In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.
|EPBC Act Listing Status||
Listed migratory - Bonn
|Adopted/Made Recovery Plans|
|Policy Statements and Guidelines||
Marine bioregional plan for the Temperate East Marine Region (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2012aa) [Admin Guideline].
Marine bioregional plan for the North Marine Region (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2012x) [Admin Guideline].
Marine bioregional plan for the North-west Marine Region (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2012y) [Admin Guideline].
Indo-Pacific humpback and Australian snubfin dolphins - A Vulnerability Assessment for the Great Barrier Reef (Great Barrier Reef Marine Park Authority (GBRMPA), 2011b) [Admin Guideline].
Seagrass - A Vulnerability Assessment for the Great Barrier Reef (Great Barrier Reef Marine Park Authority (GBRMPA), 2011k) [Admin Guideline].
Australian National Guidelines for Whale and Dolphin Watching (Department of the Environment and Heritage, 2005e) [Information Sheet].
Federal Register of
List of Migratory Species (13/07/2000) (Commonwealth of Australia, 2000b) [Legislative Instrument].
Documents and Websites
|State Listing Status||
|Non-statutory Listing Status||
|Scientific name||Sousa chinensis |
|Species author||(Osbeck, 1765)|
This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.
Scientific name: Sousa chinensis
Common name: Indo-Pacific Humpback Dolphin
Other names: Humpbacked Dolphin
The Indo-Pacific Humpback Dolphin was described by Osbeck in 1765. Although the taxonomy of the genus Sousa requires revision, most recent authors recognize only two species: S. teusziii (Atlantic Humpback Dolphin) and S. chinensis (Indo-Pacific Humpback Dolphin).
Indo-Pacific Humpback Dolphins are characterised by a robust and medium sized body with a short, slightly recurved and triangular-shaped dorsal fin. Individuals from the western part of the species' range have a prominent dorsal ridge forming part the base of the dorsal fin. However, this ridge is not present in Australian animals.
Colouration is uniformly grey, with flanks shading to off-white. Age related changes include a loss of grey colour (shading to white or pinkish) and increased ventral spotting in older animals (Ross 2002).
In Australian waters, male Indo-Pacific Humpback Dolphins are recorded to attain lengths of 2.62 m, while females have measured up to 2.6 m. The age and length at physical maturity of South African animals are 13-14 years and 2.58-2.74 m respectively. The maximum lengths and weights recorded in South African animals are 2.7 m and 260 kg for males, and 2.4 m and 170 kg for females.
Adult Indo-Pacific Humpback Dolphins may be found singly or in pairs, while immature individuals tend to associate with groups containing more than one adult. Group size is generally four to seven, but may be as large as 25 (Ross 2002). Larger Indo-Pacific Humpback Dolphin groups are comprised of all age classes, with adults representing between one half and two thirds of the group (Jefferson & Karczmarski 2001).
Goodwin (1997, cited in Ross 2006) indicated that humpback dolphins show strict female philopatry (stay in the area they were born). However Atkins and Atkins (2002) were less certain about the state of philopatry in Richards Bay, KwaZulu-Natal, South Africa, but stated that a small proportion of the animals could be considered resident.
In Australia, Indo-Pacific Humpback Dolphins are known to occur along the northern coastline, extending to Exmouth Gulf on the west coast (25° S), and the Queensland/NSW border region on the east coast (34° S) (Corkeron et al. 1997). Off the east Australian coast, their distribution appears to be continuous. Although there are few records between the Gulf of Carpentaria in the north and Exmouth Gulf in the west, this is probably due to a lack of research effort and the remoteness of the area (Bannister et al. 1996; Parra et al. 2002).
Known localities in Queensland include the Great Barrier Reef Marine Park; Moreton Bay; the lower reaches of the Brisbane River, and adjacent offshore waters. In these areas, resident populations generally occur in water less than 10 m deep, and offshore to 6 km. A hotspot of Indo-Pacific Humpback Dolphins occurs on the western side of Bathurst Head, zoned as a Special Management Area, in the Far Northern Section of the Great Barrier Reef Marine Park (Parra et al. 2006).
Groups at Tin Can Inlet and Great Sandy Strait in Queensland will approach humans for food. Several groups also appear to be resident within Ningaloo Reef, north-western Australia (Bannister et al. 1996).
The distribution of Indo-Pacific Humpback Dolphins in Australia is linked to the warm eastern boundary current. Similarly, those resident in southern South Africa live at 34° S in water temperatures of 1522 °C (Bannister et al. 1996).
The current extent of occurrence of the Indo-Pacific Humpback Dolphin in Australia is estimated to be around 310 000 km². Regionally, the estimated extent of occurrence is:
- Queensland: 121 994 km²
- Western Australia: 115 740 km²
- Northern Territory: 71 839 km².
The extent of occurrence is calculated in coastal waters 5.5 km (3 nm) seawards throughout the known distribution (V.M. Peddemors et al. 2006, pers. comm.).
The current area of occupancy of Indo-Pacific Humpback Dolphins is difficult to estimate due to the sparsity of sighting records for a large proportion of the range. However, it is likely to be greater than 2000 km² (V.M. Peddemors et al. 2006, pers. comm.).
There is a continuing decline in the area, extent and quality of preferred habitat, potentially leading to a reduction in the number of locations that the Indo-Pacific Humpback Dolphin may inhabit. This could potentially lead to a reduction of area of occupancy over the next three generations (V.M. Peddemors et al. 2006, pers. comm.).
Given that the required shallow habitat preferred by this species occurs continuously throughout its recorded range, the distribution of the Indo-Pacific Humpback Dolphin is considered to represent one continuous location. Off the east coast of South Africa the species has been shown to rapidly travel over 100 km (Keith et al. 2002) suggesting long-shore movements over substantial distances are also possible.
A single female Indo-Pacific Humpback Dolphin is currently held in captivity at Sea World on the Gold Coast. She has been captive since 1968.
No distribution fragmentation is anticipated for the Indo-Pacific Humpback Dolphin, although there do appear to be 'hotspots' of higher densities along the surveyed east coast.
Based on the premise of a single Indo-Pacific species in the genus, Indo-Pacific Humpback Dolphins are distributed continuously as local residents in shallow coastal waters from False Bay, South Africa to the South China Sea, including the Red Sea, Arabian Gulf, the Indian subcontinent, Gulf of Thailand, Malacca Straits and northern Borneo, and up the coast of China to the Changjiang River (31° 50' N). At least one animal reached the Mediterranean via the Suez Canal, the first known case of anthropogenic range extension for a marine mammal through habitat modification (Kerem et al. 2001). There is evidence of seasonal changes in abundance, as indicated by sighting rates in some populations, for example, in southern Africa, India and China (Parsons 2002).
Population densities in southern Africa vary between study sites from 0.4 dolphins per km² in the Eastern Cape, South Africa (Karczmarski & Cockcroft 1999; Karczmarski et al. 1999), to 14.7 dolphins per km² in Maputo Bay, Mozambique (Guissamulo 2000). This variation may be linked to available prey density.
Elsewhere larger populations have been recorded. More than 1000 animals reside in the Pearl River, one of at least eight sites in China that may have concentrations of these dolphins (Jefferson 2000). However, many of these populations live in close proximity to industrialized, polluted, and heavily populated areas, and are extremely vulnerable to human-induced impacts (Reeves et al. 2003). Organochlorines, especially DDTs, may be compromising the health of populations in at least southern China and the Bay of Bengal (Bannister et al. 1996; Ross 2006). Mercury levels are exceptionally high in Hong Kong dolphins (Jefferson 2000). Boat collisions may also be a direct threat to population numbers in Hong Kong (Jefferson 2000).
Habitat destruction and incidental capture represent substantial threats to the species throughout its entire range (Culik 2003e). Incidental captures in various gillnets have been recorded throughout the range of the Indo-Pacific Humpback Dolphin (Cockcroft 1990; Jefferson & Karczmarski 2001; Ross et al. 1994). In South Africa and Australia, bycatch in shark nets may be occurring at unsustainable levels (Cockcroft 1990; Corkeron et al. 1997; Patterson 1990).
It is thus unlikely that Australasian Indo-Pacific Humpback Dolphins can cross deep water barriers such as that between Australia and South Africa. The Indo-Pacific Humpback Dolphin thus probably occurs in two regional populations, one in the western tropical Pacific, and another around southern Africa. Despite this regionality, recent studies suggest that Indo-Pacific Humpback Dolphins exist as a single species (Ross 2002).
The distribution of Indo-Pacific Humbanck Dolphins throughout their range has primarily been estimated from beach-cast animals. However, some systematic surveys have been conducted, concentrating on particular areas. In Morteon Bay, Queensland, fifty individuals have been photo-identified, and population estimation surveys were carried out in 19841986 and 19851987 (Corkeron et al. 1997). Likewise, preliminary population surveys have been carried out in Cleveland Bay, in the Central Section of the Great Barrier Reef, and around Princess Charlotte Bay in the northern section of the Great Barrier Reef (Parra et al. 2002; 2006).
Data from Dugong (Dugong dugon) aerial surveys along the Queensland coast have also provided minimum estimates of Indo-Pacific Humpback Dolphin numbers. However, these counts are uncorrected for submerged animals, possibly resulting in an underestimation of population numbers in this location.
This species is notorious for poor detectability, leading to earlier aerial surveys being abandoned in favour of acoustic monitoring of Sousa sounds (Corkeron & van Parijs 2002) and the relationship between number of sounds and number of animals in the area. Continuation of surveys should allow monitoring of relative abundance for much of the Queensland coast (Bannister et al. 1996).
The total population size of the Indo-Pacific Humpback Dolphin in Australian waters is unknown.
Populations at various locations along the Queensland coast have been surveyed, and some regional population estimates made. Estimates of the population size in Moreton Bay in 1984-1986, and 1985-1987 respectively were: 163 animals (108251), and 119 animals (81166) (Corkeron et al. 1997). Preliminary results for Cleveland Bay, in the Central Section of the Great Barrier Reef, suggest a population less than 200 animals (Parra et al. 2002). Regional population levels (e.g. Queensland) are likely to be in the order of thousands rather than tens of thousands (Parra et al. 2002). Continuation of surveys should allow monitoring of relative abundance for much of the Queensland coast (Bannister et al. 1996). Fifty animals have been photo-identified in Moreton Bay (Ross 2006).
It is likely that the Indo-Pacific Humpback Dolphin occurs as one population within Australia, based on information from elsewhere in their range. In South Africa, for example, the distribution of individuals is contiguous, with occasional hotspots exhibiting higher local densities (Karczmarski & Cockcroft 1999).
Given that reliable population estimates of the Indo-Pacific Humpback Dolphin in Australian waters do not exist, it is difficult to determine the population trend for the species. However, Culik (2003e) states that it is difficult to interpret the available information optimistically. By analogy with sympatric (and better studied) Dugongs, Corkeron and colleagues (1997) suggest that hump-backed dolphins may be in decline in Australian waters.
Off the east coast it is likely that there has been a population reduction primarily attributed to continued incidental capture in gillnets and shark nets, and habitat degradation (Bannister at al. 1996; Culik 2003e). Ongoing degradation of the species' habitat is anticipated to be the primary factor negatively affecting Indo-Pacific Humpback Dolphin populations throughout their range.
Although some seasonal variation in population numbers have been recorded elsewhere, no extreme fluctuations are known for this species (Jefferson & Karczmarski 2001).
The generation length of the Indo-Pacific Humpback Dolphin is about 18 years (V.M. Peddemors et al. 2006, pers. comm.).
All cetaceans are protected within The Australian Whale Sanctuary under the EPBC Act. The Sanctuary includes all Commonwealth waters from the 3 nm state waters limit out to the boundary of the Australian Exclusive Economic Zone (EEZ) (i.e. out to 200 nm and further in some places). Shepherd's Beaked Whales are also subject to International Whaling Commission (IWC) regulations and protected within the Indian Ocean Sanctuary and Southern Ocean Sanctuary.
The Indo-Pacific Humpback Dolphin is known to occur within the Great Barrier Reef Marine Park as well as the Queensland Marine Protected Area and is regarded as a species of priority for management and research by the Great Barrier Reef Marine Park (GBRMPA 2000; Parra et al. 2006). It is also possible that the some Indo-Pacific Humpback Dolphins occur within the Ningaloo Marine Park, with several groups known to visit the Ningaloo Reef (Bannister et al. 1996).
Indo-Pacific Humpback Dolphins inhabit shallow coastal, estuarine, and occasionally riverine habitats, in tropical and subtropical regions. The species usually occurs close to the coast, generally in depths of less than 20 m, but they have been seen 55 km offshore in shallow water (Corkeron et al. 1997, Jefferson 2000). Aerial surveys in the Great Barrier Reef region have located Indo-Pacific Humpback Dolphins in waters between the outer reef and the mainland (Corkeron et al. 1997; Marsh 1990). The Great Barrier Reef region is relatively sheltered from ocean swells by the outer reefs and in some areas (e.g. northern section) reefs, sandbanks and continental islands occur almost continuously from the mainland to the mid-shelf reefs. This explains the presence of this species in offshore waters in these areas (Parra et al. 2002).
Recent surveys conducted in the far northern section of the Great Barrier Reef Marine Park showed that most sightings of Indo-Pacific Humpback Dolphins occurred in waters less than 5 km from land, 20 km from the nearest river mouth, and in waters less than 15 m deep (Parra et al. 2006).
They display no apparent preference for clear or turbid waters, and have been reported in a variety of coastal habitats, from coastal lagoons and enclosed bays with mangrove forests and seagrass beds through to open coastal waters with rock and/or coral reefs. Although the choice of key habitats varies between different geographic regions, the choice of habitat is well defined and persistent at each location (Jefferson & Karczmarski 2001).
The western section of Moreton Bay and the lower reaches of the Brisbane River have been identified as potential key habitats for this species (Hale et al. 1998), with animals occurring in waters less than 10 m deep and up to 6 km offshore (Corkeron 1990).
Female Indo-Pacific Humpback Dolphins mature at about 10 years of age, and males at about 13 years (Jefferson & Karczmarski 2001; Ross 2002). Individuals may live to more than 40 years old (Bannister et al. 1996; Ross et al. 1994).
In Algoa Bay, South Africa, the mean crude birth rate estimate ranged between 4.8% and 6.5% (Jefferson & Karczmarski 2001). Minimum mortality rate to one year of age is about 20%, and recruitment rate to age one year is less than 4%. Natural mortality for adults is low, with annual adult survival rate roughly 95% in Algoa Bay (Karczmarski 1996). However, the rate of natural mortality may change depending on location. In Moreton Bay for example, 36% of dolphins showed evidence of shark attack, suggesting mortality from sharks is significant (Bannister et al. 1996).
Very high levels of organochlorines, probably sufficiently high to kill a female's first calf, occur in South African animals. It is possible that similar high pollutant loads occur in Australasian Indo-Pacific Humpback Dolphins, but no data are available at present.
Calves may be born throughout the year, but spring and summer peaks are reported for many parts of their range (Jefferson & Karczmarski 2001). Gestation lasts between 10 and 12 months (Cockcroft 1989) and calving interval has been estimated as three years in South Africa (Kaczmarksi 1996 1999). No calving areas are known in Australian waters (Bannister et al. 1996).
Reproductive data derived from Australian and South African dolphins indicate that the length and weight at birth 0.971.08 m and around 14 kg respectively. Age and length at weaning is not known, but in South Africa lactation may last more than two years (Cockcroft 1989).
Indo-Pacific Humpback Dolphins are thought to be opportunist-generalist feeders, eating a wide variety of coastal and estuarine-associated fishes, although reef, littoral and demersal fish species are taken. Teleosts, some cephalopods and crustaceans have also been recorded as prey. Indo-Pacific Humpback Dolphins are recorded feeding in association with prawn trawlers in Moreton Bay and presumably elsewhere throughout the species' range in Australia (Bannister et al. 1996; Ross et al. 1994).
Feeding may occur in a variety of habitats, from mangroves to sandy bottom estuaries and embankments to rock and/or coral reefs. Feeding primarily occurs in shallow waters (<20 m depth) and may incorporate beaching behaviour on sandbanks.
Indo-Pacific Humpback Dolphins are considered to be migratory, with evidence of migration across international boundaries leading to listing of the species under Appendix II of Convention of Migratory Species (CMS) (Culik 2003e). Numbers of animals vary seasonally in Algoa Bay, South Africa (Karczmarski et al. 1999;1999b), KwaZulu-Natal, South Africa (Keith et al. 2002), and around Hong Kong (Jefferson 2000). Indo-Pacific Humpback Dolphins appear to be present throughout the year off southern China and northern Queensland (Ross et al. 1994). However, stranding rates differ between various seasons (with peaks during the summer monsoon), which seems to indicate variable dolphin densities and possibly seasonally differing habitats (Parsons 1998)
On the east coast of South Africa extensive movements of over 120 km have been recorded, with ranges apparently increasing during the summer in association with increased near-shore turbidity loads following rain (Keith et al. 2002). Some seasonal inshore-offshore and longshore movements are also recorded for West African groups (Bannister et al. 1996).
The daily movement patterns of the Indo-Pacific Humpback Dolphins also varies between different locations. In Algoa Bay, South Africa, dolphins are primarily seen in the morning and to a lesser extent in the evening (Karczmarski et al. 2000). Their activities appear to follow a well-defined daylight pattern that varies little between seasons (Karczmarski & Cockcroft 1999). In Maputo bay, Mozambique, they are most regularly seen in the afternoon (Guissamulo 2000).
Home ranges for this species appear to be large (Jefferson & Karczmarski 2001). In most studies home ranges have not been calculated due to their extension beyond the boundaries of the study area, but in Hong Kong and the Pearl River Estuary home ranges extend from about 29 to 395 km² (Hung 2000). Throughout their distribution range, only some animals show 'resident' tendencies.
This species exhibits a characteristic surfacing behaviour. Initially the beak rises steeply from the water before the forehead appears. The back is arched before it dives.
The tendency to live in small group sizes and the notoriously shy nature of this species leads to difficulty in detecting the species. Additionally, its regular occurrence in turbid waters near river mouths make detection difficult.
Cetacean surveys are constrained by several important factors including weather (e.g. sea state and light conditions), area to be covered, aim of the survey (abundance estimate; ecological studies), the activities of the animals themselves (e.g. travelling, resting, surface or deep feeding), and the type of craft used for the survey.
Surveys for Indo-Pacific Humpback Dolphins have included land-based observations, boat-based transects, aerial surveys, acoustic surveys, and photo-identification population estimates (Corkeron et al. 1997; Karczmarski et al. 1999b; Jefferson 2000; Keith et al. 2002; Parra et al. 2006; Saayman & Tayler 1979)
Early aerial survey methods have now largely been abandoned in favour of acoustic monitoring of Sousa sounds (Corkeron & Van Parijs 2002), and the relationship between number of sounds and number of animals in the area.
The past and current threats to the Indo-Pacific Humpback Dolphin include habitat destruction and degradation (Bannister et al. 1996), bycatch in gillnets and shark nets (Parra et al. 2002; Paterson 1990), illegal sport killing (although there have been no reports of this occurring in Australian waters: Parra et al. 2002), live capture for Oceanariums (Ross et al. 1994), overfishing of prey species, pollution and poisoning (Cosser 1997; Gaus et al. 2001) and human interaction threats arising from tourism and transport. Determination of the level of philopatry (fidelity to area of birth) in this species is important, as the impact of the loss of reproductive females from such groups is potentially greater than that for species forming large schools (Ross 2006).
Habitat Destruction and Degradation
Habitat destruction and degradation, including noise pollution and harassment, is threatening Indo-Pacific Humpback Dolphin populations, particularly those close to major cities (e.g. in Moreton Bay) (Bannister et al. 1996). This threat is primarily a concern along the Queensland coast with high levels of construction, dredging, mining, land reclamation, resource extraction, agricultural development, commerce, tourism and recreational activities currently exist and likely to continue and increase. In the Northern Territory, the development of a liquefied natural gas plant in waters at Wickham Point, Darwin, and dredging for the port of the McArthur River mine, western Gulf of Carpentaria, are major considerations. Off Western Australia, the development of a large inland marine resort at the southern end of Ningaloo Marine Park (in Maud's Landing); port expansions in areas adjacent to Exmouth Gulf mostly associated with the petroleum industry and iron ore activities; and seismic surveys and petroleum explorations are also of concern. These effects are suspected to have had an impact at local level at all affected sites (V.M, Peddemores et al. 2006, pers. comm.). These threats are considered to be likely to continue into the future, potentially with increasing impact as habitat degradation and loss increases with growing human population requirements.
Incidental capture in inshore gillnets set across rivers and estuaries to catch Barramundi (Lates calcarifer) and Threadfin Salmon (Polynemus sheridani and Eleutheronema tatradactylum) (Hale 1997) often results in drowning in this and other marine mammals. Inshore gillnets occur primarily in the northern part of the Indo-Pacific Humpback Dolphin's range, although their effect is suspected to be minimal due to low catches, limited permit licences, and their potential reduction through implementation of new laws relating to the use of gillnetting (GBRMPA 2000; Parra et al. 2006).
Shark nets set for the protection of swimmers have reportedly killed 18 Indo-Pacific Humpback Dolphins between 1968 and 2001, 11 of which were from nets off Townsville and Cairns (Parra et al. 2002; Paterson 1990). Although there is no reported incidental bycatch from trawl nets and driftnets, they are suspected of occasionally capturing this species.
Regulations to reduce incidental non-target mortalities, such as net attendance rules and gear modifications, have been introduced but enforcement is lacking in remote areas (Hale 1997; Parra et al 2006). The effect is expected to reduce as mitigation measures become more common and better policed.
Illegal killing of marine mammals such as the Indo-Pacific Humpback Dolphin, particularly for sport (by spearing or shooting), may threaten population numbers. However, there is no evidence of direct killing of Indo-Pacific Humpback Dolphins in Australian waters (Parra et al. 2002).
At present, permits for the live capture of up to 12 Indo-Pacific Humpback Dolphins are granted per year in Queensland and northern NSW (Ross 2006). At least eight Indo-Pacific Humpback Dolphins have been held in Australian Oceanariums (Ross et al. 1994), with one animal currently being held in Sea World, Surfer's Paradise (which was wild-caught in 1968 off South Stradbroke Island, Queensland). Live capture is likely to have had minor impacts on a local population scale, but is unlikely to have any future affects as the number of dolphins in Australian aquariums have reduced in recent years, and permits to capture wild animals are unlikely to be issued for animals of threatened status.
Competition with Fisheries
Continued commercial fishing of prey species is expected to become an increasing threat as fisheries turn their attention to estuarine-associated fish that have previously not been major commercial targets. No quantitative studies on the feeding habits of Australian Indo-Pacific Humpback Dolphins have been made. However, based on the Australian distribution and habitat preferences of this species, and studies of stomach contents of this species elsewhere in its distribution, it is assumed that this species feeds mainly on estuarine-associated fish species (Barros & Cockcroft 1991; Jefferson 2000; Parra et al. 2006). Prey species constitute a component of the shrimp trawl fishery bycatch, plus are targeted in some areas by estuarine fisheries (e.g. Barramundi and Threadfin Salmon). This impact can be expected throughout the Australian range of Indo-Pacific Humpback Dolphin. However, until baseline feeding data for the Indo-Pacific Humpback Dolphin are determined the effect of fishing on prey population numbers cannot be quantified.
The northern and north-western coastlines are relatively unpopulated compared to other areas within Indo-Pacific Humpback Dolphin's range. However, pollutants entering coastal and estuarine waters along Australia's northern coastline come from many different sources (e.g. industrial and sewage discharges, catchment runoff and groundwater infiltration) and include heavy metals, pesticides, herbicides, nutrients and sediments (Cosser 1997).
The ecological significance of these contaminants on populations of Indo-Pacific Humpback Dolphins along the north coast are not known. However, recent studies on contaminant levels and water quality along the urban Queensland coastline indicate that there is a significant risk that some areas might be damaged in the future. Organohalogen pollutant levels in marine mammals from north-east Queensland were higher than expected (Vetter et al. 2001), therefore also potentially affecting this species. Polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/Fs) levels off Queensland are also high (Gaus et al. 2001), potentially threatening species such as Indo-Pacific Humpback Dolphins that prefer sheltered shallow waters. Although the adverse effects of complex mixtures of organohalogen compounds and PCDD/Fs on marine mammal health are not fully understood, their toxic properties and high concentration in Bottlenose Dolphins and Dugongs along the Queensland coast is regarded as threatening for Indo-Pacific Humpback Dolphin populations in Australia (V.M, Peddemores et al. 2006, pers. comm.).
The concentration and rapid growth of human populations, especially along the urban coast of Queensland has increased pressure on coastal resources and environments (QLD EPA 1997).
Interaction between Indo-Pacific Humpback Dolphins and tourism operators for dolphin-watching and dolphin-feeding activities is increasing, e.g. at Tin Can Bay, south-eastern Queensland. These activities increase the potential for adverse reactions by the dolphins, particularly when operated from boats.
The frequencies of whistles (1.2-16 kHz; Schultz & Corkeron 1994) and broad band clicks (2-22 kHz; van Parijs & Corkeron, 2001) produced by Australian Indo-Pacific Humpback Dolphins overlap with the frequencies emanating from boat traffic, suggesting that noise pollution may be a problem for this species.
The low reproductive rate (one offspring every two to three years) and high longevity (more than 40 years) (Bannister et al. 1996; Ross et al. 1994) of the Indo-Pacific Humpback Dolphin means that population recovery is a slow process.
The threats to the Indo-Pacific Humpback Dolphin could be abated through the implementation of disentanglement workshops and action plans to prevent deaths from gill and shark nets. In the far northern section of the Great Barrier Reef Marine Park, which appears to be a hotspot for Indo-Pacific Humpback Dolphins, the number of gillnet licences has been limited to less than 10 per year, and other restrictions on netting are being implemented. In addition, the fishery is closed for three months of the year, from 1 November to 1 February (Parra et al. 2006).
Whale watching guidelines already in place to manage the whale tourism industry could be adapted to other cetaceans such as the Indo-Pacific Humpback Dolphin (Department of the Environment and Heritage 2005e).
Funding has been provided for continuation of aerial surveys by the Great Barrier Reef Marine Park Authority, Queensland Fish Management Authority and Northern Territory Conservation Commission (Bannister et al. 1996).
Marine bioregional plans have been developed for four of Australia's marine regions - South-west, North-west, North and Temperate East. Marine Bioregional Plans will help improve the way decisions are made under the EPBC Act, particularly in relation to the protection of marine biodiversity and the sustainable use of our oceans and their resources by our marine-based industries. Marine Bioregional Plans improve our understanding of Australia's oceans by presenting a consolidated picture of the biophysical characteristics and diversity of marine life. They describe the marine environment and conservation values of each marine region, set out broad biodiversity objectives, identify regional priorities and outline strategies and actions to address these priorities. Click here for more information about marine bioregional plans.
The Indo-Pacific humpback dolphin has been identified as a conservation value in the North (DSEWPaC 2012x), North-west (DSEWPaC 2012y) and Temperate East (DSEWPaC 2012aa) marine regions. See Schedule 2 of the North Marine Bioregional Plan (DSEWPaC 2012x), the North-west Marine Bioregional Plan (DSEWPaC 2012y) and the Temperate East Marine Bioregional Plan (DSEWPaC 2012aa) for regional advice. Maps of Biologically Important Areas have been developed for Indo-Pacific humpback dolphin in the North-west (DSEWPaC 2012y), North (DSEWPaC 2012x) and Temperate East (DSEWPaC 2012aa) marine regions and may provide additional relevant information. Go to the conservation values atlas to view the locations of these Biologically Important Areas. The "species group report card - cetaceans" for the North (DSEWPaC 2012x), North-west (DSEWPaC 2012y) and Temperate East (DSEWPaC 2012aa) marine regions provide additional information.
The Action Plan for Australian Cetaceans (Bannister et al. 1996) and the Review of the Conservation Status of Australia's Smaller Whales and Dolphins (Ross 2006) provide brief biological overviews and management recommendations of this species. In addition, Australian National Guidelines for Whale and Dolphin Watching (Department of the Environment and Heritage 2005e) have been published.
The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.
|Threat Class||Threatening Species||References|
|Biological Resource Use:Fishing and Harvesting Aquatic Resources:Commercial harvest||Sousa chinensis in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006xl) [Internet].|
|Biological Resource Use:Fishing and Harvesting Aquatic Resources:Habitat modification and negative impacts on species numbers due to recreational fishing||Sousa chinensis in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006xl) [Internet].|
|Biological Resource Use:Fishing and Harvesting Aquatic Resources:Mortality due to capture, entanglement/drowning in nets and fishing lines||Sousa chinensis in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006xl) [Internet].|
|Human Intrusions and Disturbance:Human Intrusions and Disturbance:Human induced disturbance due to unspecified activities|
|Pollution:Agricultural Effluents:Habitat degradation due to agricultural chemical pollution|
Atkins, S. & B.L. Atkins (2002). Abundance and site fidelity of Indo Pacific humpbacked dolphins (Sousa chinensis) at Richards Bay, South Africa. 54th Annual meeting of the International Whaling Commission, Shimonoseki, Japan, May 2002.
Bannister, J.L., C.M. Kemper & R.M. Warneke (1996). The Action Plan for Australian Cetaceans. [Online]. Canberra: Australian Nature Conservation Agency. Available from: http://www.environment.gov.au/resource/action-plan-australian-cetaceans.
Barros, N.B. & V.G. Cockcroft (1991). Prey of humpback dolphins (Sousa plumbea) stranded in eastern Cape Province, South Africa. Aquatic Mammals. 17:134-136.
Cockcroft, V.G. (1989). Biology of Indopacific humpback dolphin (Sousa plumbea) off Natal, South Africa. Abstracts of the Biennial Conference on the Biology of Marine Mammals. 8:13.
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Citation: Department of the Environment (2014). Sousa chinensis in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Thu, 18 Sep 2014 03:43:57 +1000.