Southern Great Barrier Reef Lagoon and Coast IMMA

Size in Square Kilometres

84,807 km2

Qualifying Species and Criteria

Humpback whale – Megaptera novaeangliae

Criterion B (ii); C (i)

Marine Mammal Diversity 

Balaenoptera acutorostrata, Dugong dugon, Orcaella heinsohni, Sousa sahulensis, Stenella longirostris, Pseudorca crassidens, Tursiops truncatus, Tursiops aduncus

Summary

The east Australian humpback whale population (IWC breeding stock E1; BSE1) migrate in austral winter to this core breeding area within the Great Barrier Reef World Heritage Area, which encompasses the central and southern lagoonal waters (19.5°S – 22°S). The lagoonal water is the open water embedded by the inshore and offshore reefs, dominated by sand and mud with mobile sand dunes and minimal algae or seagrass. Humpback whales occur here between June and October, with peak whale abundance in August. This area is recognised as important for humpback whale mating and calving based on opportunistic sightings data (Simmons and Marsh 1986; Paterson and Paterson 1984; Chaloupka and Osmond 1999; Smith et al. 2012), dedicated aerial surveys (Smith & Peel 2019; Smith et al. 2020) and satellite tagged whales (Gales et al. 2010). The aggregation extends from waters north of the Whitsunday Islands group (~19°S), south to Shoalwater Bay (~22°S). Within this range, groups without calves (proxy for mating areas) have a higher density offshore of Mackay and groups with calves (proxy for calving areas) occur in greatest density offshore of the Whitsunday region. As the breeding season progresses from July to September, there is a shift in distribution of groups with calves in this area, to inshore waters closer to the coast (Smith et al. 2020). The BSE1 population of humpback whales was commercially hunted extensively in the 1950’s and early 1960’s, which resulted in a decline to approximately 1% of its original population (Paterson et al. 1994; Bannister & Hedley 2001). The population, however, has recovered strongly with a rapid and consistent rate of increase of 10-11% per annum since dedicated surveys began in the early 1980s (Paterson et al. 1994; Noad et al. 2019). They form an extensive aggregation that likely includes more than 30,000 whales, one of the largest whale aggregations in the world (Noad et al., 2019). This area also supports a diversity of inshore and offshore assemblages of secondary species of marine mammals, including at least two species of mysticete, six species of odontocetes (two of which are endemic to Australia and vulnerable) and dugongs.

Description of Qualifying Criteria

Criterion B: Distribution and Abundance

Sub-criterion Bii: Aggregations 

The east Australian population of humpback whales (BSE1) annually migrate from Antarctic high latitude feeding grounds to the tropical, low latitude breeding grounds in the Great Barrier Reef (Chittleborough 1965; Dawbin, 1966). This is a well-known seasonal breeding aggregation of humpback whales and encompasses the core breeding area for this population (Chaloupka & Osmond, 1999; Simmons & Marsh, 1986; Smith et al., 2012; Smith et al., 2020). This is one of the largest whale aggregations in the world, with the population exponentially increasing at approximately 11% per year (Noad et al., 2011, 2019). The population is likely more than 30,000 whales (extrapolating from Noad et al., 2019), with the majority within the core breeding area at any point between July and September and peak whale abundance in August. The current population size is approaching or has reached modelled pre-exploitation population size (Noad et al., 2019).

Criterion C: Key Life Cycle Activities

Sub-criterion Ci: Reproductive Areas

This area is critical to reproduction for this population of humpback whales with the bulk of mating and calving presumed to occur here. Breeding activity is strongly supported by anatomical and physiological data from whaling data (Chittleborough, 1965), photographs of newborn calves (Paterson & Paterson 1984) and observations of increasing numbers of newborn calves in the area throughout the breeding season (Smith & Peel, 2019). There is evidence that groups with calves (proxy for calving areas) occur in greatest density in the northern region of this area (offshore of the Whitsundays) and groups without calves (proxy for mating area) have a higher density in the southern region of this area (offshore of Mackay) (Smith & Peel 2019). This is the main breeding area for this population (BSE1), although calving does occur to a lesser extent along the migratory corridor (Corkeron & Brown, 1995, Torres-Williams et al. 2019).

Supporting Information

Chaloupka, M. & Osmond, M. 1999. Spatial and Seasonal Distribution of Humpback Whales in the Great Barrier Reef Region. American Fisheries Society Symposium. 89-106

Corkeron, P., & Brown, M. 1995. Pod characteristics of migrating humpback whales (Megaptera novaeangliae) off the east Australian coast. Behaviour, 132(3-4), 163-179.

Chittleborough, R.G. 1965. Dynamics of two populations of the humpback whale, Megaptera novaeangliae (Borowski). Australian Journal of Marine and Freshwater Research, 16, 33-128. doi: 10.1071/MF9650033

Dawbin, W. H. 1966. The seasonal migratory cycle of humpback whales. In K. S. Norris (Ed.), Whales, dolphins and porpoises (pp. 145–170). Berkeley: University of California Press.

Gales, N., M.C. Double, M.C., Robinson, S., Jenner, C., Jenner, M., King, E., Gedamke, J., Childerhouse, S. and Paton, D. 2010. Satellite tracking of Australian humpback (Megaptera novaeangliae) and pygmy blue whales (Balaenoptera musculus brevicauda). Report (SC/62/SH21) to the Scientific Committee of the International Whaling Commission. URL:
http://www.marinemammals.gov.au/__data/assets/pdf_file/0017/137312/sc-62-sh21.pdf

Noad, M.J., Kniest, E. & Dunlop, R.A. 2019. Boom to bust? Implications for the continued rapid growth of the eastern Australian humpback whale population despite recovery. Population Ecology, 61, 198-209. doi: 10.1002/1438-390X.1014

Paterson, R., and Paterson, P. 1984. A study of the past and present status of humpback whales in East Australian waters. Biological Conservation 29:321-343.

Simmons, M.L. & Marsh, H. 1986. Sightings of humpback whales in Great Barrier Reef waters. Scientific Reports of the Whale Research Institution, 37, 31-46. URL: https://www.icrwhale.org/pdf/SC03731-46.pdf

Smith, J.N., Grantham, H.S., Gales, N., Double, M.C., Noad, M.J. & Paton, D. 2012. Identification of humpback whale breeding habitat in the Great Barrier Reef. Marine Ecology Progress Series, 447, 259-272. doi: 10.3354/meps09462

Smith, J.N. & Peel, D. & Kelly, N. 2019. Quantitative assessment of relative ship strike risk to humpback whales (Megaptera novaeangliae) in the Great Barrier Reef World Heritage Area. Final Report to Maritime Safety Queensland. pp. 38. https://researchrepository.murdoch.edu.au/id/eprint/52711

Smith, J.N., Kelly, N., Childerhouse, S., Redfern, J.V., Moore, T.J. & Peel, D. (2020) Quantifying ship strike risk to breeding whales in a multiple-use marine park: the Great Barrier Reef. Frontiers in Marine Science. doi: 10.3389/fmars.2020.00067

Torre-Williams, L., E. Martinez, J. O. Meynecke, J. Reinke, and K. A. Stockin. 2019. Presence of newborn humpback whale (Megaptera novaeangliae) calves in Gold Coast Bay, Australia. Marine and Freshwater Behaviour and Physiology 52:199-216. doi: 10.1080/10236244.2019.1671769

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