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Three decades of cetacean strandings in Western Australia: 1981 to 2010
... Anecdotal evidence (Hale & Butcher, 2007) and dolphin stranding records (Groom & Coughran, 2012) suggest that dolphins use the Peel-Harvey Estuary at least to some extent throughout the year. ...
... riverine habitat). Stranding records indicate that dolphins travel further upstream (Groom & Coughran, 2012) than the $7 km into the rivers recorded during the current study. As coastal individuals did not frequent the estuary, individuals with habitat preferences for the eastern shores of the estuarine system are not expected to interact with members of coastal communities. ...
... The estuarine dolphins overlap to a greater extent with anthropogenic activities as the Peel-Harvey Estuary is heavily used for recreational activities and supports both recreational and commercial fisheries for fin fish and blue swimmer crab (Portunus armatus) (Hale & Butcher, 2007;Gaughan, Molony & Santoro, 2019). The estuary has also been identified as a bottlenose dolphin live stranding hotspot (Groom & Coughran, 2012). Given that all (n = 6) but one dolphin that were recorded live stranded during this study were identified as members of the estuarine community (Nicholson, 2021, unpublished data), dolphins residing in the estuary are hypothesized to have a higher probability of live stranding in the estuary than coastal individuals. ...
• Investigations of population structure across multiple niche dimensions can identify discrete management units within populations. This study examined social, spatial and isotopic niche partitioning in Indo-Pacific bottlenose dolphins (Tursiops aduncus) across ca. 600 km² of coastal and estuarine waters in south-western Australia, to evaluate whether estuarine dolphins should be treated as a discrete management unit.
• Photo-identification data and tissue samples were collected in 2016 and 2017 in a study area covering the Peel-Harvey Estuary (PHE) and adjacent coastal waters. A total of 1,038 dolphin groups were encountered, and 481 individuals were identified. Tissue samples for stable isotope (δ¹³C and δ¹⁵N) analyses were collected from 96 individuals. Social structure and complexity analyses were conducted, full and core activity spaces were identified, and their size estimated for identified social communities. Differences in stable isotope composition among individuals and communities were examined.
• A socially, spatially and isotopically distinct dolphin community occurred in the PHE. The coastal waters contained four socially and spatially, but not isotopically, distinct communities as well as a substantial number of dolphins (n = 185) that were sighted infrequently and therefore were not assigned to any community. Individuals formed three levels of relationships; the majority (78%) were weak association relationships (mean half-weight index 0.006). The estuarine community had significantly higher mean δ¹³C and significantly lower mean δ¹⁵N values than any of the coastal communities.
• There is a strong scientific basis for treating the PHE dolphin community as a discrete management unit. The estuarine and coastal communities occupied different social environments, with coastal individuals sharing space with more transient individuals. This study shows the value of integrating information from multiple niche dimensions when identifying management units, and the need to consider all encountered individuals in management planning.
... Cetacean diversity in Australia is particularly rich with 45 of the 89 extant species recorded around its coastline [12] but more than half (25 species) are classified as data deficient on the IUCN Red List [13]. Much of our understanding of cetacean diversity and distributions within Australia has come from state-based stranding networks [4,[14][15][16][17][18], however, there is a distinct gap in knowledge within Victoria's waters. Victoria is part of the South-east Marine Region of Australia, identified as having between 60 and 95 percent endemism [19], yet the region is already experiencing the effects of climate change with species range shifts already documented in non-cetaceans [12,20,21]. ...
... Age class was assigned based on record notes, or morphological measurements within the record which allowed for classification. All stranding events were reported as 'single', 'mother and calf', or 'mass' (3 or more individuals [14,15]) strandings. Conservation status was assigned to each species based on their IUCN Red List classification of 'least concern', 'near threatened', 'vulnerable', 'endangered', 'critically endangered', or 'data deficient'. ...
... The diversity observed in Victoria is high when compared with international stranding records [38] but is consistent with records for neighbouring states and within the South East Australian region; South Australia, 31 species [14]; Tasmania, 28 species [37]; New South Wales, Cetacean stranding record of Victoria, Australia 33 species [16]. Whilst overall diversity is high, the actual number of stranding events is relatively low when compared with other Australian stranding records [4,[14][15][16] and those in North America [7,38,39]. ...
Cetacean stranding records can provide vital information on species richness and diversity through space and time. Here we collate stranding records from Victoria, Australia and assess them for temporal, spatial and demographic trends. Between 1920 and 2016, 424 stranding events involving 907 individuals were recorded across 31 Cetacea species from seven families, including five new species records for the state. Seven of these events were mass strandings, and six mother and calf strandings were recorded. Importantly, 48% of the species recorded are recognised as data deficient on the IUCN Red List. The most commonly recorded taxa were Tursiops spp. (n = 146) and Delphinus delphis (common dolphins, n = 81), with the greatest taxonomic richness (n = 24) and highest incidence of stranding events documented within the Otways mesoscale bioregion. We found no seasonal stranding patterns anywhere in the state. While our findings improve understanding of the spatial and temporal patterns of cetacean diversity within Victoria, we suggest greater effort to collect demographic data at stranding events in order to better study state-wide patterns through time. We conclude with guidelines for minimum data collection standards for future strandings to maximise information capture from each event.
... This paper presents data of humpback whale strandings between 1989-2012, with an unusual spike in recorded the variable human population density along the coastline (Groom and Coughran, 2012). ...
... The winter migratory and breeding season of humpback whales is associated with a period of physiological and energetic stress associated with extended fasting and the demands of travel and, in the case of adult whales, reproduction (Clapham, 2000;Jenner et al., 2001). This almost certainly leads to seasonal spikes in mortality which will be disproportionately recorded at coastal locations near human populations (Groom and Coughran, 2012). The record presented here, which runs for more than two decades, includes biases associated with reporting effort, as well as variability in coastal geography and oceanography that affects the likelihood of sick or dead whales becoming beach-cast. ...
... Therefore, a stranding of a humpback whale represents a conspicuous incident that is likely to attract attention and be reported to management authorities. We argue that Hypothesis 1 (that the increase in mortality of BSD is an artefact of increased detection and reporting), is of low plausibility given the consistency of the number of stranding events reported for this species over the preceding two decades (Groom and Coughran, 2012) and the decreasing trend since 2009. ...
An unprecedented number of humpback whales (n = 46) from Breeding Stock D (BSD) were found dead or dying on Western Australian beaches in 2009. This compares to an average of less than four stranded humpback whales in each year in the period between 1989 and 2008. The recorded number of humpback whales on beaches in the year preceding this peak (2008, n = 13) and the two years following the peak (2010, n = 16; 2011, n = 17) were also above the long term average. In 2012 (n = 7), the numbers of stranded whales was closer to the longer term average. The majority of stranded individuals were either calves (44%) or juveniles/sub-adults (49%), with only 7% classified as adults. Most whales appeared emaciated. There were insufficient data to determine cause of death. Three possible hypotheses to explain this spike in mortality are proposed: (1) the increase in mortality of BSD was an artefact of increased detection and reporting; (2) the increase was temporary and transitory; and (3) the spike in mortality represents the start of an increasing trend in mortality as the population approaches carrying capacity. We suggest that hypothesis two is the most plausible but on-going monitoring will be required to test this.
... The potential for strandings is great given the vastness of the coastline. Australia has a long history of cetacean strandings which have been the subject of several reviews (Guiler, 1978; McManus et al., 1984; Baker, 1990; Kemper & Ling, 1991; Bryden et al., 1998; Kemper et al., 2005; Groom & Coughran, 2012). Beaked whale strandings have been reported for all Australian states and territories: Northern Territory, Queensland, New South Wales, Victoria, South Australia and Tasmania (Australian Government 1999). ...
... Western Australia has the most diverse cetacean fauna of all Australian states with at least 37 species known/reported of which ten are beaked whales (Bannister et al., 1996; Groom & Coughran, 2012). This demonstrates high beaked whale diversity in this area given 21 species are currently recognized worldwide and six of those are considered restricted to the northern hemisphere (MacLeod et al., 2006). ...
... In WA, more beaked whales have been reported to live strand and subsequently die rather than beach-cast dead, than any other group of cetacean (Groom & Coughran, 2012). In these cases the cause of death is usually complications associated with the physical stresses of stranding (Stroud & Roffe, 1979; Kirkwood et al., 1997; Kemper et al., 2005). ...
Western Australia has an extensive coastline extending 12889 km (excluding islands) from latitude 35 degrees in the south to 14 degrees in the north. The extensive coastline intersects the distribution of many species of beaked whale. A total of 74 Ziphiidae were recorded as stranded along the Western Australian coast between 1940 and 2010 (70 years). Ten of the 21 species of beaked whales currently recognized taxonomically worldwide have been observed in Western Australia with True's beaked whale Mesoplodon mirus and Shepherd's beaked whale Tasmacetus shepherdi recorded more than elsewhere in Australia. Western Australia has the highest species diversity (10) of beaked whale strandings compared to other Australian states and regions. Gray's beaked whale, Mesoplodon grayi, was the most commonly reported species (33 records) and had the largest mass stranding group size (seven) of the beaked whales stranded in Western Australia. The records presented in this paper confirm the distribution of Arnoux's beaked whale Berardius arnuxii, strap-toothed beaked whale Mesoplodon layardii, Shepherd's beaked whale, Blainville's beaked whale Mesoplodon densirostris in Western Australian waters. The records presented of True's beaked whale confirm its presence in Australian waters, with Western Australia a possible key location for this species. Factors causing strandings and death should be investigated in future wherever possible, particularly the rostral injuries reported for six beaked whales. Beaked whale species identification should be confirmed through genetic analysis in future to maximize certainty of species identification.
... For some individuals, minimum age was inferred based on a consistent association with a reproductive female and/or dependent calf or, when known, the approximate birth date. Dolphin live stranding records since 1990 (Groom & Coughran, 2012) were also used to estimate the minimum age of some individuals. Individuals >10 years of age were considered sexually mature (i.e., adults) based on information on wild (Wallen et al., 2017) and captive (Brook et al., 2000;Wells et al., 1987) dolphins elsewhere. ...
... A relatively high number of dolphin live strandings have been recorded in the Peel-Harvey Estuary (Groom & Coughran, 2012). Live stranding events likely contributed to 21% of mortalities recorded during this study. ...
Wildlife management requires reliable demographic information to assess the status of a population and its vulnerability to threats. This study calculated age class‐ and sex‐specific demographic parameters and assessed the viability of a community of Indo‐Pacific bottlenose dolphins (Tursiops aduncus) resident to the Peel‐Harvey Estuary in Western Australia. Boat‐based photo‐identification surveys (n = 483) were conducted between 2016 and 2019. A population viability analysis (PVA) was used to assess the community status and evaluate the effects of adult female and calf mortality, and reproduction on population growth rate. The community comprised 88 (SD = 4.43) individuals with a sex ratio close to parity in all but the adult age class where it was skewed towards females. Demographic changes in this community are driven by births, deaths, and the likely permanent emigration of juvenile males. No immigration was observed. The population is stable (r = −0.004, SD = 0.062) given the current demographic rates. To maintain a community of ~90 individuals, management should consider action to lower adult female and calf mortality. This should involve aiming for zero human caused mortality and ensuring adverse impacts to the population are considered in future development planning.
... While some iconic and high-profile species, such as the humpback whale, have been regularly studied (McCauley et al. 2000;Jenner et al. 2001;Hedley et al. 2011;Braithwaite et al. 2012;Salgado Kent et al. 2012;Coughran et al. 2013;Christiansen et al. 2016;Irvine et al. 2018), other species have received little attention . For many, the only available information relevant to WA is through stranding records (Groom and Coughran 2012). This has made it difficult to assess the conservation status of some species (i.e. ...
... At least three odontocete species reside in Western Australian waters year round, including the Indo-pacific bottlenose dolphin (Tursiops aduncus), the Australian humpback dolphin (Sousa sahulensis) and the snubfin dolphin (Orcaella heinsohni), whereas species such as the killer whale (Orcinus orca), common dolphin (Delphinus delphis) and dwarf spinner dolphin (Stenella frontalis) are considered regular visitors and the more pelagic species (e.g. Kogia, Ziphidae) are occasional visitors that periodically strand in WA (Groom and Coughran 2012). Similarly, few pinniped species have resident populations (e.g. ...
Given limited funding and increasing pressures on our natural resources it is becoming ever more critical that science be directed at improving our understanding and management of priority issues. This relies on dialogue and alignment between researchers and managers to ensure that appropriate questions are asked and the answers incorporated in robust and transparent decision-making processes which should include relevant evidence-based science. We used a prioritisation framework as a tool to bring managers and scientists together to discuss and agree on current priorities for research on marine mammals in Western Australia, including posing relevant questions. Eight species were identified as high priorities for fundamental research, including three dolphin species (Australian humpback, snubfin and common dolphin), three baleen whale species (Antarctic and pygmy blue and dwarf minke whale), the Australian sea lion and the dugong. The pressures we evaluated resulted in a priority need for research to better understand and mitigate impacts across a range of species, including noise pollution from shipping and vessel activity, climate change and fishing by-catch. Scientists and managers agreed on a set of topics and associated research questions for the high-priority species that would best inform ongoing conservation and management of marine mammals in Western Australia and that would have broad applicability nationally and globally. We provide an example of how these priorities can be used to develop a research program with targeted funding. Overall, this process has demonstrated the value of bringing scientists and managers together with a tool that allows them to jointly determine priorities and research questions.
... Based on historical stranding data, museum specimens and opportunistic sightings collected during aerial and boat-based surveys for other fauna it has been inferred that humpback dolphins occur from the WA/NT border southwest to Shark Bay ; see Figure 1). The stranding record for humpback dolphins in WA is sparse, likely due to the remote nature of most of the northern WA coastline (Groom and Coughran, 2012). Five stranded individuals have been recorded between 1981 and 2010; the most recent from 2005 (Groom and Coughran, 2012). ...
... The stranding record for humpback dolphins in WA is sparse, likely due to the remote nature of most of the northern WA coastline (Groom and Coughran, 2012). Five stranded individuals have been recorded between 1981 and 2010; the most recent from 2005 (Groom and Coughran, 2012). Four of these animals were dead, with the cause of mortality unknown. ...
Among the many cetacean species that occupy Australian coastal waters, Australian humpback dolphins, Sousa sahulensis, are one of the most vulnerable to extirpation due to human activities. This review summarises the existing knowledge, presently occurring and planned research projects, and current conservation measures for humpback dolphins in Western Australia (WA). Rapid and wide-scale coastal development along the northern WA coastline has occurred despite a lack of baseline data for inshore dolphins and, therefore, without a precautionary approach to their conservation. The distribution, abundance, habitat use, and population structure of humpback dolphins remains poorly understood. Less than 1% of their inferred distribution has so far been studied to understand local population demography. The sparse data available suggest that WA humpback dolphins occur as localised populations in low numbers within a range of inshore habitats, including both clear and turbid coastal waters. Marine protected areas cover a third of their inferred distribution in WA, but the efficacy of these reserves in protecting local cetacean populations is unknown. There is a pressing need for coordination and collaboration among scientists, government agencies, industry bodies, Traditional Owners, and local community groups to fill in the gaps of information on humpback dolphins in WA. The recently developed strategies and sampling guidelines developed by state and federal governments should serve as a best practise standard for collection of data aimed at assessing the conservation status of humpback dolphins in WA and Australia.
... In populations in which CeMV infection is endemic, deaths tend to occur solely in juveniles as immunity in individuals surviving exposure is typically life-long (Duignan et al. 1996). The outbreak coincided with a significant increase in bottlenose dolphin strandings along the WA coast in 2009 (affecting both coastal and estuarine dolphins) in comparison to relatively constant stranding rates from 1981-2008 (Groom et al. 2012). This fact supports the hypothesis of CeMV entering a naïve population, given the mortality spike in 2009 and the relative constancy of stranding rates in the preceding 20 years. ...
... CeMV has been definitively identified as the primary aetiologic agent ultimately responsible for the deaths of Cases Two and Three, compounded by significant and severe secondary opportunistic bacterial and fungal infections. The mixed age-class presentation of these two individuals and the epidemiologic stranding data documenting a 2009 mortality spike in cetaceans, including dolphins, on the WA coast(Groom et al. 2012) suggests that (a) the Swan Canning Riverpark dolphins were a previously naïve population, and (b) CeMV may have been a contributing factor in the 2009 WA coast spike in mortalities and strandings. This constitutes the first report of CeMV-related dolphin mortality from the Indian Ocean. ...
... In populations in which CeMV infection is endemic, deaths tend to occur solely in juveniles as immunity in individuals surviving exposure is typically life-long (Duignan et al. 1996). The outbreak coincided with a significant increase in bottlenose dolphin strandings along the WA coast in 2009 (affecting both coastal and estuarine dolphins) in comparison to relatively constant stranding rates from 1981-2008 (Groom et al. 2012). This fact supports the hypothesis of CeMV entering a naïve population, given the mortality spike in 2009 and the relative constancy of stranding rates in the preceding 20 years. ...
... CeMV has been definitively identified as the primary aetiologic agent ultimately responsible for the deaths of Cases Two and Three, compounded by significant and severe secondary opportunistic bacterial and fungal infections. The mixed age-class presentation of these two individuals and the epidemiologic stranding data documenting a 2009 mortality spike in cetaceans, including dolphins, on the WA coast(Groom et al. 2012) suggests that (a) the Swan Canning Riverpark dolphins were a previously naïve population, and (b) CeMV may have been a contributing factor in the 2009 WA coast spike in mortalities and strandings. This constitutes the first report of CeMV-related dolphin mortality from the Indian Ocean. ...
... Devido ao seu peso e tamanho corporal, os misticetos encalhados, em geral, não são passíveis de remoção (Groom & Coughran, 2012;Harms et al., 2014), ainda que alguns raros casos de reabilitação já tenham sido reportados com sucesso (Andrews et al., 2001). No Brasil, os centros de reabilitação de animais marinhos existentes não possuem estrutura física para o recebimento de grandes baleias, limitando-se ao tratamento de odontocetos de pequeno porte . ...
Os projetos de monitoramento de praia são uma importante ferramenta utilizada no licenciamento ambiental para avaliar impactos de diferentes atividades humanas no ambiente costeiro e marinho. Uma das atividades realizadas por estes projetos é o resgate e reabilitação de animais, incluindo os cetáceos. Este estudo analisa os casos de reabilitação de cetáceos feitos pelo Projeto de Monitoramento de Praias da Bacia de Santos (PMP-BS) entre os anos de 2016 a 2019. O PMP-BS percorre diariamente cerca de 2100km de costa ao longo do litoral sudeste-sul brasileiro com a finalidade de registrar tetrápodes marinhos e reabilitar os animais vivos quando possível. No período analisado, foram registrados 4531 encalhes de 27 espécies de cetáceos. A grande maioria correspondeu a animais mortos (99%, n=4482) e apenas 1% (n=49) foram encontrados vivos. Para avaliar os padrões de causas de morte optou-se por utilizar apenas necropsias realizadas em carcaças mais frescas (n=863). As causas de morte antropogênicas foram as mais frequentes (n=270; 93%), estando principalmente ligadas ao sistema respiratório, possivelmente causadas por afogamento derivado de interações com artefatos de pesca. Dos animais encontrados vivos, 36 foram levados para bases de reabilitação, mas 32 acabaram vindo a óbito, a realização de uma eutanásia foi necessária e apenas três espécimes tiveram sucesso na reabilitação e foram reintroduzidos na natureza. A espécie mais frequente foi Pontoporia blainvillei, tanto nos exemplares mortos (n=2178) quanto vivos (n=18). Os resultados obtidos por projetos de monitoramento são importantes devido à sua padronização dos esforços e protocolos de atividades, e servem para direcionar pesquisas de campo dedicadas, destacando o valor dos registros precisos e contínuos de encalhes. Mesmo considerando que a quantidade de animais retornados para o ambiente foi reduzida, o aprendizado com os animais enviados para tratamento é de grande importância para casos de reabilitação futuros. Palavras-chaves: Encalhes, Cetáceos, Reabilitação, Conservação, Monitoramento.
... Strandings inherently provide opportunistic data but can also provide important information on cetacean diversity and occurrence (Ross, 1984;Pyenson, 2011;Groom and Coughran, 2012;Chan et al., 2017). There have been few studies on strandings or unusual mortality events of cetaceans within the region, with many of the stranding records either being anecdotal or unreported. ...
The south-western Indian Ocean (SWIO) is a region of global importance for marine mammal biodiversity, but our understanding of most of the species and populations found there is still rudimentary. The Indian Ocean Network for Cetacean Research (IndoCet) was formed in 2014 and is dedicated to the research of all cetacean species across the SWIO. Since 2019, there have been efforts to create a regional network for coordinated response to stranding events as well as training and capacity building in the SWIO region. The present analysis represents a first investigation of stranding data collected by various members and collaborators within the IndoCet network, covering over 14,800km of coastline belonging to nine countries/territories. Between 2000-2020, there were 397 stranding events, representing 1,232 individual animals, 17 genera and 27 species, belonging to six families: four balaenopterids, one balaenid, one physeterid, two kogiids, six ziphiids and 14 delphinids. Seven mass strandings were recorded: two were composed of three to 20 individuals and five composed of >20 individuals. Spatial analysis of stranding events indicated that local spatio-temporal clusters (excessive number of events in time and geographic space) were present in all countries/territories, except for the Comoros. The only significant cluster was detected on the southwest coast of Mauritius, just west of the village of Souillac. The SWIO region predominantly comprises relatively poor countries/territories, but imminent Blue/Ocean economy developments are prevalent throughout the region. This study highlights the importance of establishing baselines upon which any future potential impact from anthropogenic developments in the region can be measured.
... Three stranding records within the NT were previously reported by Chatto and Warneke (2000). In WA, false killer whale stranding records were collated through the Western Australian Cetacean Stranding Database, established in 1982 (Groom and Coughran, 2012). This separate database was curated by a single custodian between 1982-2017 and contains cetacean stranding events that include both live-stranded and dead, beach-cast cetaceans. ...
To help evaluate the distribution, residency, population size and structuring (and hence conservation status) of the poorly known false killer whale Pseudorca crassidens in northern Australian waters, we undertook studies of sightings, movement patterns based on satellite telemetry, and genetics. Sighting data indicates that false killer whales are regular, year-round inhabitants of coastal areas of northern Australia. Satellite-tagged animals spent extended periods of time in shallow coastal waters, with no tagged animals leaving the continental shelf. The lack of spatial overlap in the areas visited by individuals tagged in the Arafura/Timor Seas compared to those tagged in the Gulf of Carpentaria suggests that there may be more than one population in northern Australia coastal waters. All 14 genetic samples collected across 1600 km of coastline possessed the same newly identified mitochondrial control region haplotype, designated haplotype 45. Notably, haplotype 45 is distinct from all previously published false killer whale haplotypes globally and is most similar to the two haplotypes that typify the endangered main Hawaiian Islands insular false killer whale population. Based on these results and evidence from recent movement records of those tagged, false killer whales in northern Australia are apparently demographically independent from the offshore population(s). Further assessment of the population conservation status is now required.
... The male sex bias observed in the present study has also been documented in stranded bottlenose dolphins in the Mississippi Sound region (Mattson et al., 2006), and Tursiops sp. in Western Australia (Groom and Coughran, 2012). Male sex bias was also observed in stranded Indo-Pacific humpback dolphins (Sousa chinensis) off Hong Kong, however, male carcasses tested several times higher than females for concentrations of organochlorine that may have contributed to the higher number of male strandings (Jefferson et al., 2006). ...
Long-term trends in marine mammal stranding patterns can provide useful information on basic life history parameters, spatiotemporal distribution, natural and human-related mortality events, and potentially vulnerable populations. Between 1980 and 2019, a total of 5,301 marine mammal strandings were recorded in Texas, USA. In total, 23 species were identified, including 19 odontocete species (toothed whales and dolphins), 3 mysticete species (baleen whales), and 1 sirenian species (manatee). Common bottlenose dolphins (Tursiops truncatus) stranded most frequently (94%). Six unusual mortality events occurred with causes attributed to disease, harmful algal blooms, or unknown etiologies. Common bottlenose dolphin stranding events increased significantly in late winter/early spring, with an early onset in southern Texas, and had a consistent peak in March involving primarily calves and adults. Spatial analyses using kernel density estimation within seven coastal Texas stock management areas, delineated by the National Marine Fisheries Service, identified potential hotspots for common bottlenose dolphin strandings near higher human population density and deep water channels. Peak stranding density estimates in each stock area ranged from 0.32 – 4.6km-2 for presumed bay, sound and estuarine (BSE) stocks and 0.82km-2 for the presumed Western Gulf of Mexico Coastal Stock. Common bottlenose dolphin stranding events were positively male-biased, including a significantly higher number of stranded male fetuses and neonates, and sexual dimorphism was observed in total body length of adults, with significantly greater length in males. For all records where human interaction (HI) could be determined as ‘yes’ or ‘no’, 30% were positive for HI, with the highest proportion of HI events occurring in the central and southern-most BSE stock areas; however, it is unknown how many HI cases contributed to mortality. This longitudinal study provides a comprehensive overview of marine mammal stranding patterns in Texas and serves as a useful resource for stranding investigators and Gulf-wide natural resource managers.
... Australasia (Australia and New Zealand) has an international reputation for its high incidence of live mass stranding events of long-finned pilot whales (Globicephala melas edwardii), which commonly occur on the coastlines of New Zealand and Australia [14][15][16][17]. Management of these stranding events can be logistically complex, with extensive public engagement and multiple stakeholders. ...
Standard Operating Procedures (SOPs) are tools used to ensure management best practice during emergency incidents including wildlife interventions, such as cetacean strandings. The compromised state of stranded cetaceans means humane end-of-life decisions may be considered, and SOPs frequently guide this process. This study evaluated SOPs for end-of-life decision-making and technically enacting euthanasia of stranded cetaceans across Australasia. The aim was to highlight similarities and differences in management and explore directions to improve stranded cetacean welfare. SOPs were requested from the eight government authorities across Australia and New Zealand. All SOPs were evaluated for decision-making criteria, yielding 29 parameters for the implementation of end-of-life decisions. Euthanasia and palliative care were options for end-of-life, with palliative care recommended when euthanasia was not feasible or presented human safety risks. Three euthanasia methods were recommended. Ballistics was recommended in seven SOPs, chemicals in five and explosives in three SOPs. Variability existed in the exact procedures and equipment recommended in all three methods. Additionally, only five SOPs provided criteria for verifying death, while only two recommended time-to-death be recorded, hindering evaluation of the welfare impacts of end-of-life decisions and euthanasia procedures. Our findings highlight the need for detailed guidance and consistency in end-of-life decisions and euthanasia techniques to ensure reliable welfare outcomes. Systematic, standardised data collection at euthanasia events across regions is required to facilitate assessment of welfare impacts and develop evidence-based recommendations. International collaboration is key to developing objective criteria necessary to ensure consistent guidance for end-of-life decisions.
... Stenella sp. sightings may include pantropical spotted (Stenella attenuata), and dwarf spinner (Stenella longirostris) dolphins, as North West Cape stranding records include the former (Groom and Coughran, 2012) and the latter has been identified from north WA biopsy samples (Leslie and Morin, 2018). Our killer whale sighting in December 2012 is one of the rare, documented sightings of this species in the region in summer outside of the humpback whale season when most killer whale research has been undertaken (e.g., Pitman et al., 2015). ...
Understanding species’ distribution patterns and the environmental and ecological interactions that drive them is fundamental for biodiversity conservation. Data deficiency exists in areas that are difficult to access, or where resources are limited. We use a broad-scale, non-targeted dataset to describe dolphin distribution and habitat suitability in remote north Western Australia, where there is a paucity of data to adequately inform species management. From 1,169 opportunistic dolphin sightings obtained from 10 dugong aerial surveys conducted over a four-year period, there were 661 Indo-Pacific bottlenose dolphin ( Tursiops aduncus ), 191 Australian humpback dolphin ( Sousa sahulensis ), nine Australian snubfin dolphin ( Orcaella heinsohni ), 16 Stenella sp., one killer whale ( Orcinus orca ), one false killer whale ( Pseudorca crassidens ), and 290 unidentified dolphin species sightings. Maximum Entropy (MaxEnt) habitat suitability models identified shallow intertidal areas around mainland coast, islands and shoals as important areas for humpback dolphins. In contrast, bottlenose dolphins are more likely to occur further offshore and at greater depths, suggesting niche partitioning between these two sympatric species. Bottlenose dolphin response to sea surface temperature is markedly different between seasons (positive in May; negative in October) and probably influenced by the Leeuwin Current, a prominent oceanographic feature. Our findings support broad marine spatial planning, impact assessment and the design of future surveys, which would benefit from the collection of high-resolution digital images for species identification verification. A substantial proportion of data were removed due to uncertainties resulting from non-targeted observations and this is likely to have reduced model performance. We highlight the importance of considering climatic and seasonal fluctuations in interpreting distribution patterns and species interactions in assuming habitat suitability.
... Strandings of cetaceans are a global phenomenon, washed ashore either dead, ill or alive (Geraci and Lounsbury, 2005;Alvarado-Rybak et al., 2020). The primary reasons for cetacean stranding include natural causes such as the alteration in climatic events, oceanic conditions, loss of habitat, disease and infections and anthropogenic reasons such as ship strikes, pollution, acoustic disturbances, hunting, bycatch and the incidental and intentional activities of fisheries (Berman-Kowalewski et al., 2010;Bogomolini et al., 2010;Groom and Coughran, 2012;Trianni and Tenorio, 2012;Bengil et al., 2020). These threats cause direct effects such as mortalities and injuries as well as indirect effects like long term physiological and behavioural changes (Avila et al., 2018). ...
Received on: 25-10-2020; Revised on:01-02-2021; Accepted on: 02-02-2021 This paper reports cetacean stranding events along Kerala coast during 2017 to 2019 of Bryde's whale (Balaenoptera edeni), blue whale (Balaenoptera musculus), killer whale (Orcinus orca) and Indo-Pacific finless porpoise (Neophocaena phocaenoides) identified through morphological approach. DNA barcoding using mitochondrial COI gene confirmed the identification of B. edeni and B. musculus. The bushmeat trade involving striped dolphins (Stenella coeruleoalba) is also photo documented here. The paper affirms the need to form cetacean stranding response programs to build a scientific baseline for cetacean conservation and research, monitor threats to cetaceans and curtail the cetacean meat trade.
... Some of the largest stranding events such as the recent pilot whale event in New Zealand in February 2017 (BBC News, 2017) can involve hundreds of animals. While the strandings are not usually a conservation issue, the events have a negative impact on the welfare of the individuals, or groups of cetaceans, and without intervention often lead to death (e.g., Groom & Coughran, 2012;Groom et al., 2014;McGovern et al., 2018). As such, we are motivated to understand the reasons behind this seemingly inexplicable deadly behavior. ...
This paper is the primary deliverable of the very first NASA Living With a Star Institute Working Group, Geomagnetically Induced Currents (GIC) Working Group. The paper provides a broad overview of the current status and future challenges pertaining to the science, engineering, and applications of the GIC problem. Science is understood here as the basic space and Earth sciences research that allows improved understanding and physics‐based modeling of the physical processes behind GIC. Engineering, in turn, is understood here as the “impact” aspect of GIC. Applications are understood as the models, tools, and activities that can provide actionable information to entities such as power systems operators for mitigating the effects of GIC and government agencies for managing any potential consequences from GIC impact to critical infrastructure. Applications can be considered the ultimate goal of our GIC work. In assessing the status of the field, we quantify the readiness of various applications in the mitigation context. We use the Applications Readiness Level (ARL) concept to carry out the quantification.Key PointsWe provide a broad overview of the status of the GIC fieldWe utilize the Applications Readiness Levels (ARL) concept to quantify the maturity of our GIC‐related modeling and applicationsThis paper is the high‐level report of the NASA Living With a Star GIC Working Group findings
... Some of the largest stranding events such as the recent pilot whale event in New Zealand in February 2017 (BBC News, 2017) can involve hundreds of animals. While the strandings are not usually a conservation issue, the events have a negative impact on the welfare of the individuals, or groups of cetaceans, and without intervention often lead to death (e.g., Groom & Coughran, 2012;Groom et al., 2014;McGovern et al., 2018). As such, we are motivated to understand the reasons behind this seemingly inexplicable deadly behavior. ...
Cetacean mass strandings are one of the long‐standing mysteries in marine biology and many explanations have been proposed for the often‐fatal animal behavior. Geomagnetic activity that is driven by solar phenomena such as coronal mass ejections is one of the proposed explanations. In this study, we investigate if there is statistical evidence for a possible connection between mass strandings and geomagnetic storms. Fresh (live or recently deceased animals) mass stranding records from Cape Cod, USA, the United Kingdom, and New Zealand, together with global geomagnetic indices and local geomagnetic observations, are utilized in this investigation. While seasonal statistical association is found between cetacean mass strandings and geomagnetic field variations, the connection is likely a byproduct of the seasonality found in both types of data. No statistical associations are found in 30‐day or shorter time scales that are believed to be relevant for possible animal response to changes in geomagnetic conditions. If geomagnetic activity plays any role in fresh mass strandings analyzed in this investigation, the connection has to be very subtle and likely coupled with a complex combination of multiple environmental factors.
... Cetacean stranding events for this study were defined as single, including mother and calf, or more strandings during the study period. Furthermore, we defined as mass stranding events (MSE) those when more than three animals stranded and as unusual mortality events (UME) those when the stranded die off in larger numbers than "normal" 45 . To verify the stationarity of the CS data, i.e., that the mean and variance of the time series are constant over time, we performed the Augmented Dickey-Fuller test implemented in the 'tseries' package 46 using the statistical software R 47 . ...
Cetacean strandings (CS) have been reported in increasing numbers in coastal areas worldwide. Although the causes of these strandings are unknown, a number of anthropogenic and environmental factors have been suggested. This paper aims to characterize CS patterns and describe their fine-scale spatiotemporal dynamics. We analysed spatial and spatiotemporal CS patterns in Chile from January 1968 to January 2020. We identified a total of 389 CS events affecting eight cetacean families, 21 genera, and 35 species, which represent more than 85% of the reported species richness for the country. Most CS events (94.1%) were single (i.e., ≤two individuals). There were also 18 mass stranding (three to 24 individuals, 4.1%) and nine unusually large mass stranding events (>25 individuals, 2%). Purely spatial tests showed CS events appearing in random occurrence along the Chilean coast. Local tests for spatio-temporal clusters, however, identified a greater number of hotspots reported in the southernmost part of the country, namely, Chilean Patagonia. Specifically, significant spatio-temporal clusters were identified and defined as containing three or more individuals within a two-month period as a focal coastal event (<1 km radius). It is a cause of concern that CS events in Chile have been increasing consistently over the last decades, and although we were not able to identify their causes, we are able to highlight the importance of changes in climate conditions and of an increase in monitoring activities as primary drivers for such patterns, particularly important in Chilean Patagonia.
... Specifically, on their breeding grounds, southern right whale (Eubalaena australis) mother-calf pairs primarily reside in very shallow water of 5-10 m depth close to shore, in close proximity to or in the surf zone (Payne, 1986). However, little is known about potential advantages and risks of bringing newly born calves within metres of the breaking waves in a low-visibility (<20 m), acoustically noisy environment such as South Australian breeding habitats, with the risk of stranding (Australian Government Species Profile and Threats Database; Groom and Coughran, 2012). ...
Southern right whales (Eubalaena australis) invest substantial amounts of energy in their calves, while facing the risk of having them predated upon by eavesdropping killer whales (Orcinus orca). We tested the hypothesis that southern right whale mother-calf pairs employ acoustic crypsis to reduce acoustic detectability by such predators. Specifically, we deployed multi-sensor DTAGs on nine lactating whales for a total of 62.9 h in a Western Australian breeding ground, and used a SoundTrap to estimate the concomitant acoustic background noise. Vocalisations were recorded at low rates of <10 calls h-1 (1 call per dive) and at low received levels between 123±8 and 134±10 dB re. 1 µPa RMS depending on call type. We conclude that such acoustic crypsis in southern right whales and other baleen whales decreases the risk of alerting potential predators and hence jeopardizing a substantial energetic investment by the mother.
... 40 stranding events reported from South Australia (Kemper & Ling 1991, Kemper unpubl. data);and18 strandings (from 1981-2010) recorded from Western Australia (Groom & Coughran 2012). No information was available for New South Wales. ...
... In addition, off WA there was a high number of bottlenose dolphin deaths in 2009 (of which there was a peak in June during the initial phase of the El Niño in south-west WA;Fig. S2); however, the reasoning behind this remains unknown(Groom & Coughran, 2012). We suggest that the decline in dolphin abundance during the El Niño event was temporary, and the dolphins may have emigrated out of the study area due to changes in prey availability and/or potentially unfavourable water quality conditions in certain areas (e.g. the inner waters).4.1 | Importance of long-term monitoring and additional implications for coastal dolphin speciesThese findings emphasize the value of long-term, year-round monitoring to evaluate population trends and identify possible large-scale environmental drivers affecting marine top predators. ...
Large-scale climate modes such as El Niño Southern Oscillation (ENSO) influence population dynamics in many species, including marine top predators. However, few quantitative studies have investigated the influence of large-scale variability on resident marine top predator populations. We examined the effect of climate variability on the abundance and temporary emigration of a resident bottlenose dolphin (Tursiops aduncus) population off Bunbury, Western Australia (WA). This population has been studied intensively over six consecutive years (2007–2013), yielding a robust dataset that captures seasonal variations in both abundance and movement patterns. In WA, ENSO affects the strength of the Leeuwin Current (LC), the dominant oceanographic feature in the region. The strength and variability of the LC affects marine ecosystems and distribution of top predator prey. We investigated the relationship between dolphin abundance and ENSO, Southern Annular Mode, austral season, rainfall, sea surface salinity and sea surface temperature (SST). Linear models indicated that dolphin abundance was significantly affected by ENSO, and that the magnitude of the effect was dependent upon season. Dolphin abundance was lowest during winter 2009, when dolphins had high temporary emigration rates out of the study area. This coincided with the single El Niño event that occurred throughout the study period. Coupled with this event, there was a negative anomaly in SST and an above average rainfall. These conditions may have affected the distribution of dolphin prey, resulting in the temporary emigration of dolphins out of the study area in search of adequate prey. This study demonstrated the local effects of large-scale climatic variations on the short-term response of a resident, coastal delphinid species. With a projected global increase in frequency and intensity of extreme climatic events, resident marine top predators may not only have to contend with increasing coastal anthropogenic activities, but also have to adapt to large-scale climatic changes.
... In ~800 days of boat based transect surveys out to 3-4nm off Bunbury (WA) SBCD were only encountered on ~6 occasions, and group sizes were small (<5 individuals) (Murdoch University, unpublished data). The number of strandings of common dolphins in WA recorded between 1981 and 2010 were low relative to other species, and mostly occurred between 1985 and 1995, which coincided with a period of high seasonal target catch rates in the west coast purse-seine fishery (Groom and Coughran 2012). Both Murdoch and Flinders Universities have conducted biopsy sampling studies around Albany but results have not been reported yet. ...
Full report available at:
http://www.frdc.com.au/research/final-reports/Pages/2015-035-DLD.aspx
... This status takes into consideration that this species is cosmopolitan, appears abundant in Australian waters and has a distribution range that extends along the entire coast of Western Australia and potentially across the Indo-Pacific, well beyond the PFTF management areas (e.g. Groom and Coughran, 2012). However, while there are no known risks to the sustainability of this species in Western Australia, and despite the low dolphin bycatch rate reported in the PFTF, societal pressure to further mitigate cetacean interactions and mortalities remains high (see Molony et al., 2015). ...
To improve bycatch mitigation of chondrichthyans, reptiles and cetaceans for a tropical demersal fish-trawl fishery, species-specific responses to bycatch reduction devices (BRDs) were investigated using both in situ subsurface and onboard observations. There are few, if any, studies that have determined mitigation performances of BRDs from subsurface interactions for these species, as most are rarely encountered and thus require substantial levels of observer coverage for robust assessments. This study combined in-net and onboard (774 day trawls and 1320 day trawl hours of subsurface observer coverage) electronic monitoring on all fish-trawl vessels (n = 3) to compare bycatch mitigation performances among nine megafauna groups, based on escape rates and interaction durations for three BRDs over 6 months (June to December 2012). Overall, 26.9% of day trawls had no megafauna interactions and 38.3% of the 1826 interactions escaped, with most in rapid time (91.4% in ≤ 5 min). The upward inclined exclusion grid significantly improved the escape proportions for most chondrichthyans by 20–30%. All BRDs were highly effective in reducing reptile (turtles and seasnakes) bycatch, but irrelevant for the few sawfish (n = 13) that readily entangled in the anterior of the net. Cetacean (bottlenose dolphins only) interactions with BRDs were very rare (n = 7) despite high levels of attendance and depredation during trawling. Loss of targeted teleosts through the BRD hatch was rare (1.3% of day trawls). This relatively cost-effective method of electronic monitoring achieved very high levels of subsurface observer coverage (60% of day trawls or 56% of day trawl hours), and provided evidence that the subsurface expulsion of megafauna in poor condition is negligible. Furthermore, this study provides species-specific improvements toward bycatch mitigation strategies for demersal fish trawling.
... Southwestern Australia was selected as a field site due to the high diversity of species available for experimentation, combined with a relatively high incidence of stranding events (Coughran et al., 2013). A long term cetacean stranding record (Groom and Coughran, 2012) for Western Australia reports 37 cetacean species observed off the coast and 34 species in the stranding record. All animals were freshly dead, with evidence of post-mortem change indicating they had been dead for less than 12 hours. ...
Efforts to euthanise stranded cetaceans remain highly variable in their outcomes, with few field tested operational procedures available. This study sought to validate the efficacy of using modern firearms technology to euthanise small (<6m length) stranded cetaceans. Post-mortem evidence was gathered from the standardised shooting of cetacean cadavers (n = 10), representing six species, using .30 caliber (7.62mm) firearms and blunt solid copper-alloy non-deforming projectiles, in southwestern Australia. The six species studied were Risso's dolphin, common dolphin, bottlenosed dolphin, pygmy sperm whale, Cuvier's beaked whale, and humpback whale. Post-mortem data revealed that 100% of bullet wound tracts fully penetrated the skulls of shot animals, with associated indirect skull fracturing, secondary bone missiles and brain parenchyma laceration. The results suggest that appropriate firearms technology is fully capable of inducing instantaneous fatal pathology to the central nervous system of these species. In comparison to alternative methods for the euthanasia of stranded cetaceans, the use of firearms is associated with superior animal welfare outcomes, public safety levels and accessibility. This paper provides a template for the safe, humane and repeatable use of this technique to euthanise <6m length stranded cetaceans.
... The occurrence of live cetaceans being found stranded is relatively common along the West Australian coastline (Groom and Coughran 2012). The frequency of stranding events is expected to increase over coming decades (Schumann et al. 2013). ...
... (16 odontocete species; Maldini et al., 2005), San Diego, California (24 cetacean species along 125 km, Danil et al., 2010 ), southeastern Canada (19 cetacean spe- cies, Nemiroff et al., 2010), and Cape Cod-southeastern Massachusetts (16 marine mammal species along 1126 km, Bogomolni et al., 2010). An exception is Western Australia where 34 cetacean species were found, but the study encompassed 12,889 km of coastline and roughly 20 degrees of latitude (Groom and Coughran, 2012). The high diversity found in NC emanates from multiple oceanographic features and the resulting 2 converging biogeographic zones off the coast. ...
... melas) (10,15). A 30-year study of strandings in Western Australia (1981-2010) showed a pattern of mortality peaks and troughs in bottlenose dolphins similar to that seen along the US Atlantic coast (7,13). A peak in 2009 coincided with the cases we report. ...
Cetacean morbillivirus (CeMV) has caused several epizootics in multiple species of cetaceans globally and is an emerging disease among cetaceans in Australia. We detected CeMV in 2 stranded coastal Indo-Pacific bottlenose dolphins (Tursiops aduncus) in Western Australia. Preliminary phylogenetic data suggest that this virus variant is divergent from known strains.
... (16 odontocete species; Maldini et al., 2005), San Diego, California (24 cetacean species along 125 km, Danil et al., 2010), southeastern Canada (19 cetacean species, Nemiroff et al., 2010), and Cape Cod-southeastern Massachusetts (16 marine mammal species along 1126 km, Bogomolni et al., 2010). An exception is Western Australia where 34 cetacean species were found, but the study encompassed 12,889 km of coastline and roughly 20 degrees of latitude (Groom and Coughran, 2012). The high diversity found in NC emanates from multiple oceanographic features and the resulting 2 converging biogeographic zones off the coast. ...
The adjacency of 2 marine biogeographic regions off Cape Hatteras, North Carolina (NC), and the proximity of the Gulf Stream result in a high biodiversity of species from northern and southern provinces and from coastal and pelagic habitats. We examined spatiotemporal patterns of marine mammal strandings and evidence of human interaction for these strandings along NC shorelines and evaluated whether the spatiotemporal patterns and species diversity of the stranded animals reflected published records of populations in NC waters. During the period of 1997-2008, 1847 stranded animals were documented from 1777 reported events. These animals represented 9 families and 34 species that ranged from tropical delphinids to pagophilic seals. This biodiversity is higher than levels observed in other regions. Most strandings were of coastal bottlenose dolphins (Tursiops truncatus) (56%), harbor porpoises (Phocoena phocoena) (14%), and harbor seals (Phoca vitulina) (4%). Overall, strandings of northern species peaked in spring. Bottlenose dolphin strandings peaked in spring and fall. Almost half of the strandings, including southern delphinids, occurred north of Cape Hatteras, on only 30% of NC's coastline. Most stranded animals that were positive for human interaction showed evidence of having been entangled in fishing gear, particularly bottlenose dolphins, harbor porpoises, short-finned pilot whales (Globicephala macrorhynchus), harbor seals, and humpback whales (Megaptera novaeangliae). Spatiotemporal patterns of bottlenose dolphin strandings were similar to ocean gillnet fishing effort. Biodiversity of the animals stranded on the beaches reflected biodiversity in the waters off NC, albeit not always proportional to the relative abundance of species (e.g., Kogia species). Changes in the spatiotemporal patterns of strandings can serve as indicators of underlying changes due to anthropogenic or naturally occurring events in the source populations.
Derelict and active fishing gear poses a threat to marine wildlife. This study details Indo-Pacific bottlenose dolphin entanglements in recreational fishing gear in the Peel-Harvey Estuary, Western Australia between 2016 and 2022. Eight entanglements were recorded, three resulted in death. While concerning from an animal welfare perspective, the impact of entanglements on the viability of the local dolphin population was low. This is as majority of affected individuals were juvenile males. Should entanglements result in the loss of reproductive females, or impact their reproductive success, the population trajectory could quickly change. As such, management decision making should consider population level impacts as well as the welfare of entangled individuals. Government agencies, together with relevant stakeholders, should work together to maintain preparedness to respond to entanglements and take preventative action that lowers the risk of interactions with recreational fishing gear.
Sperm whales have been identified under Marine Bioregional Plans as key features in the Great Australian Bight (GAB). Although commercial whaling of sperm whales in Australian waters ceased in 1978 there is no evidence of recovery of sperm whale populations. Information on the current distribution and abundance of sperm whales in the region, which is also an important area for human activities including fishing, oil and gas exploration and tourism, is very limited. We undertook a systematic visual and passive acoustic vessel based survey in the central eastern GAB. The visual detection rate of sperm whales from the survey was 1.4 individuals per 1,000 km with an acoustic density of 0.21 individuals per 1,000km². We combined these sightings and detection data with historical and contemporary whaling and sightings data to identify critical habitat for sperm whales in the region. Using Maximum entropy modelling, suitable sperm whale habitat was predicted over the continental shelf break, but more specifically, over sub-marine canyons. Baseline information on the abundance and distribution of sperm whales, and other cetacean species, in the GAB are required to provide information to management agencies and regulators in order to assess and mitigate risks. The potential impacts of increased noise from shipping, seismic surveys and construction on cetacean species in the region need to be considered.
Long-term monitoring of cetacean strandings is essential for good management. This study updates previous summaries for South Australia by adding up to 20 years of comprehensive data, including results of necropsy examinations. A total of 1078 records were examined. Thirty-one species were recorded: 9 (7% of records) mysticetes, 22 (88%) odontocetes and the rest (5%) unidentified. The number of species new to South Australia did not reach an asymptote, with potential for at least five additional species. Small cetaceans were more frequently recorded after 1990, possibly due to increased reporting effort. Stranding records increased markedly after 1970. Records for all species occurred year-round. Beaked whales stranded primarily during January-April, baleen whales during July-January and common dolphins during February-May. Geographic hotspots were identified and related to upwelling and reporting effort. A necropsy program since 1990 resulted in 315 of 856 records being assigned to a circumstance of death, with anthropogenic circumstances accounting for 42% of these. Known Entanglement (21%, 66 of 315) and Probable Entanglement (12%, 37 of 315) were the most recorded anthropogenic circumstances of death. Future research correlating strandings with oceanographic/climatic conditions may help to explain the documented patterns but first the effects of reporting effort need to be accounted for.
The age of 86 individuals derived from groups of female sperm whale Physeter macrocephalus involved in three mass strandings on the north and west coasts of Tasmania in 1998 was determined from the number of dentinal growth layer groups in the teeth of individuals. Dorsal total lengths were also measured. Ages of females ranged from 0.75 to 64 years, with the majority (77%) aged between 20 and 45 years. Total lengths of female sperm whales ranged from 417–1200 cm, with 68% of females 1050–1200 cm long. Constraints associated with the age structure observed in this study and the representativeness of the age structure to that of the greater population are discussed. In an effort to assess the effects of underestimation of age estimates on age-specific demographic parameters, a model simulating changes in age structure as a result of tooth wear was developed and the resulting survival rates compared to those derived from the original age structures of the samples. Survival did not change significantly between the modelled and original age structures. Also, the survival rate calculated from Australian mature female sperm whales was compared to that calculated from sperm whales caught in whaling operations from Japanese waters. Australian mature female sperm whales demonstrated significantly higher survival rates (mean = 0.905 ± 0.046 SD range: 0.856–0.986) than mature females from Japanese waters (mean = 0.885 ± 0.034 SD; range = 0.859–0.970), possibly the reflection of higher fishing mortality on the Japanese whales. Growth equations using Gompertz and von Bertalanffy models were calculated for female Australian sperm whales and compared. Both models described growth in female sperm whales similarly. Changes in the demographic parameters of sperm whales with the cessation of whaling may be reflected in the growth rates of individuals and as such, these equations may provide a useful tool for monitoring continuing changes in the demographic parameters of this species. Without long-term mark–recapture studies on sperm whales in this region, the frequent stranding of sperm whales in south-eastern Australia provides an important opportunity to collect data on the life history and demography of this species.
Southern minke whales Balaenoptera acutorostrata are genetically separated from Northern Hemisphere minke whales. Seasonal migrations take them from tropical latitudes in winter to high latitudes of the Antarctic in summer. Breeding takes place in warmer waters but little is known of breeding areas. Breeding areas and southbound migrations were studied using sighting data derived from the Japanese sighting surveys during 1976 to 1987. Relatively higher concentrations were observed in the waters mainly around 10 degrees to 20 degrees S in October, the end of the main conception period of this species in the Southern Hemisphere. Spatial distribution in tropical and subtropical waters during the latter half of the conception period suggests that there are 2 breeding areas in the eastern and western South Pacific and 2 others in the eastern and western Indian Ocean. It appears that breeding populations of the southern minke whale are relatively dispersed in open waters while coastal species such as right whales Eubalaena glacialis, humpback whales Megaptera novaeangliae and gray whales Eschrichtius robustus migrate along the shore and congregate in near-shore breeding areas. Latitudinal occurrences by month suggest that southern minke whales moved southward from the breeding areas by October-November, and that most of them had migrated into Antarctic waters by January. They tend to move almost directly south from the breeding areas to feeding areas, and subsequently disperse after arriving at the feeding areas. Southbound migration speeds were estimated to average 20 nautical mites (n miles) d(-1) in waters north of the subtropical convergence and 40 to 50 n miles d(-1) in waters south of the convergence.
In this study we (1) synthesized 65 yr of odontocete stranding data around the main Hawaiian Islands (1937–2002); (2) analyzed stranding patterns and trends over time; and (3) compared occurrence patterns based on sightings of live animals with stranding data and evaluated the compatibility of these data sets. From 1937 to 2002, 202 odontocete strandings were recorded by the National Marine Fisheries Service, Pacific Islands Regional Office. Strandings increased through time due to increased reporting effort and occurred throughout the year. The four most common of 16 species reported were Kogia spp. (18%), spinner dolphins (Stenella longirostris) (15%), striped dolphins (Stenella coeruleoalba) (11%), and sperm whales (Physeter macrocephalus) (10%). The highest proportion of strandings was recorded on O‘ahu (48%), followed by Maui/Lāna‘i (24%), Kaua‘i (12%), Hawai‘i (11%), and Moloka‘i (5%). Comparison with four previously published live animal survey studies suggests that stranding records are a good indicator of species composition and yield reasonable data on the frequency of occurrence of species in the region they cover.
A well-maintained marine mammal stranding data-base can be an invaluable tool in understanding not only strandings but also changes in the marine environment. This study aimed to examine the fol-lowing aspects of marine mammal strandings in the Philippines: species composition, temporal (i.e., frequency of stranding per year and seasonality) and spatial (i.e., frequency of stranding per region and province) variation, proportions of alive or dead specimens, and stranding hotspots. In 2008, a sys-tematic collection of data on strandings, including out-of-habitat incidents, resulted in an initial 12-year database—from 1998 to 2009. A total of 178 strand-ing events were recorded: 163 single, 10 mass, and 5 out-of-habitat strandings, with an average of 15 observed stranding events annually. Twenty-three of the 28 confirmed species of marine mammals in the Philippines were recorded to strand, including first-recorded specimens for the Indo-Pacific bot-tlenose dolphin (Tursiops aduncus), pygmy sperm whale (Kogia breviceps), and Longman's beaked whale (Indopacetus pacificus). The top five most frequent species to strand included spinner dol-phin (Stenella longirostris) (n = 26), short-finned pilot whale (Globicephala macrorhynchus) (n = 14), melon-headed whale (Peponocephala electra) (n = 13), Risso's dolphin (Grampus griseus) (n = 11), and common bottlenose dolphin (T. truncatus) (n = 10). Dugongs (Dugong dugon) stranded seven times since 2001. Strandings occurred through-out the year with frequency significantly peaking during the northeast (NE) monsoon (November to March) season. Overall, Regions III (Central Luzon) and VII (Central Visayas) had the highest number of strandings (both n = 27) followed by Regions I (Ilocos) (n = 22) and V (Bicol) (n = 18). The following provinces or local government units were considered hotspots based on high number of strandings observed at each area: Zambales, Cagayan, Zamboanga City, Negros Oriental, Bohol, Pangasinan, and Bataan. Sixty-five percent of all documented stranding events involved live (n = 116) animals. This high percentage might be linked to dynamite fishing (causing acoustic trauma), fish-eries interactions, or biotoxins from harmful algal blooms coupled to their foodweb. These strandings in general validate the diverse marine mammal assemblage in the Philippines and reveal the vari-ous environmental threats with which they deal.
One hundred and fifteen sperm whales (97 female, 15 male, 3 unknown sex) were involved in three mass stranding events during the month of February 1998 along the west and northwest coastlines of Tasmania, Australia. Sixty-six of these whales stranded at Ocean Beach, Strahan; 35 at Greens Beach, Marrawah; and 11 at Black River Beach, Stanley. The remaining whales stranded singly along the coastline. Three mass strandings of this species in such close temporal proximity have not been reported in this area before, and this is the first time that data have been comprehensively collected from complete or near-complete groups of sperm whales from Tasmanian waters. Adult females dominated the three stranding groups. Total lengths ranged from 417 to 1,200 cm and ages ranged from 0.75 to 64 yr. Four females were lactating and four fetuses were found amongst the groups. Stomach contents were dominated by pelagic cephalopods.
Marine vertebrate strandings data can provide insights into the long-term dynamics of cetacean populations, and the threats
they face. We investigate whether the spatio-temporal patterns of cetacean strandings around Cornwall, SW Britain, have changed
in the past century. Analysis of strandings from 1911 to 2006 (n=2,257) show that, since the mid-1970s, the relative frequency of strandings of common dolphins (Delphinus delphis), harbour porpoises (Phocoena phocoena) and pilot whales (Globicephala melas) has increased significantly. Seasonal peaks in strandings frequencies are apparent, between December and March for harbour
porpoises and common dolphins, and between November and January for pilot whales. There were significant positive trends in
the number of common dolphin and harbour porpoise strandings, as a proportion of total strandings, over time. Strandings of
common dolphins, porpoises and all other species occur more frequently on the south coast of Cornwall. A total of 415 cetaceans
were subject to full veterinary necropsy to determine cause of death, between 1990 and 2006, and 253 (61%) of these individuals
were determined to have died due to bycatch in fishing gear. Analyses of industrialised fishing pressure in UK waters show
the seas around Cornwall to be one of the most heavily fished areas of the UK. We suggest a number of factors that could be
responsible for the recent increases in cetacean strandings in southwest UK waters in recent years, including survey effort,
as well as abundance and range shifts that are potentially linked with climate change. Although detectable levels of bycatch
rate have not increased over time, fisheries interactions are in significant part responsible for mortality patterns and are
worthy of more detailed investigation.
Two morphological forms of the bottlenose dolphin, Tursiops truncatus, are recognised in Indo-Pacific waters; a coastal form referred to as T. cf. aduncus and an offshore form, T. truncatus. The two are distinguished primarily on the basis of ventral spotting, present in adult T. cf. aduncus and absent in T. truncatus. We compared the morphology of specimens obtained from parts of their range where both forms are found; south-east Africa, the East and South China Seas and eastern Australia. Across its range, T. cf. aduncus has a shorter body and skull length and on average more teeth than T. truncatus from the same areas. No difference in body length was noted between sexes in T. cf. aduncus while male T. truncatus are larger than females. T. cf. aduncus from tropical waters are distinctly smaller than in subtropical / temperate regions. Differences in the pattern of the dorsal cape between forms from eastern Australia enabled their geographic distribution to be investigated. T. cf. aduncus was found in estuarine and near-coastal oceanic waters and T. truncatus in near-coastal oceanic and offshore waters. Differences in morphology, and likely niche separation in this partially sympatric distribution of the two forms suggests two species, but there are arguments both for and against the assignment of species status to each morphotype.
To understand the cause of death of 405 marine mammals stranded on Cape Cod and southeastern Massachusetts between 2000 and 2006, a system for coding final diagnosis was developed and categorized as (1) disease, (2) human interaction, (3) mass-stranded with no significant findings, (4) single-stranded with no significant findings, (5) rock and/or sand ingestion, (6) predatory attack, (7) failure to thrive or dependent calf or pup, or (8) other. The cause of death for 91 animals could not be determined. For the 314 animals that could be assigned a cause of death, gross and histological pathology results and ancillary testing indicated that disease was the leading cause of mortality in the region, affecting 116/314 (37%) of cases. Human interaction, including harassment, entanglement, and vessel collision, fatally affected 31/314 (10%) of all animals. Human interaction accounted for 13/29 (45%) of all determined gray seal Halichoerus grypus mortalities. Mass strandings were most likely to occur in northeastern Cape Cod Bay; 97/106 (92%) of mass stranded animals necropsied presented with no significant pathological findings. Mass strandings were the leading cause of death in 3 of the 4 small cetacean species: 46/67 (69%) of Atlantic white-sided dolphin Lagenorhynchus acutus, 15/21 (71%) of long-finned pilot whale Globicephala melas, and 33/54 (61%) of short-beaked common dolphin Delphinus delphis. These baseline data are critical for understanding marine mammal population health and mortality trends, which in turn have significant conservation and management implications. They not only afford a better retrospective analysis of strandings, but ultimately have application for improving current and future response to live animal stranding.
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.
The existence of nearshore and offshore populations of the bottlenose dolphin has been documented throughout its range. In several cases the two regional forms have been shown to be morphologically distinct, although there is considerable overlap for most characters. The populations off the eastern coast of North America have been the subject of a long-term programme of research on their distribution and movements. In this study, we compare mitochondrial and nuclear genetic markers between dolphins classified as either nearshore or offshore type. These putative populations were found to be distinct at both nuclear and mitochondrial genetic markers. Further, the level of variation among the nearshore dolphins was reduced compared with the offshore population. A broader geographical comparison suggests a shared lineage between offshore dolphins from the western North Atlantic and both offshore and nearshore dolphins from the eastern Atlantic. These results are consistent with local differentiation based on habitat or resource specialization in the western North Atlantic, and suggest differences in the character of the nearshore/offshore distinction in different parts of the world.
A method for the safe and effective euthanasia of large beached humpback whales using explosives is described. Five recent case studies involving live stranded humpback whales measuring 9.1-12.7m are described to show how the method was applied, and the capacity of the method to deal with the varying conditions encountered when dealing with large baleen whales. Issues relating to the wider application of this method to other species of baleen whale and large odontocete species are discussed along with key safety implications for the safe use of this method.
One reason for the legislative restrictions on feeding dolphins in many parts of the world is the putative increased risk of injury to dolphins conditioned to human interaction through food reinforcement. However, there are few empirical data to support this. Here, we present data for a population of Bottlenose Dolphins Tursiops sp. in Cockburn Sound, in the city of Perth, Western Australia, indicating higher incidence of boat strike injury and fishing line entanglement for dolphins conditioned to taking food from humans, compared to others in the population that were not conditioned. The data support prohibitions on feeding dolphins and rigorous enforcement of existing regulations.
During progression of a mass mortality of Australian pilchards in late 1998
and early 1999, quantities of dead pilchards on the sea-surface, sea-floor and
along beaches were estimated in three regions along southern Western Australia
(WA) by use of transects. Total mortality was estimated at 17 590, 11193 and
144.4 t for Esperance, Bremer Bay and Albany respectively. Mortality rates at
Esperance and Bremer Bay were similar at 74.5% and 64.7%
respectively, with a mean of 69.6%. In contrast, estimated mortality at
Albany was only 2.4%. Although the difference in total mortality
between regions is probably related to differences in stock size, as
determined by simulation models, the much lower estimate for Albany is
probably an artefact of an over-estimated pilchard biomass and not due to
large differences in actual mortality rates. Variability in estimates of both
pilchard biomass and quantities killed resulted in a wide range of estimated
mortality rates, with lower estimates for Esperance and Bremer Bay of
28.0% and 22.9% respectively. This represents a significant
decline in the breeding stock of WA pilchards. If the impact was closer to the
mean (69.6%), then pilchard stocks in WA are severely depressed.
This study summarizes 660 events involving captured, live-stranded and dead cetaceans in
South Australia between 1881 and 2000. Emphasis is placed on records (n = 361) during
1985-2000 when an active necropsy programme was underway. Average number of events per
year was 30.4 and the most common species were the short-beaked common dolphin
(Delphinus delphis) and Indo-Pacific bottlenose dolphin (Tursiops aduncus). Records were
assigned to nine categories of circumstance/cause of death. Summarizing the total database,
60% were unknown circumstance, 22% not obviously anthropogenic, 13% unintentional
human-related and 5% intentional human-related. In the data set of records for 1985-2000,
50% were unknown, 25% were not obviously anthropogenic, 20% were unintentional humanrelated
and 5% were intentional killings. Non-anthropogenic circumstances included neonatal
deaths, live strandings, significant diseases, shark attacks and choking. Cornynebacterium
ulcerans is recorded for the first time in a cetacean. Unintentional circumstances included
entanglement in fishing and aquaculture equipment (17% of necropsied carcasses from
1985-2000) and boat strikes. Intentional human-related circumstances were captures for live
display and illegal killing. Five percent of the necropsied carcasses during 1985-2000 were
attributed to shootings or stabbings/spearings. There is need for a formal reporting procedure
for marine mammal deaths and human interaction involving injury and for steps to be taken to
reduce human impacts.
Clear genetic and osteological characters exist to distinguish 2 sympatric species of bottlenose dolphins (genus Tursiops) in the waters of China. However, these characters are not useful for the identification of free-ranging dolphins. To determine if these species could be differentiated by external morphology, a discriminant analysis was performed on 8 external morphometric characters of 57 specimens, 40 of which were classified a priori as T. truncatus and 17 as T. aduncus using genetic, osteological, and other information. External morphological separation of the 2 species was highly significant. Furthermore, discriminant scores were nonoverlapping, and classification functions were successful in classifying several new specimens from the waters of China and Indonesia. Rostrum length as an absolute measure and as a proportion of total body length or snout-to-eye length revealed nonoverlapping distributions for the 2 species in the waters of China and thus offered useful field characters for classifying fresh carcasses, stranded individuals, captive specimens, photographs, and in some cases free-ranging individuals.
Through compilation of historical whaling data, to- gether with recent aerial and boat-based survey data, a general framework for the overall peaks of migration has been estimated for the temporal and spatial movements of Group IV humpback whales along the Western Austra- lian coast. The migratory paths of humpback whales along the Western Australian coast lie within the continental shelf boundary or 200 m bathymetry. Major resting areas along the migratory path have been identified at Exmouth Gulf (southern migration only) and at Shark Bay. The northern endpoint of migration and resting area for reproductively active whales in the population appears to be Camden Sound in the Kimberley. A 6,750 square km 2 area of the Kimberley region, inclusive of Camden Sound, has also been identified as a major calving ground. The northern and southern migratory paths have been shown to be divergent at the Perth Basin, Dampier Archipelago and Kimberley regions. In all cases the northern migratory route is further off-shore.
The oceanography of the Perth Canyon, off southwestern Australia, was examined through two major field excursions in austral spring/summer 2003/2004 combined with previous results from field analysis and numerical simulations. Water properties were used to identify water masses and vertical displacement. The field cruises and numerical simulation indicated unique circulation features of the Leeuwin Current and Undercurrent within the canyon associated with the topographic features. The input of nutrients to the euphotic zone occurred sporadically as the Leeuwin Current generally suppressed upwelling, although the Perth Canyon had increased nutrient concentrations within its rims. The distribution of chlorophyll in the surface layers indicated high spatial variability, with a prevalent deep chlorophyll (and phytoplankton biomass) maximum at ~ 80 m. Depth-integrated primary production within the study region ranged from 360 to 760 mg C m− 2 d− 1, which was on average 2.5 times higher than rates measured in continental shelf and offshore waters north of the canyon. Aggregations of krill and other acoustic backscatter targets were concentrated near the head of the canyon at a range of depths, which may have been promoted by the circulation.The findings here are consistent with seasonal variations in wind and insolation, along with variations in the Leeuwin Current, influencing the seasonal changes and mesoscale features within the region, while the canyon promotes localised upwelling, and enhances both pelagic production and physical aggregation of plankton to attract the whales. Canyon processes must be combined with outside factors to allow upwelled nutrients to reach the photic zone. It is concluded that a combination of factors, rather than one factor alone, contributes favourably to the appearance of feeding blue whales in the Perth Canyon during the summer.
1. Climate change is thought to affect the composition and structure of local ecological communities. We investigate whether ocean warming around north-west Scotland since 1981 has been associated with changes in the local cetacean community.2. Analysis of strandings from 1948 to 2003 found that no new species per decade were recorded in north-west Scotland between 1965 and 1981. This rose to 2.0 new species per decade from 1988 onwards. The new species recorded since 1988 are generally restricted to warmer waters, while those recorded prior to 1981 regularly occur in colder waters.3. In the period 1992 to 2003, the relative frequency of stranding of white-beaked dolphin, a colder water species, has declined while strandings of common dolphin, a warmer water species, have increased. Similarly, sightings surveys conducted in May–September 2002 and 2003 show that the relative occurrence and abundance of white-beaked dolphins have declined and common dolphins increased in comparison to previous studies.4. These observations are consistent with changes in the local cetacean community being driven by increases in local water temperature. If such temperature changes continue, some formerly abundant cold-water species, such as white-beaked dolphins, may be lost from this cetacean community. In a wider context, such changes may lead to populations of cetaceans moving out of areas specifically designated for their protection as they respond to changes in local oceanic conditions.
We document a human-dolphin interaction involving the illegal feeding of wild Bottlenose Dolphins (Tursiops sp.) in Cockbum Sound, Western Australia from 1993-2003. In 1993 only one dolphin was considered conditioned to human interaction through food reinforcement. By 2001, 16% (n = 12) of the resident community of 74 adult dolphins were conditioned, and at least 14 dolphins were conditioned by 2003. Of the 13 conditioned dolphins of known sex, 11 (85%) were males. We observed conditioned dolphins initiating interactions by approaching recreational fishing boats and by residing for several hours at boat ramps and shore-based fishing sites. We only observed recreational fishers feeding dolphins, although anecdotal reports indicated additional feeding sources. We used belt transects to determine the densities of recreational boats and encounter rates for conditioned dolphins across habitats within Cockbum Sound. Encounter rates and boat densities were positively correlated, suggesting an association between recreational boat density and the ranging patterns of conditioned dolphins. This study demonstrates how illegal feeding interactions can intensity over time to affect a potentially biologically significant proportion of a local dolphin population. This emphasizes the need for early and pro-active intervention and demonstrates the value of longitudinal, individual-specific wildlife studies.
Seventeen striped dolphins, Stenella coeruleoalba, were found stranded on a West Australian beach. Three animals died before a rescue attempt was made and a further three died during the rescue. The remaining dolphins were released 24 km offshore and were not seen again. One dolphin was noted to have a broken mandible. Evidence of physical trauma to the other dolphins was minimal; one adult female was observed with some peeling skin. Blood was collected for analysis. All dolphins were slightly dehydrated and had a leukogram typical of a stressed animal. Plasma biochemistry reflected primary muscle trauma. There were no clues to the cause of the stranding; observed pathology reflected damage that occurred as a direct consequence of stranding.
Dolphin deaths in the Swan Canning Riverpark and comments on the Bunbury inner waters
- Beazley L
BEAZLEY L 2010. Dolphin deaths in the Swan Canning Riverpark
and comments on the Bunbury inner waters, South-west of
Western Australia. Report to the Minister for Environment
<http://www.swanrivertrust.wa.gov.au/science/river/
Documents/Dolphin_Review_Final_30_April_2010.pdf>.
A guide to the integrated marine and coastal regionalisation of Australia Version 4.0. Department of Environment and Heritage
- Gershwin L-A Thompson R
- Owen K Commonwealth Of Australia
CHARLTON-ROBB K, GERSHWIN L-A, THOMPSON R, AUSTIN J, OWEN K COMMONWEALTH OF AUSTRALIA 2006.A guide to the integrated marine
and coastal regionalisation of Australia Version 4.0. Department
of Environment and Heritage, Canberra.
Rescue Augusta. Far Horizons
- Edwards H
EDWARDS H 1987. Rescue Augusta. Far Horizons Jan-Feb 1987,
12-15.
The Capes Current: a summer countercurrent flowing past Cape Leeuwin and Cape Naturaliste
PEARCE A & PATTIARATCHI C 1999. The Capes Current: a summer
countercurrent flowing past Cape Leeuwin and Cape
Naturaliste, Western Australia. Continental Shelf Research 19,
401-420.
A guide to the integrated marine and coastal regionalisation of Australia Version 4.0. Department of Environment and Heritage
- Commonwealth
- Australia
COMMONWEALTH OF AUSTRALIA 2006.A guide to the integrated marine
and coastal regionalisation of Australia Version 4.0. Department
of Environment and Heritage, Canberra.