Western Australian Humpback Whale Migration Route IMMA
Size in Square Kilometres
293,110 km2
Qualifying Species and Criteria
Humpback whale – Megaptera novaeangliae
Criterion C (1; 3)
Marine Mammal Diversity
Dugong dugon, Orcaella heinsohni, Sousa sahulensis, Stenella longirostris, Tursiops aduncus, Tursiops truncatus, Orcinus orca, Pseudorca crassidens, Balaenoptera musculus, brevicauda, Eubalaena australis, Balaenoptera physalus, Physeter macrocephalus, Balaenoptera edeni
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Summary
The Western Australian coastline is a known migration route for the Western Australian humpback whale population (IWC breeding stock D; BSD). The area has been selected due to our historical understanding of the movement of humpback whales during commercial whaling (Chittleborough 1965, Dawbin 1966), with more recent knowledge from aerial surveys (Bannister 1994; Bannister & Hedley 2002, Hedley et al. 2011, Salgado Kent et al. 2012), boat surveys (Jenner, 2001) and satellite tagging (Gales et al. 2010, Thums et al. 2018, How et al. 2020). Humpback whales undertake a consistent annual migration from high latitude Antarctic feeding grounds to low latitude breeding grounds. Off the Western Australian coastline, the migration occurs between June and November from temperate waters off South West Australia to the low latitude tropical breeding grounds in the Kimberley, North West Australia (15°–18°S; see IMMA Northwest Australian Humpback Whale Breeding Area). Humpback whales are primarily a coastal species when migrating and the migration typically occurs within the 200m bathymetry from the coastline. The migration route encompasses many different habitat types (e.g. seagrass, rocky seabed, sand) and the area is used by many different taxa of marine mammal (e.g. dugong, dolphins, whales and seals) due to overlapping with shallow, coastal waters.
Description of Qualifying Criteria
Criterion C: Key Life Cycle Activities
Sub-criterion C1: Reproductive Areas
Humpback whales off the Western Australian (WA) coastline migrate to discrete breeding areas in the Kimberley region during austral winter. However, the migration encompasses a spectrum in breeding behaviour along the WA coastline that can include early calving during the northern migration as well as nursing, resting and breeding behaviour on the southern migration. Initial evidence of calving on the northern migration is provided by whaling data from the 1950’s and was reported to occur as far south as Albany (35°S) (Chittleborough, 1953, 1965). Boat-based surveys (Jenner et al. 2001) and aerial surveys (Irvine et al. 2018) support these initial observations of calving on migration with increasing evidence of more calves born on the Ningaloo Coast near Exmouth Gulf (Irvine et al 2018). Exmouth Gulf is also identified as a resting area for humpback whales (in particular mothers nursing calves) between July and November. Evidence for this was initially from 1950’swhaling 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 & Jenner 2005; Irvine et al. 2018; Salgado Kent and Irvine 2018; Salgado Kent 2019). The majority of humpback whales use Exmouth Gulf as a resting area between late August and late October, during their southwards migration from the breeding grounds to the Antarctic feeding grounds (Chittleborough, 1953, Jenner et al. 2001). Mothers and their calves utilize the sheltered waters of Exmouth Gulf for resting and nursing, during which time humpback whale calves spend approximately 20% of their time suckling (Videsen et al. 2017).
Sub-criterion C3: Migration Routes
The Western Australian coastline is well established as a migration route for the Western Australian humpback whale population (IWC BSD), between low-latitude winter breeding grounds and high-latitude summer feeding areas in the Antarctic. Off the Western Australian coastline, their northward migration to the Kimberley breeding grounds typically occurs between June and August and their southward migration back to Antarctic feeding areas between August and November. There is temporal segregation of age/sex classes during migration typically with females in late lactation migrating first, followed by immature whales, mature males and ‘resting’ females that have not recently calved, and lastly late-pregnant females. This pattern is generally reversed during the southward migration from the low latitude breeding grounds (Chittleborough 1965; Dawbin 1966; Dawbin 1997). The migration has been well described from the 1940’s Discovery Tagging program (Raynor 1940), during commercial whaling (Chittleborough 1965), and from more recent vessel surveys (Jenner et al. 2001), systematic aerial surveys (Bannister 1994; Bannister & Hedley 2002, Hedley et al. 2011, Salgado Kent et al. 2012) and satellite tagging studies (Gales et al. 2010, Bestley et al. 2019, How et 2020). Humpback whales do not generally migrate further offshore than the 200m bathymetry off the entire Western Australian coastline based on all the available data; except in some specific areas off Ningaloo Reef where the continental slope occurs close to the coast.
Supporting Information
Bannister, J.L. 1994. ‘Continued Increase in Humpback Whales off Western Australia’. Report of the International Whaling Commission, 44: 309-310.
Bannister, J.L. & Hedley, S.L. 2001. ‘Southern Hemisphere Group IV humpback whales: their status from recent aerial survey’ Memoirs of the Queensland Museum, 47: 587-598.
Bestley, S., Andrews-Goff, V., van Wijk, E., Rintoul, S., Double, M.C. & How, J. 2019. ‘New insights into prime Southern Ocean forage grounds for thriving Western Australian humpback whales’ Scientific Reports, 9:13988. Doi: 10.1038/s41598-019-50497-2
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.
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.
Dawbin, W. H. 1966. The seasonal migratory cycle of humpback whales. Pages 145-170 in K. S. Norris, editor. Whales, dolphins and porpoises. University of California Press, Berkeley, CA.
Dawbin, W. H. 1997. ‘Temporal segregation of humpback whales during migration in Southern Hemisphere waters’. Memoirs of the Queensland Museum 42:105-138.
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.
Hedley, S.L., Bannister, J.L. and Dunlop, R.A. 2012. Abundance estimates of Breeding Stock ‘D’ Humpback Whales from aerial and land-based surveys off Shark Bay, Western Australia, 2008. Journal of Cetacean Research and Management (Special Issue 3) 209-221.
HowJ., D.Coughran, M.Double, K.Rushworth, B.Hebiton, J.Smith, J.Harrison, M. Taylor, D.Paton, G.McPherson, C.McPherson, A.Recalde Salas, C.Salgado-Kent and S.de Lestang 2020. Mitigation measures to reduce entanglements of migrating whales with commercial fishing gearFRDC 2014-004. Fisheries Research Report No. 304 Department of Primary Industries and Regional Development, Western Australia.118pp.
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.
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 38:749-765.
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.
Rayner, G.W. 1940. ‘Whale marking: progress and results to December 1939’. Discovery Reports, 17: 245–284.
Salgado Kent, C. & Jenner, K.C. & Jenner, M., Bouchet, P. and Rexstad, E. 2012. Southern Hemisphere Breeding Stock ‘D’ Humpback Whale Population Estimates from North West Cape, Western Australia. Journal of Cetacean Research and Management. 12: 29-38.
Salgado Kent, C.P. and Irvine, L. 2018. Distribution of humpback whales off North West Cape in relation to swim-with-whale tourism interactions in Ningaloo Marine Park, Western Australia. Report to the Department of Parks and Wildlife, Western Australia. 45 pp.
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.
Thums M, Jenner C, Waples K, Salgado Kent C, Meekan M. (2018) Humpback whale use of the Kimberley; understanding and monitoring spatial distribution. Report of Project 1.2.1 prepared for the Kimberley Marine Research Program, Western Australian Marine Science Institution, Perth, Western Australia, 78pp.
Videsen, S.K.A., Bejder, L., Johnson, M. and Madsen, P.T. 2017. High suckling rates and acoustic crypsis of humpback whale neonates maximise potential for mother–calf energy transfer. Functional Ecology, 31:1561-1573.
