Course:CONS200/2024WT1/Australia's Humpback Whales: Journey to Recovery

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Group number: 20

Nghi Phan - 75187922

Nuo Chen - 43731132

Jaden Uy - 45453677

Johnny Zhang - 19856772

Introduction

Humpback whales have a significant connection with Australia. They migrate annually along the east and west coasts of Australia, primarily along a route often referred to as the "Humpback Highway".[1] Historically, the population of Australia's humpback whale was decimated by commercial whaling in the 19th and 20th centuries.[2] By the 1960s, the total eastern Australian humpback population down to a measly 150.[3]

Over the past 30 years, with the joint efforts of the international community and Australia, the humpback whale population has miraculously recovered. As of 2023, over 40,000 humpback whales migrate from Antarctic feeding grounds to Australia’s warmer waters to breed and give birth.[3]

Overview of Humpback Whale

Humpback whale, scientifically known as Megaptera novaeangliae, is a massive and unique marine mammal, known for its acrobatic behaviour and occasional curiosity toward approaching boats.[4] A mature whale can grow up to about 15.6 meters in length and weigh around 34b metric tons.[5] It is easily recognized by its long pectoral fins, knobbly heads, and unique hump-shaped dorsal fin, which gives the whale its name. The binomial Megaptera novaeangliae given to this species was originally used by Borowski in his description of it in 1781, and refers to “big wing” (mega + preton) in Greek and “New England” in Latin.[4] This is one of the longest migrations among mammals, covering thousands of kilometers.[6]

The humpbacks feed on krill, small fish, and plankton. These productive feeding grounds provide the necessary resources to build up energy for migration and breeding. The whales use cooperative feeding techniques, such as bubble-net feeding[7], to take large amounts of prey.

They congregate along the Australian coastline in places such as the Great Barrier Reef and Ningaloo Reef where safe, shallow, warmer waters allow for calving and protecting young calves. Baby whales do not have thick blubber to insulate against colder temperatures, so they require warm waters.

Humpbacks are otherwise an open ocean whale, but they tend to hug the coast near migration or breeding sites. This behavior makes them a popular species for coastal whale-watching and helps scientists monitor their population recovery.

Life Cycle and Reproduction

From birth to adulthood, the life cycle of the humpback whale (Megaptera novaeangliae) is comprised of a series of stages, one of which is reproduction and this one element is crucial to their population dynamics. Sexual maturity for Humpback Whales occurs from 3 – 7 years of age.[8] Usually the breeding season occurs from June to September within warmer waters, after migrating north from Antarctic waters[9], with breeding every one to three years[10], females migrating away from cold waters where they feed.

The mating is done in the breeding grounds where males perform elaborate displays and vocalizations to females. Gestation is for about 11 to 12 months[11], following delayed fertilisation. Each female gives birth to 1 calf, which at birth is approximately 3 to 4.5 m long and weighs up to 1 ton.[12]

Historical information about Humpback Whale

Although we have no idea when did the first humpback whale get discovered, the whaling and conservation of humpback whale do have some history. We are here to present them.

Whaling industry in Australia

Whaling in Australia began in the late 18th century and beginning in Australia shortly after European colonisation, whaling and the export of whale products became Australia's first primary industry.[13] Whaling stations were established along the coasetline. Whaler hunt whales with small row boats venturing off the coast in search of whale species. The crews would throw harpoons and then drag the carcass' of the whale behind the boat. Once on-shore whaling stations would strip the whale for multiple products including lubricants, soaps and oil. Bone was used for decorations and the meat was eaten by both people and animals alike. While there were many whaling stations along the Australian coast, Davidson Whaling Station on the south-east coast was one of the more notorious sites.[13] The development of harpoon guns, explosive harpoons and steam-driven whaling boats start in 19th century. Later in that century, these new whaling technologies became more stable and reliable. Using of these technologies made large-scale commercial whaling so efficient that many whale species were over-exploited in the 20th century and came very close to extinction.[13] When southern right whales and blue whales became scarce, Australian whalers began to target humpback whales. Humpback whales than got commercially harvested around the Australian coast from 1912 to 1972. other tens of thousands of the marine animals became co-victims with humpback whale and got killed. The reason why humpbacks were one of the worse-hits is that whaling stations would pick off individuals on their migrations from the feeding grounds in Antarctica to their breeding grounds on the east and west coast of Australia.

Humpback Whale in Australia

By the time the International Whaling Commission banned humpback whaling in the Southern Hemisphere in 1963, over-exploitation had already reduced the population to an estimated 3.5–5% of pre-whaling abundance, leading to the collapse of Australia's east coast whaling industry. The total number of humpback whale killed by whaling industry between 1947 and 1973 is 48 702. More than half of these were taken in the two whaling seasons of 1959 – 60 and 1960 – 61.[13]

Legislation for conservation of whales

Whaling in Australia, though mainly targeting sperm whales, continued until 1978, by which time the industry was no longer viable. A change in public attitude against whaling encouraged the Australian Government to hold an Inquiry into Whales and Whaling in 1979. Following this the government, with bi-partisan support adopted a permanent ban on further whaling.[13]

In 1980, the first official government documents Whale Protection Act 1980 [14] is presented by Austrlia government and this marks the beginning of legislation to protect whales in Australia. In 1982, The world's nations banded together to stop commercial whaling by voting for a moratorium at the International Whaling Commission (IWC). Australia and AMCS were part of this movement. In 1999, the Whale Protection Act 1980[14] was replaced by the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act).[3] The Australian Whale Sanctuary, established under the EPBC Act, includes the entire Commonwealth marine area, beyond the coastal waters of each state and the Northern Territory. Within the Sanctuary it is an offence to kill, capture, injure, harass, chase or herd whales, dolphins and porpoises. The EPBC Act lists humpback whales as vulnerable and state legislation of Victoria, New South Wales and Queensland provides similar protection.[14]

Ongoing Threats to Australian Humpback Whales

Australian humpback whales (Megaptera novaeangliae) continue to face threats by ongoing ship strikes, human infractions (e.g. entanglements with fishing gear)[14], predation from killer whales and sharks, ocean acidification, and climate change [3]. Ship strikes are recognized as a global anthropogenic source of mortality or injury to large whales, posing a significant and growing threat to the humpback whales as they spend extended periods of time at the ocean's surface[3]. Interaction with human activity are another one of the primary threats, especially due to the rapid growth of global fisheries and human population, the increased use of fishing gear over the past century has resulted in bycatch and entanglement in fishing gear of the global cetacean populations. Entanglements with fishing gear often lead to severe injuries such as amputations, systemic infections, and reduction in fitness and mobility, affecting the species' potential to recover[14]. Threats from prey specialists such as killer whales and scavenging sharks are also posed as an additional natural threat[15]. Effects from climate change and ocean acidification are more key issues that are rapidly altering ocean environments, affecting the habitability and livability for these migratory humpback whales[16].

Ship Strikes

In Australia, industrial activity has significantly increased, specifically due to the global distribution of iron ore exports, averages in cargo throughput has increased a total of 3.5% through the past 5 years. The expansion of global seaborne trade has resulted in growth in quantities, size and speed of cargo vessels, including mega-container ships carrying over 10,000 containers which has increased from 6% to 40% from 2011 to 2021[3]. The effects of ship strike are increasingly recognized as a key threat for conservation of marine megafauna[3]. The rising density of marine traffic along the coasts of Australia has created serious impacts in harmful discharges, emissions, noise pollution, and physical strikes[3]. Humpback whales also tend to rest and spend long durations at the ocean's surface, leading to more frequent encounters with passing vessels. And due to their large size, slow surface mobility, and habit of surfacing, humpback whales are at greater risk of being struck by vessels. [3]. Sublethal trauma from vessel strike may also disrupt critical behaviours including feeding and breeding as whales may begin hesitating and becoming more cautious in specific areas[3].

Furthermore, ship strike activity frequently goes unreported, making it difficult for researchers to decipher the rate of incidence and estimations. Because of the lack of reports, researchers are limited on data and a lack of physical evidence such as carcasses for necropsy, making current documentation severely undermined[3]. The unreported cases are often due to various biases in data, however, there are existing records of large baleen whales (including the humpback whale) suggesting their vulnerability.[3] Yet, there has been recent shift in focus to animal welfare and conservation focus, improving risk assessment through ship strike prevention that include identifying high-risk zones, predicted whale distribution, developing the "National Strategy for Reducing Vessel Strike on Cetaceans and other Marine Megafauna", and taking ship strike management as a conservation priority for the Australian Government[3].


Human Infractions

Predation

Impact of Climate Change

Conservation Efforts

Legal protections and policies implemented in Australia

The Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) provides full legal protection to all cetaceans within Australian waters. Under the EPBC Act, the Australian Whale Sanctuary was established, encompassing all Commonwealth waters from the three-nautical-mile state waters limit to the boundary of the Exclusive Economic Zone (up to 200 nautical miles and further in some places). Within the sanctuary, it is an offence to kill, injure, or interfere with any cetacean, and violations bring heavy penalties.

Australia has also designated specific marine protected areas to enhance cetacean conservation, such as areas in the Chesterfield-Bellona archipelago.[17] These regions offer critical safe habitats, particularly during breeding and migration periods, by limiting activities that could harm or disturb whale populations.

Each Australian state and territory has enacted laws to protect whales and dolphins within their waters, creating a coordinated, national framework for cetacean protection. These combined efforts demonstrate Australia’s commitment to conserving marine biodiversity and ensuring safe environments for humpback whales.

Future directions

To ensure the long-term survival of the Australian humpback whale population, conservation efforts must adapt to emerging challenges. One priority is addressing climate change, which affects ocean temperatures, sea levels, sea ice, etc. affecting the availability and abundance of prey items for the humpbacks.[18][19] Due to increased upper water stratification in polar waters, climate change is predicted to result in a reduction in the large-scale supply of nutrients, which would lower marine primary production and, in turn, the food availability for the whales.[20] Warmer waters could alter the humpbacks’ migratory routes and disrupt breeding and feeding patterns. Immediate reducing greenhouse gas emissions [21] and promoting international cooperation on climate action are essential steps to mitigate these effects.

Reducing vessel strikes and entanglement can help preserve the Australian humpback whale population by concentrating conservation efforts in regions where mortality rates are severe.[22] Strengthened regulations on ship speeds, adjusted shipping routes to avoid migration areas, and the development of whale-safe fishing technologies can help reduce these threats. Increased public awareness and partnerships with the fishing and shipping industries are also important to effectively implement these measures.

Recovery of Whale population

Under several conservation measures, the population of humpback whale slowly walk out of the endangered situation. We are here to introduce how these measures affect humpback whale population.

The Australian Whale Sanctuary

The Australian Whale Sanctuary established from 2000 when the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act)[3] became effective. The aim of the sanctuary is to protect all Commonwealth waters from the three nautical mile state waters limit out to the boundary of the Exclusive Economic Zone (i.e. out to 200 nautical miles and further in some places). Any actions that leads to kill, injure or interfere with a cetacean is offensive in the sanctuary zone and severe penalties will apply to anyone convicted of such offences.[23] Although Individual humpbacks are still facing threats by other killer whales, pollution, climate change, ocean noise and unsustainable tourism, The setting of sanctuary provides relatively safe and suitable waters for humpback whales to survive and reproduce.

Australia's Whale Watching Industry

The recovery of the humpback population has both contributed to and benifited from the rapid growth of Australia's whale watching industry. The Australian National Guidelines for Whale and Dolphin Watching 2005 have been developed to minimise impacts on whales, dolphins and porpoises and to give people the best opportunity to enjoy and learn about. This leads to an siganificant growth in whale watching industry. People can get to know about humpback whale more and learn more about the situation humpback whales are facing. They will more likely to tend to or even contribute to conservation policies about whales and other marine animals.

Current Population of Humpback Whale

The Australian Government Department of Climate Change, Energy, The environment and Water shows that the population of humpback whale was estimated at around 8000 in 2006 and this population had shown steady recovery of around 10 –11% a year.[13] According to the report of ABC News, the population of Humpback Whale in Australia was estimated at over 40000.[24]

Conclusion

The recovery of Australia's humpback whale population is a remarkable conservation success story. Humpback whales were devastated by commercial whaling in the 20th century, with populations declining by more than 90%. The humpback whale started to be protected in the 1960s. Since then, their numbers have steadily increased, and current estimates suggest that they have rebounded to pre-whaling levels. This recovery is due to international and Australian efforts to ban whaling, stricter marine protections and continued monitoring. The International Whaling Commission and Australia's EPBC Act have contributed greatly to this. The recovery of the humpback whale population demonstrates the positive impact of targeted conservation action and gives the international community hope that endangered species can be restored. Despite the milestone progress made in the recovery of the Australian humpback whale population, continued monitoring and vigilance are still necessary. Australia's humpback whales are still facing threats such as climate change, habitat degradation and human activities.

References

  1. ↑ "Australia: Thousands of Whales Begin Their Epic Journey Up Australia's Humpback Highway". Asia News Monitor. 2023, Jun 23. Check date values in: |date= (help)
  2. ↑ Langdale, Liz (July 7, 2023). "Bumper season for whales". Port Macquarie News.
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 Heagney, Pat; Loram, Lucy (21 Oct 2023). "Experts say east coast humpback whale population has reached record numbers, as tourism booms". ABC Wide Bay. Cite error: Invalid <ref> tag; name ":3" defined multiple times with different content Cite error: Invalid <ref> tag; name ":3" defined multiple times with different content
  4. ↑ 4.0 4.1 Clapham, Phillip J. (2009). "Humpback Whale: Megaptera novaeangliae". Encyclopedia of Marine Mammals: 582–585. doi:10.1016/B978-0-12-373553-9.00135-8. Cite error: Invalid <ref> tag; name ":1" defined multiple times with different content
  5. ↑ Johnson, James H.; Wolman, Allen A. (1984). "The humpback whale, Megaptera novaeangliae". Marine Fisheries Review. 46 (4): 30–37.
  6. ↑ Jackson, Jennifer A.; Steel, Debbie J.; Beerli, P.; Congdon, Bradley C.; Olavarría, Carlos; Leslie, Matthew S.; Pomilla, Cristina; Rosenbaum, Howard; Baker, C. Scott (2014). "Global diversity and oceanic divergence of humpback whales (Megaptera novaeangliae)". Proceedings of the Royal Society B: Biological Sciences. 281 (1786). doi:10.1098/rspb.2013.3222.
  7. ↑ Pirotta, Vanessa; Owen, Kylie; Donnelly, David; Brasier, Madeleine J.; Harcourt, Robert (May 31, 2021). "First evidence of bubble-net feeding and the formation of 'super-groups' by the east Australian population of humpback whales during their southward migration". Aquatic Conservation Marine and Freshwater Ecosystems. 31 (9). doi:10.1002/aqc.3621.
  8. ↑ Chittleborough, R.G. (1960). "Marked Humpback Whale of Known Age". Nature. 187: 164. doi:10.1038/187164A0.
  9. ↑ Smith, Joshua N.; Grantham, Hedley S.; Gales, Nick; Double, Michael C.; Noad, Michael J.; Paton, David (2012). "Identification of humpback whale breeding and calving habitat in the Great Barrier Reef". Marine Ecology Progress Series. 447: 259–272. doi:10.3354/MEPS09462.
  10. ↑ "Humpback Whale (Megaptera novaeangliae)".
  11. ↑ Chittleborough, R.G. (1958). "The Breeding Cycle of the Female Humpback Whale, Megaptera nodosa (Bonnaterre)". Marine and Freshwater Research. 9: 1–18. doi:10.1071/MF9580001.
  12. ↑ Fennimore, R. "Humpback whale".
  13. ↑ 13.0 13.1 13.2 13.3 13.4 13.5 Department of the Environment and Water Resources (2007). "The humpback whales of Eastern Australia".
  14. ↑ 14.0 14.1 14.2 14.3 14.4 Attorney Generals' Department, Australia (1980). "Whale Protection Act 1980" (PDF). Cite error: Invalid <ref> tag; name ":2" defined multiple times with different content
  15. ↑ Pitman, R., Totterdell, J., Fearnbach, H., Ballance, L., Durban, J., & Kemps, H. (2015). Whale killers: Prevalence and ecological implications of killer whale predation on humpback whale calves off Western Australia. Marine Mammal Science, 31, 629-657. https://doi.org/10.1111/MMS.12182
  16. ↑ Great Barrier Reef Marine Park Authority. (2024). 8.3.7 Humpback Whales. Outlook Report. https://outlookreport.gbrmpa.gov.au/threats-responses-and-risks/8-resilience/83-case-studies-recovery-and-decline-ecosystem/837-humpback-whales
  17. ↑ Garrigue, Claire; Derville, Solène; Bonneville, Claire; Baker, C. Scott; Cheeseman, Ted; Millet, Laurent; Paton, Dave; Steel, Debbie (2020). "Searching for humpback whales in a historical whaling hotspot of the Coral Sea, South Pacific". Endangered Species Research. doi:10.3354/esr01038.
  18. ↑ Flores, H.; Atkinson, A.; Kawaguchi, S.; Krafft, B. A.; Milinevsky, G.; Nicol, S.; Reiss, C.; Tarling, G. A.; Werner, R.; Bravo Rebolledo, E.; Cirelli, V.; Cuzin-Roudy, J.; Fielding, S.; Groeneveld, J. J.; Haraldsson, M.; Lombana, A.; Marschoff, E.; Meyer, B.; Pakhomov, E. A.; Rombolá, E.; Schmidt, K.; Siegel, V.; Teschke, M.; Tonkes, H.; Toullec, J. Y.; Trathan, P. N.; Tremblay, N.; Van de Putte, A. P.; van Franeker, J. A.; Werner, T. (2012). "Impact of climate change on Antarctic krill". Marine Ecology Progress Series. 458: 1–19. doi:10.3354/meps09831.
  19. ↑ McBride, Margaret M.; Dalpadado, Padmini; Drinkwater, Kenneth F.; Godø, Olav Rune; Hobday, Alistair J.; Hollowed, Anne B.; Kristiansen, Trond; Murphy, Eugene J.; Ressler, Patrick H.; Subbey, Sam; Hofmann, Eileen E.; Loeng, Harald (2014). "Krill, climate, and contrasting future scenarios for Arctic and Antarctic fisheries". ICES Journal of Marine Science. 71 (7): 1934–1955. doi:10.1093/icesjms/fsu002.
  20. ↑ Tulloch, Vivitskaia J. D.; Plagányi, Éva E.; Matear, Richard; Brown, Christopher J.; Richardson, Anthony J. (2018). "Ecosystem modelling to quantify the impact of historical whaling on Southern Hemisphere baleen whales". Fish Fish. 19: 117–137. doi:10.1111/faf.12241.
  21. ↑ Tulloch, Vivitskaia J. D.; Plagányi, Éva E.; Brown, Christopher; Richardson, Anthony J.; Matear, Richard (February 26, 2019). "Future recovery of baleen whales is imperiled by climate change". Global Change Biology. 25: 1263–1281. doi:10.1111/gcb.14573.
  22. ↑ Rockwood, R. Cotton; Calambokidis, John; Jahncke, Jaime (August 21, 2017). "High mortality of blue, humpback and fin whales from modeling of vessel collisions on the U.S. West Coast suggests population impacts and insufficient protection". PLoS ONE. 12. doi:10.1371/journal.pone.0183052.
  23. ↑ The department of climate change, energy, the environment and water, Australian Government (2015). "Whale conservation".CS1 maint: multiple names: authors list (link)
  24. ↑ Heagney, Pat (Sun 22 Oct 2023). "Experts say east coast humpback whale population has reached record numbers, as tourism booms". Check date values in: |date= (help)


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