Size in Square Kilometres
Qualifying Species and Criteria
Dugong – Dugong dugon
Criterion A; B (2); C (1; 2)
Australian humpback dolphin – Sousa sahulensis
Criterion A; B (1); D (1)
Indo-Pacific bottlenose dolphin – Tursiops aduncus
Criterion B (1)
Marine Mammal Diversity
Megaptera novaeangliae, Tursiops truncatus, Eubalaena australis, Delphinus delphis, Arctocephalus forsteri, Balaenoptera edeni, Balaenoptera acutorostrata
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Moreton Bay in southern Queensland is a large shallow embayment (~1,500 km2) flanked by four large sand islands: North Stradbroke and Moreton Islands to the east, Bribie Island to the north, and South Stradbroke Island to the south. This area features the southernmost resident populations of dugongs and Australian humpback dolphins on the east coast, a substantial number of Indo-Pacific bottlenose dolphins and a narrow humpback whale migratory corridor along its seaward boundary. Humpback whales also often enter northern Moreton Bay as they return south, and the area is visited occasionally by New Zealand fur seals and southern right whales. Other species that are regularly sighted in shelf waters east of the sand islands include common bottlenose dolphins, common dolphins, Bryde’s whales and dwarf minke whales. Most of the IMMA is within the Moreton Bay Marine Park, which has zones that restrict commercial and recreational fishing, and Go-Slow areas to limit vessel speed in dugong foraging habitat.
Description of Qualifying Criteria
Criterion A – Species or Population Vulnerability
Threatened species that are resident in the IMMA include substantial populations of Australian humpback dolphins and dugongs, which are both listed as Vulnerable by the IUCN (Parra et al., 2017, Marsh and Sobtzick, 2019) and under the State of Queensland’s Nature Conservation Act 1992.
Sub-criterion B1: Small and Resident Populations
The population size of Australian humpback dolphins in Moreton Bay was estimated to be between 119 and 163 from 1984 to 1987 (95% CI: 81−251; Corkeron et al., 1997), and more recently between 128 and 139 from 2014 to 2016 (95% CI: 67−274, J. J. Meager & E. R. Hawkins, unpubl. data). A recent study demonstrated long-term site fidelity and consistent habitat use in Moreton Bay from 1992 to 2016 (Meager et al., 2018). The social structure of humpback dolphins in Moreton Bay is highly fragmented with five separate communities and limited spatial overlap (Hawkins et al., 2019). There are approximately 550 Indo-Pacific bottlenose dolphins in Moreton Bay in two genetically distinct sub-populations: the first in the northern Bay and the second in the southern Bay (Ansmann et al., 2012). The smaller southern subpopulation is estimated to be ~200 dolphins (Ansmann et al., 2013). Very high densities of Indo-Pacific bottlenose dolphins have been recorded adjacent to the rocky headlands of North Stradbroke Island (Chilvers and Corkeron, 2003), which is also within the IMMA.
Sub-criterion B2: Aggregations
The dugong population in Moreton Bay displays distinct aggregating behaviour that has been associated with feeding (Preen, 1995, Hodgson, 2004). The eastern seagrass banks in Moreton Bay are the only known location in the dugong’s range where a very high proportion of dugongs recorded during aerial surveys is consistently in large herds of up to several hundred animals (Preen, 1995, Hodgson, 2004, Sobtzick et al., 2017).
Criterion C: Key Life Cycle Activities
Sub-criterion C1: Reproductive Areas
The three resident species of marine mammals reproduce in the IMMA, as evidenced by observations of mating behaviour and neonates. Since 2000, the proportion of dugongs classified as calves in Moreton Bay during aerial surveys has been around 10%, varying much less than the other areas on the east coast of Queensland and indicating that Moreton Bay is a consistently important area for dugong reproduction (Sobtzick et al., 2017) .
Sub-criterion C2: Feeding Areas
Moreton Bay provides important foraging habitat for dugongs, and the locations of key foraging habitat for dugongs and humpback dolphins in Moreton Bay are well understood (e.g. Sobtzick et al., 2017, Meager et al., 2018). Moreton Bay supports extensive seagrass pastures for dugongs (Lyons et al., 2011).
Criterion D: Special Attributes
Sub-criterion D1: Distinctiveness
The humpback dolphins in Moreton Bay represent a putative population with limited gene flow to the nearest population in the Great Sandy Strait (Parra et al., 2018), and the social structure of the local population is highly fragmented with five separate communities and limited spatial overlap (Hawkins et al., 2019).
Ansmann, I. C., Lanyon, J. M., Seddon, J. M. & Parra, G. J. 2013. Monitoring dolphins in an urban marine system: total and effective population size estimates of Indo-Pacific bottlenose dolphins in Moreton Bay, Australia. PLoS One, 8, e65239.
Ansmann, I. C., Parra, G. J., Lanyon, J. M. & Seddon, J. M. 2012. Fine-scale genetic population structure in a mobile marine mammal: inshore bottlenose dolphins in Moreton Bay, Australia. Molecular Ecology, 21, 4472-4485.
Chilvers, B. L. & Corkeron, P. J. 2003. Abundance of Indo-Pacific bottlenose dolphins, Tursiops aduncus, off Point Lookout, Queensland, Australia. Marine Mammal Science, 19, 85-95.
Corkeron, P. J., Morissette, L., Porter, H. & Marsh, H. 1997. Distribution and status of humpback dolphins, Sousa chinesis in Australian waters. Asian Marine Biology, 14, 49-59.
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Hagihara, R., Jones, R. E., Sobtzick, S., Cleguer, C., Garrigue, C. & Marsh, H. 2018. Compensating for geographic variation in detection probability with water depth improves abundance estimates of coastal marine megafauna. PLOS ONE, 13, e0191476.
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