Size in Square Kilometres
Qualifying Species and Criteria
Dugong – Dugong dugon
Criterion A; B (1); C (2)
Australian humpback dolphin – Sousa sahulensis
Criterion A; B (1)
Humpback whale – Megaptera novaeangliae
Criterion C (1)
Marine Mammal Diversity
Tursiops aduncus, Balaenoptera musculus, Orcaella heinsohni, Balaenoptera acutorostrata, Orcinus orca, Eubalaena australis, Balaenoptera omurai,, Balaenoptera physalus, Pseudorca crassidens
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The Pilbara region of Western Australia encompasses a diverse array of marine habitats including coral reef, coastal islands, subterranean karst limestone waterways, extensive mangroves, seagrass beds, high intertidal cyanobacterial mats, macroalgae-dominated reef flats, intertidal sand flats, soft coral and sponge beds. This area has been recognized at a national and international level through designation of State and Commonwealth marine protected areas including Ningaloo Marine Park and Murion Islands Management Area, Barrow Island Marine Park and Montebello Islands Marine Park as well as the Ningaloo Coast World Heritage Area. Ningaloo reef is one of the world’s longest fringing coral reefs and a biodiversity hotspot that includes resident populations of Australian humpback dolphins (Sousa sahulensis) (Hunt et al., 2017), Indo-Pacific bottlenose dolphins (Tursiops aduncus) (Haughey et al., 2020, Hanf 2015, Raudion et al., in review) and dugongs (Dugong dugon) (Bayliss et al 2018, Sobztik et al 2014) and seasonally present humpback whales (Megaptera novaeangliae) (Chittleborough 1953, Jenner et al., 2001, Irvine et al., 2018). The sheltered waters of Exmouth Gulf are an important feeding and nursing/calving habitat for Australian humpback dolphin, dugongs, and Indo-Pacific bottlenose dolphins as well as an important nursery for humpback whales. Key habitat prevalent throughout the region, including coastal waters out to nearshore islands, includes sand flats, seagrass beds, sponge gardens and coral communities. A large variety of marine mammal species have been recorded in this area, some seen regularly such as minke whales, blue whales and false killer whales while others are present seasonally such as killer whales as they follow migrating humpback whales (Pitman et al 2015), and southern right whales, present in very low numbers during their annual migration. Still others are sighted more opportunistically including Omura’s whales (Ottewell et al 2016, Cerchio et al 2019) and snubfin dolphins (Allen et al 2012). The boundary for the IMMA follows the 100m bathymetry contour and aligns with existing marine protected area boundaries for the Commonwealth Ningaloo and Montebello Islands Marine Parks and the Ningaloo World Heritage Area.
Description of Qualifying Criteria
Criterion A – Species or Population Vulnerability
Dugongs and Australian humpback dolphins are both listed as Vulnerable by the IUCN and are resident to the region (Hunt 2018, Hunt et al., 2017, Allen et al., 2012, Hodgson 2007, Sobtzick et al., 2014, Bayliss et al., 2018, Marsh and Sobtzick 2019). Furthermore, this area has been recognized at a national and international level through designation of State and Commonwealth marine protected areas including Ningaloo Marine Park and Murion Islands Management Area, Barrow Island Marine Park and Montebello Islands Marine Park as well as the Ningaloo Coast World Heritage Area.
Criterion B: Distribution and Abundance
Sub-criterion B1: Small and Resident Populations
The coastal waters of the North West Cape and Exmouth Gulf support resident populations of Vulnerable Australian humpback dolphins and Near Threatened Indo-Pacific bottlenose dolphins. Australian humpback dolphins inhabit the area with the highest density recorded for this species around North West Cape, with a population size estimated at 129 individuals within a 130 km2 area (Hunt et al 2017). Haughey et al. (2020) estimated a resident population of 141 (95% CI 121-161) Indo-Pacific bottlenose dolphins at the North West Cape, highlighting the importance of these coastal waters. Resident populations have also been recorded along the Pilbara coast and islands (Hanf 2015, Raudino et al 2018a) though no abundance estimates have been made. There are early indications that the dolphins inhabiting island habitat may be geographically separate from the mainland coastal population (Raudino et al 2018b). In particular high levels of female residency in humpback dolphins (Hunt et al., 2019) suggest that these waters are important for breeding and nursing for this species and dolphin calves were sighted during this study (Hunt 2017). Exmouth Gulf also contains a significant population of Vulnerable dugongs with estimates fluctuating over the years; 1062 (±321) individuals in 1989, 95 (±62) individuals in 2000, 1411 (±561) in 2007 and 4,599 ( 1,959) in 2018 (Preen et al 1997, Prince 2001, Hodgson 2007, RPS 2010, Bayliss et al 2019). Variation in dugong abundance and use of the Exmouth Gulf is likely a result of the seagrass loss following tropical cyclones and marine heatwaves and movement of dugongs to areas supporting seagrass (Bayliss et al 2019, Gales et al 2004). Aerial surveys of dugongs between 1989 and 2018 consistently identify the nearshore eastern waters of the Gulf as critical feeding and nursing habitat (Preen et al 1997, Bayliss et al 2019). Local-scale drone surveys coupled with in-situ assessments of the benthic habitat have shown that seagrass, particularly Halophila and Halodule species, are significant factors influencing dugong presence in south-eastern Exmouth Gulf (Christophe Cleguer pers comm).
Criterion C: Key Life Cycle Activities
Sub-criterion C1: Reproductive Areas
The sheltered waters of Exmouth Gulf have been suggested to have contributed to the recovery of the Breeding Stock D humpback whale population. The Gulf is the largest known resting area for this population, initially from 1950’s whaling data (Chittleborough, 1953) and more recently from boat-based and aerial surveys that report resting behaviour occurring from a few hours to a few weeks (Jenner et al., 2001, Jenner and Jenner 2005, Braithwaite et al., 2012, Irvine and Salgado Kent 2019), where mothers and calves can spend up to 3 weeks (Jenner & Jenner, 2005) resting and gaining size and strength. In addition, the area represents a southward extension of the breeding grounds for calving and mating (Irvine et al., 2018).
Sub-criterion C2: Feeding Areas
The seagrass habitat of Exmouth Gulf is an important feeding ground for dugongs. Aerial surveys of dugongs between 1989 and 2018 consistently identify the nearshore eastern waters of the Gulf, Pilbara coastal waters and nearshore Pilbara islands as critical feeding and nursing habitat (Sobztick et al 2014, RPS 2010). Local-scale drone surveys coupled with in-situ assessments of the benthic habitat have shown that seagrass species such as Halophila and Halodule are good predictors of dugong presence and abundance in the south-east Gulf (Christophe Cleguer pers. comm.). Variation in dugong abundance and use of Exmouth Gulf and the broader Pilbara Region is likely a result of the seagrass loss following tropical cyclones and marine heatwaves and movement of dugongs to areas supporting seagrass (Gales et al 2004, Sobztick et al 2014). Safeguarding the seagrass in the Gulf will protect a feeding ground and allow dugongs to migrate from alternative feeding grounds when required.
Allen, S.J., 2012. Tropical inshore dolphins of north-western Australia: Unknown populations in a rapidly changing region. Pacific Conservation Biology 18: 56-63.
Amir, O. A., Berggren, P., Ndaro, S. G. M., Jiddawi, N S. 2005. Feeding ecology of the Indo-Pacific bottlenose dolphin (Tursiops aduncus) incidentally caught in the gillnet fisheries off Zanzibar, Tanzania. Estuarine, Coastal and Shelf Science. 63 (3) 429-437.
Bayliss, P., H. Raudino, and M. Hutton, Dugong (Dugong dugon) population and habitat survey of Shark Bay Marine Park and Ningaloo Reef Marine Park, and Exmouth Gulf. 2018.Report to the National Environmental Science Program prepared by CSIRO and Department of Biodiversity, Conservation and Attractions. p. 51.
Bayliss, P., et al. 2019. Modelling the spatial relationship between dugong (Dugong dugon) and their seagrass habitat in Shark Bay Marine Park before and after the marine heatwave of 2010/11. Final Report to the National Environmental Science Program prepared by CSIRO and Department of Biodiversity, Conservation and Attractions. p. 55.
Bejder, L., et al., Low energy expenditure and resting behaviour of humpback whale mother-calf pairs highlights conservation importance of sheltered breeding areas. Scientific Reports, 2019. 9(1).
Braithwaite, JE, Meeuwig, JJ, Jenner, KCS (2012) Estimating Cetacean Carrying Capacity Based on Spacing Behaviour. PLoS ONE 7, e51347.
Chittleborough, R.G. 1953. ‘Aerial observations on the humpback Chittleborough, R.G. 1953. ‘Aerial observations on the humpback whale Megaptera nodosa (Bonnaterre), with notes on other species’. Australian Journal of Marine and Freshwater Research, 4:219-226.
Fitzpatrick, B., et al. 2019. Exmouth Gulf, north Western Australia: A review of environmental and economic values and baseline scientific survey of the south western region. 2019, Report to the Jock Clough Marine Foundation. p. 192pp.
Gales, N., et al. 2004. Change in abundance of dugongs in Shark Bay, Ningaloo and Exmouth Gulf, Western Australia: evidence for large-scale migration. Wildlife Research, 2004. 31(3): p. 283-290.
Hanf, D.M. 2015. Species distribution modelling of Western Pilbara inshore dolphins. Murdoch University. Masters thesis, 130pp.
Haughey, R., et al., Photographic capture-recapture analysis reveals a large popualtion of Indo-Pacific bottlenose dolphins (Tursiops aduncus) with low site fidelity off the North West Cape, Western Australia. Frontiers in Marine Science, 2020.
Hodgson, A. 2007. The distribution, abundance and conservation of dugongs and other marine megafauna in Shark Bay Marine Park, Ningaloo Reef Marine Park and Exmouth Gulf. James Cook University, Townsville.
Hunt, T. et al. in review. Identifying priority habitat for conservation and management of Australian humpback dolphins within a marine protected area. Scientific Reports.
Hunt, T., et al., 2017. Demographic characteristics of australian humpback dolphins reveal important habitat toward the southwestern limit of their range. Endangered Species Research. 32: p. 71-88.
Hunt, T.N., Demography, habitat use and social structure of Australian humpback dolphins (Sousa sahulensis) around the North West Cape, Western Australia: Implications for conservation and management. 2018, Flinders University: Adelaide, Australia.
Irvine, L.G., Thums, M., Hanson, C.E., McMahon, C.R. and Hindell, M.A. 2018. ‘Evidence for a widely expanded humpback whale calving range along the Western Australian coast’. Marine Mammal Science, 34(2): 294-310.
Irvine, L. and C. Salgado-Kent,. 2019. The distribution and relative abundance of marine-megafauna, with a focus on humpback whales (Megaptera novaeangliae), in Exmouth Gulf, Western Australia, 2018. Report to the Department of Biodiversity Conservation and Attractions.
Jenner, K.C.S., M.N.M. Jenner, and K.A. McCabe. 2001. Geographical and temporal movements of humpback whales in Western Australian waters. APPEA Journal, p. 749-765.
Jenner, C. and Jenner, M.N. 2005. ‘Distribution and abundance of humpback whales and other mega-fauna in Exmouth Gulf, Western Australia, during 2004/2005’. Final Report prepared for Straits Salt Pty. Ltd.
Kiszka, J., Méndez-Fernandez, P., Heithaus, M. R., Ridoux, V. 2014. “The foraging ecology of coastal bottlenose dolphins based on stable isotope mixing models and behavioural sampling.” Marine Biology 161(4): 953-961.Marsh, H. & Sobtzick, S. 2019. Dugong dugon (amended version of 2015 assessment). The IUCN Red List of Threatened Species 2019: e.T6909A160756767. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T6909A160756767.en.
Ottewell, K., et al. 2016. A recent stranding of Omura’s whale (Balaenoptera omurai) in Western Australia. Aquatic Mammals, 2016. 42(2): p. 193-197.
Pitman, R.L., et al. 2015. Whale killers: Prevalence and ecological implications of killer whale predation on humpback whale calves off Western Australia. Marine Mammal Science, 31(2): p. 629-657.
Preen, A.R., 1997. Distribution and Abundance of Dugongs, Turtles, Dolphins and other Megafauna in Shark Bay, Ningaloo Reef and Exmouth Gulf, Western Australia. Wildlife Research, 24(2): p. 185-208.
Prince, R.I.T. 2001. ‘Aerial survey of the distribution and abundance of dugongs and associated macroinvertebrate fauna – Pilbara coastal and offshore region, WA’.
Raudino H, Douglas C, Waples K. 2018a. How many dolphins live near a coastal development? Regional Studies in Marine Science. 19:25-32.
Raudino H., Hunt T., Waples, K. 2018b. ‘Records of Australian humpback dolphins (Sousa sahulensis) from an offshore island group in Western Australia’. Marine Biodiversity Records, 11:14-20.
RPS. 2010. Nearshore Regional Survey Dugong Report, in Browse Liquefied Natural Gas Precinct Strategic Assessment Report.
Salgado-Kent, C., et al. 2012.Southern hemisphere breeding stock ‘D’ humpback whale population estimates from North West Cape, Western Australia. . Journal of Cetacean Research and Management, 12: p. 29-38.
Salgado Kent, C. 2019. Distribution, abundance and residency of humpback whales in Bateman Bay in Ningaloo Marine Park, Western Australia. Report prepared for DBCA. pp 63.
Sobtzick, S., Hodgson, A.J., Campbell, R., Smith, J.N. and Loneragan, N. 2014. Chevron Wheatstone Project Dugong Research Program: Phase 2, 2013 Final Report. A report prepared by Murdoch University Cetacean Research Unit and James Cook University, for Chevron Pty Ltd.