Abstract
Humpback whales (Megaptera novaeangliae) require a suite of essential habitats during their long migration. Therefore, the identification of critical habitats is important for continuation of their successful recovery. In this study we investigated the behaviours and habitat usage exhibited by humpback whales in two known aggregation sites on the east coast of Australia. Using a combined 5400 humpback whale records collected from Hervey Bay between 1999 and 2009 and from the Gold Coast Bay between 2011 and 2018, we analysed different types of behavioural categories. We found that humpback whales in Hervey Bay primarily exhibited surface travel and non-aggressive social behaviour, whereas both sites appeared to be similarly important for resting. Our results suggest that the Gold Coast Bay provides habitat for a wide range of critical humpback whale activities, in particular for resting mother–calf pairs, mature males seeking copulation and socialising immature whales. Hervey Bay had a higher number of mother–calf pair sightings, confirming the area as an important resting site. This study demonstrates that the two regions are critical habitats for humpback whales during their annual migration, but for different essential activities, and should be considered as a whale protection area.
Highlights
Global environmental changes, including increases in water temperature and decreases in sea ice cover (Learmonth et al 2006), and anthropogenic threats, such as water (Bengtson Nash et al 2013) and noise (Rossi-Santos 2015) pollution, entanglements (Groom and Coughran 2012) and ship strikes (Smith et al 2020), are affecting cetacean species worldwide (Simmonds and Eliott 2009; Derville et al 2018; Riekkola et al 2019; Sousa et al 2019)
This study demonstrates the importance of the Gold Coast Bay (GCB) as a critical habitat for the E1 humpback whale population and confirms the role of Hervey Bay as a habitat for nursing and courtship
The present study found a similar proportion of mother–calf pairs observed in both Hervey Bay and the GCB, despite the data collection occurring over different time periods
Summary
Global environmental changes, including increases in water temperature and decreases in sea ice cover (Learmonth et al 2006), and anthropogenic threats, such as water (Bengtson Nash et al 2013) and noise (Rossi-Santos 2015) pollution, entanglements (Groom and Coughran 2012) and ship strikes (Smith et al 2020), are affecting cetacean species worldwide (Simmonds and Eliott 2009; Derville et al 2018; Riekkola et al 2019; Sousa et al 2019) Migratory species, such as humpback whales (Megaptera novaeangliae Borowski, 1781), risk being highly affected by these threats as they migrate past cities and shipping channels, and may require access to alternative habitats for breeding, feeding and during migration. Separate cohorts (lactating females, immature whales, mature males, pregnant females) will depart their feeding grounds at various times and arrive in different habitat types at times, which increases their reproductive success (Chittleborough 1965; Dawbin 1966, 1997; Burns 2010)
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