Northern Australia, with its pristine coral reefs, mangrove forests, and expansive marine ecosystems, is home to a diverse range of shark species. This region’s tropical waters provide an ideal habitat for these ancient predators, making it one of the most exciting areas for marine biologists and shark enthusiasts alike. In this article, we’ll delve into the fascinating world of Northern Australian sharks, exploring their behaviour, ecological roles, and the conservation challenges they face.
1. The Diversity of Northern Australian Sharks
Northern Australia’s shark fauna is remarkably diverse. The region’s warm waters and varied habitats—from the Great Barrier Reef to the Timor Sea—support a broad array of species. Key sharks include:
Great White Shark (Carcharodon carcharias): This apex predator, also referred to as a White Pointer, is known for its impressive size and strength. Although more commonly associated with Southern Australian waters, great whites are occasionally spotted in Northern Australia. They are known to traverse large distances and can be seen around the reefs and offshore islands. These sharks are renowned for their ferocity and fatal attacks on people and very likely get the blame for unidentified shark attacks.
This shark species is not to be trusted by divers as it has unpredictable behaviour. Some of you reading this will probably disagree, so I ask you this, have you come face to face with a White Pointer? I have, and it circled around us a few times as we headed back to the boat then as we boarded the landing ramp the shark shot forward actually colliding with the boat – a 20ft Star aluminium runabout that was barely longer than the shark.
YouTube often shows videos of people swimming with White Pointers, but my advice is don’t push your luck and get out of the water. As they say, “there are old divers and there are bold divers, but there are no old bold divers…” – I am the later. I’m too old to be taken by a shark, when with a bit of discretion, I can keep living.
Great White Shark aka White Pointer
Bull Shark (Carcharhinus leucas): Adaptable to both saltwater and freshwater environments, the bull shark is a common sight in Northern Australia. Their robust build and aggressive behaviour make them a formidable predator. They are often found in estuaries, river mouths, and coastal areas.
I have found that other sharks like black tip and white tip reef sharks, which are a nuisance when spearfishing as they congregate around you in numbers exceeding 8 or so. This however, this often brings in a Bull shark and they soon scare off the smaller black tips and white tips. Definitely the boss of these smaller sharks. Consider this shark species very dangerous and unpredictable.
As for shark attacks by Bull sharks, which seem pretty high, I often wonder just how accurately these sharks have been identified after an attack, when tensions are high and attending a victim seems to me, to be more important than trying to identify the attacking shark species. All the same guys, why take the risk when diving if they come around, as it doesn’t prove anything other than “you’ve been told” if the wheels fall off.
Bull Shark
Tiger Shark (Galeocerdo Cuvier): Known for their distinctive stripes and broad diet, tiger sharks are frequent visitors to the Northern Australian waters. They are scavengers and opportunistic feeders, making them crucial for the ecological balance of their environment. In the north their diet also includes Turtles, and they are often found near established Turtle nesting sites during laying and hatching season.
I have had no problems (yet) with Tiger Sharks as they have kept their distance most of the time. On the couple of times, that one has got too close, and a healthy jab in their side from the business-end of a spear gun gets them on their way. Where you may come unstuck, is should you meet one in shallow water where they are known to feed on incoming tides, i.e. they are hungry. The water up north can rise 12 metres in 6 hours and drop that amount in the next 6 hours. This results in murky waters in the shallows, not a good place to meet a Tiger Sharks.
Tiger Shark
Blacktip Reef Shark (Carcharhinus Melanopterus): Commonly seen around coral reefs and shallow waters, blacktip reef sharks are recognizable by the black tips on their fins. They play a vital role in controlling fish populations and maintaining the health of coral reef ecosystems. Not considered dangerous, by me anyway, just a pain in the arse, though they have taken more than a few fish from me over the years while spearfishing.
Black Tipped Reef Shark
Whitetip Reef Shark (Triaenodon Obesus): This species is typically found in the lagoons and outer reef slopes of Northern Australia. They are shyer compared to other shark species and are often seen resting in caves or crevices during the day. These are a fairly small shark and more of a nuisance than anything else to divers. They do however, get very excited and aggressive when they manage to take a speared fish form you in shallow waters. Often seen with Black Tipped Reef sharks around reefs. Not considered dangerous to divers by me.
White Tipped Reef Shark
Hammerhead Sharks (Sphyrnidae family): The hammerhead sharks, particularly the scalloped hammerhead (Sphyrna Lewini), are found in Northern Australian waters. Their unique head shape aids in hunting and navigation. Schools of hammerhead sharks can be seen in certain areas, especially during their migratory periods.
I have come up on these guys from time to time and have never found one that was even interested in me. I did once nearly crap myself when I was rising in 80 feet of water on SCUBA, when the largest Hammerhead I have ever seen, brushed between the two of us from below heading upwards. Guys, if you like excitement, then that would do the trick.
At the end of the day guys, diving up north sharks are a worry, and you need to be vigilant. However, crocodiles are much more dangerous to divers and beach goers than any shark. To me they are off the scale dangerous once they exceed 8-10 feet.
Hammerhead Shark
2. Ecological Roles of Sharks
Sharks are apex predators and play a critical role in marine ecosystems. In Northern Australia, their influence is particularly significant due to the region’s complex and rich biodiversity. They are however, considered to be on the endangered species list and so are protected in Australian waters. Here’s how sharks contribute to the health of these ecosystems:
Population Control: Sharks regulate the populations of various marine species, including fish, rays, and cephalopods. By preying on these animals, sharks help maintain balance within the food web, preventing any single species from becoming overly dominant.
Habitat Health: By controlling the populations of grazing fish, such as parrotfish, sharks indirectly help in preserving coral reefs. Overpopulation of herbivorous fish can lead to coral overgrowth and degradation, so sharks help ensure that coral reefs remain healthy and vibrant. The rise and fall of tide bringing in nutrients is another major factor that sists the coral growth.
Nutrient Cycling: Sharks contribute to nutrient cycling through their feeding behaviour. Their waste and that of all fish species aid in the decomposition of their carcasses. That in turn adds nutrients to the marine environment, which supports the growth of plankton and other small organisms at the base of the food chain.
3. Behavioural Patterns
Understanding the behaviour of sharks in Northern Australia provides insight into their role in the marine environment and their interactions with humans. In the North of Western Australia the shark population is far greater than the South in my personal opinion. This is largely due to the abundance of fish species and their undamaged habitat with no overfishing by humans, yet.
Feeding Habits: Sharks in Northern Australia exhibit diverse feeding behaviours. For instance, tiger sharks are known for their broad diet, consuming everything from fish to marine mammals and even garbage. Turtles play a role in the Tiger Sharks diet unfortunately. In contrast, blacktip reef sharks primarily feed on smaller fish and invertebrates found around coral reefs.
Due to the very low interaction with divers in the north compared to the south, sharks have no or little experience with humans and so tend to be more inquisitive, sometimes leading to aggression, especially in dirty water.
Migration and Movement: Some shark species in Northern Australia are migratory. Great white sharks, for instance, can travel vast distances between feeding and breeding grounds. Bull sharks, known for their ability to move between saltwater and freshwater, are often seen in estuaries and river systems, particularly during the breeding season.
Social Behaviour: While some sharks, like the White Pointer, are solitary hunters, others, such as the hammerhead shark, form schools. These schools can number in the hundreds and are believed to offer advantages in hunting and protection from predators.
4. Conservation Challenges
Sharks face numerous threats in Northern Australia, driven by both human activities and environmental changes. Addressing these challenges is crucial for ensuring the survival of these apex predators.
Overfishing: Many shark species are targeted for their fins, meat, and liver oil. Overfishing, both legal and illegal, poses a significant threat to shark populations. Bycatch—sharks unintentionally caught in fishing gear aimed at other species—is also a major concern, as is shark fin harvesting by Asian fishermen where the fins are cut off the shark and it is returned to the sea where it slowly dies. Having found a couple of sharks finless on the bottom in their death throws, it brings home this barbaric fishing method and the cruelty it is to sharks. Should I come in contact again with a finless shark on the bottom, you can be assured that we will video and still image shoot the scene for all its worth. It hasn’t been until recently that I have high quality underwater video cameras and still cameras or I would have done this years ago.
I love this next image. It is of Navy personnel locating some illegal fishermen after Border Force didn’t have time to look at them. Local tour guides and traditional owners have spotted five boats moored at Kuri Bay in far Northern WA. These fishermen were found by local indigenous folk and tourist operators. Read the caption as taken from the WA Newspaper 3rd September, 2024. Unbelievable!!!
Can you believe this, it’s Northern Australia and guess what, it is bloody hot here, what does the female Commander think??? Crazy.
During the writing of this article some Indonesian fishing boats were actually apprehended with a cargo of sea cucumbers, fish and shark fins. They had their cargoes confiscated and some were let go so they can come back and do it all again. Does this make sense to you , the reader? This barbaric fishing by Asian fishermen in Australian waters needs to be called out publicly if we are going to make a change.
Letting these criminal fishermen go so they can come back again, is like giving a gunman some more bullets because he missed you the first time.
Habitat Destruction: Coastal development, pollution, and climate change are leading to the degradation of critical shark habitats, such as coral reefs and mangroves. This destruction affects not only sharks but also the entire marine ecosystem that depends on these habitats. Luckily this is mainly caused in the south but with population growth and easier access to the north, I think we will soon see similar issues developing there unfortunately. That said, should you visit Coral Bay, you will be astonished at the degraded coral structures there compared to just 5 kilometres north of the bay. Cause: Too many stupid bloody tourists, divers and boats.
Climate Change: Rising sea temperatures and ocean acidification are altering the marine environment in ways that can impact shark populations: as can changes in prey availability and habitat conditions affect shark health and reproductive success. Plastic pollution, by way of discarded plastic bottles and floats, shoes etc, soon break down in the sun with the high UV and wave action on the reefs and to some extent on the shores. This breakdown into micro plastic particles then enters the sea and the build-up of the particles is of particular interest to me as it is known to contribute to the death of some species of whales for example. I want to collect water samples at regular intervales on this proposed trip across the top of Australia and down the Barrier reef. These results will at least form the basis for future testing and hopefully, more controls due to public awareness.
5. Conservation Efforts
Efforts to protect and conserve sharks in Northern Australia are multi-faceted and involve various stakeholders, including governments, conservation organizations, Fisheries Department, Customs and local communities. But conservation is also assisted by YOU, the reader.
Protected Areas: Establishing marine protected areas (MPAs) is one of the most effective ways to safeguard shark habitats. In Northern Australia, the Great Barrier Reef Marine Park Authority oversees the protection of one of the world’s largest coral reef systems, providing a haven for many shark species. “Oversees” is probably stretching the truth, as in reality the local population together with Indigenous local Aboriginals play a larger role than Government agencies. Due most likely to the money allocated to these Agencies is not enough to protect our fish and environment over such a large area.
Fishing Regulations: Implementing and enforcing sustainable fishing practices is crucial for shark conservation. Regulations that limit shark catches and bycatch are essential for reducing pressure on shark populations. That is the theory, however not the practice as above.
Public Awareness: Raising awareness about the importance of sharks and the threats they face is key to garnering public support for conservation efforts. Educational programs, media campaigns, and community engagement will help people foster an appreciation for sharks and their role in marine ecosystems. We have to remove them from the title of ‘man-eaters’ as this has only resulted in unscrupulous targeting sharks, by fishing for no other reason than that of ‘bragging rights’.
Research and Monitoring: Ongoing research and monitoring are vital for understanding shark populations, their behaviour, and the impacts of environmental changes. Tagging and tracking programs provide valuable data that informs conservation strategies and helps in the management of shark fisheries.
6. The Future of Sharks in Northern Australia
The future of sharks in Northern Australia depends on our collective ability to address the challenges they face. Conservation efforts must continue to evolve in response to emerging threats and changing environmental conditions. Actually, I think this is also applicable right across Australia and not for sharks alone.
Integrative Management: A holistic approach to marine management that considers the interconnectedness of species and habitats is crucial. This includes balancing the needs of human activities with the preservation of marine ecosystems. Easy to say but hard to do, as it is driven by money at the end of the day, and politicians don’t get many votes for the dollar in funding this. Coral Bay is an example that chasing the dollar often outweighs any management that is in place.
International Collaboration: Since many shark species migrate across international boundaries, global cooperation is necessary to ensure their protection, not just in Australia. International agreements and partnerships can help coordinate conservation efforts and enforce regulations. In our case here in Australia, our largest threat to overfishing, is blatant illegal fishing and diving by foreign fishermen, and the diseases they can bring to the north of Australia.
Illegal Fishing.
The following is courtesy of WA Newspapers, as copied:
Foreign fishers booted out of Australian waters after a series of Australian Border Force operations
Phil Hickey The West Australian Tue, 10 September 2024 2:29PM
Credit: Australian Border Force/Australian Border Force
Another four illegal fishing boats have been intercepted off the Kimberley coast after it was revealed foreign fishers are at an 18-year high and Australia’s border patrols are struggling to keep up. In a statement issued on Tuesday, the Australian Border Force said a maritime border command vessel intercepted three foreign fishing vessels in the vicinity of Heywood Shoal on Monday. A total of 20 crew were identified aboard.
“Officers boarded and inspected the vessels, identifying 100kg of salt along with a variety of fishing equipment,” the ABF said. “In consultation with the Australian Fisheries Management Authority, MBC determined a legislative forfeiture be conducted and seized both the fishing equipment and catch.”
“One of the four vessels was seized and will be disposed of at sea in accordance with Australian law. The crew were transferred onto the remaining two vessels and escorted out of the Australian exclusive economic zone.”
The ABF said that on the same day it also intercepted a fourth foreign fishing vessel near Augustus Island. Six crew were identified on that vessel before officers boarded and conducted an inspection.
“In consultation with AFMA, MBC determined that a legislative forfeiture be undertaken,” the border force statement said.
Officers also seized 180kg of salt, 20kg of sea cucumber (trepang), 10kg of shark fin, and a variety of fishing and fishing-related equipment from the boat. The vessel and crew were later escorted out of the Australian exclusive economic zone.
It comes as it was revealed on Tuesday that the boats and aircraft tasked with keeping watch over Australia’s borders keep breaking down and have been plagued with crew shortages. The issues — highlighted in internal Australian Border Force documents — are being blamed for a double-digit drop in patrols over recent years, despite authorities warning of increased threats from both people smuggling and illegal foreign fishing.
People smuggling remains an “existent threat” to Australia, particularly boats coming from Indonesia, while illegal fishing has reached an 18-year high, briefings prepared for Operation Sovereign Borders Commander Brett Sonter ahead of Senate estimates in May reveal.
The briefings were released under freedom of information laws. By the end of March, Border Force’s 14 vessels had done 1563 patrol days for the financial year, which was forecast to lift to 2200 by the end of June.
If the forecast lift was achieved, the number of maritime patrols would be on par with the previous year — but a drop of about 17 per cent from pre-pandemic levels. The briefing puts the fall in patrol days down to the oldest boat in the fleet, ABFC Cape St George, being out for five-yearly maintenance, along with “significant emergent defects amongst the ABF Fleet units and crewing deficiencies”.
Adaptation to Climate Change: Developing strategies to mitigate the impacts of climate change on marine ecosystems will be essential. This includes protecting and restoring habitats, reducing greenhouse gas emissions, and enhancing the resilience of coral reefs and other critical environments. Of course, if you are one of the few that believe that the climate is not changing, then may I suggest that you ignore this paragraph. Though coral growth is showing that it can regenerate after bleaching and cyclone damage, this should not down-play the strategies required to protect reefs and other environments.
Conclusion
Sharks in Northern Australian waters are not only fascinating creatures but also integral components of the region’s marine ecosystems. Their diverse species, behaviours, and ecological roles highlight the complexity and beauty of the marine environment. However, the threats they face, and I don’t just mean the sharks, but Turtles, Fish stocks and crustaceans —ranging from overfishing, habitat destruction, to climate change—underscore the need for concerted conservation efforts.
By supporting protection measures, advocating for sustainable practices, and enhancing public awareness, we can help ensure that these ancient predators continue to thrive in the vibrant waters of Northern Australia. The future of sharks, and by extension, the health of our oceans, relies on our commitment to preserving the delicate balance of marine life.
I probably sound like some “Greenie” to most, but if you knew me, that thought wouldn’t occur. I personally find the ‘Green movement’ in Australia are not targeting the marine conservation like they should; they would probably get at least one extra vote, from me of course, if they change their direction to include the Australian marine environment…
What we’re proposing with our venture is another positive step toward improving attitudes and knowledge about marine conservation. Our goal is to establish baseline data for each of the hundreds of islands we visit. This way, future conservationists can measure changes and progress from our initial findings. We believe that Australia has the potential to set a leading example in conservation practices, inspiring neighboring countries rather than just advising them on what they should do.