentiation was significant among all populations analyzed with the most divergence occurring between isolated riverine populations. These analyses add more evidence for the necessity of conservation efforts directed towards riverine and other isolated populations of the Irrawaddy dolphin.

A geographically isolated population of Irrawaddy dolphins was recently discovered in Malampaya Sound, Palawan, Philippines. Line-transect surveys conducted in April-November 2001 covered 884km of trackline in the entire Sound and resulted in a total population estimate of 77 individuals (CV = 27.4%), confined to the inner portion (133.7km2 ). For all Irrawaddy dolphin sightings, where ecological data were collected (n = 48), the mean temperature was 30.2°C, depth 6.5m, salinity 28.3ppt and turbidity 2.2NTUs. Significantly higher turbidity, lower salinity and shallower depth were recorded in the inner Sound compared to adjacent waters. Bottlenose dolphins Tursiops sp. (probably truncatus) were observed in waters just outside of where Irrawaddy dolphins were recorded. During the study, at least two Irrawaddy dolphins were accidentally killed in bottom-set nylon gillnets used to catch crabs, locally called matang quatro. Reports from local fishermen also indicated that as many as three additional animals may have been killed in these nets during the same period. These findings strongly suggest that the Irrawaddy dolphin population in Malampaya Sound is in immediate danger of extirpation due to low numbers, limited range and high mortality. This is the only known population of the species in the Philippines and the nearest known other population is in northern Borneo, some 550km to the south. Recommendations for conserving the population include that: (1) socioeconomic alternatives be developed to promote the conservation goal of reducing the incidence of dolphin entanglement in matang quatro gillnets; (2) gillnet free zones be established in core areas of dolphin distribution; (3) Irrawaddy dolphins be promoted as a flagship species of environmental health in the Sound; (4) a long-term programme be established to monitor the dolphin population; and (5) additional investigations be conducted to determine if Irrawaddy dolphins occur in other areas of the Philippines.

River cetaceans are particularly vulnerable to anthropogenic impacts due to their constrained ranges in freshwater systems of China, South Asia, and South America. We undertook an exhaustive review of 280 peer-reviewed papers and grey literature reports (1998-2020) to examine the current status of knowledge regarding these cetaceans and their conservation. We aimed to better understand the scale of threats they face, and to identify and propose priority future efforts to better conserve these species. We found that the species have been studied with varying frequency and that most of the research on threats has focused on habitat degradation and fragmentation (43%, mainly driven by dams and extractive activities such as sand mining and deforestation), and fishery interactions (39%, in the form of bycatch and direct take). These threats occur across all species, but more information is needed, primarily on quantifying the population impacts as a basis for designing mitigation measures. Other threats identified include pollution, vessel collisions, traditional use, and poorly managed tourism. Emerging methods such as environmental DNA and unmanned aerial vehicles are described for studying these species. Promising conservation interventions include cetacean-specific protected areas, natural ex situ protection, community-led conservation, and education programmes. However, transnational political will is required for a step change towards broad-scale protection in freshwater environments. In addition, we propose increasing capacity building, developing management plans, working closely with fishing communities, enhancing public awareness, expanding regional collaborations, and diversifying funding.

Cetacean-watch tourism in developing countries remains poorly documented, and often poorly managed as a result of limited in-country capacity, ineffective governance, conflicting policy goals, and limited accountability. The dolphin-watch tourism that targets the population of Irrawaddy dolphins, Orcaella brevirostris, in the Mekong River in Cambodia and Laos is used as a case study to illustrate growing concerns associated with cetaceanwatch tourism in developing countries. In the early 1990s, unregulated and unmanaged dolphinwatching tourism began in two of the most important habitats for this population, which now numbers less than 100 individuals. An Integrated Conservation Development Project, ‘Dolphins for Development’, was initiated in Kampi Village, Cambodia in 2004. This Project included an attempt to manage the existing dolphin-watch tourism through: (1) promoting the sharing of tourism revenue to the local community; (2) encouraging effective management of the industry to minimize threats to the dolphins; (3) promoting visitor satisfaction; and (4) raising community and visitor awareness of the status of the dolphins and the need for conservation. Although the initial results were encouraging, subsequent government intervention has resulted in: (1) a large increase in the number of boats operating in prime dolphin habitat and an increase in the harassment of dolphins; (2) reduction in the benefit to local communities; and (3) little or no information being provided to national or international tourists. Although management agencies are implementing significant conservation measures to reduce the threat to the dolphins from gillnet fishing by subsistence fishers, few efforts are being directed towards management of the dolphin-watch tourism industry. The urgent need to develop dolphin-watching tourism management initiatives in Cambodia was highlighted at the 2010 International Whaling Commission meeting, where a ‘no vessel-based’ dolphin tourism policy was recommended. A precautionary approach to management is needed to address the problem of unsustainable cetacean-watching currently occurring in numerous developing countries. This approach should be informed by location-specific and comprehensive studies on both the ecology of the dolphin–tourism interactions and the social, economic, managerial and political influences on cetacean-watch operations.

New data are reported from analyses of stomach contents from 114 long-finned pilot whales mass-stranded at four locations around Tasmania, Australia from 1992-2006. Identifiable prey remains were recovered from 84 (74%) individuals, with 30 (26%) individuals (17 females and 13 males) having empty stomachs. Prey remains comprised 966 identifiable lower beaks and 1244 upper beaks, belonging to 17 families (26 species) of cephalopods. Ommastrephidae spp. were the most important cephalopod prey accounting for 16.9% by number and 45.6% by reconstructed mass. Lycoteuthis lorigera was the next most important, followed by Ancistrocheirus lesueurii. Multivariate statistics identified significant differences in diet among the four stranding locations. Long-finned pilot whales foraging off Southern Australia appear to be targeting a diverse assemblage of prey (≥10 species dominated by cephalopods). This is compared to other similar studies from New Zealand and some locations in the Northern Hemisphere, where the diet has been reported to be primarily restricted to ≤3 species dominated by cephalopods. This study emphasises the importance of cephalopods as primary prey for Southern long-finned pilot whales and other marine vertebrates, and has increased our understanding of long-finned pilot whale diet in Southern Ocean waters.

In threatened wildlife populations, it is important to determine whether observed low genetic diversity may be due to recent anthropogenic pressure or the consequence of historic events. Historical size of the Irrawaddy dolphin (Orcaella brevirostris) population inhabiting the Mekong River is unknown and there is significant concern for long-term survival of the remaining population as a result of low abundance, slow reproduction rate, high neonatal mortality, and continuing anthropogenic threats. We investigated population structure and reconstructed the demographic history based on 60 Irrawaddy dolphins samples collected between 2001 and 2009. The phylogenetic analysis indicated reciprocal monophyly of Mekong River Orcaella haplotypes with respect to haplotypes from other populations, suggesting long-standing isolation of the Mekong dolphin population from other Orcaella populations. We found that at least 85% of all individuals in the two main study areas: Kratie and Stung Treng, bore the same mitochondrial haplotype. Out of the 21 microsatellite loci tested, only ten were polymorphic and exhibited very low levels of genetic diversity. Both individual and frequency-based approaches suggest very low and non-significant genetic differentiation of the Mekong dolphin population. Evidence for recent bottlenecks was equivocal. Some results suggested a recent exponential decline in the Mekong dolphin population, with the current size being only 5.2% of the ancestral population. In order for the Mekong dolphin population to have any potential for long-term survival, it is imperative that management priorities focus on preventing any further population fragmentation or genetic loss, reducing or eliminating anthropogenic threats, and promoting connectivity between all subpopulations.

The Australian snubfin dolphin is a close relative of the Irrawaddy river dolphin and occurs largely in nearshore areas, as does the latter. It was only recently described as a separate species, largely by skull morphology and recent genetics.

The Australian humpback dolphin, Sousa sahulensis, has recently been described to occur in northern Australian coastal waters. However, its distribution in adjacent waters of the Pacific Islands and New Guinea remains largely unknown. Although there have been few studies conducted on inshore dolphins in these regions, the available information records humpback dolphins primarily from the Kikori Delta in Papua New Guinea, and Bird's Head Seascape in West Papua. Research in southern Papua New Guinea indicates that humpback dolphins are indeed S. sahulensis, based on cranial and external morphometrics, external colouration and the preliminary genetic analysis presented here. A similar situation exists for the Australian snubfin dolphin, Orcaella heinsohni, where it is assumed that the species also occurs along the Sahul Shelf coastal waters of northern Australia and New Guinea. There are anecdotal reports of direct catch of Australian humpback dolphins for use as shark bait, coastal development is increasing, and anthropogenic impacts will continue to escalate as human populations expand into previously uninhabited regions. Future research and management priorities for the Governments of the Pacific Islands and Indonesia will need to focus on inshore dolphins in known regional hotspots, as current bycatch levels appear unsustainable.

Biodiversity assessments by research scientists are often logistically difficult and expensive to implement in remote areas. Locally-based approaches have the potential to overcome some of these challenges by capitalising on the knowledge and capacity of local people. Many Indigenous people in northern Australia are custodians of coastal areas that support globally significant populations of tropical marine mammals, including coastal dolphins and dugongs. The objective of our study was to design and implement a locally-based approach in a cross-cultural environment to assess the distribution of marine mammals in the remote waters of the Gulf of Carpentaria, Northern Territory. The study was conducted as a partnership between Yanyuwa Aboriginal families, research scientists, government officers and the li-Anthawirriyarra Sea Rangers. We conducted a series of participatory mapping workshops to share and record local observations of dolphins and dugongs. These observations provided the longitudinal information required to inform the design of the first dedicated marine mammal vessel survey in the Gulf of Carpentaria. The vessel surveys found three species of dolphins present in the area (Australian snubfin, humpback and bottlenose dolphins), even though sightings were low; dugongs being much more common. We found that the integrative and locally-based approach built the capacity of both the li-Anthawirriyarra Sea Rangers and research scientists to assess the distribution of marine mammals. If replicated over longer time-frames and coordinated over broader spatial scales, information on distribution and abundance derived from locally-based approaches has the potential to inform the status of marine mammals.

The population of Irrawaddy dolphins that occupies the Mekong River in southern Lao People's Democratic Republic and Cambodia is classified as Critically Endangered by the IUCN. Based on capture-recapture of photo-identified individuals, we estimated that the total population numbered 93 +/- SE 3.90 individuals (95% CI 86-101), as of April 2007. The combined photo-identification and carcass recovery program undertaken from 2001 to 2007 established that the Irrawaddy dolphin population inhabiting the Mekong River has reached a critical point with regards to its continued survival, where immediate research and management actions are required to greatly reduce adult mortality, and establish the cause of newborn mortality. In addition, community consultation is required to initiate, and evaluate, urgently required conservation measures. An ongoing well-designed combined program of abundance estimation (i.e., photo-identification) and carcass recovery is required to monitor total population size and mortality rates, to inform and evaluate management initiatives. The conclusions of this paper are likely generic to river dolphin populations, particularly where photo-identification is possible.

This study describes the stranding record of the Pygmy Sperm Whale, Kogia breviceps, in Tasmanian waters, and the diet of a single individual. The Pygmy Sperm Whale is one of the most commonly stranded cetaceans in some parts of Australia, although it occurs infrequently in the Tasmanian stranding record, with only seven known stranding events. Dietary items were investigated from a single juvenile male Pygmy Sperm Whale stranded in southeast Tasmania. The recoverable diet consisted of approximately three kilograms of reconstructed cephalopod prey mass from at least 11 cephalopod species within nine families. Using reconstructed biomass, the most important family was Histioteuthidae (Histioteuthis atlantica and H. miranda: 29% of reconstructed biomass), followed by Ommastrephidae (unknown sp.: 27% of reconstructed biomass), Enoploteuthidae (Enoploteuthis sp): 25% of reconstructed biomass), Cranchiidae (Cranchia scabra and Teuthowenia pellucida), Chiroteuthidae (Chiroteuthis veranyi), Brachioteuthidae (Brachioteuthis linkovskyi), Neoteuthidae (Nototeuthis dimegacotyle), Pyroteuthidae (Pyroteuthis margaritifera) and Sepiolidae (Heteroteuthis sp.). Collection and analysis of biological material from Pygmy Sperm Whale strandings around Australia should be a high priority to better understand the ecology of this poorly known species.

Conservation management relies on being able to identify and describe species. Recent morphological and molecular analyses of the dolphin genus Orcaella show a species-level disjunction between eastern Australia and South-east Asia. However, because of restricted sampling, the taxonomic affinities of the geographically intermediate populations in the Northern Territory and Western Australia remained uncertain. We sequenced 403 base pairs of the mitochondrial control region from five free-ranging Orcaella individuals sampled from north-western Western Australia and the Northern Territory. Low net nucleotide divergence (0.11–0.67%) among the Australian Orcaella populations show that populations occurring in the Northern Territory and Western Australia belong to the Australian snubfin (O. heinsohni) rather than the Asian Irrawaddy dolphin (O. brevirostris). Clarifying the distribution of Orcaella is an important first step in the conservation and management for both species; however, an understanding of the metapopulation structure and patterns of dispersal among populations is now needed.

The inshore waters of northern Australia support globally significant populations of three species of marine mammals of conservation concern: the endemic Australian Snubfin dolphin, a likely new endemic species of Humpback dolphin, and the dugong. Together, the Australian ranges of these coastal dolphins and dugong extend along some 32,000 kilometres of northern Australian coastline; around eighty percent of this region is in or adjacent to Sea Country over which Traditional Owners have significant legal rights and burgeoning logistical capacity through the development of Sea Ranger groups. We developed a decision process based on expert (qualitative) knowledge using the Yanyuwa Sea Country of the Northern Territory as a case study. We developed a Community Engagement Tool for Sea Country Planning to collect information from Traditional Owners, representatives of the local (non-Indigenous) Fishing Club and the field notebooks of John Bradley, an anthropologist who has worked with Yanyuwa Traditional Owners for thirty years. We combined all of this information with sightings obtained on a dedicated vessel survey conducted by scientists in collaboration with the li-Anthawirriyarra Sea Rangers in a Community GIS. The combined approach provided more information on the distribution of the coastal dolphins than either the expert informants or the scientific survey could have provided alone. The study further substantiated the importance of Yanyuwa Sea Country for dugongs and sea turtles, species of great cultural importance to the Yanyuwa. The project also confirmed the presence of all three species of coastal dolphins (Snubfin, Humpback and Bottlenose) in the Sea Country of the Yanyuwa. These three species are well known to the Traditional Owners and have Yanyuwa names. The coastal, shallow estuarine waters of the Yanyuwa Sea Country (which includes the fifth largest river system in the Northern Territory) appeared to be prime habitat for these species. The qualitative information from expert informants indicated that dolphins are widely distributed, particularly in shallow inshore waters. Nonetheless, the vessel surveys indicated that the numbers of each of the three species of dolphin that use Yanyuwa Sea Country were small in November 2010. Further vessel surveys are required to determine if there are seasonal patterns in the distribution and abundance of the coastal dolphins. If the low number of dolphins sighted is consistent across seasons, it will be impossible to monitor trends in their abundance in a management time frame because precise estimates of abundance will be unattainable. The survey also confirmed the value of the TDS Nomad handheld computer, the CyberTracker-based GPS software1 and the dedicated data recording sequence as a data-logging tool suitable for use by trained Sea Rangers. The Sea Ranger Marine Wildlife Tracker software sequence developed for this project will enable Sea Rangers to systematically collect details about whale, dolphin, dugong and turtle sightings. Long-term standardised collection of these data will be critical in determining the spatial and temporal patterns coastal dolphins in the remote coastal waters of northern Australia, and guiding future research effort through use of the CyberTracker will also allow the data to be incorporated into I-Tracker, a network of Indigenous land and sea managers across remote northern Australia who are using the CyberTracker to collect and manage information about their natural and cultural resources. To be successful, this approach will require high standards of observer training and data management. Australian governments are increasing investment in programs such as Working on Country to provide the resources to enable Indigenous peoples to continue to manage their country. In most of the remote range of coastal dolphins and dugongs in northern Australia, the Indigenous Sea Ranger effort ‘on-country’ now far surpasses that of non-Indigenous officers and scientists and has considerable potential to provide the data required to inform the planning and management of inshore waters in remote regions using the techniques developed in this project.

Several attempts have been made to conserve the critically endangered population of Irrawaddy dolphins inhabiting the lower Mekong River. In January 2001, the Mekong Dolphin Conservation Project (MDCP) was initiated as part of the first author's PhD research at James Cook University, Australia. All activities were conducted in cooperation with the Cambodian Department of Fisheries, which was extremely supportive of all aspects of the project. Beasley was the full-time project manager for 4.5 years. All project activities were designed to contribute toward a comprehensive understanding of the dolphin population on which to base initiatives to ensure the population's long-term survival. The research results from the MDCP till April 2005, confirmed that the Irrawaddy dolphin population inhabiting the Mekong River is very small, declining, and facing continuing threats. In 2001, MDCP initiated a carcass recovery program throughout the lower Mekong River to collect and conduct necropsy on all dead dolphins and attempt to determine the cause of mortalities. At the end of 2002, MDCP conducted a large-scale awareness campaign about the importance of reporting dolphin carcasses. As a result of these efforts, dolphin carcasses were often reported within days of death from 2003 onwards.