By Emily Grilly, Ariane Wilkinson and Chris Johnson
A new report, Protecting Blue Corridors, visualises satellite tracks of 1,000 migratory whales worldwide. It brings together 30 years of scientific data from more than 50 research groups to help us better understand the growing threats to whales along their migration routes or ‘blue corridors’. These blue corridors are essential for whale survival, allowing them to move between critical ocean habitats - where they feed, mate, give birth, nurse young and socialise.
But growing threats to whales along these corridors, including entanglement in fishing gear (bycatch), ship strikes, chemical and noise pollution, habitat loss and climate change, are creating a hazardous and sometimes fatal obstacle course for our whales.
Whales matter to nature and people. Growing evidence shows whales play a critical role in maintaining ocean health and our global climate while contributing to a global economy.
Australian humpback whales – a conservation success story, but there is trouble ahead.
In Australia, each year, more than 60,000 humpback whales make mega-migrations along the east and west coast in the tropics, to and from Antarctica. Between June to August, they can be found in the key breeding areas in the Great Barrier Reef in the east and along the Kimberley Coast in the west, before setting off on their annual migration of up to 10,000km to feeding grounds in East Antarctica and the Ross Sea.
While a significant reduction of commercial whaling since the 1960s has allowed some whale populations to bounce back, including in Australian waters, growing threats are making migratory routes of whales and other marine species increasingly difficult and dangerous to navigate.
Growing industrialisation along both coasts, linked to increasing exports of resources and an ever-expanding fleet of ship traffic in seasonal humpback breeding grounds and along migration routes, is increasing the risk of ship strikes and underwater noise pollution. Female humpback whales and their calves are the most at risk of ship strikes - due to their inshore movement and coastal dependence while nursing their young. Currently, the whale protection area in the Great Barrier Reef does not cover critical mating and nursing areas.
There is also risk of entanglement in fishing and shark nets along Australia’s east and west coasts - regions where high human population density, high fishing effort and high density of migrating humpback whales all occur.
After humpback whales complete their three-month journey, dodging shipping vessels and entanglement risks, they will finally reach the Southern Ocean around Antarctica to feed on their favourite food source, Antarctic krill. However, within the Southern Ocean awaits additional threats that they must face.
Climate change is transforming the Antarctic in lasting and fundamental ways. Sea ice is critical habitat for Antarctic krill, but as ice shelves continue to shrink, krill are shifting southward; this change in krill distribution may impose high energetic costs on migrating whales as they must migrate further in the search for food.
And climate change is not the only threat to krill and their predators. As fisheries around the world are exploited, there is growing interest to expand industrial krill fishing in the Southern Ocean.
The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is an international, intergovernmental organisation made up of 26 members, of which Australia is a party. The objective of CCAMLR is the conservation of Antarctic marine life, which excludes the extraction of species. Under the current CCAMLR management, industrial krill fishing operates around the Antarctic continent.
Antarctic krill is a key link in the food chain, contributing iron and other nutrients that fertilise the ocean and are a vital food source for whales as well as playing an integral part in the carbon cycle.
Since 2017, there has been exploratory krill fishing by China and Norway in East Antarctica, in areas where Australian humpback whale subpopulations are migrating to feed, creating risks of bycatch and competition for their natural food source. If the fishery were to expand, this would both directly and indirectly increase risks to humpback whales.
Making connections – implementing networks of marine protected areas and managing threats along blue corridors is crucial.
To protect Australian humpback whales so they can continue to thrive, we have to manage these blue corridors throughout their entire range. We can achieve this through “connectivity conservation” – conserving these whales across their entire range and recognising that species survive and adapt better when their habitats are managed as large interconnected networks.
To achieve this, we must implement networks of marine protected areas (MPAs) around Australia and in the Southern Ocean. MPAs are conservation tools intended to protect biodiversity, promote healthy and resilient marine ecosystems, and provide societal benefits. Today, only about 7.91% of the world’s oceans are protected by actively managed MPAs. WWF, the scientific community and over 75 governments have all now backed a call to protect 30% of our ocean by 2030 through implementing networks of MPAs.
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Protecting blue corridors for Australian whales requires a holistic strategy that engages both our domestic government and international organisations responsible for formulating policies across a range of areas and industries.
WWF encourages the Australian Government to: